RESUMO
INTRODUCTION: Previous articles reported on the tip-apex distance, lag screw placement, fracture pattern, reduction quality, osteoporosis and other factors associated with second surgery. The current study focused on investigating the association of the matching degree between proximal femoral intramedullary nail and femoral medullary cavity on reoperation rate. PATIENTS AND METHODS: A retrospective cohort study was conducted. It included patients with intertrochanteric fracture who were treated with proximal femoral anti-rotatory intramedullary nail (PFNA) between January 2016 and April 2021. The gap between the intramedullary nail and the femoral medullary cavity was equal to the difference in diameter between the two. According to the gap size, all patients were divided into three groups, as follows: high-matching group: gap ≤ 2 mm; middle-matching group: 2 < gap < 4 mm; and low-matching group: gap ≥ 4 mm. The mean gap was measured through standard images. The primary observational index was whether the reoperation was needed, and secondary observational indexes included operative time, length of hospital stay. Patient characteristics were recorded, as follows: age, sex, follow-up time, fracture pattern, reduction grade and length of intramedullary nail. RESULTS: A total of 203 eligible patients were recorded, including 78 males (38.4%) and 125 females (61.6%). They had a mean age of 77.8 ± 9.9 years old and an average follow-up time of 58.1 ± 24.0 weeks. Twenty-seven patients (13.3%) needed a second operation. Coxa varus combined with screw cutting was the most common reason for reoperation (11 cases). Unstable fracture pattern with poor reduction grade tended to contribute to reoperation, whose odds ratio (OR) was 6.61 (95% confidence interval [CI], 1.98-22.09; P = 0.002). The three groups had 11 cases (13.7%), 12 cases (13.8%) and 4 cases (11.1%) of reoperation, respectively, and logistic regression showed no significant association was noted between matching degree of intramedullary nail and reoperation rate. CONCLUSIONS: The matching degree between proximal femoral intramedullary nail and femoral medullary cavity did not seem to be an important factor for reoperation, which offered more options of intramedullary nail size intraoperatively and reduced implants stock from inventory.