Different Radiological Indices of Patellar Height Predict Patients' Diverse Outcomes Following Total Knee Arthroplasty

Abstract

Background: Total knee arthroplasty (TKA) is a common surgical procedure for patients with knee osteoarthritis. The patellar component plays a crucial role in knee biomechanics and can influence postoperative outcomes. This study aimed to investigate the relationship between radiological indices of patellar height and patient outcomes following TKA.

Methods: A retrospective analysis was conducted on patients who underwent TKA for osteoarthritis. Radiographic measurements of patellar height, including the Insall-Salvati (IS) ratio, modified Blackburne-Peel (mBP) ratio, Caton-Deschamps ratio, and plateau-patellar angle (PPA), were obtained. Clinical outcomes were assessed using the Knee Society Score (KSS) and the Forgotten Joint Score-12 (FJS-12). Patient satisfaction and postoperative complications were also evaluated. Statistical analyses, including correlation analysis and multiple regression models, were performed to determine the association between radiological indices and patient outcomes.

Results: The study included 330 cases that met the inclusion criteria. The analysis revealed significant correlations between different radiological indices of patellar height and patient outcomes. Lower postoperative PPA was correlated with worse KSS and range of motion scores. A decreased mBP ratio was associated with poorer FJS-12 responses and higher risks of dissatisfaction and patellar clunk or crepitus. Increased IS ratio was linked to a lower likelihood of incidental giving way of the knee. Advanced age was associated with reduced dissatisfaction and incidental giving way probabilities.

Conclusions: The findings of this study demonstrate that radiological indices of patellar height can predict patient outcomes following TKA. Assessing patellar height using various radiographic measurements provides valuable information for surgical planning and prognostic evaluation. Understanding the impact of patellar height on clinical outcomes can aid in optimizing TKA procedures and improving patient satisfaction. These findings emphasize the importance of considering patellar height as a predictive factor in TKA and highlight its potential role in guiding postoperative management and rehabilitation strategies.

Keywords: Patella clunk; Patella height; Patient outcome assessment; Patient satisfaction; Total knee arthroplasty.

Fig. 1. Flowchart illustrating the study cohort and patients excluded from the analysis. TKA: total knee arthroplasty.

Fig. 2. Univariate and multivariate logistic regression analyses of variables affecting dissatisfaction, patellar clunk or crepitus, and incidental giving way of the knee. OR: odds ratio, CI: confidence interval, IS: Insall-Salvati, mBP: modified Blackburne-Peel, PPA: plateau-patellar angle, CD: Caton-Deschamps, BMI: body mass index. A p < 0.05 was considered statistically significant.

Fig. 3. Receiver operating characteristic (ROC) curve distribution. (A) The modified Blackburne-Peel (mBP) ratio, age, and their combination in predicting dissatisfaction. (B) MBP ratio in predicting patellar clunk or crepitus. (C) Insall-Salvati (IS) ratio, age, and their combination in predicting incidental giving way of the knee. AUC: area under the curve.