WO2019155195A1

WO2019155195A1 - Transcutaneous port and method for manufacture

Info

Publication number: WO2019155195A1
Application number: PCT/GB2019/050304
Authority: WO
Inventors: James Armstrong; Philip AGG; James MEROTRA; James Shawcross; Catherine Pendegrass; Gordon Blunn
Original assignee: Accentus Cardiac Ltd; Ucl Business Plc
Priority date: 2018-02-06
Filing date: 2019-02-05
Publication date: 2019-08-15
Also published as: GB2587550B; GB2587550A; GB202017441D0; GB201801916D0

Abstract

The invention provides a transcutaneous port which promotes tissue integration for anchoring in the skin and which reduces the risk of infection. The transcutaneous port of the invention comprises a port body (1) having an external end (2a) and a subcutaneous end (2b) and at least one channel (5) which extends longitudinally through the port body. The port body (1) comprises a first impermeable portion (3) extending longitudinally from the external end (2a) and a mesh portion (4) extending longitudinally from the subcutaneous end (2b) of the port body (1). The thickness of the mesh portion (4) has a smaller thickness T1 proximate to the first impermeable portion (3) of the port body (1) and a larger thickness T2 proximate to the subcutaneous end (2b) of the port body (1). The thicker part of the mesh portion (4) is suitable for contacting the dermis when the transcutaneous port is implanted. The invention further relates to a method of manufacturing the transcutaneous port and a method of implanting the port in the human or animal body.

Description

TRANSCUTANEOUS PORT AND METHOD FOR MANUFACTURE

FIELD OF THE INVENTION

The present invention relates to a transcutaneous port. The invention further relates to a method of manufacturing the transcutaneous port of the invention, and to a method of inserting the transcutaneous port into the human or animal body.

BACKGROUND TO THE INVENTION

Transcutaneous ports provide a point of access into a human or animal body from the outside. Transcutaneous ports can usefully provide sites for intermittent access to the body, for instance to allow administration of intravenous fluids or pharmaceutical products.

Transcutaneous ports are also useful in providing long-term access, such as for a power supply cable to an implanted medical device. Transcutaneous ports may also be potentially used to support stoma for ileostomy, colostomy, neurostimulation or urostomy.

However, existing transcutaneous port devices suffer from various disadvantages.

A common problem arising with transcutaneous ports is the high risk of infection at the port site. It is thought that infections are caused because after the skin is broken to provide an entry site for the transcutaneous port, although the skin generally locally heals it does not form a secure and skin tight seal with the implanted port. Small gaps between skin and port provide sites for entry of foreign bodies which cause infection. Furthermore, during the healing process epidermal cells (cells forming the top layer of skin) have a tendency to migrate inwards along the side of the port, towards the soft tissue below the skin (also referred to as growth or migration of skin“downwards”). Epidermal cells also grow outwards along the port edge, forming a raised lip on the skin surface. The epidermal layer separates the vascularised tissue and dermis beneath from the transcutaneous port, preventing this tissue from bonding to the port. The migration of epidermal cells inwards or outwards along the sides of the port also creates folds within the skin, or pockets between the skin and the device, which cannot be easily cleaned and disinfected. These pockets can fill with bodily fluids and/or foreign bodies, and are thus highly susceptible to infection. Infection can lead to painful swellings, abscesses and even sepsis. US 2003/0120215 suggests a transcutaneous access device having a flat button portion which is implanted under the skin. The button has a neck which can receive a catheter. The neck is attached to a highly flexible sleeve or tube. The button and neck positioned beneath the skin are covered with a porous coating such as a Dacron velour. This coating is intended to promote the formation of subcutaneous tissue. When the device is implanted, skin cells migrate down the sleeve or tube towards the coating and it is hoped that a tight seal will form with the subcutaneous tissue at the covering. However, this device still suffers from the difficulty that epidermal cells migrating down the sleeve or tube form pockets which are difficult to clean, and the risk of infection remains.

Transcutaneous devices can be subject to considerable torsional forces. The problem is particularly pronounced for transcutaneous devices which are attached to tubes outside a patient’s body, which can be easily pulled or twisted. Another common problem with transcutaneous devices is therefore that they are easily torn away from the skin, and in some cases ripped out entirely. Even in the absence of large or sudden torsional forces, frequent micro-motion of a transcutaneous device against the adjacent skin can lead to undesirable consequences such as abrasion, inflammatory response and infections.

A possible solution to the problem of torsional forces is proposed in the article“Development of a new percutaneous access device for implantation in soft tissues”, Jansen et al ., Journal of Biomedical Materials Research, Vol. 25, 1535-1545, 1991. This article proposes a two-part device consisting of a sheet of fibre web which is implanted subcutaneously and a

transcutaneous part which is screwed into the subcutaneous portion. However, this device has considerable disadvantages. Firstly, the subcutaneous portion must be implanted several months before the transcutaneous portion can be attached, meaning that the process is very slow. Secondly, in some cases epidermal downgrowth was found to occur, meaning that epidermal skin cells were growing down the sides of the transcutaneous portion and preventing connections forming between the device and connective tissue. Moreover, this downgrowth caused pockets which could harbour infection.

The present invention aims to overcome the disadvantages of the above devices and to provide a transcutaneous port which reduces the likelihood of infection and which can effectively withstand torsional forces. SUMMARY OF THE INVENTION

The present inventors have surprisingly found that excellent integration of a transcutaneous port with the skin can be achieved by encouraging growth of the dermis into the port body while restricting the space available for epidermal cell growth. This has been achieved by providing a mesh scaffold in contact with the dermis to encourage dermal ingrowth into the device. The mesh has a greater thickness below the epidermis, meaning that the volume available for dermal growth into the mesh is larger than the volume available for epidermal cell growth into the mesh. This is surprisingly found to promote ingrowth of the dermis and discourage downgrowth of epidermal cells. The transcutaneous port further comprises an impermeable surface portion which is found to discourage epidermal cells from growing up over the transcutaneous port and forming folds or pockets.

The device of the invention therefore reduces the occurrence and size of folds formed within the skin or pockets formed between the skin and the device, and therefore reduces the instance of infection. Furthermore, the excellent integration of skin tissue with the transcutaneous port means that is it resistant to being tom out of the skin. The excellent resistance to torsional forces means that the transcutaneous port can be surprisingly small, and need not necessarily be separately anchored in subcutaneous soft tissue or bone. Small size is a particular advantage for a transcutaneous port as the implantation of a small device is less traumatic for a patient. Moreover, the smaller the wound site, the more quickly it can heal, which again reduces the likelihood of infection.

The invention therefore provides a transcutaneous port comprising:

a port body (1) having an external end (2a) and a subcutaneous end (2b); and

at least one channel (5) which extends longitudinally through the port body (1) from the external end (2a) to the subcutaneous end (2b);

wherein the port body (1) comprises:

a first impermeable portion (3) extending longitudinally from the external end (2a) of the port body (1); and

a mesh portion (4) extending longitudinally from the subcutaneous end (2b) of the port body (1), which mesh portion (4) extends laterally from an inner mesh surface (4a) to an outer mesh surface (4b) by a thickness T; wherein T has a value Tl proximate to the first impermeable portion (3) and a value T2 proximate to the subcutaneous end (2b), and Tl is less than T2.

The mesh portion (4) comprises pores, which may advantageously be of a suitable size to promote growth of tissue into the port body (1). Thus, in a preferred embodiment the mesh portion (4) comprises pores with a diameter of 50 to 2000 microns.

In another preferred embodiment, the mesh portion (4) comprises a stiff mesh. The stiff mesh is robust and advantageously assists in firmly attaching the transcutaneous port to the skin of a patient when implanted.

The mesh portion (4) may comprise a plurality of ribs arranged in a diamond hexagonal lattice. A diamond hexagonal lattice is strong, leading to a robust device. A diamond hexagonal lattice of ribs can also be formed into a cylinder (which is one preferred shape of the mesh portion (4)) leaving few ribs protruding from the cylinder and thus reducing discomfort and tissue damage for the patient when the transcutaneous port is implanted. Furthermore, a diamond hexagonal lattice can conveniently be manufactured by an integral method such as 3D printing.

In order to avoid the difficulty of protruding ribs from the mesh portion (4) causing discomfort and tissue damage for the patient when the transcutaneous port is implanted, it is generally preferred that where the mesh portion (4) comprises a plurality of ribs arranged in a lattice, at least 90% of the ribs terminate (i) in a vertex with another rib or (ii) in an impermeable portion (3, 6).

The first impermeable portion (3) may have a smooth surface located adjacent to the outer mesh surface (4b). The surface of the first impermeable portion (3) adjacent to the outer mesh surface (4b) typically protrudes from the skin when the transcutaneous port is implanted in a patient. The smooth surface discourages epidermal cells from growing up the side of the port body (1) (that is, away from the dermis). This prevents the device from becoming buried in the skin and reduces the occurrence of skin folds and pockets which may harbour infection. In a further preferred embodiment, the transcutaneous port may comprise a coating or surface treatment on all or part of the port body (1) with properties that promote tissue integration or discourage infection when the transcutaneous port is implanted. For instance, the port body (1) may comprise a surface treatment or coating on all or part of its surface which comprises a biocidal metal such as silver. This discourages infection.

The transcutaneous port of the invention can conveniently be obtained by integrally forming the port body (1). Integrally forming the port body (1) leads to a device which is strong and durable and will not come apart over time. Moreover, integral formation is a highly convenient method of forming a device having a complex internal structure, which may be the case for a transcutaneous port according to the invention.

Thus, also provided is a method of manufacturing a transcutaneous port comprising a port body (1) according to the invention, wherein the method comprises integrally forming the port body (1).

The transcutaneous port of the invention is suitable for implantation in the human or animal body. The invention therefore also provides a method of inserting a transcutaneous port according to the invention into the human or animal body, the method comprising:

making an incision in the skin of the body;

placing the mesh portion (4) of the port body (1) in contact with the dermis exposed by the incision; and

placing at least part of the first impermeable portion (3) to stand proud of the epidermis at the incision.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 shows a longitudinal cross-section through the centre of an exemplary port body (1).

