Early versus Late Supinator to Posterior Interosseous Nerve Transfers in Spinal Cord Injury: a Systematic Review and Individual-Patient-Data Meta-analysis

Introduction: Cervical spinal cord injury (SCI) can result in hand paralysis. The supinator to posterior interosseous nerve (SPIN) transfer has augmented reanimation of hand opening in tetraplegia with a robust impact in the quality of life of these patients. There are scarce reports studying the effect of timing of surgery on outcomes specifically of the SPIN transfer. We sought to analyze outcome of the SPIN transfer in early (≤6 mo) vs late (>6 mo) transfers in the setting of SCI.

Methods: A systematic literature review was performed according to the PRISMA guidelines. All studies reporting outcomes of the SPIN transfer in the setting of SCI were included and analyzed.

Results: A total of 10 studies with 79 patients and 123 SPIN transfers were included. Successful finger and thumb extension (MRC >=3) recovered in 89% (110/123) and 78% (96/123) transfers, respectively. Individual-patient-data were available for 61 transfers in 40 patients (12 female, 28 male) with a mean age 30.2 years (range 15-60). Mean timing from injury to surgery was 15.9 months (range 2-91). 18 of the nerve transfers were performed early (≤6 mo) while the remaining 43 were performed late (>6 mo). There was no difference in the rates of thumb (early=15/18-83.3%; late=34/42-80.9%; OR: 0.85; 95% CI 0.19-3.65, p=0.82) and finger (early=15/18-83.3%; late=42/43-97%; OR: 8.4; 95% CI 0.81-87.08, p=0.07) extension recovery in early vs late transfers over a mean follow-up of 22.6 months. One patient developed supination weakness; however, this patient had pre-existing bicep weakness. Four patients developed temporary wrist extension weakness.

Conclusion : The SPIN transfer can be performed early or late after SCI with similar finger and thumb extension outcomes.