Surgical Fixation Versus Cast Immobilization for Adults With Bicortical Scaphoid Fractures: A Target Trial Emulation of the SWIFFT Trial.

Abstract

The Scaphoid Waist Internal Fixation for Fractures Trial (SWIFFT) reported no notable difference in functional outcomes between surgical fixation and cast immobilization for minimally displaced scaphoid waist fractures in UK settings. We aimed to emulate SWIFFT using Chinese hospital electronic health record (EHR) data to evaluate whether similar treatment effects are observed in a population with different risk profiles and to identify subgroups that may benefit differentially from surgery. This target trial emulation used a clone-censor-weight design with inverse probability of treatment and censoring weighting. Deidentified EHR data were extracted from three Tertiary A teaching hospitals in China (July 2018 to August 2024). Adults aged 16 years or older with a bicortical scaphoid waist fracture (displacement ≤2 mm) presenting within 14 days of injury were eligible. Patients received either headless compression screw fixation (n = 2,544) or below-elbow cast immobilization (n = 4,225). The primary outcome was the Disabilities of the Arm, Shoulder, and Hand (DASH) score at 52 weeks. Among 6,769 patients (mean age 32.1 years; 81.6% male; 42.4% current smokers), surgery produced statistically significant DASH improvements at all time points. At 52 weeks, the adjusted mean difference was -4.2 (95% CI, -4.9 to -3.5; P < 0.001), below commonly cited MCID estimates (10 to 15 points) but approaching lower proposed thresholds (7 to 10 points). Surgery halved nonunion risk (8.4% vs 17.5%; RR 0.48, 95% CI, 0.41 to 0.55) but increased complications sevenfold (14.1% vs 2.0%), predominantly screw-related. Subgroup analyses showed larger surgical benefits among patients with displaced fractures (-8.5) and current smokers (-6.7). Nearly one in five cast-treated patients (18.1%) ultimately required surgery for nonunion. Surgery was associated with statistically significant but modest DASH improvements, halved nonunion risk, and a sevenfold increase in complications. Cast immobilization remains a reasonable initial strategy for undisplaced fractures, while surgery offers measurable advantages for displaced fractures or smokers.