WO2010127854A2

WO2010127854A2 - Device for treating a shoulder with a severely damaged rotator cuff, and surgical implantation

Info

Publication number: WO2010127854A2
Application number: PCT/EP2010/002784
Authority: WO
Inventors: Benedetto Pinto
Original assignee: Biosurtech S.R.L.
Priority date: 2009-05-06
Filing date: 2010-05-06
Publication date: 2010-11-11
Also published as: ITPI20090054A1; WO2010127854A3; EP2427146A2; IT1394588B1; WO2010127854A4

Abstract

A subacromial spacer (10) is provided as a device for treating a shoulder with a severe or irreparable lesion of the rotator cuff, by keeping a predetermined distance between an acromion and a corresponding humeral head. The subacromial spacer (10) has an articulating surface (11) whose radius of curvature (R) is longer than the radius of curvature of the humeral head of any possible patient, in particular radius (R) is longer than 60 mm, such that articulating surface (11) of subacromial spacer (10) and humeral head (52) reciprocally engage in a substantially punctiform contact, and humeral head (52) and articulating surface (11) roll without sliding with respect to each other. This way, a low friction arrangement is obtained, which drastically reduces articulation wear, i.e. the patient's healthy humeral head wear. The subacromial spacer according to the invention is therefore particularly suitable for treating those patients whose humeral head is not substantially compromised. In a preferred embodiment, a toolkit for implanting subacromial spacer (10) into the subacromial location 1 through a front transdeltoid approach comprises a clamp, and a means for fixing subacromial spacer (10) to acromion (51) comprising a plurality of anchor blades (13). Subacromial spacer (10) is pressed against acromion (51) such that anchor blades (13) penetrates the lower surface (53) of the acromion (51), optionally by deepening respective incisions that are previously made upon the lower surface (53) of the acromion (51). The compression can be obtained by tightening a screw (15), which extends along through hole (55) previously made within the acromion and engages a screw threaded hole 14 of the subacromial spacer (10). The compression may also be obtained by means of a hand press that is constrained to the clamp and has a plate-like pressing element that in use is arranged above the shoulder. The anchor blades (13) may also have transversal through holes (17), which allow bone growth and subsequent joining of bone edges of incisions (54), to provide a secondary stabilization step of subacromial spacer (10).

Description

TITLE

DEVICE FOR TREATING A SHOULDER

WITH A SEVERELY DAMAGED ROTATOR CUFF,

AND SURGICAL IMPLANTATION INSTRUMENTS THEREFOR DESCRIPTION

Field of the invention

The present invention relates to a device for the articulation of a shoulder affected by irreparable lesion of the rotator cuff, i.e. a lesion of the group of muscles and tendons that act to stabilize a shoulder. The invention also relates to a toolkit for implanting the device into a subacromial location.

Background of the invention

As well known, a high number of degrees of freedom is allowed between each arm and the trunk of a human body by the shoulder articulations. The main articulation of a shoulder is the glenohumeral joint, which comprises the humeral head and the glenoid cavity or glenoid fossa of the scapula.

The stability of the glenohumeral joint is assured by a rotator cuff, which is a muscle structure that comprises the end portions of subscapularis, supraspinatus, subspinatus and teres minor muscles; the rotator cuff extends between front, rear and upper sides of the humeral head, and the acromion process of the scapula, or briefly the acromion.

The rotator cuff stabilizes the humeral head by contrasting the action exerted by the deltoid muscle that, during elevation of the arm, tends to displace the humeral head according to a cranial direction. In case of an irreparable damage of the rotator cuff, which may have been caused by an accident as well as by an articular disease, the humeral head tends to migrate upwards, and a consequent sub-acromial impingement takes place, i.e. a condition in which the humeral head scrapes the acromion. In particular, such a condition hinders the abduction movement of the arm, or makes it painful. Besides, a serious sufferance of the cartilaginous tissue arises, which is likely degenerate into arthritis. In case of a severe to irreparable lesion of the rotator cuff, in particular in case of an irreparable damage of the supraspinatus muscle, the common practice at most consists in an immediate and/or periodic physiotherapy treatment; when an arthritic degenerative process of the articulation has reached such a level that cannot be no longer tolerated by the patient, which may occur after some to several years, a replacement of the patient's shoulder articulation with a prosthesis is normally necessary. In fact, no treatment is available which is adapted to avoid a degenerative process of a substantially healthy shoulder articulation in case of a severe or irreparable lesion of the rotator cuff.

