A Prospective Observational Assessment of Unicortical Distal Screw Placement During Volar Plate Fixation of Distal Radius Fractures

Purpose: Although volar plating of the distal radius is performed frequently, the necessity of distal bicortical fixation in the metaphyseal and epiphyseal areas of the distal radius has not been proven. This study aimed primarily to quantify the ability of unicortical distal screws to maintain operative reduction of adult distal radius fractures and secondarily to determine if unicortical screw lengths could be predicted based on anatomical measurements. Methods: This prospective trial enrolled 75 adult patients undergoing volar locking plate fixation of a unilateral distal radius fracture at a tertiary center. Study inclusion required screw fixation in the distal rows of the plate performed with unicortical screw placement. The primary outcome was maintenance of operative reduction, according to predefined parameters, quantified by comparing initial operative reduction to final reduction after fracture healing. Repeated measures analysis of variance analyzed for systematic change in radiographic parameters between injury, operative, and healed images. Correlation coefficients quantified the relationship of screw lengths with lunate width and other anatomical measurements. Results: Seventy-five patients (mean age, 54 years ± 15 years; 79% women) were enrolled and followed to fracture union. Fracture severity varied and included AO type A (40%), B (12%), and C (48%) fractures. There was no significant change in mean lateral translation, intra-articular gap, intra-articular stepoff, radial inclination, or lateral tilt of the radius between the time of fixation and union for the cohort. Two patients lost reduction (increased dorsal tilt, 10° 20° respectively), potentially attributable to provision of unicortical fixation (3%; 95% confidence interval [95% CI], 0%–9%). No extensor tenosynovitis or extensor tendon ruptures occurred. Eighty percent of screws were 18 mm or less and screw lengths were not correlated with lunate width or any other anatomical measurements. Conclusions: Unicortical distal fixation during volar locking plate fixation effectively maintains operative reductions of distal radius fractures while potentially minimizing the incidence of extensor tendon ruptures. Type of study/level of evidence: Therapeutic IV.