Double Supinator Branch Transfer to Posterior Interosseous Nerve May Confer Superior Hand Opening Restoration Outcomes in Brachial Plexus and Spinal Cord Injury Compared to Single Branch.

Background and objectives: Cervical spinal cord injury (SCI) and lower trunk brachial plexus injury (BPI) commonly result in hand paralysis. The supinator to posterior interosseous nerve (SPIN) transfer is a well-established surgical approach that can achieve restoration of hand opening with similar outcomes in SCI and BPI. Most often, the radial nerve has 2 branches to the supinator. Studies have reported utilization of either single or double supinator branches as donors for the SPIN transfer. The aim of this study was to study whether using one or both supinator branches can affect recovery of hand opening.

Methods: A systematic literature review was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. All studies reporting outcomes of the SPIN transfer were included.

Results: A total of 16 studies with 108 patients and 152 SPIN transfers were included (132 with double and 20 with single supinator donor branches; 123 for SCI and 29 for BPI). Four of the 16 included studies reported the use of a single motor supinator branch as a donor, while the remaining 12 studies used both branches. The average time interval from injury to surgery was <12 months in each study. Finger extension (Medical Research Council ≥3/5) recovered in 65% (13/20) and 86.3% (114/132) of the single and double donor transfers (P = .016), respectively. Thumb extension restoration was achieved in 60% (12/20) and 83.3% (110/132) of the single and double branch transfers (P = .014), respectively. The median reported follow-up was more than 20 months per study. One patient in the cohort developed supination weakness; however, this patient had preexisting biceps weakness. Four patients developed temporary wrist extension weakness.

Conclusion: Utilization of both supinator branches for the SPIN transfer might achieve superior hand opening outcomes in SCI and BPI, compared with the single supinator branch.