Do we need to use the largest possible size of the Proximal Femoral Nail Anti-rotation (PFNA) in well-reduced intertrochanteric fracture? A study of distal PFNA intramedullary canal occupying ratio (ICOR).

PURPOSE: To assess the impact of the intramedullary canal occupying ratio (ICOR) on bone union and the stability of fixation in intertrochanteric fracture treatment using proximal femoral nail anti-rotation (PFNA) surgery. METHODS: A retrospective analysis included 151 patients aged 60 years and above who underwent PFNA for unilateral intertrochanteric fractures between June 2020 and 2022. Patients were categorised into 3 groups based on ICOR percentiles (0.48-0.93). Bone healing was assessed using the Radiographic Union Score for Hip (RUSH) at 2, 6, and 12 weeks postoperatively. Fixation stability was assessed by comparing immediate and 3-month postoperative radiographs. Multivariate regression was used to assess the relationship between ICOR, RUSH scores, and fixation stability. RESULTS: No significant differences in RUSH scores or stability measurements were found among the 3 ICOR-based groups. Multivariate regression showed no clear correlation between ICOR and RUSH scores, except for a statistically significant but not clinically relevant association with changes in neck-shaft angle. In contrast, RUSH scores were significantly associated with fracture severity according to the OTA/AO Classification. CONCLUSION: ICOR was not a significant predictor of fracture healing or fixation stability. In uncertain cases regarding nail size, using a smaller nail was not linked to inferior radiographic or fixation-related outcomes.