Zhou Xiang, Li Xishan, Böker Kai Oliver, Schilling Arndt F, Lehmann Wolfgang
Department of Trauma Surgery, Orthopedics and Plastic Surgery, University Medical Center Göttingen, Göttingen, Germany.
Department of Articular and Traumatic Orthopedic Surgery, Fourth People's Hospital of Guiyang, Guiyang, Guizhou, China.
Front Bioeng Biotechnol. 2024 Oct 9;12:1374299. doi: 10.3389/fbioe.2024.1374299. eCollection 2024.
Gotfried positive reduction offers an alternative strategy for femoral neck fracture (FNF) when achieving anatomical reduction is challenging. However, the biomechanical consequences of positive reduction remain unclear. The purpose of this study was to investigate the biomechanical behavior of positive reduction across different Pauwels classification, providing a reference for quantifying positive reduction in clinical practice.
Three-dimensional (3D) models of FNF were established and categorized according to the Pauwels classifications (Pauwels I, II, and III), each of them contained seven models with different reduction qualities, including an anatomical reduction model, two negative reduction models, and four positive reduction models, all of which were stabilized with dynamic hip screws (DHS) and cannulated screws (CS). We investigated the maximal von-Mises stress of internal fixation and proximal femoral, femoral fragment displacement, and maximal von-Mises strain at the proximal fragment fracture site when a 2100 N load was applied to the femoral head.
The maximum von-Mises stress on the internal fixators in each Pauwels group was lowest in the anatomical reduction model. In the Pauwels I group, positive reduction exceeding 3 mm resulted in the maximum von-Mises stress on the internal fixators surpassing that of the negative reduction model. For the Pauwels II group, positive reduction beyond 2 mm led to the maximum von-Mises stress on the internal fixators exceeding that of the negative reduction model. In the Pauwels III group, positive reduction beyond 1 mm caused the maximum von-Mises stress on the internal fixators to be higher than that of the negative reduction model. The maximum von-Mises strain at the fracture site of proximal femur fragment increased with positive reduction. Varus displacement increased in positive reduction models as the Pauwels angle rose, potentially exacerbating rotation deformity in Pauwels III group.
Excessive positive reduction may increase the risk of FNF failure after internal fixation. From a biomechanical stability perspective, positive reduction should be limited to 3 mm or below in the Pauwels I group, restricted to not exceed 2 mm in the Pauwels II group, and should not exceed 1 mm in the Pauwels III group. Negative reduction should be avoided in all Pauwels groups.
当实现解剖复位具有挑战性时，Gotfried阳性复位为股骨颈骨折（FNF）提供了一种替代策略。然而，阳性复位的生物力学后果仍不清楚。本研究的目的是研究不同Pauwels分类下阳性复位的生物力学行为，为临床实践中量化阳性复位提供参考。
建立FNF的三维（3D）模型，并根据Pauwels分类（Pauwels I、II和III）进行分类，每个分类包含七个具有不同复位质量的模型，包括一个解剖复位模型、两个阴性复位模型和四个阳性复位模型，所有模型均用动力髋螺钉（DHS）和空心螺钉（CS）固定。当对股骨头施加2100 N载荷时，我们研究了内固定和股骨近端的最大von-Mises应力、股骨碎片位移以及近端碎片骨折部位的最大von-Mises应变。
每个Pauwels组中内固定器上的最大von-Mises应力在解剖复位模型中最低。在Pauwels I组中，阳性复位超过3 mm导致内固定器上的最大von-Mises应力超过阴性复位模型。对于Pauwels II组，阳性复位超过2 mm导致内固定器上的最大von-Mises应力超过阴性复位模型。在Pauwels III组中，阳性复位超过1 mm导致内固定器上的最大von-Mises应力高于阴性复位模型。股骨近端碎片骨折部位的最大von-Mises应变随阳性复位增加。随着Pauwels角增加，阳性复位模型中的内翻位移增加，可能会加重Pauwels III组中的旋转畸形。
过度的阳性复位可能会增加FNF内固定后失败的风险。从生物力学稳定性角度来看，Pauwels I组的阳性复位应限制在3 mm或以下，Pauwels II组应限制在不超过2 mm，Pauwels III组不应超过1 mm。所有Pauwels组均应避免阴性复位。
