Functional and Radiological Outcome in Atypical Subtrochanteric Femur Fracture After Surgical Fixation: A Retrospective Observational Study

Background: Treatment for osteoporosis can have catastrophic side effects, including the uncommon fracture known as an atypical femur fracture (AFF), which is related to the long-term usage of antiresorptive agents. Bisphosphonate therapy may lead to significant and chronic suppression of bone turnover, impairing the bone's remodelling property and finally leading to incomplete or complete atypical femur fracture. AFF was defined by the American Society for Bone and Mineral Research (ASBMR) Task Force in 2010 and is far less prevalent than proximal femur (hip) fracture, with an incidence of 2 to 78 per 100,000 patients per year following two to eight years of bisphosphonate therapy, respectively. Due to the rarity of the fracture, it is still not clear what the functional and radiological outcome will be after surgery. Aim: To identify the functional and radiological outcomes of surgical fixation of atypical femur fractures. Methods: The study was conducted in a tertiary healthcare centre after scientific and ethical clearance from the competent authority. Between January 2018 and December 2021, individuals who were diagnosed with an atypical subtrochanteric femoral fracture associated with the use of bisphosphonates and treated surgically were retrospectively evaluated. The study's inclusion and exclusion criteria were used to include 20 patients. The features of an atypical subtrochanteric fracture were congruent with the radiographic findings. Most of the patients were treated with internal fixation with intramedullary osteosynthesis in standard with or without plate osteosynthesis. They were then followed up for a year to look at the functional and radiological outcomes. Results: All of the 20 patients who were included had an atypical subtrochanteric fracture, with 15 of them being female and 5 of them being male. The patients' mean age at surgery was 65.12 (range 49 to 82) years, and their average history of bisphosphonate use was 3 (range 2.5 to 5) years. All patients were treated surgically. We found that five months was the mean period for bone union (p = 0.990). Within six months, bone union was achieved in 11 patients (55 %) (p = 0.884). Five patients (about 25%) had implant failure and non-union, requiring two to three revision surgeries. At three, six, and nine months, the mean visual analogue score (VAS) was 4.14, 3.12, and 1.85, respectively. The modified Hip Harris Score had a mean of 72.66 and 15 patients (about 75% of them) could walk normally again after a fracture. The mean of the modified HHS was 72.66, and the VAS at three, six, and nine months was 4.14, 3.12, and 1.85, respectively. Conclusion: AFFs are rare fractures that must be treated effectively, and most of them require surgery. Successful treatment of AFF is possible by the use of intramedullary fixation, which enhances axial stability, serves as an internal splint, and lessens the likelihood of implant failure. A good functional and radiological prognosis can come from a stable fixation and a fracture that has been reduced anatomically.