gms | German Medical Science

Objective: The aim of this study was to analyze the long term impact on the Scaphotrapezium Trapezoid (STT) joint after the implantation of a Trapezium Metacarpal Prosthesis (CMC).

Introduction: The STT joint is the second most common site in the wrist affected by degenerative arthritis, usually associated with CMC osteoarthritis. Besides, the function of the STT in the biomechanics of the wrist and thumb is not well known. We evaluated the repercussion of the CMC over time on the STT joint.

Materials and Methods: An observational descriptive retrospective study with 100 patients with CMC osteoarthritis grade III of Eaton who had undergone non cemented "ball & socket" total CMC prosthesis, (an average follow-up of 5,9 years -range 4 to 9 years-), was iniciated to evaluate the clinic, radiological and functional changes over STT joint.

In order to avoid the bias of the effect the prosthesis, we decided to evaluate the patient 6 months after the surgery and nowadays. Results were compared by DASH and VAS scales, articular range of motion and clamp force with Jamar dynomometer. The STT radiological changes on RX and scanner images were classified according to Crosby et al JHandSurg 1978.

Results: Through this study we found out that 95.2% of the patients were satisfied with EVA scale under 3.5.

DASH scale parameters changed from an average of 16.5 to 20.1.

Thumb mobility and clamp force slightly modified from the obtained at 6 months.

Radiologic study showed that in most cases (97%) the osteoarthritic degeneration of STT was not modified by the previous surgery compared with contralateral hand.

Conclusions: Osteoarthritic degeneration of STT after the implantation of a CMC prosthesis did not change significantly way compared with its standard evolution.

More studies in patients treated by other techniques or non treated would help its evaluation.