Postoperative residual patellar bone thickness and patellar height in patients with quadriceps tendon rupture after total knee arthroplasty: A retrospective case-control study
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Davide Pellicanò1, Mirco Lo Presti1, Maria Pia Neri1
1II Orthopaedic and Traumatology Clinic, IRCCS Istituto Ortopedico Rizzoli Bologna Italy.
Purpose:
Quadriceps tendon rupture following total knee arthroplasty is a rare but serious complication. This study aimed to compare postoperative residual patellar bone thickness and patellar height between patients who developed quadriceps tendon rupture after primary total knee arthroplasty and matched controls.
Methods:
A retrospective case-control study included 17 patients who developed quadriceps tendon rupture within 6 months after primary total knee arthroplasty and 100 controls without extensor mechanism complications. Controls were selected using group-level frequency matching for age, sex and body mass index. All patients underwent patellar resurfacing. Patellar height was assessed preoperatively and postoperatively using the Insall-Salvati index, while postoperative residual patellar bone thickness was measured on immediate postoperative lateral radiographs. Group comparisons were performed using the Wilcoxon rank-sum and Fisher's exact tests. Logistic regression was used to evaluate the association between residual patellar bone thickness and tendon rupture, with adjustment for age, sex and body mass index.
Results:
No significant differences were observed between groups in age, sex, body mass index or diabetes mellitus. Median postoperative residual patellar bone thickness was numerically lower in patients with tendon rupture than in controls (11.3 vs. 11.8 mm), but the between-group difference was not statistically significant. Residual patellar bone thickness was also not significantly associated with tendon rupture after adjustment for age, sex and body mass index (adjusted odds ratio 0.77, 95% confidence interval 0.55-1.08; p = 0.127). No significant differences were observed in preoperative or postoperative Insall-Salvati index or changes in patellar height.
Conclusions:
No significant association was identified between postoperative residual patellar bone thickness, patellar height parameters and quadriceps tendon rupture in this cohort. Given the limited number of rupture cases, smaller or moderate associations cannot be excluded.
Level Of Evidence:
Level III.