Figure 2 is a view of the port body (1) corresponding to the device in Figure 1.

Figure 3a shows the port body (1) of Figure 2 and indicates the internal impermeable portion (6) and an end of the channel (5). Also shown by a solid line is plane X, which is the position of the lateral slice through the port body (1) at which the cross-section in Figure 3b is taken. Figure 3b is a cross-section of the port body (1) taken through the plane X indicated in Figure 3 a. The area of the cross-section through the internal impermeable portion (6) is labelled A and the thickness of the mesh portion (4) in plane X is labelled T.

Figure 3c is a cross-section of the port body (1) taken through a lateral plane. An internal impermeable portion (6) laterally surrounded by a mesh portion (4) is shown. The internal impermeable portion (6) comprises a plurality of channels (5). The cross-sectional area A of impermeable portion (6) is shaded in grey, and includes all area contained within that portion including the channels (5).

Figure 4 is a cross-section of the exemplary transcutaneous port according to Figures 1 to 3b implanted in the skin of a patient.

Figure 5 shows a section of the exemplary transcutaneous port according to Figures 1 to 3b with the front half cut away. Thicknesses Tl and T2 are labelled on the Figure.

DETAILED DESCRIPTION OF THE INVENTION

The particular features of the transcutaneous port of the invention, and suitable methods for manufacturing and implanting the device of the invention, are described in more detail below.

Structure of transcutaneous port

The transcutaneous port of the invention comprises at least a first impermeable portion (3), a mesh portion (4) and a channel (5). These structural elements are arranged to form a port body (1) which can be firmly anchored in skin and which resists infection.

The transcutaneous port of the invention is described herebelow with reference to Figures 1 to 5. However, it should be appreciated that the embodiments of Figures 1 to 5 are merely exemplary and that the present invention encompasses variations of these embodiments.

Figure 1 shows a longitudinal cross-section through the centre of an exemplary port body (1) comprised in the transcutaneous port of the invention. As will be discussed in more detail below in relation to the individual elements, the transcutaneous port preferably has a rounded profile at all points of the transcutaneous port which are suitable for implantation within the skin . The rounded profile avoids the growth of dermal tissue around comers or points, as corners or points would lead to regions of particularly high torsional stress in the skin with a high risk of tissue damage or ripping. A convenient shape for the port body (1) which avoids comers is a cylindrical (annular) shape. Thus, in a preferred embodiment the port body (1) has an approximately circular cross-section in all planes perpendicular to the longitudinal axis.

The port body (1) comprises an external end (2a), shown at the top of the cross-section, and a subcutaneous end (2b), shown at the bottom of the cross-section. A first impermeable portion (3) extends longitudinally from the external end (2a). An internal impermeable portion (6) is typically present, abutting the first impermeable portion and extending longitudinally from the first impermeable portion (3), towards the subcutaneous end (2b) of the port body (1). Arranged laterally around internal impermeable portion (6) and extending longitudinally from the subcutaneous end (2b) of the port body (1) is a mesh portion (4). The mesh portion (4) has a thickness T (shown in Fig. 3b) which corresponds to the distance in a lateral direction between the inner mesh surface (4a), which in this embodiment is located at the interface with the internal impermeable portion (6), and the outer mesh surface (4b). The port body (1) further comprises at least one channel (5) which extends longitudinally through the port body (1) from the external end (2a) to the subcutaneous end (2b) of the port body (1). In this instance the channel passes through the first impermeable portion (3) and the internal impermeable portion (6).

By“external end (2a)” is meant the end of the device from which the first impermeable portion (3) extends. By“subcutaneous end (2b)” is meant the end of the device which is located distally to the first impermeable portion, i.e. distally to the external end.

As will be appreciated, in embodiments where the mesh portion (4) is not symmetrical about a longitudinal axis, the distance in a lateral direction between the inner mesh surface (4a) and the outer mesh surface (4b) (i.e. the thickness T) may have multiple values in any lateral plane. In such a case, the thickness T in that plane may be defined as the minimum or shortest distance in a lateral direction between the inner mesh surface (4a) and the outer mesh surface (4b). Figure 2 is a diagrammatic view of the outside of the port body (1) shown in Figure 1. An end of the channel (5) is visible extending through the first impermeable portion (3) at the external end (2a) of the port body (1). The mesh portion (4) at the subcutaneous end (2b) of the port body (1) is also visible. Specifically, the outer mesh surface (4b) of the mesh portion (4) is visible. The inner mesh surface (4a) and the internal impermeable portion (6) are present but not visible.

Figure 3a corresponds to Figure 2, except that the location of the internal impermeable portion (6) and the end of a channel (5) at the subcutaneous end (2b) of the port body (1) are indicated. Also shown by a solid line is plane X; plane X is the position of the lateral slice through the port body (1) at which the cross-section in Figure 3b is taken.

Figure 3b is a cross-section of the port body (1) of Figures 1, 2 and 3a taken through the plane X indicated in Figure 3a. The port body (1) has a circular cross-section in plane X. Visible in the cross-section are: a lateral slice through a channel (5), which channel (5) passes longitudinally through the internal impermeable portion (6); the internal mesh surface (4a) at the interface between the mesh portion (4) and the internal impermeable portion (6); the mesh portion (4) and the outer mesh surface (4b). Also indicated is the thickness T in plane X. Thickness T in plane X is the shortest distance between the inner mesh surface (4a) and the outer mesh surface (4b), as measured along the direction of a straight line in plane X originating at a longitudinal axis through the port body (1). In this embodiment, the longitudinal axis lies along a channel (5).

Figure 4 shows a longitudinal cross-section of an exemplary transcutaneous port of the invention (corresponding to the port body (1) of Figures 1 to 3b) implanted in the skin of a patient. The port body (1) comprises a first impermeable portion (3) standing proud of the skin, a cone-shaped internal impermeable portion (6) and a mesh portion (4) surrounding the cone-shaped internal impermeable portion (6). The thickest part of the mesh portion (4) at the subcutaneous end (2b) of the port body (1) is placed in contact with the innermost part of the dermis. The thinnest part of the mesh portion (4) proximate to the first impermeable portion (3) of the port body (1) is placed adjacent to or in contact with the epidermis.

Further preferred features of the transcutaneous port of the invention are described below. The first impermeable portion is typically exposed to the environment when the transcutaneous port is implanted in a patient, as shown in Fig. 4. However, the first impermeable portion (3) may alternatively be covered entirely or partly by a coating or surface treatment, or a further structural moiety. Typically, as shown in Figures 2 and 3a, the first impermeable portion (3) extends across the entire external end (2a) of the port body (1) (excepting the opening to a channel (5)). As is seen in Fig. 4, where the first impermeable portion (3) is configured to cover the entire external end (2a) of the port body (1) except the opening of the channel, (5), the first impermeable portion (3) covers the whole incision site when the device is implanted (except the opening of a channel, (5)). The first impermeable portion (3) can thereby prevent environmental contaminants from entering the body at the implant site.

The first impermeable portion (3) is configured to stand proud of the skin when the transcutaneous port is implanted into a body. Figure 4 shows the entire longitudinal height of the first impermeable portion (3) protruding from the skin when the port is implanted;

however, alternatively the first impermeable portion (3) may be positioned partly beneath the plane of the skin. This arrangement prevents growth of skin over the top of the port body (1) when it is implanted in a body.

The first impermeable portion (3) and if present the second impermeable portion - also referred to as the internal impermeable portion - (6) typically comprise an impermeable material. As used herein,“impermeable” means“impermeable to tissue growth”. Suitable impermeable materials include inert metals such as surgical steel or titanium, and biologically compatible plastics such as Dacron; however, other materials may be used if they are coated with a biologically compatible, impermeable material.

The first impermeable portion typically comprises a layer of impermeable material that is sufficiently high (in the longitudinal direction) to impart strength to the port body (1) and to stand proud of the skin when implanted. Thus, typically the height of the first impermeable portion in a longitudinal direction is at least 0.5 mm, preferably at least 1 mm and more preferably at least 2 mm. To ensure that the device is compact, it is desirable that the height of the first impermeable portion in a longitudinal direction is not excessive. For instance, the height of the first impermeable portion in a longitudinal direction is typically 2 cm or less; preferably 1 cm or less. Usually, therefore, the height of the first impermeable portion in a longitudinal direction is from 1 mm to 1 cm.

Preferably the first impermeable portion has a rounded profile in a lateral direction, which shape avoids sharp comers and hence regions of particularly high torsional stress in the skin. This is exemplified in Figures 1, 2 and 3a where the first impermeable portion (3) has a circular profile in the lateral plane. In a preferred embodiment, the first impermeable portion comprises a rounded disc such as a circular or oval disc, approximately 1 mm to 10 mm high in the longitudinal direction, and comprises an opening for a channel.

The first impermeable portion comprises an opening to allow a channel to extend through the first impermeable portion. Where the port body(l) comprises two or more channels, the first impermeable portion typically comprises one opening per channel, to allow each channel to extend through the first impermeable portion. Typically, an opening is located approximately in the middle of the first impermeable portion. Alternatively or additionally, the first impermeable portion may comprise an opening located away from the middle of the first impermeable portion.

In some embodiments, the first impermeable portion comprises a smooth surface. A typical smooth surface is a polished surface. Other examples of typical smooth surfaces include grit blasted surfaces, machine finished surfaces and shot peened surfaces. A surface of the first impermeable portion which is suitable for exposure to the environment when the

transcutaneous port is implanted (which may be referred to as the upper surface) is typically smooth; for example it may be a smooth polished surface. This prevents catching of the device on clothing and makes it easy to clean. Moreover it discourages bacterial attachment and allows for easier removal of bacteria.

At its smooth surface, the first impermeable portion may alternatively or additionally comprise a coating to improve its smoothness, and/or to reduce attachment of external species. This coating may for instance be provided on a polished, grit blasted, machine finished or shot peened surface, or to a roughened surface. Suitable coatings include diamond-like carbon coating (DLC coating). More particularly, the first impermeable portion may comprise a smooth surface at any point which may contact the epidermis when the port body (1) is implanted. In particular, the first impermeable portion (3) may comprise a smooth surface located adjacent to the outer mesh surface (4b). This advantageously discourages or even prevents epidermal growth up the sides of the port body (1) in a direction towards the external end (2a) of the port body (1).

