WO2016181168A1 - Talus prosthesis - Google Patents
Talus prosthesis Download PDFInfo
- Publication number
- WO2016181168A1 WO2016181168A1 PCT/GB2016/051396 GB2016051396W WO2016181168A1 WO 2016181168 A1 WO2016181168 A1 WO 2016181168A1 GB 2016051396 W GB2016051396 W GB 2016051396W WO 2016181168 A1 WO2016181168 A1 WO 2016181168A1
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- WIPO (PCT)
- Prior art keywords
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- prosthesis according
- prosthesis
- bone
- talus
- Prior art date
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Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2/42—Joints for wrists or ankles; for hands, e.g. fingers; for feet, e.g. toes
- A61F2/4202—Joints for wrists or ankles; for hands, e.g. fingers; for feet, e.g. toes for ankles
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
- A61F2002/30316—The prosthesis having different structural features at different locations within the same prosthesis; Connections between prosthetic parts; Special structural features of bone or joint prostheses not otherwise provided for
- A61F2002/30329—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
- A61F2002/30331—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements made by longitudinally pushing a protrusion into a complementarily-shaped recess, e.g. held by friction fit
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
- A61F2002/30316—The prosthesis having different structural features at different locations within the same prosthesis; Connections between prosthetic parts; Special structural features of bone or joint prostheses not otherwise provided for
- A61F2002/30329—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
- A61F2002/30476—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements locked by an additional locking mechanism
- A61F2002/30507—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements locked by an additional locking mechanism using a threaded locking member, e.g. a locking screw or a set screw
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
- A61F2002/30316—The prosthesis having different structural features at different locations within the same prosthesis; Connections between prosthetic parts; Special structural features of bone or joint prostheses not otherwise provided for
- A61F2002/30535—Special structural features of bone or joint prostheses not otherwise provided for
- A61F2002/30604—Special structural features of bone or joint prostheses not otherwise provided for modular
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2/30767—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
- A61F2/30771—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves
- A61F2002/30878—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2/42—Joints for wrists or ankles; for hands, e.g. fingers; for feet, e.g. toes
- A61F2/4202—Joints for wrists or ankles; for hands, e.g. fingers; for feet, e.g. toes for ankles
- A61F2002/4207—Talar components
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2/42—Joints for wrists or ankles; for hands, e.g. fingers; for feet, e.g. toes
- A61F2/4202—Joints for wrists or ankles; for hands, e.g. fingers; for feet, e.g. toes for ankles
- A61F2002/4212—Tarsal bones
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
- A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
- A61F2/02—Prostheses implantable into the body
- A61F2/30—Joints
- A61F2/42—Joints for wrists or ankles; for hands, e.g. fingers; for feet, e.g. toes
- A61F2/4202—Joints for wrists or ankles; for hands, e.g. fingers; for feet, e.g. toes for ankles
- A61F2002/4212—Tarsal bones
- A61F2002/422—Medial row of tarsal bones
Definitions
- the invention relates to an ankle prosthesis, particularly a talus prosthesis for ankle arthroplasty.
- ankle arthrodesis The current standard treatment of talus AVN is ankle arthrodesis, subtalar arthrodesis and pantalar arthrodesis.
- a problem with fusion of the ankle joint is that it can cause an increased rate of subtalar and talonavicular arthritis with a resultant limp and disability in performance of daily activities.
- ankle arthodesis does not provide a normal gait pattern.
- available total ankle replacements often only replace the talus dome and implantation of the talus component depends on the remaining talus bone stock and, as a result, they are contraindicated for talus AW. Therefore, in a significant proportion of patients, total ankle replacement is not viable.
- Custom made total and partial talus replacements have been implanted in limited numbers of patients around the globe; however, these implants are expensive to produce and are time consuming to manufacture because they have to be patient specific. Furthermore, there are high failure rates noted, especially due to implant subsidence in the talus neck and calcaneum. Additionally, these implants are cumbersome to implant and require bone osteotomies in the majority of the cases.
- the present invention is directed to a talus prosthesis for ankle arthroplasty comprising:
- a second part adapted for connection to the navicular bone and/or at least one cuneiform bone
- a third part adapted for connection to the calcaneus bone.
- the combination of the three parts in a talus prosthesis provides a simple to use and adaptable prosthesis that can be readily installed into patients during ankle, hemi or total arthroplasty.
