Treatment of osteoartritis of the carpometacarpal joint of the thumb: Evaluation of the Swanson prosthesis

Osteoarthritis of the CMC-1 joint is a noninfectious degeneration of the
cartilage of the carpometacarpal joint of the thumb. There are a number of
conservative options such as immobilization splint therapy and intra-articular
injections with cortocosteroiden. Furthermore a surgical treatment is possible,
including atrodesis, excision of the trapezium with ligament reconstruction,
excision of the trapezium with a prosthesis or with interposition-arthroplasty.
Another possibility is a combination of ligament reconstruction and
interposition arthroplasty, LRTI. The present study was conducted to establish
the long-term results and to highlight the problems associated with the implant
of an Swanson prothesis. Instability of the prosthesis and silicone-induced
synovitis have led most surgeons to abandon use of the Swanson trapezium
implant for the treatment of primary osteoarthritis. However, the literature
contains little information on the results of long-term follow-up.

The aim of this study is to:
- Analyse the survival of the Swanson implant
- Analyse the functional outcome of the CMC-I joint after placing a Swanson
implant
- Analyse subluxation of the CMC-I joint after placing a Swanson implant
- Analyse cyst formation after placing a Swanson implant

Research hypotheses:
- The five-years survival of a Swanson implant is 90%
- After a Swanson prosthesis is implanted a grip strength of 85% standard for
age and sex is expected (Appendix 1)
- After a Swanson prosthesis is implanted a good DASH score is expected (<50
points)
- No subluxation is expected after implanting a Swanson prothese
- After a Swanson prosthesis is implanted there is cyst formation in
surrounding structure expected

Descriptive retrospective cross-sectional cohort study

This study contains no additional risks for the included patients. The patients
fill out two questionnaires which takes about an hour to complete. In addition,
the patients are invited for a clinical visit for a half hour. During this
clinic visit some functional tests will proformed of the hand and a X-ray of
both hands is taken.