A smooth surface typically has an average surface roughness (RA) of 0.2 microns or less, typically 0.1 microns or less. The average surface roughness (RA) as used herein refers to the arithmetic mean surface roughness, which is defined as the arithmetic average of the absolute values of the profile height deviations from the mean surface plane. Average surface roughness is typically measured by stylus, interferometry or SEM.

Preferably, some or all of the surface(s) of the port body that are for contacting tissue when the device is implanted may be rough. For instance, where the port body comprises an internal impermeable portion the surface(s) of the internal impermeable portion that are for contacting tissue (e.g. epithelial tissue, particularly the dermis) when the device is implanted may be rough. In another example, all or part of the mesh portion may comprise a rough surface(s). For instance, such surfaces may have an average roughness of at least 0.2 microns, or at least 0.5 microns. For instance, they may have an average roughness of up to 5 microns or up to 10 microns.

The roughened surface is advantageous in that it promotes tissue growth onto the roughened surface and thus promotes the formation of a tight seal between the port and the skin. It is additionally of assistance during the implantation process as it grips the skin and reduces sliding, which is convenient for the surgeon. The ability of the port body of the invention to grip the skin is also promoted by the porous structure of the mesh portion, which allows partial infilling of the dermis into the mesh portion (i.e. the porous body) upon implantation of the transcutaneous port.

The mesh portion (4) is located at the subcutaneous side of the first impermeable portion (3). As can be seen in each of Figures 1, 2, 3a and 4, the mesh portion (4) is located underneath the first impermeable portion when the device is implanted. Thus, when the transcutaneous port of the invention is implanted into a body, all or part of the mesh portion (4) is placed within or below the skin (Fig. 4); typically, the mesh portion (4) is not exposed to the environment once the transcutaneous port is implanted and the wound has healed.

The mesh portion (4) is configured to allow the ingrowth of skin cells, causing the

transcutaneous port and specifically the port body (1) to become anchored in the skin. The mesh portion (4) has a thickness, T, which has a value Tl proximate to the first impermeable portion (3) and a larger value T2 proximate to the subcutaneous end (2b) of the port body (1).

The thickness T is illustrated in Figure 3b. T varies longitudinally through the mesh portion (4). The exact value of T will therefore depend on the lateral plane in which it is measured.

T may also vary depending on which part of the mesh portion (4) is measured in that plane if the mesh portion (4) is not symmetrical. T may therefore be defined as being equal to the shortest distance between the inner mesh surface (4a) and the outer mesh surface (4b) measured along the direction of a straight line in a plane perpendicular to a longitudinal axis of the port body and originating at the longitudinal axis. By“inner mesh surface” (4a) is meant the surface of the mesh portion (4) nearest to the centre of the port body (1), illustrated in Figures 1, 3a and 3b. The inner mesh surface (4a) is typically the surface abutting the channel (5) or the internal impermeable portion (6). By“outer mesh surface” (4b) is meant the surface of the mesh portion (4) furthest from the centre of the port body (1) in a lateral direction. The outer mesh surface extends laterally around the outside of the mesh portion (4) and also often along the subcutaneous end (2b) of the port body (1).

The thickness of the mesh portion T has a value Tl proximate to the first impermeable portion (3) and a value T2 proximate to the subcutaneous end (2b). Tl is smaller than T2. Typically, T varies from Tl to T2 in a longitudinal direction away from the first impermeable portion (3). It may equally be said that T varies from Tl to T2 in a longitudinal direction towards the subcutaneous end (2b) of the port body (1).

A longitudinal axis of the port body (1) is an axis that passes in a straight line between the external end (2a) and the subcutaneous end (2b) of the port body (1). Typically, a

longitudinal axis lies along the straight line which connects the centre of the external end (2a) and the subcutaneous end (2b) of the port body (1). Also typically, a longitudinal axis lies along a channel (5). However, the longitudinal axis may not coincide with a channel, for instance where a channel (5) is off-set or lies at an angle to a straight line connecting the external end (2a) to the subcutaneous end (2b). Similarly, the port body (1) may not be symmetrical about a longitudinal axis. For instance, one or more of the first impermeable portion (3), the mesh portion (4), the channel (5) and the internal impermeable portion (6) may not be symmetrical about the longitudinal axis. Typically, though, the port body is substantially symmetrical about the longitudinal axis. In a one embodiment, the port body (1) has a longitudinal axis joining the centre of the external end (2a) to the centre of the subcutaneous end (2b) of the port body (1) and the channel (5) lies along that longitudinal axis.

The part of the mesh portion (4) which has a thickness Tl extends longitudinally from the first impermeable portion (3) of the port body (1). Thus, the thinnest part of the mesh is typically adjacent the first impermeable portion. The mesh portion (4) typically extends from the subcutaneous end (2b) of the implant to the first impermeable portion (3), as in Figures 1 to 4. Thus, when the transcutaneous port of the invention is implanted into a body, the part of the mesh portion (4) having a thickness Tl typically contacts the epidermis (Fig. 4). It is desirable to encourage the epidermis to grow closely against the port body (1) or even into the port body (1) to a limited extent, to promote healing and create a barrier against foreign bodies entering the mesh portion (4). However, it is desirable to prevent excessive ingrowth of the epidermis to prevent downgrowth and hence Tl is typically small, as will be discussed in more detail below.

In other embodiments (not shown), when the transcutaneous port of the invention is implanted the part of the mesh portion (4) having thickness Tl may contact the upper layers of the dermis. In such embodiments, the first impermeable portion (3) is typically situated at least partly within the skin ( i.e . below the skin surface, for instance in contact with the epidermis).

The thickness T of the mesh portion (4) may fall to zero at the end of the mesh portion (4) nearest to the external end (2a) of the port body (1). For instance, in Figure 1, the end of the mesh portion (4) which is nearest to the external end (2a) of the port body (1) is located at the interface between the mesh portion (4) and the first impermeable portion (3) and is very small or even zero. Thus, in some embodiments, Tl is zero. In other embodiments, the mesh portion (4) may have a non-zero thickness T at the end of the mesh portion (4) nearest to the external end (2a) of the port body (1). When the transcutaneous port of the invention is implanted into a body, the part of the port body (1) which is placed furthest into the body is the subcutaneous end (2b). Typically, the subcutaneous end (2b) of the port body (1) contacts the dermis when implanted (see Figure 4). It is desirable to encourage dermal growth and even vascularisation into the port body (1) to ensure that the port body (1) is well secured and that the tissue within, underneath and around it is healthy. Thus the greater thickness T2 of the mesh portion (4) at or proximate to the subcutaneous end (2b) encourages maximal ingrowth of the dermis to the port body (1) (the dermis being the portion of the skin under the epidermis). The subcutaneous end may also contact the hypodermis, beneath the dermis (Fig. 4).

In certain embodiments (not shown), the subcutaneous end (2b) may protrude through the hypodermis to contact the soft tissue or even bone underneath the skin. In such

embodiments, the mesh portion (4) at the subcutaneous end (2b) of the port body (1) is typically configured to promote ingrowth of the said soft tissue or bone into the port body (1). Alternatively or additionally, the transcutaneous port of the invention may comprise a coating, surface treatment or further structural moiety at the subcutaneous end (2b) of the port body (1) such that the mesh portion (4) does not extend longitudinally to the extreme subcutaneous end (2b) of the port body (1).

The smaller thickness Tl of the mesh portion (4) proximate to the first impermeable portion (3) of the port body (1) in comparison to the larger thickness T2 of the mesh portion (4) proximate to the subcutaneous end (2a) discourages migration of the epidermal cells in a direction towards the subcutaneous end (2b) of the port body, i.e. discourages downgrowth of epidermal cells.

The first impermeable portion (3) may or may not contact the mesh portion (4). In some embodiments, the mesh portion (4) is directly attached to the first impermeable portion (3).

In some embodiments, the mesh portion (4) is directly attached to the internal impermeable portion (6), where present. In further embodiments (such as are shown in Figures 1, 2 and 3a) the mesh portion (4) is attached to the first impermeable portion (3) and to the internal impermeable portion. In Figures 1, 2 and 3a the mesh portion (4) is attached to the first impermeable portion (3) at the point where the outer mesh surface (4b) meets the first impermeable portion (3). In other embodiments the mesh portion (4) may contact a larger area of the first impermeable portion (3).

Preferably, an internal impermeable portion (6) is present (Figures 1, 3a, 3b, 4). The internal impermeable portion (6) can define a part of a channel (5) through the port body (1) and can advantageously anchor any conduit such as a tube, hose, needle, cable, electrode, wire, catheter, gas line or drain passing through the port body (1).

Therefore, in a preferred embodiment, the port body (1) of the transcutaneous port of the invention further comprises an internal impermeable portion (6); the internal impermeable portion (6) being located between the first impermeable portion (3) and the subcutaneous end (2b) of the port body (1) (in a longitudinal direction) and located at least partly within the mesh portion (4); and a channel (5) extends longitudinally through the internal impermeable portion (6). The internal impermeable portion is clearly shown in Figure 1 and indicated in Figure 3 a.

In a preferred embodiment, the internal impermeable portion (6) extends longitudinally from the first impermeable portion (3). The internal impermeable portion (6) extends from the first impermeable portion (3) in a direction towards the subcutaneous end (2b) of the port body (1)^.

The internal impermeable portion (6) is located at least partly within the mesh portion (4)

(see Figure 1). By this is meant that the mesh portion (4) is disposed around at least a part of the internal impermeable portion (6). Typically, the first impermeable portion is laterally surrounded by the mesh portion in at least one lateral plane. In some embodiments, such as the embodiments of Figures 1 and 4, the internal impermeable portion (6) extends

longitudinally to the subcutaneous end (2b) of the port body (1). In other embodiments (not shown), the internal impermeable portion (6) may not extend as far as the subcutaneous end (2b) of the port body (1). In such cases, the mesh portion (4) may extend further in the direction of the subcutaneous end (2b) than the internal impermeable portion (6). In other embodiments, the internal impermeable portion (6) may extend further towards or more proximally to the subcutaneous end (2b) of the port body (1), such that at least a part of the internal impermeable portion (6) extends beyond the mesh portion (4) in the direction of the subcutaneous end (2b). The internal impermeable portion may therefore have a height in a longitudinal direction which is greater than, equal to or less than the height of the mesh portion in a longitudinal direction. Thus, in some embodiments, the height of the internal impermeable portion is up to 50 mm, for instance up to 20 mm. More typically, the height of the internal impermeable portion is up to 10 mm, for instance up to 5 mm or preferably up to 2500 microns.

