Correction of non-traumatic extensor tendon dislocation and ulnar drift at the metacarpophalangeal joint by the modified Dell technique.

Background: Chronic ulnar extensor tendon dislocation at the metacarpophalangeal joint causes permanent extension deficit and ulnar drift. Several soft tissue procedures have been described for realignment of the extensor tendon in post-traumatic reducible instability or in combination with joint replacement in case of altered metacarpophalangeal joint in inflammatory conditions. However, no studies reported correction of both extension lag and ulnar deviation following isolated surgical treatment of ulnar extensor tendon dislocation at the metacarpophalangeal joint. The present study evaluated the clinical and functional results of isolated correction of chronic non-traumatic ulnar extensor tendon dislocation at metacarpophalangeal level using the modified Dell technique.

Hypothesis: The study hypothesis was that the modified Dell technique allows realignment of the extensor apparatus and correction of both metacarpophalangeal extension lag and ulnar drift.

Patients and methods: 10 patients (24 fingers), operated on between June 2012 and May 2019, were evaluated at a mean follow-up of 36 months. The etiologies were rheumatoid arthritis in 17 cases, Jaccoud arthropathy due to systemic lupus erythematosus in 4, and degenerative in 3. A radial strip of distal-based extensor tendon, passed around the radial collateral ligament of the metacarpophalangeal joint downward from the surface, was sutured proximally to the remaining extensor tendon using the Pulvertaft technique.

Results: Extension deficit improved significantly, by a mean 26° (-9° postoperatively vs -35° preoperatively, p < 0.001). MP joint ulnar drift also improved significantly, by a mean 15° (6° vs 21°, p < 0.001). Four fingers had preoperative swan neck deformity that improved postoperatively. There were 2 cases of recurrent dislocation.

Conclusion: The modified Dell technique showed favorable results in treating chronic non-traumatic ulnar extensor tendon dislocation at metacarpophalangeal level in the long fingers, with realignment of the extensor system and correction of both metacarpophalangeal extension lag and ulnar drift.

Level of evidence: Level 4, single-center retrospective observational study.