Risk Factors of Early Periprosthetic Femoral Fracture After Total Knee Arthroplasty

Abstract

BackgroundPeriprosthetic femoral fracture (PFF) is a serious complication after total knee arthroplasty (TKA). However, the risk factors of PFF in the early postoperative setting are not well documented. This study determines the risk factors of early PFF after primary TKA.MethodsThis study recruited 24 patients who had early PFF within postoperative 3 months and 96 control patients. Demographic data (age, gender, weight, height, body mass index, Deyo-Charlson comorbidity index, diagnosis, operated side, underlying diseases and history of steroid usage intraoperative outcomes), intraoperative outcomes (operative time, surgical approach, type and brand of the prosthesis), and radiographic outcomes (distal femoral width; DFW, prosthesis-distal femoral width ratio; PDFW ratio, anatomical lateral distal femoral angle; LDFA, femoral component flexion angle; FCFA and anterior femoral notching; AFN) were recorded and compared between groups. Details of PFF, including fracture pattern, preoperative deformity, and time to PFF were also documented.ResultsIn univariate analysis, the PFF group had significantly older, right side injury, rheumatoid, dyslipidemia, Parkinson patients than the control group (p < 0.05). No cruciate-retaining design was used in PFF group (p = 0.004). Differences between the prosthetic brand used were found in this study (p = 0.046). For radiographic outcomes, PFF group had significantly lower DFW but higher PDFW ratio and LDFA than the control group (p < 0.05). While FCFA and AFN were similar between groups. The fracture patterns were medial condylar (45.8%), lateral condylar (25.0%) and supracondylar fracture (29.2%). The mean overall time to PFF was 37.2 ± 20.6 days (range 8 – 87 days). Preoperative deformity was significantly different among the three patterns (p < 0.05). When analyzed using the logistic regression model, age and dyslipidemia were only two independent risk factors for early PFF. The cut-off point of age was > = 75 years, with a sensitivity of 75.0% and specificity of 78.1%. The odds ratio of dyslipidemia was 6.63 (95% confidence interval, 1.11 to 39.8).ConclusionThis study determined that age and dyslipidemia were the independent risk factors for early PFF. However, further well-controlled studies with a larger sample size were needed to address this issue.