- the prosthesis is connected to the navicular bone and/or at least one cuneiform bone, along with the calcaneus bone to hold the foot and tibia in place and provide an adaptable implant, thereby enabling a user to avoid joint fusion.
- the prosthesis does not require bespoke manufacture, it can be readily made and stored, thus reducing the lag time for installation of the joint.
- the convexly curved upper surface of the first part has an associated radii of curvature of from 15 to 35 mm, typically 20 to 30 mm.
- the radius of curvature of the convexly curved upper surface is similar to the radius of curvature of the lateral facet of the naturally occurring talus bone and is around 22 mm +/- 4 mm.
- the radius of curvature of the convexly curved upper surface is similar to the radius of curvature of the medial facet of the naturally occurring talus bone and is around 26 mm +/- 6 mm.
- the radius of curvature of the convexly curved upper surface is similar to the radius of curvature of the central portion of the naturally occurring talus bone and is around 25 mm +/- 4 mm.
- the second part comprises at least one protrusion extending in a first direction and that protrusion is adapted to engage the navicular bone and/or at least one cuneiform bone. Additionally, it is preferable that the second part is substantially
- the anterior portion of the second part may be slightly convexly curved, with the convexity facing the navicular bone.
- the associated radius of curvature is likely to be less than 15 mm, generally 5 to 10 mm.
- the use of at least protrusion that extends from the second part and engages the navicular bone and/or at least one cuneiform bone allows the prosthesis to be securely anchored to the foot of the patient.
- the protrusion(s) may be substantially perpendicular to the surface of the second part or angled thereto.
- the use of a substantially cuboidal part makes manufacturing simpler and the part is easy to handle, particularly when wet.
- the third part comprises a protrusion extending therefrom in a second direction and adapted to engage the calcaneus bone.
- the protrusion has an associated radius of curvature of 25 to 45 mm, generally 30 to 40 mm, suitably of around 36 mm +/- 6 mm.
- the third part may be substantially hemi-spherical.
- the generally hemi-spherical third part may have an associated radius of curvature of 25 to 45 mm, generally 30 to 40 mm, suitably of around 36 mm +/- 6 mm.
- the protrusion adapted to engage the calcaneus bone may be substantially hemi-spherical, and slightly flattened or less curved inferiorly to allow better seating, promoting calcaneal bone stock preservation.
- the portion of the third part adapted to engage the lateral and medial aspects may be slightly less curved or flattened to allow better seating.
- the connecting area comprises a textured surface.
- a section of the surface of the part which might include a protrusion, may be textured for keying into bone cement, or alternatively for use in cementless techniques.
- the use of a rough surface increases the surface area for the adhesive on the part, or parts, and may provide for a stronger and more effective bond.
- Suitable textured surfaces would be known to one skilled in the art. Mention may be made of hydroxyapatite surfaces.
- the prosthesis may be formed as a one-piece structure, wherein all three parts are formed integrally as a one-piece implant.
- the constructing of a one-piece prosthesis reduces the manufacturing cost and also reduces the need to observe tolerance levels in respect of parts that need to be joined together.
- at least two of the three parts are formed integrally and, preferably, the three parts are separate components that can be connected to one another to form the implant.
- a modular system is created.
- a result of employing such a modular prosthesis is to allow the three parts to be chosen according to the size of the patient's anatomy, particularly their bone and joints. Therefore, the three parts are selected according to the patient size and so a combination of the three parts that most suits the patient's dimensions can be selected, thereby reducing the risk of stress on the bones that are in contact with the prosthesis, when in place inside a patient.
- connection members are all sized to fit together regardless of the size of the anatomically engaging/connecting components. Additionally, where the prosthesis cannot be attached using a protrusion to engage the bone due to degradation of the bone, a different part may be selected that does not require an aperture in the bone in order to be fixed in place.
- the use of a modular construction allows for implantation from a single anterior approach, thereby avoiding bone osteotomies and preserving the major ankle ligaments.
- the parts can be assembled within the patient, thereby reducing the level of access required.
- the surfaces of the parts that are adjacent one another when assembled are substantially planar. This allows for the parts to be closely connected and reduces the risk of any pinching due to misalignment. It is advantageous that the parts are fixedly connected to one another and such connection is performed in conjunction with threaded members, particularly screws. It is further advantageous that the relevant parts are provided with apertures to receive the threaded members. The use of screws allows the parts to be securely fastened together and retained in that position.