US 5,944,757 relates to a total trochitero-achromial shoulder prosthesis comprising a trochiterian element which has the shape of a convex spherical sector and is equipped with a means for fastening to the site of the trochiter, and an acromial element which has a bearing surface for the trochiterian element and is equipped with a means for fastening to the lower face of the acromion; the acromial element is configured to cover the trochiterian element and is dimensioned to remain free to move, without overshooting the clavicule, as one with the acromion, which has been sectioned at the level of the scapular spine. The device is aimed at restoring the freedom of movement of a shoulder and to eliminate the pain due to mechanical and rheumatic disorders, as in case of scapulo-humeral periarthritis and of rupture of the rotator cuff rupture, which lead to unnatural articulation between the acromion and the trochiter.

FR 2 541 890 discloses a total shoulder prosthesis comprising a humeral element which has an egg-shaped head integral to a stem for fixation within the humerus, and a large-radiused central portion between an internal and an external narrow-radiused hemispherical end portions, and an acromial-glenoidal element which has a spherical shape whose axis passes through the centre of the glenohumeral joint, and whose diameter is at least equal to the diameter of the central portion of the egg-shaped head to which the glenoidal element provides a rotation supporting surface; the acromial-glenoidal element is large enough to support and to be fixed to the acromion, to the basis of the coracoid process as well as to the borders of the scapula. US 4,550,450 discloses a total shoulder replacement arthroplasty system which encompasses replacement of the articular surface of the humerus and adjacent glenoid articular surface with a humeral component having a convex surface and a shallow trapezoidal fixation keel and with a concave overmounted glenoid component having a similar keel. The lower face of the acromion is resurfaced with an acromial component for replacement of the acromial clavicular joint.

Various devices are known for contrasting the cranial migration of the humeral head that takes place when the rotator cuff of a patient has been irreparably damaged. All these devices comprise a prosthesis to be implanted between the lower surface of the acromion and the humeral head, i.e. into a subacromial location. However, the prior art devices show at least one of the following drawbacks: a replacement of the patient's humeral head is required, as in the case of the devices disclosed in US 5,944,757, FR 2 541 890 and possibly also a replacement of the glenoid articulating surface, as it is disclosed in US 4,550,450; such devices are not suitable for treating a patient whose glenohumeral articulation is not compromised, for instance, a substantially healthy patient whose rotator cuff has been seriously injured in an accident; - the patient's shoulder articulation is assimilated to or replaced with a spherical joint, which cannot provide a number degrees of freedom suitable for reproducing the natural movement of the shoulder, in particular the adduction and abduction movements of the shoulder. This is still the case of the device disclosed in US 4,550,450 and of the device disclosed in DE 10164328; - all the above mentioned documents disclose shoulder articulation prosthesis, in which the articulating surfaces slide on each other according to a substantially spherical joint, and unavoidably are worn, as in the case of US 6,712,854 and of DE 10164328.

Summary of the invention It is therefore an object of the present invention to provide device for treating a patient who has a severe lesion of the rotator cuff, to maintain a physiological distance between the acromion and the patient's healthy humeral head, in case of severe lesion of the rotator cuff. - A -

It is also an object of the present invention to provide a device which is adapted to treat such a patient, whose glenohumeral joint is not compromised and the replacement of a member of the articulation is not necessary or advisable. It is another object of the invention to provide such a device, which prevents the patient's healthy humeral head from being worn due to the contact and to the relative movement between the humeral head and the device.

It is also an object of the present invention to provide such a device which does not substantially hinder the natural movement of the shoulder.

It is a particular object present invention to provide such a device which does not substantially limit abduction and adduction movements of the patient's arm .

It is another object of the invention to provide a device that can be easily manufactured, and that is adapted to engage without significant interference with a patient's healthy humeral head and that can be easily fixed to the acromion.

It is also a further object of the invention to provide such a device, and a toolkit to implant the device into a subacromial location through a minimally invasive approach.

These and other objects are achieved by a subacromial spacer that is adapted to be arranged in a subacromial location between an acromion and a healthy humeral head of a patient, the spacer comprising:

— an articulating surface suitable for cooperating with the healthy humeral head;

— a fastening means for fastening the spacer to the acromion; wherein the articulating surface has a radius of curvature such that the articulating surface engages the healthy humeral head in a substantially punctiform contact. This way, the subacromial spacer and the healthy humeral head does not substantially slide upon each other but roll on each other, contrary to what happens in the case of the prior art devices; this feature drastically reduces the friction between the spacer and the patient's healthy humeral head, as well as humeral head wear . Moreover, the subacromial spacer according closely fits the patient's humeral head of the, in all the cases when the shoulder articulation is substantially healthy and only a severe or irreparable lesion of the rotator cuff is present. Moreover, it is not necessary to know the topography of the humeral head surface, as disclosed in the prior art, where the known prosthesis has be made by a CAM tool to match the humeral head surface.

