Reconstructive Techniques and Outcomes for Large (≥4 cm) Peripheral Nerve Defects: A Meta-analysis.

Background: Nerve injury causing loss of sensation and motor function, and impairing quality of life. While surgical treatment for short nerve defects is well established, larger defects remain challenging. Moreover, there is no consensus on measuring clinical outcomes after nerve reconstruction. This meta-analysis summarizes surgical techniques and outcomes for peripheral nerve defects measuring 4 cm or more in length. Methods: A systematic literature search was performed for studies published between 1990 and 2024. Human studies on surgical nerve reconstruction with defect lengths measuring 4 cm or more and follow-up periods longer than 3 months were included. Data on sample size, affected nerve, treatment type, follow-up duration, and outcomes were extracted. Results: Overall, 24 studies were deemed eligible for analysis. Six reconstruction techniques were identified, with flap-associated autologous nerve grafting being the most common. Motor function was most frequently assessed using the British Medical Research Council muscle strength grading scale and dynamometer, whereas sensory outcomes were mainly evaluated using the 2-point discrimination method, the British Medical Research Council score as modified by Mackinnon and Dellon, and the Semmes-Weinstein filament test. No reconstruction technique demonstrated clear superiority in terms of motor or sensory recovery. Conclusions: Several approaches are used to repair long peripheral nerve defects. None has demonstrated clear superiority in terms of motor or sensory recovery. The absence of standardized outcome measures for motor and sensory function complicates comparisons between studies and hampers treatment development. Establishing standardized assessment forms, as proposed in this work, is essential to advancing the field of nerve repair.