Femoral Neck System for young and middle-aged adult femoral neck fractures: a trade-off between reduced lateral irritation and increased neck shortening

Objective: To compare the short-term clinical efficacy and radiographic outcomes of the Femoral Neck System (FNS) versus cannulated screws (CS) in treating femoral neck fractures among young and middle-aged adults. Methods: A retrospective cohort study was conducted on 55 patients with femoral neck fractures treated between January 2021 and March 2024 at Daping Hospital. Patients were divided into the FNS group ( n = 28) and the CS group ( n = 27) based on the internal fixation method. Baseline characteristics, perioperative indicators, reduction quality, and complication rates were compared. Primary outcomes included postoperative time to full weight-bearing, Hip Harris Score (HHS) and EQ-5D-5L score at 6 and 12 months, and femoral neck shortening at 12 months. Results: Baseline characteristics were comparable between groups ( p > 0.05). The FNS group demonstrated longer operative time (166.25 ± 50.16 vs. 126.48 ± 35.02 minutes, p = 0.001), larger incisions (5 vs. 3 cm, p < 0.001), and significantly higher treatment costs (35,400 vs. 13,400 CNY, p < 0.001). The FNS group achieved full weight-bearing significantly earlier than the CS group (4 vs. 6 weeks, p < 0.001). However, the FNS group exhibited significantly greater femoral neck shortening at 12 months (3.19 mm vs. 1.83 mm, p = 0.002), with a higher incidence of moderate-to-severe shortening (⩾5 mm) ( p = 0.042). No significant differences were observed in HHS, EQ-5D-5L scores, or overall complication rates at 6 or 12 months ( p > 0.05). The CS group reported 4 cases of lateral thigh pain due to screw tail prominence, while the FNS group reported none. Conclusions: In short-term follow-up, FNS and CS demonstrate comparable functional outcomes for young and middle-aged femoral neck fractures. While the FNS implant combined with an accelerated rehabilitation protocol facilitates earlier weight-bearing rehabilitation, it is associated with higher medical costs and a greater risk of femoral neck shortening. Clinical decision-making should balance the need for rapid rehabilitation against the risks of anatomical shortening and cost.