- the first part comprises at least one recess and the other part, or at least one of the other parts, comprises a corresponding protrusion that, in the assembled position, is received into the recess of the first part.
- the use of protrusions and recesses to connect the parts allows for the parts to be placed into the patient separately and the respective protrusions and recesses connected to form the assembled prosthesis.
- protrusion and recess mechanism can be employed to assist with reducing movement between the parts. Mention may be made of the use of 'Morse tapering' interlocking. However, other standard implant interlocking techniques will be known to the skilled man to secure the components together.
- the first part may comprise two recesses, each on separate faces of the first part, and each of the second and third parts comprise a respective protrusion that, in the assembled position, is received in respective recesses of the first part. Having the recesses on the first part and the protrusions on the second and third parts allows for the second and third parts to be positioned and the first part arranged around them, which may be easier when implanted into a patient.
- the three parts are separate components that can each be connected to a fourth central part.
- This allows for a central underlying framework to be employed to which the three parts are attached, each part being a separate component.
- the underlying framework can be employed to further reduce the size of the components.
- the convexly-curved upper surface of the first part is further provided with side portions extending in the same direction as the convex surface, thus providing the first part with a saddle-shaped upper surface.
- the use of a saddle-shaped upper surface provides a convenient shape for engaging the tibia of a patient. This is particular useful in hemi-arthroplasty situations.
- the prosthesis of the present invention is appropriately sized for the patient.
- the sizing of the parts will depend on the type of patient to be treated, the size of the patient, and the amount of damage to the ankle joint and surrounding bones (tibia and fibula most notably).
- the level of talar avascular necrosis and the degree of subtalar and/or talonavicular arthritis at the time of implantation are also relevant factors in the sizing of the prosthesis.
- the invention extends to a method of implanting an ankle prosthesis as described herein.
- Figure 1 shows a first part of a prosthesis according to a first embodiment of the present invention
- Figure 2 shows a second part of a prosthesis according to the first embodiment of the present invention
- Figure 3 shows a third part of a prosthesis according to the first embodiment of the present invention
- Figure 4 shows the parts of Figures 1 to 3 in an assembled form
- Figure 5 shows the embodiment of Figures 1 to 4 implanted in a foot
- Figure 6 shows a second embodiment of a prosthesis according to the present invention
- Figure 7 shows a top view of the prosthesis of Figure 6 in situ
- Figure 8 shows a side view of the prosthesis of Figure 6 in situ.
- Figures 1 to 5 show an ankle prosthesis device 10 comprising three separate parts: first part 12, a second part 14 and a third part 16.
- the first part 12 comprises a convexly arcuate top surface 18 and has substantially planar sides 20a and 20b.
- the first part 12 is provided with a first protrusion 22 arranged on its intended front surface 24, and a second protrusion 26 on its intended lower surface 28.
- One side of each of the protrusions 22 and 26 is provided with at least one fixing recesses 22a and 26a and 26b.
- the second part 14 is substantially cuboidal in shape and comprises a joining recess 30 on its intended rear surface, which is in the form of a slot having an opening to its upper surface.
- Two elongate anchor pins 32a are provided on the opposite, intended front, surface with a third, longer, elongate anchor pin 32b arranged above the other two pins 32a.
- the joining recess 30 comprises a slot, in an alternative arrangement this may be a closed, concave, recess.
- the second part 14 is provided with a fixing aperture 34 on one side that passes through the side wall of the second part 14 to the joining recess 30.
- the third part 16 is substantially hemispherical in shape and comprises a joining recess 36 in its substantially planar surface 16a.
- Two fixing apertures 38a and 38b are provided in the side of the third part 16 and these apertures extend through to the joining recess 36.
- a truncated cone extension 40 extends from the arcuate surface of the third part 16, which is omitted from Figure 3 but shown on Figure 4.
- the third part 16 is inserted into the patient and the extension 40 is connected into the calcaneus bone, which leaves the planar surface 16a and joining recess 36 therein facing towards the tibia and fibula of the patient.
- the second part 14 is inserted into the foot of the patient and the anchor pins 32 extend into the navicular bone, leaving the joining recess 30 facing the rear of the patient's foot and substantially perpendicular to the joining recess 36 of the third part 16.
- the first part 12 is then positioned so that the joining protrusions 22 and 26 engage the respective joining recesses 30 and 36 on the second part 14 and the third part 16.