Advantageously, the radius of curvature is not less than 60 mm at any contact point thereof. The radius of curvature is, in fact, widely larger than the humeral head of any patient.

Advantageously, the fastening means comprises anchor blades that are adapted to make an incision in the acromion, by a compression of the spacer against the acromion, in particular the anchor blades arranged symmetrically with respect to a midplane of the spacer. The incision can be obtained by pressing a so-called "phantom" cutting template against the acromion.

Preferably, the anchor blades have transversal through holes, the transversal through holes adapted to allow the growth of bone tissue through them, which results into a secondary stabilization of the spacer. The subacromial spacer may comprise a screw and a screw threaded hole that is made on a fixing surface opposite to the articulating surface, wherein the screw is adapted to engage with the screw threaded hole and to attain the screw threaded hole on the fixing surface of the spacer via a through hole of the acromion, provided the subacromial spacer is placed in the subacromial location such that the through hole is suitably aligned with the through hole of the acromion. This way, by tightening the screw, the fixing surface of the subacromial spacer is pressed against the lower surface of the acromion, and the anchor blades penetrate the lower surface of the acromion, until a fastening arrangement of the subacromial spacer to the acromion is achieved. In particular, the screw threaded hole of the subacromial spacer is a blind hole.

Preferably, the spacer has such a thickness that the predetermined distance is set between 4 and 12 millimetres, the thickness measured excluding the height of the fastening means for fixing the spacer to the acromion. In particular, the thickness of the spacer is selected from the group comprised of 5, 7, 9 and 11 millimetres. This way, the spacer according to the invention is suitable for insertion within a subacromial space of any age and/or size patient. Advantageously, any cross section of the spacer can be contained within a 20 to 30 mm x 14 to 20 mm rectangle. In particular, the cross section can be contained within a 23 to 27 mm x 15 to 28 mm rectangle. Preferably, the subacromial spacer has rounded corner rectangular or elliptic cross section.

To improve biological acceptance of the spacer, the spacer may be made of an alloy of cobalt, copper and molybdenum.

Similarly, to enhance biomechanical compatibility of the spacer and the patient's humeral head, the articulating surface may have a metal coating, preferably a lapped metal coating. Advantageously, the metal coating may be a Titanium coating, in particular a Titanium coating deposited by Vacuum Plasma Spraying (TiVPS) technique.

In alternative, the coating may be made of a ceramic material, or of a PEEK(polietherterketone) -based material.

In order to cause the anchor blades penetrate the acromion, a kit is provided which comprises the above spacer, and also comprises: — a positioning means for bringing and for releasing the spacer in the subacromial location, the positioning means having:

— a clamping end portion suitable for clamping the spacer and adapted to be inserted into the shoulder of the patient, in particular, through a frontal trans deltoid approach, for bringing the spacer at the subacromial location;

— a holding end portion for guiding the positioning means;

— a pressing means for providing the compression of the spacer against the acromion.

In a particular exemplary embodiment, the positioning means and the pressing means of the kit are provided by a pliers, said clamping end portion arranged integral to the load arm of a first lever of the pliers, a pressing means that has a pressing surface arranged integral to the load arm of a second lever of the pliers, the holding end portion and the pressing means provided by respective effort arms of the first lever and of the second lever, the clamping end portion in use arranged at the subacromial location, the pressing surface in use arranged resting upon the shoulder of the patient, such that the compression of the spacer against the acromion is carried out by operating the pliers. Preferably, the pliers comprise a resilient opening means and a locking means for locking the pliers in a predetermined relative position of the first lever with respect to the second lever.

In particular, the positioning means of the kit comprises a clamp in which the clamping end portion and the holding end portion are opposite end portions of the clamp which has a central portion between the clamping end portion and the holding portion, the intermediate portion comprising a bent portion, such that the subacromial location can be reached through the frontal trans deltoid approach contouring the side portion of a shoulder which is not concerned by the access. This way, a same clamp can be used for treating both a right shoulder and a left shoulder, provided the clamp is properly oriented about its own longitudinal axis.

Preferably, the clamp is made of a material selected from the group comprised of stainless steel and an aluminium alloy.

