The effects of the positioning of a bolt in the femoral neck system on the short-term outcomes of middle-aged and young adults with displaced femoral neck fractures.

Background: To analyze the effects of the positioning of a bolt in the femoral neck system (FNS) on the short-term outcomes of middle-aged and young adults with displaced femoral neck fractures (FNFs). Methods: This was a retrospective study involving 114 middle-aged and young adults with displaced FNFs who were surgically treated with internal fixation via the FNS in the Department of Orthopedics, Suzhou Municipal Hospital, from December 2019 to January 2023. The degree of deviation of the central axis of the femoral head and neck from the tip of the bolt (W), the tip‒apex distance (TAD) and the length of femoral neck shortening (LFNS) were measured on postoperative X-ray and computed tomography (CT) scan images. Clinical efficacy was assessed with the Harris Hip Score (HHS) and the EuroQol five-dimensional questionnaire-5L (EQ-5D-5L) utility index. The enrolled patients were divided into the central group (W ≤ 20%) and deviation group (W > 20%) on the basis of postoperative W value. The quality of fracture reduction, time to postoperative weight-bearing of the affected limb, time to fracture healing, and the TAD, LFNS, HHS and EQ-5D-5L utility index at the last follow-up visit were compared between the groups. Postoperative complications and cases of revision surgery were recorded. Results: Preoperative baseline characteristics, the quality of fracture reduction, the need for auxiliary reduction and the follow-up time were comparable between the central group and deviation group (all P > 0.05). No significant difference in the time to postoperative partial weight-bearing of the affected limb was detected between the groups (P > 0.05). Patients in the central group presented with a significantly shorter time to full weight-bearing of the affected limb, time to fracture healing, and TAD and LFNS at the last follow-up visit but a greater HHS and EQ-5D-5L utility index than those in the deviation group did (all P < 0.05). The incidence of revision surgery was significantly lower in the central group than in the deviation group (P < 0.05). Conclusion: Positioning of the FNS bolt closer to the central axis of the femoral head and neck favors a shorter time to fracture healing, greater hip function and a lower incidence of revision surgery in middle-aged and young adults with displaced FNFs. [ABSTRACT FROM AUTHOR]