A Study On The Relationship Between The Difference Between The Diameter Of The Femoral Medullary Cavity And The Diameter Of PFNA And The Rate Of Reoperation

Objective: To study the relationship between the difference between the diameter of the femoral medullary cavity and the diameter of the proximal femoral anti rotation intramedullary nail(PFNA)and the reoperation rate,and to provide a basis for the selection of internal fixation device types for intertrochanteric fractures of the femur.Methods: 203 patients with intertrochanteric fractures of the femur who underwent proximal femoral anti rotation intramedullary nail surgery from January 1,2016 to April 1,2021 at the Orthopedics Department of the First Affiliated Hospital of Harbin Medical University were selected..The gap between the intramedullary nail and the femoral medullary cavity was equal to the diference 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.Patient character-istics were recorded,as follows: age,sex,follow-up time,fracture pattern,reduction grade and length of intramedul-lary nail.The statistical analysis was performed using R version 4.0.3.A Chi-Square Test was used to compare homogeneous distribution among categorical variables by evaluating frequencies within the groups.A one-way analysis of variance(ANOVA)test was used for comparing homogeneous distribution among numerical variables.Logistic regression was performed to analyze the relationships of reoperation with age,sex,fracture pattern and reduction quality,nail length and matching degree.Result: 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% confdence 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 signifcant association was noted between matching degree of intramedullary nail and reoperation rate.Conclusion: This study found that the difference in diameter between the PFNA and the femoral medullary cavity does not seem to be an important factor in reoperation,provideing more options for intraoperative intramedullary nail size selection and reducing the cost of healthcare systems.