In particular, the pressing means of the kit comprises a hand press that comprises:

— a hand press screw having a manoeuvre end portion;

— a headframe comprising:

— an elongated female screw element that houses the hand press screw and is rotatably engaged by the screw of the hand press; — an extension member of the elongated female screw element comprising a transverse portion, which is substantially perpendicular to the elongated female screw element, and a longitudinal portion which extends according to the direction of the elongated female screw element,

— a substantially plate-like pressing element that is in use arranged according to a plane that is substantially perpendicular to the screw.

The holding end portion of the clamp and the substantially plate-like pressing element suitable for engaging, respectively, a holding end portion of the screw opposite to the manoeuvre end portion and the extension member of the elongated female screw element, or vice versa, such that the spacer, which is held in use by the holding end portion of the clamp, and the substantially plate-like pressing element have substantially aligned axis, such that by operating the manoeuvre end portion it is possible to adjust the relative position of the substantially plate-like pressing element and of the clamp, bringing the hand press from an open position, in which the substantially plate-like pressing element is more distant from the clamp to a closed position, in which the substantially plate-like pressing element is closer to the clamp, thus performing the compression of the spacer against the acromion, and vice-versa. In particular, the substantially plate-like pressing element engages a hollow seat of the transverse portion of the extension member of the elongated female screw element through a hollow support, and the through hole is made on the acromion when the spacer is placed in the subacromial location, by means of a drilling tool that is introduced through respective aligned holes of the seat, of the support and of the substantially plate-like pressing element.

This way, by operating the manoeuvre end portion it is possible to adjust a relative position of the substantially plate-like pressing element and of the clamp, bringing the hand press from an open position in which the substantially plate-like pressing element is more distant from the clamp to a closed position, in which the substantially plate-like pressing element is closer to the clamp, thus performing the compression of the spacer against the acromion, and vice- versa. According to this procedure, the subacromial spacer is fastened to the acromion by means of the screw and of the at least one threaded hole, which has not to be centred with a respective through hole of the acromion. Advantageously, the toolkit comprises also a surgical file, which is adapted to be inserted through the front transdeltoid approach, for preparing preliminary notches to be penetrated by the anchor blades of the subacromial spacer.

Brief description of the drawings The invention will be made clearer with the following description of an exemplary embodiment thereof, exemplifying but not limitative, with reference to the attached drawings wherein: Fig. 1 shows two perspective views of the spacer according to the invention;

- Fig. 2 shows a clamp of a toolkit for implanting the spacer according to the invention; - Fig. 3 shows the clamping end portion of the clamp of Fig. 2 engaged with a spacer according to an exemplary embodiment alternative to the embodiment of Fig. 1 ;

Fig. 4 diagrammatically shows an implant of the spacer of the invention within a subacromial location, according to a first implant procedure, which provides fixing the spacer to the acromion by means of a screw;

- Fig. 5 shows a pliers for implanting the spacer of Fig. 1 and 2;

Fig. 6 shows an embodiment of the hand press for implanting the spacer of Fig. 1 and 2;

Fig. 7 shows another embodiment of the hand press for implanting the spacer of Fig. 1 and 2, alternatively.

Description of a preferred exemplary embodiment

Fig. 1 shows a subacromial spacer 10, according to the invention, which is suitable for insertion into a subacromial location 1 , i.e. between an acromion 51 and a healthy humeral head 52 of a shoulder of a patient (Fig. 4). Subacromial spacer 10 has an articulating surface 11 that articulates with humeral head 52. Subacromial spacer 10 has such a thickness S that, when subacromial spacer 10 is connected to acromion 51 within subacromial location 1 , articulating surface 11 is arranged at a predetermined distance S' from acromion 51. Thickness S is preferably set between 4 and 12 mm, in particular thickness S is 5 or 7 or 9 or 11 mm.

At each point where articulating surface 11 engages humeral head 52, articulating surface 11 has a radius of curvature R that is larger than the radius of curvature T of a healthy humeral head 52 of any human patient. This way, once subacromial spacer 10 has been implanted into subacromial location 1 , articulating surface 11 of subacromial spacer 10 and humeral head 52 reciprocally engage in a substantially punctiform contact, and humeral head 52 and articulating surface 11 roll without sliding upon each other. Radius of curvature R of articulating surface 11 is preferably larger than 60 mm, which may be regarded as a maximum curvature of a humeral head 52.

In a preferred embodiment, subacromial spacer 10 has substantially a rounded corner rectangular shaped cross section. In use, subacromial spacer 10 has longer faces 18 arranged substantially parallel to the coronal plane of the patient. Longer faces 18 have a length L which is preferably set between 23 and 27 mm, in particular length L is about 25 mm. The shorter faces 19 of subacromial spacer 10 have a length I which is preferably set between 15 and 18 mm, in particular length I is about 16 mm. In another embodiment, a subacromial spacer 20 is provided (Figs. 2 and 3), which has substantially elliptical cross section, whose longer and shorter axes respectively have length L and I, as above described.

