Ultrasound for Diagnosing Hand and Digital Nerve Trauma: A Systematic Review and Meta-Analysis.

Purpose: To evaluate the diagnostic accuracy and clinical utility of ultrasound in traumatic hand and digital nerve injuries and to compare its performance with conventional diagnostic modalities such as EMG and nerve conduction studies (NCS). Methods: A systematic review and meta-analysis were performed in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines (PROSPERO CRD420251107777). MEDLINE and Embase were searched to July 18, 2025. Eligible studies included English-language retrospective studies assessing ultrasound for traumatic hand or digital nerve injury with a surgical, clinical, or electrodiagnostic reference standard. Two reviewers independently screened studies, extracted data, and assessed quality using the Newcastle-Ottawa Scale. Sensitivity and specificity were synthesized when extractable; additional outcomes included time to diagnosis, injury characterization, and impact on surgical planning. Results: Twelve retrospective studies encompassing 607 injuries were included. Nine studies provided extractable diagnostic data, with a pooled ultrasound sensitivity of 93% across diverse trauma types. Specificity was reported in only two studies and remained limited because of small disease-negative cohorts. Sonographic findings included complete transection (29%), neuroma in continuity (24%), increased cross-sectional area (18%), and partial transection (8%). In six studies directly comparing modalities, ultrasound and EMG/NCS demonstrated sensitivities ≥90%, with full concordance in 2 series and near-equivalence in others. Ultrasound additionally identified structural features such as neuromas, fascicular disruption, and perineural scarring that guided operative referral. Studies using ultrahigh-frequency (70 MHz) probes achieved sensitivities approaching 98% for superficial digital nerves. Overall study quality was moderate, with common limitations including retrospective design and incomplete reporting of specificity. Conclusions: Ultrasound is a highly sensitive, noninvasive tool for diagnosing traumatic hand and digital nerve injuries, offering advantages over electrodiagnostic studies by directly visualizing structural pathology. An "ultrasound-first" strategy in the acute phase, followed by EMG/NCS for functional assessment in the subacute phase, may optimize timely diagnosis, guide referral, and assist surgical planning. Type of study/level of evidence: Diagnostic III.