Changes in PFNA nail position do not influence bone healing and femoral head varus in patients with stable intertrochanteric fractures: a comprehensive clinical and biomechanical study.

Abstract

<h4>Background</h4>Nail positioning is highly adjustable during the proximal femoral nail anti-rotation (PFNA) procedure for treating intertrochanteric fractures. Our published study demonstrates that changes in nail position can significantly affect local stress distribution, and ventral side nail insertion may increase the risk of varus deformity in the femoral head, particularly in unstable fracture types. However, adjusting the guidewire position tends to prolong operation time and increase blood loss. The necessity of this adjustment in stable fracture cases remains to be clarified.<h4>Methods</h4>This retrospective study reviewed the clinical data of patients with stable intertrochanteric fractures (AO 31-A1 and A2.1) who were treated with PFNA operation and had a minimum follow-up of 6 months. Nail position was assessed using immediate postoperative lateral radiographs. A correlation between nail positioning and femoral head varus has been established. Furthermore, to corroborate the clinical findings, the biomechanical effects of nail position variation were evaluated using a stable fracture model. Specifically, femoral head displacement, as well as stress values within the femoral head and at the bone-screw interfaces, were analyzed.<h4>Results</h4>This study integrated retrospective clinical data analysis with computational mechanical simulations, which yielded a similar trend. The clinical review included a total of 53 patients, comprising 27 with ventral and 26 with dorsal nail positions. No statistically significant difference was observed in the femoral head varus angle between the ventral and dorsal placement groups (t = - 0.683, p = 0.497). Furthermore, computational simulations indicated that variations in nail position did not significantly alter the stress distribution or displacement of either the femoral head or the anti-rotation blade under compressive or physiological loading conditions.<h4>Conclusions</h4>The position of the PFNA nail has only a minimal impact on fixation stability and stress distribution around the femoral head in stable intertrochanteric fractures. Therefore, intraoperative guidewire adjustments are unnecessary when treating such stable fractures with PFNA.