Subacromial spacer 10 or 20 is preferably made of a cobalt-copper- molybdenum alloy. Articulating surface 11 may have a ceramic coating; in alternative articulating surface 11 may have a metal coating, preferably a lapped or specularly-finished metal coating. In particular, the metal coating is a Titanium coating, most preferably a Titanium coating deposed by Vacuum Plasma Spraying (TiVPS) technique. The above materials provides a maximum biomechanical compatibility of subacromial spacer 10,20 with the implant subacromial location, in particular the coating material and the structure of articulating surface 11 minimizes friction between articulating surface 11 and humeral head 52.

In order to fasten subacromial spacer 10,20 to a lower surface 53 of acromion 51 , subacromial spacer 10,20 has a plurality of anchor blades 13, protruding out of fixing surface 11 ' opposite to articulation surface 11. In the embodiment of Figs, four blades 13 are provided, which are symmetrically arranged with respect to an axis of symmetry 12 of the spacer 10,20. Anchor blades are conceived to be inserted into acromion 51 by reciprocally pressing subacromial spacer 10 or 20 and acromion 51 against each other, such that anchor blades 13 create respective incisions of surface 53, or penetrate and preferably deepen preformed, suitably shaped respective notches of surface 53. The fastening means of subacromial spacer 10 (Fig. 1 ) to acromion 51 comprises also at least one preferably blind screw threaded hole 14, that is accessible from fixing surface 11 ', and a screw 15 (Fig. 4) that is adapted to engage with screw threaded hole 14.

The invention also provides a toolkit for fastening subacromial spacer 10 or 20 to acromion 51 , by pressing spacer 10 or 20 and acromion 51 against each other. The toolkit comprises a preferably stainless steel or aluminium alloy clamp 30, a conventional screw driving means for driving screw 15, and possibly general surgical tools. Clamp 30 is shown in Fig. 2 and, more in detail, in Fig. 3, and extends along a plane between a holding end portion 31 and a clamping end portion 32 opposite to the holding end portion 31. Clamp 30 is suitable for: clamping and holding subacromial spacer 10 or 20

- entering subacromial location 1 through a shoulder opening, in particular through a minimally invasive front transdeltoid approach,

- releasing subacromial spacer 10 or 20 at subacromial location 1. Clamp 30 comprises two halves that are rotatably arranged with respect to each other by a common hinge 36, to allow clamping a couple of lateral grooves 18' (Fig. 1) that are made on longer faces 18 of subacromial spacer 10 or 20, and to allow subsequent releasing of subacromial spacer 10 or 20. A central portion 33 between end portions 31 and 32 of clamp 30 has a curve 34, such that subacromial location 1 can be reached by clamping end portion 32 and subacromial spacer 10 or 20 through a front transdeltoid approach avoiding a side portion 3 of the shoulder. Clamp 30 can be used for implanting spacer 10 or 20 both in a right shoulder and in a left shoulder, provided that clamp 30 is properly oriented about its own longitudinal axis 35. According to a first implant procedure, two shoulder openings are required to implant subacromial spacer 10 or 20, i.e a first front transdeltoid approach and a second top approach, which is made above the shoulder. The transdeltoid approach is used to carry out the preliminary steps of: moving humeral head 52 and acromion 51 away from each other, and, possibly, providing preliminary notches upon lower surface 53 of acromion 51 , according to a pattern which corresponds to anchor blades 13; the preliminary notches may be made by means of a conventional surgical file; the top approach is used, instead, to carry out a step of piercing acromion 51 , wherein a through hole 55 is made through acromion 51 , wide enough for receiving screw 15 (Fig. 4); the implant procedure also provides a step of arranging subacromial spacer 10 at clamping end portion 32 of clamp 30 (Fig. 3), and, once more through the transdeltoid approach, steps of

- introducing and placing clamp 30 with subacromial spacer 10 into subacromial location 1 , wherein subacromial spacer 10 is moved within subacromial location 1 until blind screw threaded hole 14 is aligned with through hole 55 of acromion 51 ; - inserting through the top opening of the shoulder and through hole 55 of acromion 51 , until screw 15 properly engages with blind screw threaded hole

14 of subacromial spacer 10; fastening subacromial spacer 10 to acromion 51 by manoeuvring on a holding end portion 16 of screw 15, wherein a pressing of the subacromial spacer 10 and acromion 51 against each other takes place, and anchor blades

13 penetrate and deepens the preliminary notches upon lower surface 53 of acromion 51 ;

- disengaging subacromial spacer 10 from clamp 30 and releasing it in subacromial location 1 ; - extracting clamp 30 from the shoulder of the patient.