- fixing members 42 in the form of threaded members, or screws, are provided through the fixing apertures 38a and 38b that extend into the respective fixing recesses 22a and 26a and 26b.
- the fixing recesses may be provided on both sides of one, or each, of the protrusions 22 and 26 of the first part, with corresponding fixing apertures on the second part 14 and the third part 16.
- Figures 6 to 8 show a second embodiment 50 of the present invention.
- the second embodiment comprises a first part 12', a second part 14', and a third part 16'.
- the first part 12' is provided with a convexly curved upper surface 18' and substantially planar sides 20a (not shown) and 20b' .
- the second part is provided with two anchor pins 32a' that, when in use, as shown in Figures 7 and 8, engage the navicular bone.
- a truncated cone extension 40' extends in a rearward direction from the third part 16' and, in use, engages the calcaneus bone.
- the prosthesis engages the one or more of the cuneiform bones, it will pass through the navicular bone unless the latter has been removed, for example during revision surgery.
- the joining protrusions and joining recesses may be provided with a snap-fit mechanism to allow the parts to engage and be held in position, rather than fixing them using threaded members. Alternatively, or additionally, fixing pins or other connecting means may be employed.
- the protrusions on the first part and the corresponding recesses on the second and third parts may be swapped such that one or more of the protrusions is present on the second and/or third part and the corresponding recess is provided on the first part.
- the bone-engaging protrusions may be used in combination with bone cement to more securely fix the prosthesis in place.
- arthroplasty covers conventional arthroplasty, wherein both sides of the ankle joint are replaced or repaired and also hemi-arthroplasty, wherein only one side of the joint is being repaired or replaced.
- the device of the present invention would be engages with a suitably prepared tibia.
- the device of the present invention would contact the natural tibia.
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- Health & Medical Sciences (AREA)
- Orthopedic Medicine & Surgery (AREA)
- Cardiology (AREA)
- Oral & Maxillofacial Surgery (AREA)
- Transplantation (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Heart & Thoracic Surgery (AREA)
- Vascular Medicine (AREA)
- Life Sciences & Earth Sciences (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Veterinary Medicine (AREA)
- Prostheses (AREA)
Abstract
A talus prosthesis (10) for ankle arthroplasty comprising a first part (12) having a convexly-curved upper surface (18), a second part (14) adapted for connection to the navicular bone and/or at least one cuneiform bone and a third part (16) adapted for connection to the calcaneus bone.
Description
TALUS PROSTHESIS
- 1 -
Field of the Invention The invention relates to an ankle prosthesis, particularly a talus prosthesis for ankle arthroplasty.
Background to the Invention In patients with avascular necrosis (AVN) of the talus, it may be necessary to provide a total talus replacement. This may be undertaken in circumstances of talus dislocations, talus neck fractures and as components in failed total ankle arthroplasty.
Talus fractures frequently occur in younger, more demanding patients that wish to retain full function of their ankle j oint.
The current standard treatment of talus AVN is ankle arthrodesis, subtalar arthrodesis and pantalar arthrodesis. However, a problem with fusion of the ankle joint is that it can cause an increased rate of subtalar and talonavicular arthritis with a resultant limp and disability in performance of daily activities. Additionally, ankle arthodesis does not provide a normal gait pattern.
Currently, available total ankle replacements often only replace the talus dome and implantation of the talus component depends on the remaining talus bone stock and, as a result, they are contraindicated for talus AW. Therefore, in a significant proportion of patients, total ankle replacement is not viable.
Custom made total and partial talus replacements have been implanted in limited numbers of patients around the globe; however, these implants are expensive to produce and are time consuming to manufacture because they have to be patient specific. Furthermore, there are high failure rates noted, especially due to implant subsidence in the talus neck and calcaneum. Additionally, these implants are cumbersome to implant and require bone osteotomies in the majority of the cases.
Failed total ankle replacements occur mainly due to talus component loosening and talus bone subsidence. Subsequently, revision surgeries are available, but the end result is usually a fusion surgery.
Summary of the Invention
Accordingly, the present invention is directed to a talus prosthesis for ankle arthroplasty comprising:
a first part having a convexly-curved upper surface;
a second part adapted for connection to the navicular bone and/or at least one cuneiform bone; and
a third part adapted for connection to the calcaneus bone.