In some embodiments, the height of the internal impermeable portion is at least 100 microns, for example at least 200 microns or at least 500 microns.

In a preferred embodiment, the height of the internal impermeable portion is from 100 to 5000 microns, particularly preferably from 200 to 2500 microns. In a preferred aspect of this embodiment, the port body (1) is intended for implantation in the skin specifically.

In the embodiments shown, the internal impermeable portion (6) contacts the mesh portion (4). As shown in Figures 1 and 3b, the mesh portion (4) can contact the internal impermeable portion (6) at the inner mesh surface (4a). However, in other embodiments (not shown), a gap, a coating or a further structural element may intervene between the inner mesh surface (4a) and the internal impermeable portion (6). In a preferred embodiment the mesh portion (4) is fused to the internal impermeable portion (6), as occurs for example when the port body (1) is integrally formed.

In the embodiments shown, the internal impermeable portion (6) contacts the first impermeable portion (3), as in Figure 1. Typically, the first impermeable portion (3) and the internal impermeable portion (6) are in direct contact, for example they may be fused together or provided as a single integral part. In other embodiments (not shown), a gap, a coating or a further structural element may intervene between the first impermeable portion (3) and the internal impermeable portion (6).

The internal impermeable portion defines a region into which skin cannot grow. The internal impermeable portion can therefore advantageously be shaped so as to restrict the area available for growth of epidermal cells through the port body and hence to discourage downgrowth of epidermal cells and promote dermal integration. Preferably, therefore, the internal impermeable portion has a larger cross-section (measured in a plane perpendicular to a longitudinal axis, as in Figure 3b) proximate to the first impermeable portion (3) and a smaller cross-section (measured in a plane perpendicular to a longitudinal axis) proximate to the subcutaneous end (2b) of the port body (1). This shape allows more space inside the port body for ingrowth of the dermis and correspondingly restricts space for growth of epidermis.

Therefore in a preferred embodiment the invention provides a transcutaneous port wherein: the internal impermeable portion (6) has a cross-section of area A in a plane perpendicular to the longitudinal axis which has a value Al proximate to the first impermeable portion (3) of the port body (1), and a value A2 proximate to the subcutaneous end (2b) of the port body (1), and Al is larger than A2. Cross-sectional area A varies from Al to A2 in a direction away from the first impermeable portion. It may equally be said that A varies from Al to A2 in a direction towards the subcutaneous end of the port body.

Cross-sectional area A includes not only the area of the internal impermeable portion (6) in a plane perpendicular to a longitudinal axis, but also includes the area of any channels within the internal impermeable portion (6) in that plane. Area A is shown as the shaded area in Figure 3C.

The change in cross-section from Al to A2 may be achieved in a stepped manner. For instance, in some embodiments, the internal impermeable portion comprises steps of differing cross-section. For instance, the internal impermeable portion may comprise from two to twenty steps, each step being a sub-portion of a particular cross-section. The step which is proximate to the first impermeable portion of the port body has cross-section Al, while the step which is proximate to the subcutaneous end of the port body has cross-section A2.

The internal impermeable portion can have a tapering shape, meaning that cross-sectional area A of the internal impermeable portion (6) decreases in a graduated manner from the part of this portion nearest to the external end (2a) to the part of this portion nearest to the subcutaneous end (2b).

The decrease of the cross-sectional area may occur in a non-linear manner from Al to A2.

For instance, the cross-sectional area may decrease exponentially moving in a longitudinal direction along all or part of the length of the internal impermeable portion. Where the internal impermeable portion is approximately symmetrical about the longitudinal axis, this may lead to a curved conical (e.g. concave conical) or frustoconical shape of the internal impermeable portion. Alternatively, the decrease of the cross-sectional area may occur in a linear manner. Where the internal impermeable portion is approximately symmetrical about the longitudinal axis, this may lead to a conical or frustoconical shape of the internal impermeable portion. In some embodiments, the decrease of the cross-sectional area of the internal impermeable portion in a longitudinal direction from Al to A2 may occur partly in a linear manner and partly in a non-linear manner.

In a preferred embodiment, the internal impermeable portion is frustoconical (Figures 1, 3a). Preferably, internal impermeable portion (6) is frustoconical and the base (the larger of the two circular faces) of the frustocone is located adjacent to the first impermeable portion (3).

In this embodiment, the channel (5) typically passes approximately between the centres of the two circular faces of the frustoconical shape.

Generally, a channel (5) passes approximately through the centre of the cross-section of the internal impermeable portion (6) in all planes perpendicular to the longitudinal axis.

However, in some embodiments no channel passes through the centre of the said cross- section, or a channel (5) does not pass through the centre of the said cross-section in all planes. For instance, in embodiments where the port body (1) comprises two or more channels (5), one or more, e.g. all, of said channels are located in a non-central position. Where the port body (1) comprises a plurality of channels (5), said channels may for instance extend longitudinally through the port body (1), arranged in a ring.

Typically, Al is at least 10 mm². For instance, Al may be at least 25 mm² or at least 50 mm². Also typically, Al is up to 1500 mm². For instance, Al may be up to 1000 mm², or up to 500 mm², or up to 100 mm². Typically, A2 is at least 0.15 mm². For instance, A2 may be at least 0.5 mm², or at least 1 mm², or at least 5 mm². Also typically, A2 is up to 60 mm².

For instance, A2 may be up to 25 mm² or up to 10 mm². Where the internal impermeable portion has a frustoconical shape, Al may be equal to the cross-sectional area of the base of the frustoconical shape and A2 may be equal to the cross-sectional area of the other circular face of the frustoconical shape. In embodiments where the internal impermeable portion has a non-circular face proximate to the subcutaneous end of the port body, A2 may be equal to the cross-sectional area of said non-circular face.

In some embodiments, the entire cross-sectional area A2 may be taken up with an opening to a channel (5).

In some embodiments, the internal impermeable portion (6) may have a face located adjacent to or in contact with the first impermeable portion (3), wherein said face has a shape that is identical to the shape of the facing part of the first impermeable portion (3). In a preferred aspect of this embodiment, the first and the internal impermeable portions are in contact and are fused at their interface, or provided as a single integral part.

In some embodiments, the shape of the internal impermeable portion (6) complements the shape of the mesh portion (4). In this embodiment, the port body (1) as a whole has an approximately identical cross-section in all planes perpendicular to the longitudinal axis. For example, in this embodiment the port body (1) may be substantially cylindrical. As the cross- sectional area of the internal impermeable portion decreases in a direction towards the subcutaneous end (2b), the thickness T of the mesh portion (4) correspondingly increases to maintain the contact between the inner mesh surface (4a) and the internal impermeable portion (6).

For instance, where the cross-section of the internal impermeable portion varies from Al to A2 in a stepped manner, the mesh portion (4) may have a thickness which varies in a complementary stepped manner along the length of the port body. For instance, the mesh portion may comprise from two to twenty steps, each step being a sub-portion of a particular thickness. The step nearest to the external end of the port body has thickness Tl, while the step proximate to the subcutaneous end of the port body has thickness T2.

In another instance, where the internal impermeable portion has a tapering shape (meaning that its cross-sectional area A decreases in a graduated manner in a direction from the external end to the subcutaneous end of the port body), the mesh portion (4) may have a thickness which varies in a complementary graduated manner along the length of the port body. Thus, the thickness of the mesh portion (4) may remain in contact with the internal impermeable portion (6) along the inner edge of the mesh portion (4a) along the length of the internal impermeable portion (6) in a longitudinal direction. Where the cross-sectional area changes in a non-linear manner (e.g. exponentially in a longitudinal direction along the internal impermeable portion), the thickness of the mesh portion may increase in a complementary non-linear (e.g. exponential) manner. For instance, where the internal impermeable portion (6) has a concave conical shape, the mesh portion may have a complementary convex shape.

However, it should be noted that a tapering (e.g. frustoconical) internal impermeable portion (6) is not necessarily required in combination with a mesh portion (4) having a graduated thickness T. In some embodiments, the thickness T of the mesh portion (4) may increase in a graduated (e.g. linear) manner from Tl to T2 and thus form a cavity between the first impermeable portion (3) and the mesh portion (4). This cavity may optionally be filled wholly or partly with the internal impermeable portion (6).

A channel (5) is a passage through which matter can pass between the external end (2a) and the subcutaneous end (2b) of the port body (1). A single channel (5) is shown in Figure 1, but two or more, for example 2, 3, 4, 5 or 10 channels, may be present. An opening to a channel (5) is shown in Figures 2 and 3a. Typically, the or each channel (5) passes longitudinally through the first impermeable portion (3) and the mesh portion (4). Where the port body (1) comprises an internal subcutaneous portion (6), one or more, typically each channel (5) passes through the first impermeable portion (3) and the internal impermeable portion (6). The internal impermeable portion (6) is located at least partly within the mesh portion (4) and hence, in this latter embodiment, one or more, e.g. each channel (5) necessarily also passes through the mesh portion (4).

Generally, a channel (5) comprises a cavity suitable for receiving a linear conduit such as a tube, hose, cable, electrode, wire, catheter, gas line, drain or needle. Usually, therefore, a channel (5) comprises an approximately cylindrical cavity having an approximately circular opening at each end; one opening located in the external end (2a) and the other being located in the subcutaneous end (2b) of the port body (1).

