Recurrent Motor Branch Injury During Open Carpal Tunnel Release: A Case Report and Recommendations for Prevention of This Surgical Hazard

Background: The purpose of this article is to present a case reconstruction of iatrogenic recurrent motor branch of the median nerve (RMN) injury following open carpal tunnel release (OCTR). Additionally, we review the literature on safe incision lines to minimize risk of iatrogenic injury to the RMN. Methods: A 48-year-old right-handed woman developed progressive thenar atrophy and thumb dysfunction after OCTR. Surgical reexploration 7 months post-OCTR revealed a transected RMN embedded in scar tissue. Microsurgical epineural nerve repair was performed, combined with tendon transfer and structured rehabilitation, including motor imagery. Results: At 7 months postrepair, significant functional recovery was observed in thumb opposition, grip strength, and fine motor control. The literature review emphasized that an incision along the fourth-ray axis minimizes the risk of RMN injury compared with more radial incisions. Conclusions: Precise incision placement along the third webspace is paramount to reduce the risk of RMN injury during OCTR. Early recognition of postoperative motor deficits enables timely reexploration and microsurgical repair, allowing substantial functional recovery even after delayed diagnosis. Structured rehabilitation, including motor imagery, can further optimize outcomes.