Anchor blades 13 have preferably transversal through holes 17, which allows bone growth and subsequent joining of bone edges of incisions 54, which provides a secondary, long lasting stabilization step of subacromial spacer 10 or 20. In alternative, the implant of the spacer according to the invention can be carried out by using only a front transdeltoid approach. In this case, a toolkit is provided, according to the invention, comprising a pliers 80 that is diagrammatically shown in Fig. 5. Pliers 80 has a couple of levers 81 and 82, whose load arms 78,79 respectively have clamping end portion 32 for clamping and holding subacromial spacer 20 and a pressing surface 84.

A second implant procedure comprises the step of pressing spacer 10 or 20 and lower surface 53 of acromion 51 against each other.

Construction of pliers 80 is such that clamping end portion 32 and spacer 20 can be brought into subacromial location 1 , and at the same time pressing surface 84 can be arranged upon the shoulder of the patient. By clenching effort arms 85,86 of levers 81 ,82 a compression of spacer 20 against acromion 51 is obtained.

One or more bending springs 87 may be provided for retaining pliers 80 in an open state, along with a locking means 88 for locking pliers 80 in a prefixed opened position, in order to maintain the compression between subacromial spacer 10 and acromion 51.

With reference to Figs. 6 and 7, the toolkit may comprise a hand press 60 and/or 90 to carry out the step of pressing subacromial spacer 10 or 20 and acromion 51 against each other. Hand press 60 and 90 comprise a screw 61 provided with a manoeuvre end portion 62; screw 61 of hand press 60 is housed in a nut screw 64, from which an extension member 65 extends that has a transverse portion 67 and a longitudinal portion 68, respectively substantially perpendicular and parallel to nut screw 64. A third implant procedure provides the preliminary steps of: locking subacromial spacer 10 or 20 in clamping end portion 32 of clamp 30, and

- assembling clamp 30 on hand press 60 or 90. To this end, holding end portion 31 of clamp 30 is adapted to integrally engage with longitudinal portion 68 of extension member 65 of hand press 60 and/or with a holding end portion 63 opposite to manoeuvre end portion 62 of screw 61 of hand press 90. A plate-like pressing element 66 is adapted to engage with holding end portion 31 of screw 61 and/or in case with transverse portion 67 of extension member

65 of hand press 90. In the latter case, a hollow cylindrical support 69 is provided which can be inserted in a hollow seat 74 of the housings slots that are made along transverse portion 67. The axis of plate-like pressing element

66 and the axis of subacromial spacer 10 or 20 are substantially aligned, in particular screw threaded hole 14 of subacromial spacer 10, when mounted on hand press 90, has its axis aligned with the axis of cylindrical hollow support 69 of plate-like pressing element 66.

The third implant procedure comprises, furthermore, the steps of: introducing clamping end portion 32 of clamp 30 into subacromial location 1 through transdeltoid approach, subacromial spacer 10 or 20 locked at clamping end portion 32; arranging subacromial spacer 10 or 20 at subacromial location 1 ;

- arranging plate-like pressing element 66 above the shoulder of the patient;

- pressing subacromial spacer 10 or 20 and acromion 51 against each other; during this step, the distance between subacromial spacer 10 or 20 and plate-like pressing element 66 is gradually reduced, by manoeuvring manoeuvre end portion 62 of screw 61 of hand press 60 or 90. In case of hand press 60, nut screw 64 and extension member 65 are fixed with respect to subacromial location 1 , and plate-like pressing element 66, which is integral to screw 61 , is brought nearer subacromial spacer 10. In case of hand press 90, the position of screw 61 does not change with respect to subacromial location 1 , whereas nut screw 64 and extension member 65 moves towards the shoulder of the patient and plate-like pressing element 66 is brought nearer subacromial spacer 10. In both cases, a connection is created between subacromial spacer 10 or 20 and acromion 51 by means of anchor blades 13 (Figs. 1 and 3), as already described.