The combination of the three parts in a talus prosthesis provides a simple to use and adaptable prosthesis that can be readily installed into patients during ankle, hemi or total arthroplasty. The prosthesis is connected to the navicular bone and/or at least one cuneiform bone, along with the calcaneus bone to hold the foot and tibia in place and provide an adaptable implant, thereby enabling a user to avoid joint fusion. Additionally, because the prosthesis does not require bespoke manufacture, it can be readily made and stored, thus reducing the lag time for installation of the joint.
Generally the convexly curved upper surface of the first part has an associated radii of curvature of from 15 to 35 mm, typically 20 to 30 mm.
According to one embodiment, the radius of curvature of the convexly curved upper surface is similar to the radius of curvature of the lateral facet of the naturally occurring talus bone and is around 22 mm +/- 4 mm.
According to one embodiment, the radius of curvature of the convexly curved upper surface is similar to the radius of curvature of the medial facet of the naturally occurring talus bone and is around 26 mm +/- 6 mm.
According to one embodiment, the radius of curvature of the convexly curved upper surface is similar to the radius of curvature of the central portion of the naturally occurring talus bone and is around 25 mm +/- 4 mm.
Preferably, the second part comprises at least one protrusion extending in a first direction and that protrusion is adapted to engage the navicular bone and/or at least one cuneiform bone. Additionally, it is preferable that the second part is substantially
cuboidal.According to one embodiment, the anterior portion of the second part may be slightly convexly curved, with the convexity facing the navicular bone. The associated radius of curvature is likely to be less than 15 mm, generally 5 to 10 mm. The use of at least protrusion that extends from the second part and engages the navicular bone and/or at least one cuneiform bone allows the prosthesis to be securely anchored to the foot of the patient. The protrusion(s) may be substantially perpendicular to the surface of the second part or angled thereto. The use of a substantially cuboidal part makes manufacturing simpler and the part is easy to handle, particularly when wet.
Advantageously, the third part comprises a protrusion extending therefrom in a second direction and adapted to engage the calcaneus bone. Generally, the protrusion has an associated radius of curvature of 25 to 45 mm, generally 30 to 40 mm, suitably of around 36 mm +/- 6 mm.
According to one embodiment, the third part may be substantially hemi-spherical. The generally hemi-spherical third part may have an associated radius of curvature of 25 to 45 mm, generally 30 to 40 mm, suitably of around 36 mm +/- 6 mm. Employing a hemispherical profile allows for the third part to be positioned more readily and reduces the risk of damage to other parts of the anatomy, whilst filling the space created during the removal of the talus. According to one embodiment, the protrusion adapted to engage the calcaneus bone may be substantially hemi-spherical, and slightly flattened or less curved inferiorly to allow better seating, promoting calcaneal bone stock preservation. Similarly, the portion of the third part adapted to engage the lateral and medial aspects may be slightly less curved or flattened to allow better seating.
Fixation of the prosthesis, or implant, to the calcaneum and the navicular and/or cuneiform bones gives a longer lever arm for force distribution, and thus
reduces/eliminates the risk of painful subtalar and talonavicular arthritis.
It is preferable that, on at least one of the parts, where the part is adapted for connection to a bone, the connecting area comprises a textured surface. A section of the surface of the part, which might include a protrusion, may be textured for keying into bone cement, or alternatively for use in cementless techniques. The use of a rough surface increases the surface area for the adhesive on the part, or parts, and may provide for a stronger and more effective bond. Suitable textured surfaces would be known to one skilled in the art. Mention may be made of hydroxyapatite surfaces. In one arrangement, the prosthesis may be formed as a one-piece structure, wherein all three parts are formed integrally as a one-piece implant. The constructing of a one-piece prosthesis reduces the manufacturing cost and also reduces the need to observe tolerance levels in respect of parts that need to be joined together. Alternatively, at least two of the three parts are formed integrally and, preferably, the three parts are separate components that can be connected to one another to form the implant. By creating the prosthesis in parts that are assembled together, a modular system is created. A result of employing such a modular prosthesis is to allow the three parts to
be chosen according to the size of the patient's anatomy, particularly their bone and joints. Therefore, the three parts are selected according to the patient size and so a combination of the three parts that most suits the patient's dimensions can be selected, thereby reducing the risk of stress on the bones that are in contact with the prosthesis, when in place inside a patient. The connection members (recesses and protrusions) are all sized to fit together regardless of the size of the anatomically engaging/connecting components. Additionally, where the prosthesis cannot be attached using a protrusion to engage the bone due to degradation of the bone, a different part may be selected that does not require an aperture in the bone in order to be fixed in place.
