Expanding suture anchor

Abstract: The suture anchor comprises a first main body (11) of a generally cylindrical shape having a front portion (1), a rear portion (2), a longitudinal axis (3), a curved surface (4) with protrusions (5), a central through-going bore (19) extending from said front portion (1) to said rear portion (2), and a longitudinal slit (12) which opens at said front portion (1) and curved surface (4) and is closed at said rear portion (2). It further comprises a second body (14) having a smaller base (15), a larger base (16), a curved surface (17) and a longitudinal axis (13), said second body (14) being wedge-shaped coaxially introducible with its smaller base (15) into said slit (12) thereby causing expansion of said first main body (11). The second body (14) is provided with a through-hole (6) running transversely to said longitudinal axis (13) and two channels (7) positioned on said curved surface (17) and extending from the orifices (18) of said through-hole (6) to said smaller base (15).

Description: This invention relates to a suture anchor according to the preamble of claim 1. Sutures are used in surgery i.a. for attachment of soft tissue to bone. They are used in repair of tissue avulsions from bone as well as in reconstructive procedures, including reattaching avulsed tendons , ligaments and joint capsules to bone. The field of application extends to treatment of shoulder instability and rotator cuff tears, knee instability, maxillofacial surgery, hand surgery and ligamentous repair of the foot, ankle and wrist. The shoulder is of particular interest because dislocation of this joint occurs more frequently than any other human joint causing limitation of motion and pain in athletes and nonathletes of all ages. Anchoring of the suture is either made directly in the bone mass or by means of an anchor to be implanted into the bone. The classic BANKART procedure is a widely accepted method of treating anterior-inferior gleno-humeral instability, using sutures that are inserted directly through transosseous tunnels without an anchor. Although the surgical exposure involves minimal trauma and skin incision and leads to excellent clinical results with reported recurrence rates of 3.5% to 4.0%, the procedure of reattaching the torn ligament or tendon can be time consuming and difficult. While modifications that decrease the operating time for standard rotator cuff and Bankart lesion repairs are available, these approaches are technically demanding. The use of staples has a tendency to cut through the bone and tendon. An expanding suture anchor is known from EP-A1 0 502 509 having a slotted main body and a second conical body being coaxially introducible therein thereby causing expansion of said main body. The suture is trapped upon assembly of the expanding suture anchor (between the main body and the conical body), so that the suture is not free to slide upon assembly. The entrapping of the suture causes furthermore a reduction in the ultimate tensile strength of the suture. The invention aims at solving the above described problems by providing a suture anchor which can be easily and safely assembled without blocking of the suture in the anchor. The sliding quality of the suture after assembly of the expanding suture anchor is very important for the surgeon in order to apply a sliding knot to the suture. In accordance with the invention, this object is accomplished by a suture anchor having the features of the characterizing part of claim 1. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming part of this disclosure. For the better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings, examples and descriptive matter in which are illustrated and described preferred embodiments of the invention. In the drawings: Fig. 1 is a perspective view of the expanding suture anchor according to the invention, the longitudinally curvature of the through-hole (6) being however not shown in the drawing, prior to introduction of the suture; Fig. 2 is a perspective view of the expanding suture anchor according to the invention, the longitudinally curvature of the through-hole (6) being however not shown in the drawing, after introduction of the suture; Fig. 3 is a perspective view of the expanding suture anchor according to Fig. 1 rotated by 90°; Fig. 4 is a perspective view of the expanding suture anchor according to Fig. 2 rotated by 90°; and Fig. 5 is a perspective view of the expanding suture anchor after introduction of the conical part into the main body and expansion of the latter. The suture anchor as represented in Figs. 1 to 4 consists basically of a first main body 11 and a conical body 14. The main body 11 has a generally cylindrical shape with a front portion 1, a rear portion 2 and a longitudinal axis 3. The curved surface 4 of the main body 11 is provided with protrusions 5, in the form of barbs distributed over the full length of the main body to facilitate retention of the suture anchor in cortical bone or cortical and cancellous bone. The rear portion 2 is provided with connection means 9 in the form of a central hole for receiving a manipulation instrument. A central through-going bore 19 extends from the front portion 1 to the rear portion 2 for receiving the two ends of the loop of suture 10. A longitudinal slit 12 which opens at the front portion 1 and curved surface 4 and is closed at the rear portion 2 allows for the expansion of the main body 11. The closed end 23 of slot 12 is rounded in order to evenly distribute stresses when the two legs 21,22 are spreaded. The second - approximately conical - body 14 has a smaller base 15, a larger base 16, a curved surface 17 and a longitudinal axis 13. This second conical body 14 is wedge-shaped coaxially introducible with its smaller base 15 into the slot 12 of the first main body 11 thereby causing expansion of the latter. The expansion of the suture anchor leads to an improved fixation of the anchor in the bone mass. A through-hole 6 is running transversely to the longitudinal axis 13 of the conical body 14 and is destined to receive the suture 10. The through-hole 6 is located at a distance from the larger base 16 which corresponds to 5 to 25 % of the total length of the second body 14. This location results in maximum strength of the suture fixation. Two channels 7 are positioned on the curved surface 17 of the second body 14 and extend from the orifices 18 of the through-hole 6 to the smaller base 15. The function of the channels 7 is to take up the suture 10 - as shown in Figs. 3 and 4 - after its introduction in the through-hole 6 and to prevent its blocking between the curved surface 17 and the main body 11 (the suture 10 is passed through the through-hole 6 prior to assembly of the anchor). To this effect the depth of these channels 7 should exceed the smallest diameter of the through-hole 6. The depths of the channels 7 may diminish from said orifices 18 to said smaller base 15 due to the shape of the conical or wedge-shaped second body 14. According to the invention the course of the through-hole 6 is curved whereby its apex is facing the larger base 16. The curved configuration allows a smooth running of the suture 10 within the through-hole 6 and prevents sharp edges which could lead to damage of the suture 10. The main body 11 and the second body 14 may either be two distinct parts or - as shown in Figs. 1 and 2 - temporarily connected coaxially by an intermediate portion 20, which upon applying a certain pulling force to the suture 10 breaks away bringing the conical body 14 in abutment with the main body 11 as shown in Figs. 3 and 4. The application of the pulling force occurs by holding the main body 11 with a suitable instrument using the connecting means 9 and pulling the two ends of the loop of suture 10 introduced through the trough hole 6 and the central bore 19. The intermediate portion 20 is provided with a passage 24 for allowing space for introduction of the suture 10 between the main body 11 and the second body 14. As shown in Fig. 5, upon further pulling of the suture 10 the second body 14 enters slot 12 with its smaller base 15 and spreads the two legs 21,22 formed by said slot 12 leading to expansion of said main body 11 and fixation thereof in the bone mass. The suture anchor can be made of any known implant material, e.g. stainless steel or titanium. Preferably it is made of a resorbable material, e.g. a polylactide. In the presence of enzymes in the human body, polylactides degrade to lactic acid, and subsequently to carbon dioxide and water. These are removed from the body via respiratory routes and kidneys respectively. By using resorbable materials irritation of soft tissue from metallic corrosion is eliminated. It also eliminates interference with certain imaging diagnostic or therapeutic treatments near the site, such as magnetic resonance imaging, and where the use of such imaging is indicated any metal implants may first have to be surgically removed. Preferably the suture anchor has an over-all length of 21 mm at most (preferably 18 mm at most) before introduction into the bone. In a restricted area such as the shoulder, this limited dimension (compared to prior art devices which are 25 mm long) gives the clinician more freedom of choice for the site of insertion.

