# Patent

## Title
Surgical technique using a contoured allograft cartilage as a spacer of the carpo-metacarpal joint of the thumb or tarso-metatarsal joint of the toe

## Abstract

A spacer for implantation into a subject is provided that includes a sterilized piece of cartilaginous allograft tissue. The piece forms a Y-shape with a base adapted to insert within a first carpo-metacarpal joint or carpo-metatarsal joint of the subject, and has a first arm adapted to secure to a trapezium bone adjoining the joint, and a second arm adapted to secure to a proximal metacarpal or metatarsal bone adjoining the joint. A procedure for implanting the spacer includes exposing a target joint and abrading a bone surface interior to the joint to induce surface bleeding. The spacer base is then inserted into the joint. The spacer first arm is adhered to the first bone of the joint and the spacer second arm is adhered to the second bone of the joint. A kit is also provided for surgical implantation of the spacer.

## Background
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority of U.S. Provisional Patent Application No. 61/301,310 filed Feb. 4, 2010, which is incorporated herein by reference.


FIELD OF THE INVENTION
The present invention in general relates to a spacer used to treat basal joint arthritis of the thumb or toe and in particular to the surgical implantation of an allograft of knee cartilage as the spacer.
BACKGROUND OF THE INVENTION
A variety of surgical procedures have been developed for the treatment of basal joint osteoarthritis (OA—arthritis causing wearing down and changes in joint surfaces) of the thumb. These include ligament (band of tissue that connects bones) reconstruction (repair through rebuilding), metacarpal osteotomy (bone removed or divided), trapezium excision (surgical procedure of hand joint), soft tissue interposition (repositioning) with or without ligament reconstruction, trapeziometacarpal (bones located in hand) arthrodesis (surgical joint immobilization), silicone (polymeric organic compound) arthroplasty (restoration of a joint), hematoma (mass of clotted blood) and distraction (separation) arthroplasty, and total joint arthroplasty. Problems with persistent pain and poor function have been reported for each of these procedures.
Recently, the ARTELON® CMC (carpo-metacarpal) spacer composed of a biodegradable (broken down by body) polycaprolactone-based polyurethane urea has been introduced for the treatment of basal joint osteoarthritis. A three year prospective pilot study demonstrated that all patients treated with the ARTELON® CMC spacer were stable clinically, had no signs of synovitis (inflammation of synovial membrane), and were pain free. (Nilsson, A., Liljensten, E., Bergstrom, C., Sollerman, C. “Results from a degradable TMC Joint Spacer (Artelon) compared with tendon arthroplasty”. Journal of Hand Surgery (Am.), 30:2, 2005 380-389.) However, clinical complications have been reported with the use of this implant, causing many surgeons to abandon its use. A recent case report demonstrated a foreign-body tissue reaction associated the ARTELON® CMC spacer, requiring implant removal and revision with hematoma and distraction arthroplasty. (Choung, E. W., Tan, V. “Foreign-Body Reaction to the Artelon CMC joint Spacer: Case report”. Journal of Hand Surgery (Am.), 33:9, 2008 1617-1620.)
Thus, there is a need for less reactive and smoother surfaced allograft of knee meniscal tissue as an implant will provide improved pain relief and hand function, while reducing complications in patients being treated surgically for osteoarthritis of the thumb.
SUMMARY OF THE INVENTION
A spacer for implantation into a subject is provided that includes a sterilized piece of cartilaginous allograft tissue. The piece forms a Y-shape with a base adapted to insert within a first carpo-metacarpal joint or carpo-metatarsal joint of the subject, and has a first arm adapted to secure to a trapezium bone adjoining the joint, and a second arm adapted to secure to a proximal metacarpal or metatarsal bone adjoining the joint.
A procedure for implanting the spacer includes exposing a target joint and abrading a bone surface interior to the joint to induce surface bleeding. The spacer base is then inserted into the joint in contact with the bleeding surface and the intact surface the other bone defining the joint. The spacer first arm is adhered to the first bone of the joint and the spacer second arm is adhered to the second bone of the joint. A kit is also provided for surgical implantation of the spacer.



BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a schematic depicting an inventive spacer secured within the first carpo-metacarpal joint; and
FIG. 2 is a top view of a kit containing the inventive spacer.