Additionally, the use of a modular construction allows for implantation from a single anterior approach, thereby avoiding bone osteotomies and preserving the major ankle ligaments. The parts can be assembled within the patient, thereby reducing the level of access required.
Preferably, where the device is modular, the surfaces of the parts that are adjacent one another when assembled are substantially planar. This allows for the parts to be closely connected and reduces the risk of any pinching due to misalignment. It is advantageous that the parts are fixedly connected to one another and such connection is performed in conjunction with threaded members, particularly screws. It is further advantageous that the relevant parts are provided with apertures to receive the threaded members. The use of screws allows the parts to be securely fastened together and retained in that position.
It is preferable that the first part comprises at least one recess and the other part, or at least one of the other parts, comprises a corresponding protrusion that, in the assembled position, is received into the recess of the first part. The use of protrusions and recesses to connect the parts allows for the parts to be placed into the patient separately and the respective protrusions and recesses connected to form the assembled prosthesis.
Additionally, the protrusion and recess mechanism can be employed to assist with reducing movement between the parts. Mention may be made of the use of 'Morse
tapering' interlocking. However, other standard implant interlocking techniques will be known to the skilled man to secure the components together.
Where the device comprises a three-part arrangement, the first part may comprise two recesses, each on separate faces of the first part, and each of the second and third parts comprise a respective protrusion that, in the assembled position, is received in respective recesses of the first part. Having the recesses on the first part and the protrusions on the second and third parts allows for the second and third parts to be positioned and the first part arranged around them, which may be easier when implanted into a patient.
In one construction, the three parts are separate components that can each be connected to a fourth central part. This allows for a central underlying framework to be employed to which the three parts are attached, each part being a separate component. The underlying framework can be employed to further reduce the size of the components.
It is advantageous that the convexly-curved upper surface of the first part is further provided with side portions extending in the same direction as the convex surface, thus providing the first part with a saddle-shaped upper surface. The use of a saddle-shaped upper surface provides a convenient shape for engaging the tibia of a patient. This is particular useful in hemi-arthroplasty situations.
The prosthesis of the present invention is appropriately sized for the patient. The sizing of the parts will depend on the type of patient to be treated, the size of the patient, and the amount of damage to the ankle joint and surrounding bones (tibia and fibula most notably). The level of talar avascular necrosis and the degree of subtalar and/or talonavicular arthritis at the time of implantation are also relevant factors in the sizing of the prosthesis.
The invention extends to a method of implanting an ankle prosthesis as described herein.
Brief Description of the Drawings
An embodiment of the invention will now be described, by way of example only, and with reference to the accompanying drawings, in which:
Figure 1 shows a first part of a prosthesis according to a first embodiment of the present invention;
Figure 2 shows a second part of a prosthesis according to the first embodiment of the present invention;
Figure 3 shows a third part of a prosthesis according to the first embodiment of the present invention;
Figure 4 shows the parts of Figures 1 to 3 in an assembled form;
Figure 5 shows the embodiment of Figures 1 to 4 implanted in a foot;
Figure 6 shows a second embodiment of a prosthesis according to the present invention;
Figure 7 shows a top view of the prosthesis of Figure 6 in situ; and
Figure 8 shows a side view of the prosthesis of Figure 6 in situ.
Detailed Description of Exemplary Embodiments
Figures 1 to 5 show an ankle prosthesis device 10 comprising three separate parts: first part 12, a second part 14 and a third part 16. The first part 12 comprises a convexly arcuate top surface 18 and has substantially planar sides 20a and 20b. The first part 12 is provided with a first protrusion 22 arranged on its intended front surface 24, and a second protrusion 26 on its intended lower surface 28. One side of each of the protrusions 22 and 26 is provided with at least one fixing recesses 22a and 26a and 26b.
The second part 14 is substantially cuboidal in shape and comprises a joining recess 30 on its intended rear surface, which is in the form of a slot having an opening to its upper surface. Two elongate anchor pins 32a are provided on the opposite, intended front, surface with a third, longer, elongate anchor pin 32b arranged above the other two pins 32a. Whilst the joining recess 30 comprises a slot, in an alternative arrangement this may be a closed, concave, recess. The second part 14 is provided with a fixing aperture 34 on one side that passes through the side wall of the second part 14 to the joining recess 30.
