Camitz tendon transfer using flexor retinaculum as a pulley in advanced carpal tunnel syndrome.

Purpose: To report the outcomes of modified Camitz abductor plasty using the released flexor retinaculum as a pulley in patients with advanced carpal tunnel syndrome.

Methods: A retrospective review of 46 hands in 43 patients who underwent modified Camitz abductor plasty was performed. Active palmar abduction of thumb and pulp pinch strength were assessed. Patient-reported outcome measures were assessed using the Disabilities of the Arm, Shoulder, and Hand and Carpal Tunnel Syndrome instrument. As an electrophysiological assessment, compound muscle action potential (CMAP) from abductor pollicis brevis (APB) was investigated.

Results: At 3 months, active palmar abduction of thumb and pulp pinch strength significantly improved. Although pulp pinch strength further improved, active abduction of thumb did not improve at the final follow-up. Both the patient-reported outcome measures improved at 3 months and further improved at final follow-up. Approximately 75% of improved scores were obtained at the first 3 months after surgery and the balance of improved scores (25%) was obtained by the time of final follow-up. Useful recovery of postoperative APB-CMAP (amplitude > 1.8 mV) was obtained in 3 hands (7%) at 3 months after surgery and in 23 hands (50%) at final follow-up. There was no statistical significance of the postoperative results including active palmar abduction of thumb and improvement of patient-reported outcome measures at final follow-up between the hands with useful recovery of postoperative APB-CMAP and the hands without it.

Conclusions: Modified Camitz abductor plasty benefitted the early improvement of activity of daily living in patients with advanced carpal tunnel syndrome. It acted not only as an internal orthosis in patients who eventually recovered thenar muscle function but also as the sole palmar abductor of the thumb in patients who failed to recover useful thenar muscle function.

Type Of Study/level Of Evidence: Therapeutic IV.