Objective To explore the clinical efficacy and biomechanical characteristics of modified SuperCap approach for femoral head replacement (FHR) in the treatment of elderly femoral neck fractures (FNF). Methods The clinical data of 88 elderly patients with femoral neck fractures who underwent FHR in Luoyang Central Hospital from January 2023 to January 2025 were retrospectively collected. According to the different surgical approaches, they were divided into group A (modified SuperCap approach, 44 cases) and group B (posterior lateral approach, 44 cases). The perioperative related indexes, pain degree, hip joint function, biomechanical related indexes and complications were compared between the two groups. Results Group A exhibited shorter hospitalization duration, shorter surgical incision length (all P＜0.05), and earlier postoperative ambulation time compared to group B (P＜0.05), with less intraoperative blood loss than group B (P＜0.05). After surgery, both groups showed a decreasing trend in visual analog scale (VAS) scores, with group A having lower VAS scores than group B on postoperative days 1, 3, and 7 (all P＜0.05). Postoperative Harris hip function score (HHS) showed an upward trend in both groups, but there was no significant difference in HHS scores at 1 week, 3 months, and 6 months postoperatively between the two groups (all P＞0.05). Six months after surgery, there was no significant difference in the peak stress and displacement of the femur between the two groups (all P＞0.05). There was no significant difference in postoperative complications between the two groups (all P＞0.05). Conclusion Both the posterior lateral approach and the modified SuperCap approach for FHR can improve hip joint function in elderly patients with FNF.Moreover, the biomechanical stability after the surgery is comparable. Among them, the modified SuperCap approach has more advantages in reducing the surgical incision size, minimizing intraoperative blood loss, facilitating early ambulation of patients, and alleviating early postoperative pain. It is also more conducive to the rapid recovery of patients after surgery.