The third part 16 is substantially hemispherical in shape and comprises a joining recess 36 in its substantially planar surface 16a. Two fixing apertures 38a and 38b are provided in the side of the third part 16 and these apertures extend through to the joining recess 36. A truncated cone extension 40 extends from the arcuate surface of the third part 16, which is omitted from Figure 3 but shown on Figure 4.
In use, the third part 16 is inserted into the patient and the extension 40 is connected into the calcaneus bone, which leaves the planar surface 16a and joining recess 36 therein facing towards the tibia and fibula of the patient.
The second part 14 is inserted into the foot of the patient and the anchor pins 32 extend into the navicular bone, leaving the joining recess 30 facing the rear of the patient's foot and substantially perpendicular to the joining recess 36 of the third part 16. The first part 12 is then positioned so that the joining protrusions 22 and 26 engage the respective joining recesses 30 and 36 on the second part 14 and the third part 16. Once the joining protrusions 22 and 26 are received within the respective joining recesses 30 and 36, fixing members 42, in the form of threaded members, or screws, are provided through the fixing apertures 38a and 38b that extend into the respective fixing recesses 22a and 26a and 26b.
The fixing recesses may be provided on both sides of one, or each, of the protrusions 22 and 26 of the first part, with corresponding fixing apertures on the second part 14 and the third part 16.
Figures 6 to 8 show a second embodiment 50 of the present invention. The second embodiment comprises a first part 12', a second part 14', and a third part 16'. The first part 12' is provided with a convexly curved upper surface 18' and substantially planar sides 20a (not shown) and 20b' . The second part is provided with two anchor pins 32a' that, when in use, as shown in Figures 7 and 8, engage the navicular bone. A truncated cone extension 40' extends in a rearward direction from the third part 16' and, in use, engages the calcaneus bone.
Clearly, where the prosthesis engages the one or more of the cuneiform bones, it will pass through the navicular bone unless the latter has been removed, for example during revision surgery. The joining protrusions and joining recesses may be provided with a snap-fit mechanism to allow the parts to engage and be held in position, rather than fixing them using threaded members. Alternatively, or additionally, fixing pins or other connecting means may be employed. It will be appreciated that the protrusions on the first part and the corresponding recesses on the second and third parts may be swapped such that one or more of the protrusions is present on the second and/or third part and the corresponding recess is provided on the first part. The bone-engaging protrusions may be used in combination with bone cement to more securely fix the prosthesis in place.
It is intended that "arthroplasty" covers conventional arthroplasty, wherein both sides of the ankle joint are replaced or repaired and also hemi-arthroplasty, wherein only one side of the joint is being repaired or replaced. In arthroplasty, the device of the present invention would be engages with a suitably prepared tibia. In hemi-arthroplasty, the device of the present invention would contact the natural tibia.
Claims
Claims
A talus prosthesis for ankle arthroplasty comprising:
a first part having a convexly-curved upper surface;
a second part adapted for connection to the navicular bone and/or at least one cuneiform bone; and
a third part adapted for connection to the calcaneus bone.
A prosthesis as claimed in claim 1 wherein the radius of curvature of the convexly curved upper surface is 20 to 30 mm.
A prosthesis according to either one of claims 1 and 2, wherein the second part comprises at least one protrusion extending in a first direction and adapted to engage the navicular bone and/or at least one cuneiform bone.
A prosthesis according to any preceding claim, wherein the second part is substantially cuboidal.
A prosthesis according to any preceding claim, wherein the third part comprises protrusion extending therefrom in a second direction and adapted to engage the calcaneus bone.
A prosthesis according to any preceding claim, wherein the third part is substantially hemi-spherical.
A prosthesis as claimed in claim 6 wherein the third part has an associated radius of curvature of around 25 to around 45 mm.
A prosthesis according to any preceding claim, wherein, on at least one part,
where the part is adapted for connection to a bone, the connecting area comprises a textured surface.
A prosthesis according to any preceding claim, wherein all three parts are formed integrally as a one-piece implant.
A prosthesis according to any one of claims 1 to 8, wherein at least two of the three parts are formed integrally.
A prosthesis according to any one of claims 1 to 8 or claim 10, wherein the three parts are separate components that can be connected to one another to form the implant.
A prosthesis according to claim 10 or claim 11, wherein the surfaces of the parts that are adjacent one another when assembled are substantially planar.
