Do wrist anatomical differences predispose to scapholunate ligament injury? A case-control radiographic study

Purpose: Scapholunate interosseous ligament (SLIL) injury is the most common cause of carpal instability and may lead to scapholunate advanced collapse if untreated. While several anatomical wrist variations have been implicated in other wrist pathologies, limited studies have explored their role in SLIL injuries. This study aimed to compare specific anatomical parameters on wrist radiographs between patients with arthroscopically confirmed SLIL injuries and healthy individuals to identify potential anatomical predispositions. Methods: This study analyzed bilateral wrist radiographs of 87 patients who underwent arthroscopic dorsal capsulodesis for SLIL injuries between 2010 and 2023. A control group of 87 asymptomatic individuals with normal wrist radiographs was also included. Standardized anteroposterior and lateral wrist X-rays were collaboratively evaluated by three orthopedic surgeons. Parameters measured included radial inclination (RI), lunate fossa inclination (LFI), ulnar variance (UV), lunate tilting angle (LTA), lunate uncovering index (LUCI), carpal height ratio (CHR), palmar tilting angle (PTA), and lunate morphology. Group comparisons were performed, and a multiple logistic regression analysis was conducted using variables found to be significant in univariate analysis to identify independent anatomical predictors of SLIL injury. Results: There were no significant differences between the SLIL-injured patient group and the control group in terms of gender, age, and side (p > 0.05). RI (p < 0.001) and LFI (p = 0.016) were significantly lower, while LTA (p < 0.001) was significantly higher in the SLIL-injured patient group. Multiple logistic regression analysis revealed that lower RI (OR: 0.853, 95% CI: 0.769–0.946; p = 0.003) and higher LTA (OR: 1.126, 95% CI: 1.052–1.204; p = 0.001) were independently associated with SLIL injury. LFI did not remain significant in the final model. No significant differences were observed in UV, LUCI, PTA, CHR, or lunate type between groups. Conclusion: Low RI and increased LTA may represent anatomical risk factors for SLIL injury. Other parameters were not associated with an increased risk of injury. This study was not designed to establish a radiological diagnosis of SLIL injury; rather, it demonstrates that SLIL injuries may be influenced by individual anatomical variations. Further large scale studies are needed to validate these findings and to better understand the anatomical contributions to SLIL injury susceptibility.