A deformity of hyperextension of the metacarpophalangeal joint of the
thumb occurring in thirteen children with spastic cerebral palsy was
corrected by capsulodesis of the joint. The technique involves shifting the
metacarpal attachment of the volar plate more proximally in the metacarpal.
When combined with selective release of the involved intrinsic muscles and
selective transfer of the extrinsic motors, when indicated, the thumb is
brough away from the palm and its function and appearance are improved.
Moreover, there is not risk to growth of the thumb such as might follow
arthrodesis in a growing child. Results were satisfactory except in two
athetoid patients, in whom some of the intial correction was lost, but even
their thumbs did not revert into hyperextension. In five patients, for
reasons not entirely clear, the previously flexed interphalangeal joint had
better extension postoperatively. This improved the function of the thumb,
because the broad pulp of the thumb could then be used firmly against the
side of the index finger.