Kozin and Ezaki flexor digitorum superficialis opponensplasty with ulnar collateral ligament reconstruction. A, Four-flap Z-plasty. B, Incisions. C, Ring finger flexor digitorum superficialis identified at base of finger. D and E, Pulley construction. E, Ring finger flexor digitorum passed through flexor carpi ulnaris loop. F, Flexor digitorum superficialis tendon passed through subcutaneous tunnel to radial side of thumb. G, Kirschner wire drilled across metacarpal head. H, Flexor digitorum superficialis tendon passed through metacarpal head to ulnar side of thumb. SEE TECHNIQUE 80.25.