When the transcutaneous port is implanted, a channel (5) is typically perpendicular to the skin, and therefore allows matter to cross the skin via the shortest possible route. The diameter of a channel (5) is generally sufficiently large to receive conduit such as a tube, hose, cable, electrode, wire, catheter, gas line, drain or needle. By“diameter” is meant the minimum width of the channel in a direction perpendicular to the direction from one opening to the channel to the other. Typically, the diameter of the channel is at least 0.1 mm, preferably at least 0.5 mm, for example at least 1 mm. Typically, the diameter of the channel is 2 cm or less, preferably 1 cm or less, for example 8 mm or less. For instance, the diameter of the channel is typically from 0.1 mm to 1 cm, preferably 0.5mm to 8 mm.

Typically, the channel (5) may be suitably dimensioned to prevent any conduit (such as a needle, tube, cable, electrode, wire, catheter, gas line, drain or hose) therein from falling out of the port body (1). Typically, therefore, the maximum diameter of the channel is 4 cm or less. Preferably said maximum diameter of the channel is 2 cm or less, for example 1 cm or less.

Alternatively or additionally, one or more of the channels (5) may comprise a means suitable for anchoring the conduit in the channel. For instance, a channel may comprise a part having a shape that is complementary to the shape of part of the conduit. A channel itself may have a shape suitable for anchoring the conduit. A channel may for instance be threaded, and consequently may anchor a threaded conduit. Alternatively or additionally, a channel may comprise a separate anchoring means, for instance a bayonet fitting, a snap fitting, a click fitting, a bulkhead or a crimp. A channel may be shaped to receive such an anchoring means, or the anchoring means may be an integral part of a channel.

In some embodiments, the transcutaneous port of the invention further comprises a conduit within a channel (5) of the port body (1). An example of such a conduit is a needle, tube, cable, electrode, wire, catheter, gas line, drain or hose. In other embodiments, the

transcutaneous port does not comprise a conduit within a channel. In yet further

embodiments, the invention relates to a kit comprising a transcutaneous port of the invention and a needle, tube, cable, electrode, wire, catheter, gas line, drain or hose suitable for insertion into a channel (5) of the port body (1).

The port body (1) is typically arranged in as compact a manner as possible. In a preferred embodiment, the transcutaneous port comprises:

a port body (1) having an external end (2a) and a subcutaneous end (2b); and at least one channel (5) which extends longitudinally through the port body (1) from the external end (2a) to the subcutaneous end (2b);

wherein the port body (1) comprises:

a first impermeable portion (3) extending longitudinally from the external end (2a) of the port body (1);

an internal impermeable portion (6) extending longitudinally from the first impermeable portion (6); and

a mesh portion (4) extending longitudinally from the subcutaneous end (2b) of the port body (1), which mesh portion (4) extends laterally from an inner mesh surface (4a) to an outer mesh surface (4b) by a thickness T, the inner mesh surface (4a) being in contact with the internal impermeable portion (6);

wherein T has a value Tl proximate to the first impermeable portion (3) of the port body (1) and a value T2 proximate to the subcutaneous end (2b) of the port body (1), and Tl is less than T2.

The lateral extent of the first impermeable portion is the distance across the first impermeable portion in a lateral direction, i.e. the diameter for a cylindrical (or annular) first impermeable portion. To incorporate one or more channels, the minimum lateral extent of the first impermeable portion is typically at least 5 mm. The maximum lateral extent of the first impermeable portion (3) is usually 5 cm or less. Preferably the maximum lateral extent of the first impermeable portion is 3 cm or less. For instance, where the first impermeable portion is approximately circular in a lateral direction, the diameter of the first impermeable portion is preferably from 8 mm to 3 cm, for instance from 1 cm to 2 cm.

The transcutaneous port of the invention can take a conveniently small and compact shape. A small and compact shape reduces impact on the patient. Typically, the maximum extent of the port body (1) in a lateral direction is 5 cm or less, and the maximum height of the port body (1) in a longitudinal direction is 5 cm or less. Preferably, the maximum extent of the port body (1) in a lateral direction is 2 cm or less, and the maximum height of the port body (1) in a longitudinal direction is 2 cm or less. Mesh

The term“mesh” is taken to mean a structure comprising pores, i.e. a porous body. The mesh may be regular or irregular, as discussed in more detail below. Typically, the pores are interconnected, i.e. each pore is typically in communication with one or more other pores within the mesh. A porous body comprising interconnected pores can suitably be formed of a series of ribs or strands, arranged in a regular or irregular lattice; however, other materials comprising a plurality of interconnected pores are also suitable for forming the mesh.

The pores are required to allow ingrowth of skin, particularly the dermis but also possibly the epidermis, into the port body (1). In some cases, the pores also allow soft tissue and/or bone to grow into the transcutaneous port. Preferably, therefore, the size of the pores is selected to promote ingrowth of skin cells, particularly dermal cells. Further, the porous structure is suitable for receiving a gel containing a biologically active agent to encourage tissue ingrowth into the device.

The size of a pore may be defined in terms of a diameter. The diameter of a pore is the diameter of the largest sphere that can fit inside that pore. Preferably, the shape of a pore is approximately spherical. However, other pore shapes are envisaged.

Usually, the mesh portion (4) comprises pores with a diameter of 50 to 2000 microns. This size range is found to be particularly useful in promoting vascularisation. Preferably, the mesh portion comprises pores with a diameter from 50 to 1500 microns. For instance, the pore size of the mesh portion may be from 100 to 1250 microns, e.g. from 200 to 1000 or 400 to 800 microns. If the mesh portion has a regular structure, the mesh may comprise pores of only one specific size or of a limited number of specific sizes falling within the above ranges. However, if the mesh portion has an irregular structure the pore size will vary. If the pore size varies, the average pore size preferably therefore falls within the above ranges, more preferably all pores or substantially all pores (e.g. at least 90%, preferably at least 95% of pores) have sizes falling within the above ranges.

The mesh portion may comprise pores of a suitable diameter to encourage ingrowth of the epidermis. Preferably, the mesh portion may comprise pores of a suitable size to encourage ingrowth of dermal tissue, which may preferably be 500 pm in diameter or larger, for instance from 500 pm to 1250 pm in diameter.

The mesh may comprise pores of differing sizes. The size of the pores may vary in a lateral direction through the mesh portion, and/or in a longitudinal direction through the mesh portion.

The mesh portion may comprise larger pores (e.g. at least 400 pm) located proximately to the outer mesh surface (4b) and smaller mesh pores (e.g. no more than 200 pm) located proximate to the inner mesh surface (4a). That is, the pore size may increase in a direction from the inner mesh surface (4a) to the other mesh surface (4b). This may allow the outer pores to be less rigid (i.e. more flexible), increasing patient comfort.

In one embodiment of the transcutaneous port of the invention, the mesh portion (4) comprises pores of a size to promote epidermal growth therein located proximate to the external end (2a) of the port body (1) and pores of a size to promote dermal growth therein located proximate to the subcutaneous end (2b) of the port body (1).

In the port body (1) of the invention, the pores may contain a gel. For instance the mesh portion may be coated in a gel. Typically said gel is a biologically compatible gel, such as a hydrogel. The gel typically further comprises a biologically active agent, such as an antibiotic or a tissue-promoting agent. This gel may advantageously therefore, by the action of said biologically active agent, reduce infection and promote tissue ingrowth. Moreover, the gel can be resorbed into the tissue as the tissue grows, and so does not prevent tissue ingrowth by restricting the space available.

The mesh portion may preferably have a rough surface to promote tissue integration. For instance, the surface of the material making up the mesh portion may have an average roughness of at least 0.2 microns, or at least 0.5 microns. For instance, said surface may have an average roughness of up to 5 microns, or up to 10 microns or up to 50 microns. Where the mesh is produced by 3D printing, the roughness of the mesh may be adjusted by varying the 3D printing conditions, e.g. by varying the size of the particles from which the mesh is printed. The mesh portion may typically have a smooth or rounded outer mesh surface (4b). For example in some embodiments, the mesh portion may have a circular cross-section in all planes perpendicular to the longitudinal axis, e.g. the external profile of the mesh portion may be in the form of a cylinder. The smooth or rounded outer mesh surface avoid comers and other such locations of high torsional stress which can lead to abrasions, skin damage and significant discomfort for the patient.

In some embodiments, mesh portion (4) comprises a stiff mesh. By“stiff mesh” is meant a mesh that is resistant to deformation. Typically, a stiff mesh is a rigid (i.e. self-supporting) mesh. Typically, a stiff mesh has a compressive stiffness of 5 N or more, for example 10 N or more.

A typical test to determine whether a mesh has compressive stiffness (the force needed to compress the mesh) can be performed by placing a 10 mm x 10 mm x 10 mm cube of the mesh between an upper plate and an immoveable surface and applying a force to the upper plate. In one embodiment, therefore, a stiff mesh is one which does not deform under a force of 5 N or less, preferably under a force of 10 N or less.

Another measure of a mesh’s stiffness is its resistance to bending. This may be referred to as its“deformation stiffness”. Typically, a stiff mesh has a deformation stiffness of 5 N or more, for instance of 10 N or more. A typical test to determine the deformation stiffness of a sample can be performed by securing a 10 mm x 10 mm x 1 mm cuboid of the mesh at one end and applying a force to the other end. The“deformation stiffness” is the stiffness required to bend the mesh in this test. In one embodiment, therefore, a stiff mesh is one which does not bend under a force of 5 N or less, preferably under a force of 10 N or less.

A stiff mesh is advantageous for the purpose of providing a robust transcutaneous port. However, flexible meshes also have advantages. In particular, flexible meshes often have excellent biological compatibility. By“flexible mesh” is meant a mesh which is readily deformed. A flexible mesh typically comprises flexible fibres. Typical flexible meshes may not satisfy the requirements of the above test for a stiff mesh.

Typical flexible meshes include meshes made of less stiff materials, such as low modulus titanium alloys (e.g. Ti-29Nb-l lTa-5Zr). Typical flexible meshes also include those made of more flexible materials such as polymers, preferably biopolymers. For instance flexible meshes may comprise PEEK, polyethylene, polyurethane, PVC, polypropylene,

thermoplastics, nylon, ceramics, acrylates, or nitinol. Flexible meshes may comprise biological cells. Alternatively or additionally, flexible meshes may comprise traditionally stiff materials provided in a less stiff arrangement, for instance as thin ribs or entangled rather than joined ribs. Thus, typical flexible meshes also include meshes comprising titanium, beta phase titanium alloys, steel, tantalum, and so on.

