Relative motion orthoses for early active motion after finger extensor and flexor tendon repairs: A systematic review.

BACKGROUND: The relative motion (RM) orthosis was introduced over 40 years ago for extensor tendon rehabilitation and more recently applied to flexor tendon repairs. PURPOSE: We systematically reviewed the evidence for RM orthoses following surgical repair of finger extensor and flexor tendon injuries including indications for use, configuration and schedule of orthosis wear, and clinical outcomes. STUDY DESIGN: Systematic review. METHODS: A PRISMA-compliant systematic review searched eight databases and five trial registries, from database inception to January 7, 2022. The protocol was registered prospectively (CRD42020211579). We identified studies describing patients undergoing rehabilitation using RM orthoses after surgical repair of acute tendon injuries of the finger and hand. RESULTS: For extensor tendon repairs, ten studies, one trial registry and five conference abstracts met inclusion criteria, reporting outcomes of 521 patients with injuries in zones IV-VII. Miller's criteria were predominantly used to report range of motion; with 89.6% and 86.9% reporting good or excellent outcomes for extension lag and flexion deficit, respectively. For flexor tendon repairs, one retrospective case series was included reporting outcomes in eight patients following zones I-II repairs. Mean total active motion was 86%. No tendon ruptures were reported due to the orthosis not protecting the repair for either the RME or RMF approaches. DISCUSSION: Variation was seen in use of RME plus or only, use of night orthoses and orthotic wear schedules, which may be the result of evolution of the RM approach. Since Hirth et al's 2016 scoping review, there are five additional studies, including two RCTs reporting the use of the RM orthosis in extensor tendon rehabilitation. CONCLUSIONS: There is now good evidence that the RM approach is safe in zones V-VI extensor tendon repairs. Limited evidence currently exists for zones IV and VII extensor and for flexor tendon repairs. Further high-quality clinical studies are needed to demonstrate its safety and efficacy.