A split-EPB tendon sling for chronic post-traumatic palmar instability of the thumb metacarpophalangeal joint.

Kessler's extensor pollicis brevis (EPB) palmar tendon sling is a simple and reliable reconstruction for symptomatic palmar instability of the thumb metacarpophalangeal (MP) joint. However, we encountered subluxation of the extensor pollicis longus tendon and extension lag at the MP joint when the entire tendon was used. We modified the technique, splitting the tendon to preserve its function as an MP joint extensor. Six thumb MP joints with anteroposterior instability secondary to hyperextension injury were reconstructed using the split-EPB technique. At an average of 22 months postoperatively, all patients had stable and pain-free MP joints. Pinch strength improved an average of 5.6 kg. MP joint flexion was decreased an average of 17.5 degrees and two patients had flexion contractures of 5 degrees and 20 degrees, respectively. Extensor pollicis longus subluxation and MP extension lag did not occur, and there were no recurrences.