In some embodiments, the mesh portion (4) comprises a flexible mesh. In some preferred embodiments, the mesh portion (4) comprises a stiff mesh and a flexible mesh. For instance, the mesh portion (4) may comprise a stiff mesh located along the inner mesh surface (4a), and a layer of flexible mesh around the outside of the stiff mesh (i.e. a region of stiff mesh and a region of flexible mesh). That is, the flexible mesh layer may be arranged along the outer mesh surface (4b). The region of flexible mesh may be integral with the region of stiff mesh.

In a preferred embodiment, therefore, the invention provides a transcutaneous port as described herein wherein the mesh portion (4) comprises a region of stiff mesh located along all or part of the inner mesh surface (4a) and a region of flexible mesh located along all or part of the outer mesh surface (4b).

In some embodiments, the stiffness of the mesh may be graduated. For instance, a mesh portion may comprise a region of stiff mesh and a region of flexible mesh, and the stiffness of the mesh may vary in a graduated manner between the two regions. In a preferred aspect, the invention provides a transcutaneous port as described herein wherein the stiffness of the mesh in the mesh portion (4) decreases or increases (preferably decreases) in a graduated manner from the inner mesh surface (4a) to the outer mesh surface (4b). In other embodiments, the stiffness of the mesh may vary in a stepped manner. For instance, the stiffness of the mesh portion (4) may decrease or increase (preferably decrease) in a stepped manner from the inner mesh surface (4a) to the outer mesh surface (4b).

Suitable porous materials with a graduated structure and hence graduated properties would be recognised by the skilled person. An example of a such a material is a functional graded material. Functional graded materials are materials whose composition and properties vary throughout the body of the material. Functional graded materials are therefore suitable for forming a mesh with varying properties, e.g. graduated stiffness. For instance, such materials may transition from a largely or entirely metallic composition to a largely or entirely ceramic composition throughout their structure; in another example, such materials may transition from a first metallic composition to a second metallic composition throughout their structure.

An exemplary method of providing a functional graded material comprises providing the desired constituent materials in particulate form (for instance in the form of powder or granules) and distributing these powders within a mould in the desired spatial arrangement. The particulate species in the mould are then fused, for instance by the application of pressure and/or heat. Exemplary methods and materials are described in Godoy et al ., European Cells and Materials, Vol. 31, pp250-263 (2016). Exemplary materials for forming such functional graded materials include ceramics and metals, e.g. transition metals such as titanium, cobalt, chromium, manganese and niobium. Biologically compatible metals such as titanium are preferred.

Functional graded materials provide variation throughout their structure in physical properties such as pore size, strength, compression stiffness, bending stiffness, roughness and so on. They may also vary throughout their structure in biological compatibility, susceptibility to coating, etc.

In some embodiments, the flexible mesh region may not be integral with the stiff mesh region but may be formed by the addition of an additional flexible mesh layer around the port body (1). Alternatively, the flexible mesh may be integral with the region of stiff mesh. The flexible mesh may differ from the stiff mesh in its composition (for instance, the stiff mesh may be made of a different and more rigid material). The flexible mesh may alternatively or additionally differ from the stiff mesh in the thickness of the strands (e.g. fibres or ribs, see below) from which the mesh is formed, the flexible mesh being formed of thinner strands. Also alternatively or additionally, the flexible mesh may differ from the stiff mesh in its design, for instance having a larger pore size than the rigid mesh, or having tangled rather than joined ribs.

The mesh portion (4) may comprise a regular mesh or an irregular mesh. Often, the mesh portion comprises a regular mesh. By a“regular mesh” is meant a mesh having a repeating pattern within its structure. It may be preferred that the mesh portion comprises a regular mesh as such meshes are strong and are simple to design and manufacture integrally, for instance by 3D printing.

In some embodiments of the transcutaneous port of the invention, the mesh portion (4) comprises a plurality of ribs arranged in a lattice. The ribs can form an array of polyhedra, with each side of each polyhedron formed by all of part of a rib. The ribs are preferably approximately linear but may also be non-linear. The ribs may, for instance, be in the form of wires. Typically the ribs have a first dimension (a“length”) that is considerably greater than its other dimensions. Usually, the length of a rib is at least as large as Tl. Typically, the length of a rib is up to T2, although it may be longer if the rib bends within the mesh portion. Generally the length of a rib is at least 0.1 mm, for instance at least 0.5 mm. Generally, the length of a rib is up to 50 mm, for instance up to 20 mm. Preferably, the length of a rib may be from 0.1 to 50 mm, more preferably from 0.5 mm to 20 mm, particularly preferably from 1 mm to 10 mm.

The diameter of the rib is the diameter of the largest circle which can fit inside the rib in a plane perpendicular to a line along the length of the rib. Typically the diameter of a rib is at least 1 micron or 5 microns, preferably at least 10 or at least 50 microns. Usually, the diameter of a rib is 1000 microns or less; more preferably, the diameter of a rib is 500 microns or less, or 300 microns or less. For instance, the diameter of a rib may be less than 200 or less than 100 microns. In some embodiments the diameter of a rib is from 5 to 500 microns, for instance from 50 to 200 microns.

The diameter of a rib may vary along its length and/or the rib diameter may vary through the mesh. For instance, the diameter of a rib may be larger proximate to the inner mesh surface (4a) and smaller proximate the outer mesh surface (4b). In this embodiment, the rib diameter may decrease in a graduated manner or in a stepped manner along its length or through the mesh. The rib diameter may for instance, decrease by at least 10 %, or at least 20 %, or at least 50%, and by up to 80%, 90% or even 95%, along the length of the rib; and/or the rib diameter may decrease by at least 10 %, or at least 20 %, or at least 50%, and by up to 80%, 90% or even 95% from the diameter at inner surface of the mesh to that at the outer surface of the mesh. Typically, a lattice comprises a regular arrangement of unit cells. A unit cell is a structural motif that is repeated throughout the whole lattice. The lattice comprises an arrangement of adjacent unit cells. In some embodiments, each side of the unit cell may comprise a rib or a portion of a rib. This is typically the case where the lattice comprises plurality of ribs arranged in cubes. However, the unit cell does not necessarily comprise a rib along each side (as in, for instance, in a diamond hexagonal lattice).

The pore size in a lattice formed by ribs is determined by the size of the spaces between the ribs. Each unit cell may comprise one, two, three or more pores, and/or may share pores with a neighbouring unit cell. Preferably the lattice, and the unit cell, are dimensioned so as to provide pores of 50 to 2000 microns in diameter, more preferably pores of 50 to 1000 microns in diameter. In some embodiments, the side of each side of each unit cell is from 50 to 2000 microns in length.

In a preferred embodiment, the lattice is a diamond hexagonal lattice. The diamond hexagonal lattice is advantageously strong, leading to a robust transcutaneous port. Further, the diamond hexagonal lattice can conveniently be manufactured by integral manufacturing techniques such as 3D printing.

In another embodiment, the mesh portion (4) comprises a plurality of ribs arranged irregularly. An example of an irregular arrangement is an entangled mesh of ribs.

The port body (1) of the transcutaneous port of the invention typically has an approximately circular cross-section in all planes perpendicular to the longitudinal axis. This shape advantageously avoids comers which are subject to high torsional stress when the port is implanted. This means, therefore, that the mesh portion (4) is typically formed into an approximately cylindrical shape. However, where the mesh portion comprises a stiff mesh having a regular lattice, cutting a cylinder out of the mesh may leave incomplete unit cells with protruding fibres or ribs. By“protruding” is meant that the fibre or rib in question protrudes from the mesh portion. A protruding fibre or rib does not terminate either (i) at a vertex with another fibre or rib, or (ii) at a point of contact with an impermeable portion; it protrudes into a region which may contact the skin. These can be sharp and can cause discomfort to a patient when implanted. It is therefore preferable to avoid a port body having protruding fibres or ribs. Thus, in some embodiments, the transcutaneous port of the invention comprises substantially no protruding ribs. For instance, at least 90% of the ribs terminate in (i) a vertex with another rib, or (ii) an impermeable portion. Preferably at least 95% and in some embodiments all of the ribs terminate in a vertex or join with (i) another rib, or (ii) an impermeable portion.

In some embodiments of the transcutaneous port of the invention, the unit cells in the mesh are substantially all complete. By“complete” is meant that no structural element required in the unit cell (for instance a rib or part of a rib) is missing. For example at least 90%, or at least 95% of the unit cells in the mesh are complete. In some embodiments all of the unit cells of the mesh are complete.

In order to avoid protruding ribs while maintaining a mesh structure into which skin can grow, in some embodiments the thickness Tl corresponds to the thickness of a single unit cell. By“thickness of a unit cell” is meant the smallest lattice parameter, or the smallest length of a side of the unit cell. In some embodiments, the thickness Tl is the smallest thickness of mesh which comprises a complete pore within that thickness. For example, Tl may be approximately equal to the diameter of a single pore within the mesh. In order to avoid protruding ribs, Tl may be equal to the smallest thickness permitting a complete pore to be formed by the arrangement of ribs.

The thickness T2 is greater than Tl. Accordingly, in some embodiments the thickness T2 corresponds to the thickness of two or more unit cells, preferably 5 or more unit cells. For instance, T2 may correspond to the thickness of at least three or at least four unit cells. T2 may have a thickness corresponding to the thickness of up to 10 or 20 unit cells. In some embodiments, the thickness T2 is approximately equal to the thickness of five or more pores. For instance, T2 may correspond to the thickness which comprises at least three or four pores within that thickness, up to ten or twenty pores. In order to avoid protruding ribs, T2 may take a value which allows a whole number of complete pores to be formed by the

arrangement of ribs.

T2 is generally at least 1 mm, for instance at least 5 mm. T2 is generally up to 20 mm, for instance up to 10 mm. Preferably, T2 is from lmm to 20 mm, more preferably from 5 mm to 10 mm. Tl is generally at least 0.1 mm, for instance at least 0.5 mm. Tl is generally up to 10 mm, for instance up to 5 mm. Preferably, Tl is from 0.1 mm to 10 mm, more preferably from 0.5 mm to 5 mm.

