Increasing the angle between caudal screw and the transverse plane may aggravate the risk of femoral head necrosis by deteriorating the fixation stability in patients with femoral neck fracture

• Published in: European journal of medical research Vol. 29; no. 1; p. 170
• Main Authors: Zhang, Jian, Wan, Shengyu, Luo, Xiaozhong, Zhang, Caidong, Wu, Chao, He, Lipeng, Li, Jingchi
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 12.03.2024; BioMed Central; BMC
• Subjects: Biomechanics; Bone Screws; Care and treatment; Femoral head necrosis; Femoral neck fracture; Femoral Neck Fractures - surgery; Femur Head Necrosis; Finite element analysis; Fixation stability; Fracture Fixation, Internal - methods; Fractures; Humans; Internal fixation in fractures; Necrosis; Patients; Retrospective Studies; Risk factors; Screw trajectory optimization; Simulation methods; Software; Stress concentration; Titanium alloys; Femoral neck fracture; Fixation stability; Finite element analysis; Femoral head necrosis; Screw trajectory optimization
• ISSN: 2047-783X; 0949-2321; 2047-783X
• DOI: 10.1186/s40001-024-01737-3

Necrosis of the femoral head is the main complication in femoral neck fracture patients with triangle cannulated screw fixation. Instant postoperative fixation instability is a main reason for the higher risk of femoral head necrosis. Biomechanical studies have shown that cross screw fixation can effectively optimize fixation stability in patients with proximal humerus fractures and pedicle screw fixation, but whether this method can also effectively optimize the fixation stability of femoral neck fractures and reduce the corresponding risk of femoral head necrosis has yet to be identified. In this study, a retrospective review of imaging data in femoral neck fracture patients was performed. The cross angle between the femoral neck and the caudal cannulated screw was reported; if the angle between the screw and the transverse plane increased, it was recorded as positive; otherwise, it was recorded as negative. Angle values and their corresponding absolute values were compared in patients with and without femoral head necrosis. Regression analysis identified potential risk factors for femoral head necrosis. Moreover, the biomechanical effect of the screw-femoral neck angle on fixation stability was also verified by numerical mechanical simulations. Clinical review presented significantly larger positive angle values in patients with femoral head necrosis, which was also proven to be an independent risk factor for this complication. Moreover, fixation stability progressively deteriorated with increasing angle between the caudal screw and the transverse plane. Therefore, increasing the angle between the caudal screw and the transverse plane may aggravate the risk of femoral head necrosis by deteriorating the fixation stability in patients with femoral neck fracture.