Reconstruction of metacarpophalangeal joint of thumb in rheumatoid arthritis. A, Metacarpophalangeal joint of thumb with extensive tendon damage. After rupture of insertion of extensor pollicis brevis tendon proximal retraction, extensor hood becomes attenuated and allows abductor pollicis brevis and extensor pollicis longus to migrate volarward below center of rotation of metacarpophalangeal joint. B, Extensor pollicis brevis and adductor pollicis insertions are dissected free from remaining attenuated extensor tendon hood. C, Synovectomy is facilitated by joint flexion. Collateral ligaments are preserved. D, Attachment of extensor pollicis brevis tendon into base of proximal phalanx. When extensor pollicis brevis cannot be advanced, extensor indicis proprius can be transferred from index finger and inserted into base of proximal phalanx.