Influence of Screw Length, Diameter, and Immobilization on Percutaneous Scaphoid Fixation: A Retrospective Study of 249 Acute Scaphoid Fractures.

INTRODUCTION: Articular screw protrusion remains frequent after percutaneous fixation of acute scaphoid fractures and may be influenced by screw length and positioning. This study evaluated the influence of screw length, diameter, direction, and postoperative immobilization on fracture union and CT-detected articular protrusion. HYPOTHESIS: Shorter screws are associated with a lower rate of CT-detected articular protrusion without an observed reduction in fracture union. METHODS: This retrospective single-center study included 249 adults treated with percutaneous screw fixation for acute scaphoid fractures between 2017 and 2026. Fracture union and CT-detected articular protrusion on postoperative CT were the primary outcomes. Protrusion was defined as ≥1 mm beyond the osseous articular boundary. Screw length was primarily analyzed as a continuous variable, with an additional comparison between screws ≤20 mm and ≥22 mm. A screw-to-scaphoid length ratio was also calculated. Multivariable logistic regression was performed to identify factors associated with CT-detected articular protrusion. RESULTS: Overall union was achieved in 232 cases (93.2%), whereas CT-detected articular protrusion was observed in 130 cases (52.2%). Protrusion was significantly less frequent with screws ≤20 mm than with screws ≥22 mm (25.9% vs 60.2%; p < 0.001), while union rates were similar (93.1% vs 93.2%; p = 1.000). Each 1-mm increase in screw length was independently associated with higher odds of CT-detected articular protrusion (OR 1.32; 95% CI 1.16-1.50; p < 0.001). Similarly, a higher screw-to-scaphoid length ratio was independently associated with protrusion (OR 1.73 per 0.10 increase; 95% CI 1.26-2.37; p < 0.001). Screw diameter, fixation direction, and postoperative immobilization duration were not significantly associated with union. CONCLUSION: In this retrospective cohort, shorter screws were associated with a substantially lower rate of CT-detected articular protrusion, while no lower union rate was observed. The association persisted after normalization of screw length to individual scaphoid length. These findings support considering shorter screw fixation when anatomy and fracture configuration allow, although prospective studies incorporating clinical outcomes are required to determine the clinical significance of CT-detected protrusion and the optimal screw length. LEVEL OF EVIDENCE: III.