Claims: Suture anchor comprising A) a first main body (11) of a generally cylindrical shape having a front portion (1) for facing a body member to be treated, a rear portion (2), a longitudinal axis (3), a curved surface (4), a central through-going bore (19) extending from said front portion (1) to said rear portion (2), and a longitudinal slit (12) which opens at said front portion (1) and at said curved surface (4) and is closed at said rear portion (2); and B) a second body (14) having a smaller base (15), a larger base (16), a curved surface (17) and a longitudinal axis (13), said second body (14) being coaxially introducible with its smaller base (15) into said slit (12) thereby causing expansion of said first main body (11), said second body (14) being provided with a through-hole (6) running transversely to said longitudinal axis (13), characterized in that C) two channels (7) are positioned on said curved surface (17) of said second body (14) and extending from the orifices (18) of said through-hole (6) to said smaller base (15), and D) said through-hole (6) is longitudinally curved with the apex facing said larger base (16). Suture anchor according to claim 1, characterized in that said second body (14) has the shape of a cone. Suture anchor according to claim 1, characterized in that said second body (14) has the shape of a wedge. Suture anchor according to one of the claims 1 to 3, characterized in that said through-hole (6) is located at a distance from said larger base (16) which corresponds to 5 to 25 % of the total length of said second body (14). Suture anchor according to one of the claims 1 - 4, characterized in that said channels (7) have a depth exceeding the smallest diameter of said through-hole (6). Suture anchor according to one of the claims 1 - 5, characterized in that the depths of said channels (7) is diminishing from said orifices (18) to said smaller base (15). Suture anchor according to one of the claims 1 - 6, characterized in that said rear portion (2) is provided with connection means (9) for releasably receiving a manipulation instrument. Suture anchor according to one of the claims 1 - 7, characterized in that it is made from a resorbable material, preferably from a polylactide. Suture anchor according to one of the claims 1 - 8, characterized in that said first curved surface (4) of the first body is provided with protrusions (5), preferably in the form of threads or barbs. Suture anchor according to one of the claims 1 - 9, characterized in that said main body (11) and said second body (14) are temporarily connected coaxially by an intermediate portion (20), which upon applying a predetermined axial force breaks away bringing said second body (14) in abutment with said main body (11). Suture anchor according to one of the claims 1 - 10, characterized in that the closed end (23) of said longitudinal slit (12) is rounded. Suture anchor according to one of the claims 1 - 11, characterized in that it has an over-all length of 21 mm at most before introduction into the bone. Suture anchor according to one of the claims 1 - 12, characterized in that it has an over-all length of 18 mm at most before introduction into the bone.

Inventors: CURTIS RAYMOND, HELDSTAB THOMAS, SCHLEGEL URS, CURTIS, RAYMOND, HELDSTAB, THOMAS, SCHLEGEL, URS
Applicants: SYNTHES AG, SYNTHES AG, CHUR
Application year: 1995
Main classification: A61B17
IPC codes: A61B19, A61B17, A61F2