The mesh portion (4) may have a thickness which varies from Tl to T2 in a stepped manner along the length of the port body. For instance, the mesh portion may comprise from two to twenty steps, each step being a sub-portion of a particular thickness. The step proximate to the first impermeable portion of the port body has thickness Tl, while the step proximate to the subcutaneous end of the port body has thickness T2.

The mesh portion (4) may have a thickness which varies from Tl to T2 in a graduated manner along the length of the port body. For instance, the thickness of the mesh portion may increase from Tl to T2 in a linear manner or a non-linear (e.g. exponential) manner.

The thickness T may increase from Tl to T2 partly in a linear manner and partly in a non linear manner.

The height of the mesh portion in a longitudinal direction is generally approximately equal to the thickness of the skin of the body. The height of the mesh portion may therefore vary with the intended patient. Further, in some embodiments the mesh portion may be extended to allow ingrowth of soft tissue or bone when the transcutaneous port is implanted.

Typically, the height of the mesh portion is at least 500 microns, for instance at least 1000 microns or at least 1500 microns. The height of the mesh portion may be up to 50 mm, for instance up to 20 mm. More typically, the height of the mesh portion is up to 10 mm, for instance up to 5 mm or up to 2500 microns.

In some embodiments, the height of the mesh portion is at least 2 mm, for instance at least 5 mm or at least 8 mm. In such embodiments, the height of the mesh portion is up to 50 mm, for instance up to 20 mm. For instance, where the port body (1) is intended for implantation in the skin specifically, the height of the mesh portion may be between 2 mm and 20 mm, preferably from 5 to 15 mm. However, in a preferred embodiment, the height of the mesh portion is from 1000 to 5000 microns, particularly preferably from 1500 to 2500 microns. In a preferred aspect of this embodiment, the port body (1) is intended for implantation in the skin specifically.

The height of the mesh portion is large enough to contain at least one pore. The height of the mesh portion is greater than or equal to the diameter of a pore. Typically, the height of the mesh portion is greater than or equal to two pore diameters or three pore diameters. Also typically, the height of the mesh portion is up to twenty pore diameters or ten pore diameters, for example eight pores. Thus, in some embodiments the height of the mesh portion is from 1 to 10 pore diameters, for example from 2 to 8 or 2 to 5 pore diameters.

Where the pores are arranged in a regular arrangement or lattice, the pores may be regarded as being arranged in layers. In such cases, the mesh height typically contains 1 to 10 layers of pores, for example 2 to 8 or preferably 2 to 5 layers of pores. Preferably, the height of the mesh portion may contain 2, 3, 4 or 5 layers of pores. In such embodiments, the layers of pores may be regarded as a regular arrangement of pores in a lateral plane.

In some embodiments, the height of the mesh portion is approximately equal to an integer number of pores. For example, the height of the mesh portion may be approximately equal to the height of an integer number of layers of pores, such as 1 to 10, 2 to 8 or preferably 2 to 5 layers of pores.

Thus, in some preferred embodiments, the height of the mesh portion is from 1000 to 5000 and the pore size (also referred to as pore diameter) is from 200 to 1000 microns. In a preferred aspect of this embodiment, the diameter of a rib is from 5 to 500 microns. In a further preferred aspect of this embodiment, the height of the mesh portion is from 1 to 10 pore diameters.

In some further preferred embodiments the height of the mesh portion is from 1500 to 2500 microns and the pore size (also referred to as pore diameter) is from 400 to 800 microns. In a preferred aspect of this embodiment, the diameter of a rib is less than 300 microns, for instance from 50 to 200 microns. In a further preferred aspect of this embodiment, the height of the mesh portion is from 2 to 5 pore diameters. It is recognised by those skilled in the art that the transcutaneous port of the invention will be optimised for the particular intended anatomical location of the transcutaneous port. For instance, the size of the transcutaneous port (e.g. the maximum extent of the port in a lateral and a longitudinal direction) may be optimised for the particular intended anatomical location of the port. For instance, one or all of the height of the mesh portion, the pore size, the height of the first impermeable portion, the height of the internal impermeable portion (where present), the lateral cross section and the rib diameter may be optimised.

Where the transcutaneous port of the invention is to be implanted into the skin of a subject, it may be optimised in view of the dermal and epidermal skin layer thickness so as to encourage growth of the dermis into the port body while restricting the space available for epidermal cell growth into the port body or over the external port body. For instance, one or more of the mesh height, the pore size, and the height of the first impermeable portion may be optimised to achieve this.

The transcutaneous port of the invention is preferably made of one or more biologically compatible materials. The material(s) are also preferably strong so that the port is robust and can withstand the stresses placed on it when implanted in a patient. Suitable materials include metals and/or polymeric materials such as plastics. Examples of these materials include titanium, titanium alloys, steel, surgical steel, biopolymers, PEEK, polyethylene, polyurethane, PVC, polypropylene, thermoplastics, nylon, ceramics, acrylates, hydrogels or nitinol. Preferred among these are titanium, surgical steel, and biologically acceptable plastics such as Dacron. Particularly preferred is titanium.

In some embodiments, the transcutaneous port may comprise a cells in a biologically acceptable carrier such as a gel, e.g. a hydrogel. Thus, the transcutaneous port may comprise biological cells, e.g. skin cells.

In a preferred embodiment, at least one of the first impermeable portion, the internal impermeable portion and the mesh portion comprises titanium. In a further preferred embodiment, each of the first impermeable portion, the mesh portion, and where present the internal impermeable portion comprise titanium. In a further preferred embodiment, the port body of the transcutaneous port of the invention comprises at least 80% titanium by weight, for instance at least 90% or at least 95% titanium by weight. Titanium is especially strong and has good biological compatibility.

In a further preferred embodiment, the transcutaneous port of the invention comprises means for receiving sutures. Means for receiving sutures allow the device to be securely attached to the patient before tissue ingrowth has occurred.

Suitable means for receiving sutures are cavities. Thus, in some embodiments the transcutaneous port comprises two or more cavities suitable for receiving sutures. The means for receiving sutures may be attached directly to the port body or to another part of the transcutaneous port. The means for receiving sutures may comprise one or more loops or rings of material externally attached to the first impermeable portion or the mesh portion. Alternatively or additionally, the mesh portion may comprise one or more pores that are sufficiently large to receive sutures. Such pores are typically at least 0.5 mm in diameter, for instance between 0.5 mm and 2 mm in diameter.

The sutures which can be received in the means for receiving sutures may be resorbable or non-resorbable sutures.

In some embodiments, the transcutaneous port of the invention further comprises one or more additional means for anchoring the device in the human or animal body. In some

embodiments, the transcutaneous port comprises means for attaching the device to bone, and/or to soft tissue. For instance, the port may comprise a further mesh portion suitable for allowing the ingrowth of bone and/or soft tissue at the subcutaneous end (2b) of the port body.

Coatings and surface treatments

The transcutaneous port of the invention may comprise a coating and/or a surface treatment. The coating or surface treatment typically imparts an additional desirable property to the port body. For instance, the coating may provide improved biological compatibility, improved tissue integration, improved durability and resistance to corrosion, or anti-infective properties. Thus, in a preferred embodiment, the port body comprises a coating on at least part of its surface. For instance, the mesh portion may comprise a coating. Alternatively or additionally, the first impermeable portion and/or the internal impermeable portion may comprise a coating. In a preferred embodiment, the entire port body is coated. This is particularly convenient as the entire port body may be coated without requiring masking and de-masking to protect parts of the port during coating.

For instance, as discussed above, the first impermeable portion may comprise a coating which discourages tissue growth over its surface and reduces the likelihood of dirt or clothes sticking to it. Suitable coatings include diamond-like carbon. Such coatings may incorporate a biocidal agent. By contrast, as discussed above, the mesh portion and/or the internal impermeable portion may comprise one or more coatings to promote dermal attachment. Thus, the mesh portion and/or the internal impermeable portion may comprise a rough coating such as a coating comprising hydroxyapatatite, e.g. electrodeposited hydroxyapatite.

The mesh portion and/or the internal impermeable portion may alternatively or additionally comprise a coating to encourage tissue growth. Such a coating may comprise one or more growth-promoting agents such as growth factors, proteins (e.g. collagen, keratin, cadherin or fibronectin), growth hormones or biological cells (e.g. stem cells). Such a coating may alternatively or additionally comprise agents to promote the growth of healthy tissue such as antibiotics or biocidal agents. Suitable carriers for such growth promoting agents include gels such as hydrogels, or gels comprising hyaluronic acids. However, it is not necessary to provide a carrier as some species such as proteins can be derivatised and attached directly to the mesh portion and/or the internal impermeable portion. Further, hydroxyapatite has an affinity for proteins and so proteins may be adsorbed within a hydroxyapatite coating on the mesh portion and/or the internal impermeable portion.

To reduce the chance of infection, the coating on the port of the invention preferably comprises a biocidal agent typically a biocidal metal. Suitable biocidal metals include silver, copper, nickel, antimony, barium, bismuth, gold, thallium, tin and zinc. Among these, silver is preferred as it has good biocidal properties and is not particularly soluble in bodily fluids. To improve tissue integration by promoting dermal growth, the coating may comprise one or more proteins. Suitable proteins include cadherin and fibronectin. The coating may further comprise hydroxyapatite to improve tissue integration.

In a preferred embodiment of the invention the transcutaneous port comprises a coating wherein the coating comprises one or more of silver, hydroxyapatite, cadherin or fibronectin.

A coating may be applied by any suitable method including electrochemical treatment or spray-coating. For instance, a hydroxyapatite coating may be applied to all or part of the surface of the port body (1) by depositing thereon a ceramic coating containing

hydroxyapatite by thermal spraying using a plasma spray system. Further species may be applied to the hydroxyapatite coating. For instance, a biocidal metal (such as silver) may be incorporated into the hydroxyapatite coating by contacting the coated or partially coated port body with a solution of a soluble salt of the biocidal metal (e.g. silver).

