Volar Versus Dorsal Approach for Scaphoid Nonunion: A Randomized Controlled Trial of Task-Specific Wrist Kinematics

BACKGROUND: The optimal surgical approach for scaphoid nonunion remains debated. This study compared task-specific wrist kinematics following volar versus dorsal reconstruction using wearable inertial sensors, with operated-healthy side difference as the primary endpoint. METHODS: In this single-center prospective randomized controlled trial, 21 patients with waist-type scaphoid nonunion eligible for either approach were randomized in a 1:1 ratio to volar or dorsal reconstruction; 18 patients (9 per group) completed 12-month follow-up and were included in the analysis. Surgical fixation, distal radius bone grafting, and rehabilitation were standardized. The primary outcome was the operated-healthy side difference in peak wrist extension during a simulated phone-handling task at 12 months, measured using wearable inertial measurement units. Secondary outcomes included Patient-Rated Wrist Evaluation (PRWE), scapholunate angle correction, and goniometric wrist motion. Patient-Rated Wrist Evaluation, radiographic correction, and standard goniometric extension were comparable between groups. Secondary kinematic analyses suggested task-specific differences in other planes of motion. CONCLUSIONS: Both approaches yielded similar union and patient-reported outcomes. The dorsal group demonstrated a numerically smaller extension asymmetry during a functional task, although this between-group difference did not reach statistical significance. Wearable sensor-based assessment may reveal clinically meaningful functional asymmetries not captured by traditional outcome measures. Larger adequately powered studies are needed to determine whether these exploratory differences are reproducible and clinically meaningful. LEVEL OF EVIDENCE: Therapeutic Level I.