Treatment of a symptomatic trapezial dysplasia with metacarpal instability following thumb metacarpal lengthening with an addition-subtraction osteotomy.

The most important problem of trapezial dysplasia with thumb metacarpal instability is of bony origin. Together with the progressive capsuloligamentous decompensation it evolves in a progressive adduction deformity of the thumb metacarpal secondary to the dysplasia of the trapezium with its increased articular slope. The addition-subtraction osteotomy restores the anatomy combining two techniques: an abduction-extension osteotomy of the first metacarpal to correct the axis of the first metacarpal and an opening wedge osteotomy of the trapezium to reorientate the trapezial saddle. We present a case of an addition-subtraction osteotomy in a case of symptomatic trapezial dysplasia with metacarpal instability following a thumb metacarpal lengthening in a severely mutilated hand. This technique was especially effective in reducing the instability and pain but mainly in maintaining mobile the only remaining joint of the thumb.