Subclinical median nerve alterations after distal radius fractures: a comparative analysis of volar plate fixation and cast immobilization using dynamic ultrasonography and electrophysiology

BACKGROUND: Distal radius fractures may affect the median nerve through trauma-related and treatment-related mechanisms. While overt neurological deficits are uncommon, subclinical median nerve alterations may occur following both conservative and surgical treatment. PURPOSE: To determine whether treatment modality influences subclinical median nerve behavior using combined dynamic ultrasonographic and electrophysiological assessment. METHODS: This retrospective observational study included 42 patients with unilateral distal radius fractures. 18 patients were treated conservatively with circular casting, and 24 patients underwent volar plate fixation. Ultrasonographic assessment of the median nerve was performed at the distal radius level in neutral wrist position, as well as during wrist flexion and extension, using a dynamic ultrasonographic approach, and was combined with electrophysiological evaluation including sensory and motor nerve conduction studies. In the surgically treated group, only patients with Soong type 1 or type 2 plate positioning were included. RESULTS: Clinical functional outcome scores were comparable between groups, despite a higher frequency of mild clinical signs such as positive Tinel test and night pain in the plate group. However, ultrasonographic evaluation demonstrated significantly greater position-dependent median nerve enlargement and flattening in the volar plate group, particularly during wrist flexion and extension (p < 0.05). Electrophysiological assessment revealed a significant reduction in sensory nerve conduction velocity on the affected side in surgically treated patients compared with the cast group (p < 0.05), while motor conduction parameters remained preserved. These differences were observed despite comparable clinical functional outcomes between groups. CONCLUSION: Patients treated with volar plate fixation demonstrated more pronounced subclinical ultrasonographic and electrophysiological median nerve alterations compared with those treated conservatively with cast immobilization. However, given the retrospective and non-randomized design, these findings should be interpreted as associative rather than causal. Combined ultrasonographic and electrophysiological assessment may be useful for detecting early median nerve involvement and guiding follow-up evaluation, even in the absence of clinically overt symptoms.