Flexor pollicis longus abductor-plasty for spastic thumb-in-palm deformity

Seven patients with thumb-in-palm deformity due to spasticity of the flexor pollicis longus (FPL) were treated by transferring the tendon of the FPL to the radical side of the proximal phalanx of the thumb and stabilizing the interphalangeal (IP) joint in 15 degrees of flexion by tenodesis or arthrodesis. Surgery was not performed unless: (1) the affected limb was used spontaneously for bimanual activities, (2) there was functional disability due to the thumb-in-palm deformity, (3) the thumb could be passively extended and abducted with the wrist palmar flexed, or (4) the thumb could be actively adducted and the metacarpophalangeal joint flexed with the wrist palmar flexed. Neither low intelligence nor sensory deficit was considered an absolute contraindication to treatment. After the operation, there was improved appearance in the hands of all seven patients. The thumb was no longer held clenched in the palm. Each patient was able to use the operated hand for assistive grasp; however, ability to use the hand for manipulation of small objects and for pinch was not improved. In fact, one patient had decreased small object manipulative ability postoperatively and required subsequent tendon transfer to restore thumb adduction. Release of the FPL from its insertion, stabilization of the IP joint of the thumb, and transfer of the FPL to the radical side of the thumb can achieve improved thumb balance and function in patients with spastic FPL thumb-in-palm deformity who have functioning adductor pollicis and thumb extensors. The operation lessens thumb flexion and adduction and improves thumb extension and abduction.