In the case of hand press 90 a step is also provided of making a through hole 55 within acromion 51 (Fig. 4) by means of a piercing tool, for example a boring tool 70 of a drill, not shown, boring tool 70 is inserted into a top approach of the shoulder through hollow seat 74, through hollow support 69 of plate-like pressing element 66 and through a hole made through plate-like pressing element 66; internal centring means, not shown, are provided within hollow support 69 for centring boring tool 70 with respect to screw threaded hole 14 of subacromial spacer 10 (Fig. 1 ). If through hole 55 is drilled during the implant, instead of before introducing spacer 10 or 20 into subacromial location it is preferable to use subacromial spacer 10, which is provided with screw threaded hole 14: in this case it is not necessary to align at the moment of the implant screw threaded hole 14 with and previously made hole 55. In this case, the subsequent fastening step of spacer 10 to acromion 51 is carried out by tightening screw 15, which extends along through hole 55 and engages screw threaded hole 14, such that a compression of subacromial spacer 10 against lower surface 53 of acromion 51 is obtained, which stabilizes the connection of subacromial spacer 10 and acromion 51. A secondary stabilization of the implant, which is a long lasting process, comprises the formation of bone tissue through transversal holes 17 of anchor blades 13, wherein bone edges of incisions 54 are joined together.

By means of hand press 60 it is possible to implant spacer 20, shown in Fig. 3, according to an exemplary embodiment thereof in which no screw threaded hole 14 (Fig. 1 ) may be present, and anchor blades 13 may form a continuous cross-shaped blade (Fig. 3), whose arms extend along the planes of symmetry of spacer 20. Hand press 90, instead, is preferred when a subacromial spacer 10 having at least one blind screw threaded hole 14 has to be implanted.

Transverse portion 67 of extension member 65 has engagement seats 74 for insertion of screw 61 of hand press 60 and/or of hollow support 69 of plate- like pressing element 66; similarly, longitudinal portion 68 of hand press 60 has engagement seats 75 for integrally joining clamp 30, while longitudinal portion 68 of hand press 90, has a longitudinal groove 76 to allow clamp 30 to move along longitudinal portion 68 when moving it along transverse portion 67. Engagement seats 74 and 75 are chosen responsive to the size of the shoulder where the implant has to be carried out.

The foregoing description of specific embodiments will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such embodiments without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. The foregoing description of specific embodiments will so fully reveal the invention according to the conceptual point of view, so that others, by applying current knowledge, will be able to modify and/or adapt for various applications such embodiments without further research and without parting from the invention, and it is therefore to be understood that such adaptations and modifications will have to be considered as equivalent to the specific embodiments. The means and the materials to realise the different functions described herein could have a different nature without, for this reason, departing from the field of the invention. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Claims

1. A spacer (10,20) suitable for being arranged in a subacromial location (1 ) between an acromion (51 ) and a healthy humeral head (52) of a patient, said spacer (10,20) comprising: — an articulating surface (11 ) suitable for cooperating with said healthy humeral head (52);

— a fastening means for fastening said spacer (10,20) to said acromion (51 ), such that said articulating surface (11 ) is arranged at a predetermined distance from said acromion (51 ) when said spacer (10,20) is fastened to said acromion (51 ), wherein said articulating surface (11 ) has a radius of curvature (R) such that said articulating surface (11 ) engages said healthy humeral head (52) in a substantially punctiform contact.

2. A spacer (10,20) according to claim 1 , wherein said radius of curvature (R) is not less than 60 mm at any contact point.

3. A spacer (10,20) according to claim 1 , wherein said fastening means comprises anchor blades (13) that are adapted to make an incision in said acromion (51 ) by a compression of said spacer (10,20) against said acromion (51), in particular said anchor blades (13) are arranged symmetrically with respect to a midplane of said spacer (10,20).

4. A spacer (10,20) according to claim 3, wherein said anchor blades (13) have transversal through holes (17), said transversal through holes (17) adapted to allow the growth of bone tissue through said transversal through holes (17).

5. A spacer (10) according to claim 3, wherein said subacromial spacer comprises at least one screw threaded hole (14), in particular a blind screw threaded hole (14) that is accessible opposite of said articulating surface (11 ), and can be associated to a screw (15) that is suitable for engaging with said at least one screw threaded hole (14) via a respective through hole (55) that is made through said acromion (51 ), said at least one screw threaded hole (14) and said respective through hole (55) arranged substantially aligned such that by tightening said screw (15), said spacer is pressed against said acromion (51 ), and the introduction of said anchor blades (13) into said bone tissue is assisted.

6. A spacer (10,20) according to claim 1 , said spacer (10,20) having a thickness (S) such that said predetermined distance is set between 4 and

12 millimetres,

7. A spacer (10,20) according to claim 1 , said spacer (10,20) having a a thickness (S) selected from the group comprised of: 5, 7, 9 and 11 millimetres, said thickness (S) measured excluding the height of said fastening means.