DETAILED DESCRIPTION OF THE INVENTION
The present invention has utility in the treatment of basal joint arthritis of the thumb with reduced complications. A replacement tissue spacer is formed in a “Y” shape and shown generally at 10 with a base 12 and a first arm 14 and a second arm 16 and sterilized according to conventional tissue preparation techniques, such as those detailed in U.S. Pat. Nos. 3,415,613 and 4,944,919, and by other conventional techniques illustratively including chemical sterilization such as with ethylene oxide; radiation sterilization such as with gamma radiation; and thermal sterilization. It is appreciated that surfactant decellularization is also operative herein to retain a proteinaceous scaffold free of donor cells and therefore precludes antigenicity.
The present Tissues from which an inventive spacer 10 is formed are harvested from a cadaver. It is appreciated that the cadaver need not be of the same species as the recipient. Cartilaginous tissues suitable for excision to form a spacer 10 illustratively include those of the knee meniscus, mandibular condyle of the temporomandibular joint, and intervertebral disks. Preferably, the tissue is fibrocartilage having an appreciable amount of collagen type I. Hyaline- and elastic-rich cartilage are also operative as a source of tissue for spacer 10. By way of example, knee meniscus tissue is obtained from a cadaver. Preferably, cadaver tissue is from the same species as the subject to limit the possibility of an immune response to the spacer 10.
The spacer 10 is placed with the base 12 of the “Y” spacer 10 within the first carpo-metacarpal (CMC-1) joint with the arms 14 and 16 of the “Y” secured to the trapezium bone B and metacarpal bone C defining CMC-1, respectively. It is appreciated that an inventive spacer and procedure are also suitable with only dimensional modifications of the spacer for repair of the corresponding metatarsal joint anatomy. Securements 20 for the arms are illustratively performed with tissue adhesives, suture anchors, screws, sutures, or a combination thereof as detailed in FIG. 1. Preferably, the first arm 14 of the Y and the second arm 16 are within 30% of being equal in length.
A kit is provided that includes a spacer 10 along with instructions for the surgical implantation of the spacer into the first carpo-metacarpal joint. Preferably, the spacer is provided in a sterile, implement-compatible solution. Optionally, the kit includes securements 20 for adhering the arms 14 and 16 of the spacer 10 to the trapezium bone B and metacarpal bones C, respectively. Optionally, the kit also includes a trimming instrument such as a scissors for sizing the spacer 10 to the anatomy of the subject CMC-1 joint. The securements 20 are a suture anchor 20a, a screw 20b, suture ligament 20c, or tissue adhesive 20d. 
The procedure for implantation corresponds to that detailed for the prior art ARTELON® CMC-1 spacer with the proviso that the inventive spacer is formed of sterile cadaver cartilagenous tissue and not biodegradable polyurethaneurea. An inventive spacer is immersed in sterile saline or other physiologically suitable liquid to assure adequate hydration. Typical soaking times for an inventive spacer are from 3 to 30 minutes and preferably at least 5 minutes. The joint of insertion, whether CMC-1 or a metatarsal joint analog, is opened with a dorsal incision. A periosteal flap is dissected from the trapezium bone including the joint capsule. The resultant flap is extended for a length of approximately 1 to 2 centimeters. It is appreciated that the flap is readily dissected in distal or proximal directions. The distal joint surface is then resected along with approximately 1 to 2 millimeters of subcondral bone of the articular surface of the trapezium bone. The articular surface of the metacarpal bone of CMC-1 or the equivalent metatarsal bone is preferably left intact. The goal of this resection is to create a bleeding surface on the trapezium bone to promote cellular regrowth and adhesion to the inventive spacer while the intact surface of the metacarpal or metatarsal bone, depending on the situs of insertion, is left intact to create a new joint surface against which articulation can occur. Preferably, osteophytes are then removed from along the joint lines and relative positions are marked for the arms 14 and 16. The cortical bone in the marked area is then burred to create a bleeding surface against which the arms 14 and 16 will subsequently be in contact. The burring is intended to only be sufficiently deep so as to achieve bleeding surfaces. Fixation of the arms 14 and 16 readily occurs with suture anchors, screws, or sutures by methods conventional to the art. Subsequent to fixation of the arms 14 and 16 to the trapezium bone B and metacarpal or metatarsal bone C, depending on the joint situs, by conventional means, the periosteal flap is then reattached and the skin closed. With some weeks of casting, a stabilized and flexible joint results.

## Claims

1. An implant for implantation into a subject comprising: a sterilized piece of cartilaginous allograft tissue harvested from knee meniscus tissue, said piece forming a Y shape with a base sized to insert within a first carpo-metacarpal joint or tarso-metatarsal joint of the subject;
a first arm adapted to secure to a trapezium bone adjoining the joint; and
a second arm adapted to secure to a proximal metacarpal or metatarsal bone adjoining the joint.

2. The implant of claim 1 wherein the first arm of the Y shape and the second arm are within 30% of being equal in length.

3. The implant of claim 1 further comprising a first securement for securing the first arm to the trapezium bone and a second securement for securing the second arm to the metacarpal bone.

4. The implant of claim 3 where the first securement is one of tissue adhesives, suture anchors, screws, sutures, or a combination thereof.

5. The implant of claim 1 wherein said tissue is from a cadaver of the same species as the subject.

6. A procedure for implanting said spacer of claim 1 comprising: exposing a target joint; inducing bleeding on a surface of a first bone of said joint; inserting the base of said spacer into contact with the surface and an intact second bone of said joint; and adhering a first arm to said first bone and said second arm to said second bone.

7. The procedure of claim 6 wherein the joint being repaired is a metatarsal joint.

8. The procedure of claim 6 wherein the joint being repaired is a carpo-metacarpal joint.

9. A kit comprising: an implant according to claim 1, along with instruction for the surgical implantation thereof into first carpo-metacarpal joint with the arms of the “Y” secured to trapezium and metacarpal bones defining joint.

10. The kit of claim 9 and further comprising: at least two securements each independently being a suture anchor, a screw, or a suture.

11. The kit of claim 9 wherein the at least two securements are all suture anchors.

12. The kit of claim 9 wherein the at least two securements are all screws.

13. The kit of claim 9 and further comprising: a tissue adhesive and applicator therefor.

14. An implant for implantation into a subject comprising:
a sterilized piece of cartilaginous allograft tissue harvested from knee meniscus tissue, said piece forming a Y shape with a base sized to insert within a first carpo-metacarpal joint or tarso-metatarsal joint of the subject, said cartilaginous allograft tissue comprising fibrocartilage having collagen type I;
a first arm adapted to secure to a trapezium bone adjoining the joint; and
a second arm adapted to secure to a proximal metacarpal or metatarsal bone adjoining the joint.

15. The implant of claim 14 wherein the first arm of the Y shape and the second arm are within 30% of being equal in length.

16. The implant of claim 14 wherein said implant further comprises a first securement for securing the first arm to the trapezium bone and a second securement for securing the second arm to the metacarpal bone.

17. The implant of claim 16 wherein the first securement is one of tissue adhesives, suture anchors, screws, sutures, or a combination thereof.

18. The implant of claim 14 wherein said tissue is from a cadaver of the same species as the subject.