A prosthesis according to any one of claims 10 to 12, wherein the parts are fixedly connected to one another.
A prosthesis according to claim 13, wherein the parts are fixedly connected with threaded members.
A prosthesis according to claim 14, wherein the parts are provided with apertures to receive the threaded members.
A prosthesis according to any one of claims 9 to 14, wherein the first part comprises at least one recess and the other part, or at least one of the other parts, comprises a corresponding protrusion that, in the assembled position, is received into the recess of the first part.
A prosthesis according to claim 11 or any one of claims 12 to 15 when appended to claim 11 , wherein the first part comprises two recesses on two separate faces and each of the second and third parts comprise a protrusion that, in the assembled position, is received in a respective recess of the first part.
A prosthesis according to any one of claims 1 to 8, wherein the three parts are separate components that can each be connected to a fourth central part.
A prosthesis according to any preceding claim, wherein the convexly-curved upper surface of the first part is further provided with side portions extending in the same direction as the convex surface, thus providing the first part with a saddle-shaped upper surface.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
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GB1508300.9 | 2015-05-14 | ||
GBGB1508300.9A GB201508300D0 (en) | 2015-05-14 | 2015-05-14 | A prosthesis |
Publications (1)
Publication Number | Publication Date |
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WO2016181168A1 true WO2016181168A1 (en) | 2016-11-17 |
Family
ID=53489667
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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PCT/GB2016/051396 WO2016181168A1 (en) | 2015-05-14 | 2016-05-13 | Talus prosthesis |
Country Status (2)
Country | Link |
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GB (1) | GB201508300D0 (en) |
WO (1) | WO2016181168A1 (en) |
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN108309516A (en) * | 2017-10-27 | 2018-07-24 | 常非 | A kind of astragalus prosthese |
CN111134910A (en) * | 2020-01-13 | 2020-05-12 | 北京市春立正达医疗器械股份有限公司 | Calcaneus prosthesis |
CN111870410A (en) * | 2020-09-07 | 2020-11-03 | 广州华钛三维材料制造有限公司 | Talus prosthesis |
WO2022075595A1 (en) * | 2020-10-06 | 2022-04-14 | 주식회사 코렌텍 | Customized talus implant |
WO2022094502A1 (en) * | 2020-10-28 | 2022-05-05 | Wright Medical Technology, Inc. | Talar implant |
EP3937853A4 (en) * | 2019-03-11 | 2022-11-02 | Wright Medical Technology, Inc. | Talar dome with angled holes |
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WO2008078082A2 (en) * | 2006-12-23 | 2008-07-03 | Corin Limited | Improvements in and relating to an ankle prosthesis |
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WO2013025194A1 (en) * | 2011-08-15 | 2013-02-21 | Concepts In Medicine Vi, Llc | Subtalar joint prosthesis and its method of implantation |
US20140188230A1 (en) * | 2012-12-31 | 2014-07-03 | Richard A. Rogachefsky | Bone prosthesis for maintaining joint operation in complex joints |
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Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN108309516A (en) * | 2017-10-27 | 2018-07-24 | 常非 | A kind of astragalus prosthese |
CN108309516B (en) * | 2017-10-27 | 2023-12-29 | 常非 | Talus prosthesis |
EP3937853A4 (en) * | 2019-03-11 | 2022-11-02 | Wright Medical Technology, Inc. | Talar dome with angled holes |
US11752001B2 (en) | 2019-03-11 | 2023-09-12 | Wright Medical Technology, Inc. | Talar dome with angled holes |
CN111134910A (en) * | 2020-01-13 | 2020-05-12 | 北京市春立正达医疗器械股份有限公司 | Calcaneus prosthesis |
CN111870410A (en) * | 2020-09-07 | 2020-11-03 | 广州华钛三维材料制造有限公司 | Talus prosthesis |
WO2022075595A1 (en) * | 2020-10-06 | 2022-04-14 | 주식회사 코렌텍 | Customized talus implant |
KR20220046713A (en) * | 2020-10-06 | 2022-04-15 | 주식회사 코렌텍 | Customized Talus Implant |
KR102413390B1 (en) | 2020-10-06 | 2022-06-30 | 주식회사 코렌텍 | Customized Talus Implant |
WO2022094502A1 (en) * | 2020-10-28 | 2022-05-05 | Wright Medical Technology, Inc. | Talar implant |
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