Abstract
OBJECTIVE: Revision surgeries for aseptic loosening following prosthesis implantation in patients treated for knee tumors have become increasingly prevalent, although analyses of associated risk factors remain limited. This study aimed to systematically identify risk factors for aseptic knee prosthetic loosening following implantation and establish early predictive indicators through multimodal analysis integrating clinical, radiographic, and quantitative gait parameters. METHODS: Data from patients treated for knee tumors between January 2020 and December 2024 were retrospectively collected via a case‒control design. Patients were divided into two groups: an experimental group (n = 11) requiring revision due to aseptic loosening and a matched control group (n = 11) with stable prostheses. All patients underwent the same type of rotationally hinged knee prosthetic implantation performed by a team of experienced joint surgeons. To explore the risk factors for aseptic loosening, clinical data, gait parameters, and imaging characteristics were analyzed. Multivariate logistic regression analyses were implemented to quantify associations between clinical data and the risk of aseptic prosthetic loosening. Gait parameters were quantitatively analyzed via the Intelligent Device for Energy Expenditure and Activity (IDEEA® v3.1, MiniSun LLC) to predict early indicators of aseptic loosening. RESULTS: According to the regression models, a higher body mass index (BMI) and hip-knee-ankle angle (HKAA) were significant (p = 0.04, p = 0.043), whereas sex and age at first prosthetic implantation were not significant. The femoral internal diameter at 20 cm proximal to the knee was significant according to the univariate regression analysis (p = 0.05) but not according to the multivariate regression model. The difference in the cortical bone thickness was not significant. Significant reductions in the single-support phase time (p = 0.045) and energy expenditure (p = 0.05) were observed in patients who underwent revision for aseptic loosening relative to those in the control group. CONCLUSION: Aseptic loosening after knee prosthetic implantation for knee tumor treatment is associated with several factors, and a higher BMI and HKAA constitute significant risk factors. A decreased single-support phase time and reduced energy expenditure in gait analysis can assist in predicting early signs of loosening and facilitate early clinical intervention.