Abstract
Background The treatment of vertical femoral neck fractures in young patients remains a challenge. This study is aimed at comparing ordinary cannulated compression screw (OCCS) and double-head cannulated compression screw (DhCCS) fixation in vertical femoral neck fractures both clinically and biomechanically. Materials and Methods Clinically, the radiographs of 81 patients with Pauwel's III femoral neck fractures, including 54 fractures fixed with three parallel OCCSs and 27 fractures fixed with three parallel DhCCSs, were reviewed retrospectively. Complications consisting of fixation failure (screw loosening, obvious fracture displacement, varus deformity, or femoral neck shortening), bony nonunion, and avascular necrosis (AVN) were determined. Biomechanically, twenty synthetic femur models of vertical femoral fractures with an 80° Pauwel's angle were divided into two groups and subsequently fixed with three parallel OCCSs or DhCCSs. All specimens were tested for axial stiffness, load to 5 mm displacement, and a maximum load to failure with a loading rate of 2 mm/min. Results Clinically, 22 fractures in the OCCS group experienced fixation failure, including 19 screw loosening, 18 femoral neck shortening, 14 varus deformities, and 8 obvious fracture displacements, whereas only 4 fractures experienced fixation failure in the DhCCS group, including 3 screw loosening, 3 femoral neck shortening, 3 varus deformities, and 1 obvious fracture displacement. Additionally, 11 fractures in the OCCS group exhibited nonunion, whereas only 3 in the DhCCS group exhibited nonunion. Nine fractures with AVN were noted in the OCCS group, whereas only 1 was observed in the DhCCS group. Biomechanically, the axial stiffness of the DhCCS group was greater than that of the OCCS group (154.9 ± 6.81 vs. 128.1 ± 7.41 N/mm), and the load to 5 mm displacement was also significantly greater in the DhCCS group (646.1 ± 25.87 vs. 475.8 ± 21.46 N). Moreover, the maximum load to failure in the DhCCS group exhibited significant advantages compared with that of the OCCS group (1148 ± 39.47 vs. 795.9 ± 51.39 N). Conclusion Our results suggested that using three DhCCSs improved the outcome of vertical femoral neck fractures compared to three OCCSs, offering a new choice for the treatment of femoral neck fracture.
Highlights
Femoral neck fracture in young adults is usually the result of high energy, and salvage of the femoral head with anatomic reduction and stable fixation is preferred [1, 2]
The right hip was affected in 31 patients (57.4%) in the ordinary cannulated compression screw (OCCS) group and 16 (59.3%) in the double-head cannulated compression screw (DhCCS) group
The mean follow-up period of patients treated with OCCS was 18:15 ± 6:45 months, which is similar to that in the DhCCS group (18:48 ± 3:47) (Table 1)
Summary
Femoral neck fracture in young adults is usually the result of high energy, and salvage of the femoral head with anatomic reduction and stable fixation is preferred [1, 2]. For more vertical femoral neck fractures that are axial and rotationally unstable, strong shear forces across the hip frequently lead to fixation failure when fixed with ordinary cannulated compression screw (OCCS) with overall complication rates ranging from 20% to 86% [4, 5]. This study is aimed at comparing ordinary cannulated compression screw (OCCS) and double-head cannulated compression screw (DhCCS) fixation in vertical femoral neck fractures both clinically and biomechanically. Twenty synthetic femur models of vertical femoral fractures with an 80° Pauwel’s angle were divided into two groups and subsequently fixed with three parallel OCCSs or DhCCSs. All specimens were tested for axial stiffness, load to 5 mm displacement, and a maximum load to failure with a loading rate of 2 mm/min. Our results suggested that using three DhCCSs improved the outcome of vertical femoral neck fractures compared to three OCCSs, offering a new choice for the treatment of femoral neck fracture
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