Use of a relative motion flexion orthosis for postoperative management of zone I/II flexor digitorum profundus repair: A retrospective consecutive case series.

Study Design: A retrospective, single-center, consecutive case series.

Introduction: In concept, a relative motion flexion (RMF) orthosis will induce a "quadriga effect" on a given flexor digitorum profundus (FDP) tendon, limiting its excursion and force of flexion while still permitting a wide range of finger motion. This effect can be exploited in the rehabilitation of zone I and II FDP repairs.

Purpose Of The Study: To describe the use of RMF orthoses to manage zone I and II FDP 4-strand repairs.

Methods: Medical record review of 10 consecutive zone I and II FDP tendon repairs managed with RMF orthosis for 8 to 10 weeks in combination with a static dorsal blocking or wrist orthosis for the initial 3 weeks.

Results: Indications included sharp lacerations (n = 6), ragged lacerations (n = 2), staged flexor tendon reconstruction (n = 1), and type IV avulsion (n = 1). In 8 of the 10 cases that completed follow-up, the mean arc of proximal interphalangeal/distal interphalangeal active motion were as follows: sharp, 0° to 106°/0° to 75°; ragged, 0° to 90°/0° to 25°; reconstruction, 0° to 90°/10° to 45°; and avulsion, 0° to 95°/0° to 20°. Grip performance available for 6 of 10 cases was 62% to 108% of the dominant hand. There were no tendon ruptures, secondary surgeries, or proximal interphalangeal joint contractures.

Conclusion: Based on this small series, the RMF approach appears to be safe and effective. It can lead to similar mobility and functional recovery as other early active motion protocols, with certain practical advantages and without major complications. Further investigation with larger, multicenter, prospective, longitudinal cohorts and/or randomized clinical trials is necessary.