8. A spacer (10,20) according to claim 1 , wherein any cross section of the spacer is contained within a 20 to 30 mm x 14 to 20 mm rectangle, in particular, the cross sections is contained within a 23 to 27 mm x 15 to 28 mm rectangle.

9. A spacer (10,20) according to claim 1 , wherein the subacromial spacer has rounded corner rectangular or elliptic cross section.

10. A spacer (10,20) according to claim 1 , wherein the articulating surface has a coating selected from the group comprised of:

— a metal coating, in particular a lapped metal coating; — a ceramic material coating

— a PEEK(polietherterketone) -based material coating.

11. A spacer (10,20) according to claim 10, wherein the metal coating is a Titanium coating deposited by Vacuum Plasma Spraying technique.

12. A toolkit for implanting said spacer (10,20), as defined in claim 3, in said subacromial location (1 ), said toolkit comprising:

— a positioning means (30,80) for bringing and for releasing said spacer (10,20) in said subacromial location (1 ), said positioning means (30,80) having:

— a clamping end portion (32,78) suitable for clamping said spacer (10,20) and adapted to be inserted into said shoulder of said patient, in particular, through a frontal trans deltoid approach, for bringing said spacer (10,20) at said subacromial location (1 ); — a holding end portion (31 ,85,86);

— a pressing means for providing said compression of said spacer (10,20) against said acromion (51 ).

13. A toolkit according to claim 12, wherein said positioning means and said pressing means are provided by a pliers (80), said clamping end portion

(32) arranged integral to the load arm (78) of a first lever (81 ) of said pliers (80), a pressing means (83) that has a pressing surface (84) arranged integral to the load arm (79) of a second lever (82) of said pliers (80), said holding end portion and said pressing means provided by respective effort arms (85,86) of said first lever (81 ) and of said second lever (82), said clamping end portion arranged in use at said subacromial location (1 ), said pressing surface (84) arranged in use resting upon said shoulder of said patient, such that said compression of said spacer (10,20) against said acromion (51 ) is carried out by operating said pliers (80), in particular, said pliers (80) comprising an elastic recall opening means (87) and a locking means (88) for locking said pliers in a predetermined relative position of said first lever (81 ) with respect to said second lever (82).

14. A toolkit according to claim 13, wherein said positioning means comprises a clamp (30) in which said clamping end portion and said holding end portion are opposite end portions of said clamp, which has an intermediate portion (33) between said clamping end portion (32) and said holding end portion (31 ), said intermediate portion (33) comprising a bent portion (34), such that said subacromial location (1 ) can be reached through said frontal trans deltoid approach contouring the side portion of a shoulder which is not concerned by said access.

15. A toolkit according to claim 14, wherein said pressing means is provided by a hand press (60,90) comprising: — a hand press screw (61 ) having a manoeuvre end portion (62);

— a headframe comprising:

— an elongated female screw element (64) that houses said hand press screw (61 ) and is rotatably engaged by said screw (61 ) of said hand press (60);

— an extension member (65) of said elongated female screw element (64) comprising a transverse portion (67), which is substantially perpendicular to said elongated female screw element (64), and a longitudinal portion (68) which extends according to the direction of said elongated female screw element (64), — a substantially plate-like pressing element (66) that is arranged in use according to a plane that is substantially perpendicular to said screw (61 ); said holding end portion (31 ) of said clamp (30) and said substantially plate-like pressing element (66) suitable for engaging, respectively, a holding end portion (63) of said screw (61) opposite to said adjusting end portion (62) and said extension member (65) of said elongated female screw element (64), or vice versa, such that said spacer (10,20), which is held in use by said holding end portion (32) of said clamp (30), and said substantially plate-like pressing element (66) have substantially aligned axis, in particular, said substantially plate-like pressing element (66) engaging a hollow seat (74) of said transverse portion (67) of said extension member (65) of said elongated female screw element (64) through a hollow support (69), and said through hole (55) is made in said acromion (51 ) when said spacer (10) is placed in said subacromiale location (1 ), by means of a boring tool (70) that is introduced through respective aligned holes of said seat (74), of said support (69) and of said substantially plate-like pressing element (66), such that by operating said manoeuvre end portion (62) it is possible to adjust a relative position of said substantially plate-like pressing element (66) and of said clamp (30), bringing said hand press (60) from an open position in which said substantially plate-like pressing element (66) is more distant from said clamp (30) to a closed position, in which said substantially plate-like pressing element (66) is closer to said clamp (30), thus performing said compression of said spacer (10,20) against said acromion (51 ), and vice versa.