Which implant for Pauwels type 2 femoral neck fractures: a biomechanical study

Abstract

Objective: Femoral neck fractures (FNF) in young patients are relatively rare but can lead to severe complications if not treated appropriately. Pauwels type 2 fractures, characterized by moderate inclination, require surgical stabilization. However, no consensus exists regarding the optimal implant that provides superior biomechanical stability. This study aims to compare the biomechanical properties of 3 different fixation systems for the surgical treatment of Pauwels type 2 FNF. Methods: A total of 21 bovine femurs of similar age and size were selected and divided into 3 fixation groups: dynamic hip screw (DHS), cannulated screws (CS), and major plate (MP). Each specimen underwent axial compression testing to assess the maximum load-bearing capacity, shear force resistance, and deformation characteristics of the fixation methods. Results: The results showed that the CS group exhibited the highest shear stress resistance, followed by the DHS group, while the MP group showed significantly lower mechanical strength and elongation (P < .05). Although DHS provided substantial stability, CS demonstrated superior overall mechanical performance. In contrast, the MP system showed significantly lower resistance compared to the other 2 fixation methods. Conclusion: This biomechanical study highlights the importance of implant selection in the management of Pauwels type 2 FNF. Although previous investigations have questioned the adequacy of CS fixation in highly unstable Pauwels type 3 fractures, the results suggest that CS may be a reliable and effective option for the relatively more stable Pauwels type 2 pattern. Because the tests were performed on bovine femur models, which do not fully reflect the structural characteristics of human bone, these findings should be interpreted with caution. Further biomechanical studies using human cadaveric specimens are required to confirm the applicability of these results to clinical practice.