The method of applying a coating to the port body is not particularly limited. A coating may conveniently be provided on all or part of the port body by spraying, by application as a sol gel, by dip coating, by physical vapour deposition or by chemical vapour deposition.

In a further preferred embodiment, the invention provides a transcutaneous port as described herein wherein the port body (1) comprises a surface treatment on at least part of its surface. The port body may comprise a surface treatment in addition to a coating.

A surface treatment on the port body is the state of the surface resulting from treating the surface by a surface treatment method. An exemplary surface treatment method is a method of incorporating biocidal metals such as silver into the surface of the port body. Thus, in a preferred aspect of this embodiment the port body (1) comprises a surface treatment comprising a biocidal metal selected from silver, copper, nickel, antimony, barium, bismuth, gold, thallium, tin and zinc, preferably silver.

Exemplary methods for providing a surface treatment on a surface are described in WO 2005/087982, WO 2010/112910, WO 2010/112908, WO 2009/044203, WO 2012/095672 and WO 2016/185186, all of which are incorporated herein by reference. Typically, the method for providing a surface treatment on a surface of the port body comprises anodising the port body at a voltage above 50 V for a period of at least 30 min, and then performing ion exchange with a solution of a soluble salt of the biocidal metal so as to incorporate ions of a biocidal metal into the anodised surface. The method may preferably comprise stepping down the voltage or cycling the voltage.

Where the biocidal metal to be incorporated is silver, a preferred method for providing a surface treatment comprising silver on the port body comprises:

(a) immersing the port body comprising a metal in an anodising electrolyte containing a solvent, and passivating the metal to form an anodised integral surface layer on the port body;

(b) continuing the application of a potential to produce pits through the integral surface and into the port body;

(c) producing a hydrous metal oxide or phosphate by

(i) either applying a negative voltage to the port body that has been anodised during steps (a and b) , while in contact with the anodising electrolyte or

(ii) contacting the transcutaneous port that has been anodized during steps (a and b) with an electrolyte solution containing a reducible soluble salt of titanium or the metal of the port body and applying a negative voltage or

(iii) contacting the port body with a chemical reducing agent after steps (a and b); and

(d) removing or separating the anodised port body resulting from step (c) from the anodising electrolyte, the electrolyte solution or chemical reducing agent, and contacting the anodised port body with a solution containing a biocidal material so as to incorporate said biocidal material into the surface layer.

Preferably, step (c) is carried out by either (i) or (ii).

Method of manufacturing the transcutaneous port

The device of the invention may be made by moulding or machining by usual techniques. However, in a particularly preferred embodiment of the invention, the port body is integrally formed. By“integrally formed” is meant that the port body is formed as one entity, rather than by forming the separate parts and joining them together. Thus, in this embodiment the port body does not comprise adhesives. The first impermeable portion is integrally formed with the mesh portion. Where present, the internal impermeable portion is integrally formed with the first impermeable portion and the mesh portion.

In a preferred embodiment of the invention, therefore, the transcutaneous port is integrally formed.

A suitable method of integrally forming the transcutaneous port comprises forming the port body by 3D printing. Typically, 3D printing involves fusing a powdered raw material according to a predetermined design. The fusing of the powder is typically effected by the localised application of heat. Suitable methods of 3D printing are selective laser sintering (SLS), direct metal laser sintering (DMLS), stereolithography (SLA), fused deposition modelling (FDM), multi-jet modelling or polyjet printing. Suitable methods are described in more detail in“Surgical applications of three-dimensional printing: a review of the current literature and how to get started”, Hoang et al. , Ann. Transl. Med., 2016 Dec, 4(23) 456.

According to the method of the invention, the integrally formed device may be subjected to further process steps. For instance, in one embodiment, the method further comprises providing a coating on at least part of the surface of the transcutaneous port. Typically the coating provided in the method comprises one or more of silver, hydroxyapatite, cadherin or fibronectin.

In another embodiment, the method further comprises applying a surface treatment to at least a part of the surface of the port body (1). Typically the surface treatment comprises a biocidal metal, e.g. silver.

An exemplary method of treating the port body to produce a surface treatment thereon comprising silver comprises method steps (a) to (d), described above.

The method may comprise other additional process steps. For instance, the method may comprise applying an additional outer layer such as a portion of flexible mesh to the port body. Method of implanting the transcutaneous port

The transcutaneous port of the invention is suitable for insertion into the human or animal body. The invention therefore provides a method of inserting a transcutaneous port into the human or animal body, wherein the transcutaneous port is as defined above, the method comprising:

making an incision in the skin of the body;

placing the mesh portion in contact with the dermis exposed by the incision; and

placing the first impermeable portion to stand proud of the epidermis at the incision.

An exemplary method for forming an incision in the skin is to use a punch to make a hole for the implant.

By“stand proud” is meant that the first impermeable portion extends out of the skin into the environment.

The body is preferably a human body.

In the method of the invention, the incision made usually requires time to heal. The skin does not immediately grow into the transcutaneous port. Thus, in a preferred embodiment, the method further comprises attaching the transcutaneous port to the body with temporary attachment means. Exemplary temporary attachment means are sutures, for instance dissolvable sutures.

Claims

1. A transcutaneous port comprising:

a port body (1) having an external end (2a) and a subcutaneous end (2b); and

wherein the port body (1) comprises:

a mesh portion (4) extending longitudinally from the subcutaneous end (2b) of the port body (1), which mesh portion (4) extends laterally from an inner mesh surface (4a) to an outer mesh surface (4b) by a thickness T;

wherein T has a value Tl proximate to the first impermeable portion (3) and a value T2 proximate to the subcutaneous end (2b), and Tl is less than T2.

2. A transcutaneous port according to claim 1 wherein T is equal to the shortest distance between the inner mesh surface (4a) and the outer mesh surface (4b) measured along the direction of a straight line in a plane perpendicular to a longitudinal axis of the port body and originating at the longitudinal axis.

3. A transcutaneous port according to claim 1 or claim 2 wherein:

the port body (1) further comprises an internal impermeable portion (6);

the internal impermeable portion (6) is located between the first impermeable portion (3) and the subcutaneous end of the port body (2b) and located at least partly within the mesh portion (4); and

at least one channel (5) extends longitudinally through the internal impermeable portion (6).

4. A transcutaneous port according to claim 3 wherein the internal impermeable portion (6) has a cross-section of area A in a plane perpendicular to the longitudinal axis, wherein A has a value Al proximate to the first impermeable portion (3) and a value A2 proximate to the subcutaneous end (2b), and Al is larger than A2.

5. A transcutaneous port according to claim 3 or 4 wherein the internal impermeable portion (6) is frustoconical and the base of the frustocone is located adjacent to the first impermeable portion (3).

6. A transcutaneous port according to any preceding claim wherein the mesh portion (4) comprises pores with a diameter of 50 to 2000 microns.

7. A transcutaneous port according to any preceding claim wherein the mesh portion (4) comprises pores of 500 to 1250 pm in diameter.

8. A transcutaneous port according to any preceding claim wherein the mesh portion (4) comprises a stiff mesh.

9. A transcutaneous port according to any preceding claim wherein the mesh portion (4) comprises a region of stiff mesh located along all or part of the inner mesh surface (4a) and a region of flexible mesh located along all or part of the outer mesh surface (4b).

10. A transcutaneous port according to any preceding claim wherein the mesh portion (4) comprises a plurality of ribs arranged in a lattice.

11. A transcutaneous port according to claim 10 wherein the lattice comprises a regular arrangement of unit cells.

12. A transcutaneous port according to claim 10 or 11 wherein the lattice is a diamond hexagonal lattice.

13. A transcutaneous port according to any one of claims 10 to 12 wherein at least 90% of the ribs terminate in (i) a vertex with another rib, or (ii) an impermeable portion (3, 6).

14. A transcutaneous port according to any one of claims 10 to 13 wherein the thickness Tl corresponds to the thickness of a single unit cell and the thickness T2 corresponds to the thickness of five or more unit cells.

15. A transcutaneous port according to any preceding claim wherein the first impermeable portion (3) comprises a smooth surface located adjacent to the outer mesh surface 4b.

16. A transcutaneous port according to any preceding claim wherein the mesh portion (4) comprises a rough surface.

17. A transcutaneous port according to any preceding claim wherein each of the first impermeable portion (3), the mesh portion (4) and where present the internal impermeable portion (6) comprise titanium.

18. A transcutaneous port according to any preceding claim wherein the port body (1) comprises a coating on at least part of its surface.

19. A transcutaneous port according to claim 18 wherein the coating comprises one or more of a biocidal metal, hydroxyapatite, cadherin or fibronectin.

20. A transcutaneous port according to any preceding claim wherein the port body (1) comprises a surface treatment incorporating a biocidal metal on at least part of its surface.

21. A transcutaneous port according to any preceding claim wherein the port body (1) has an approximately circular cross-section in all planes perpendicular to the longitudinal axis.

22. A transcutaneous port according to any preceding claim wherein the port body (1) is integrally formed.

23. A transcutaneous port according to any preceding claim wherein the height of the mesh portion (4) is from 1000 to 5000 microns.

24. A method of manufacturing a transcutaneous port comprising a port body (1), wherein the transcutaneous port is as defined in any one of claims 1 to 23, comprising integrally forming the port body (1).

25. A method according to claim 24, wherein the method comprises 3D printing the port body (1).

26. A method according to claim 24 or 25 wherein the method further comprises providing a coating on at least part of the surface of the port body (1), and wherein the coating comprises one or more of a biocidal metal, hydroxyapatite, cadherin or fibronectin.

27. A method according to claim 24 or 25 wherein the method further comprises applying a surface treatment to at least a part of the surface of the port body (1), said surface treatment comprising incorporating a biocidal metal into the surface.

28. A method of inserting a transcutaneous port comprising a port body (1) into the human or animal body, wherein the transcutaneous port is as defined in any one of claims 1 to 23, the method comprising:

making an incision in the skin of the body;

placing at least a part of the first impermeable portion (3) to stand proud of the epidermis at the incision.

29. A method according to claim 28 wherein the method further comprises attaching the transcutaneous port to the body with temporary attachment means.