Poster 247: Predictors of Poor Outcomes Following Quadriceps Tendon Repair

Objectives: Ruptures of the quadriceps tendon can lead to significant morbidity and are nearly always treated with surgical repair. Although relatively uncommon, they present most frequently in older adults and individuals with underlying medical conditions. Specifically, spontaneous bilateral ruptures have been shown to be associated with gout, diabetes, or steroid use. In other areas of orthopedics, factors such as an obese BMI have been shown to be predictive of poor outcomes after surgical treatment. To date, there has been little published literature to demonstrate how factors such as age, BMI, and smoking status are associated with quadriceps tendon tear or outcomes. The purpose of this study was to examine the relationship between patient factors such as age, sex, BMI, and smoking status, as well as intraoperative factors and the outcome of quadriceps tendon repair. We hypothesize that older age, higher BMI, and poor smoking habits will be associated with worse range of motion and complication rates following quadriceps tendon repair. Methods: All patients undergoing Quadriceps tendon repair from 1/1/2016-9/1/2021 were retrospectively identified at our institution using CPT codes, and patients who had definitive documentation of a quadriceps tendon tear within the operative report were included in the study. Patients under the age of 18 years were excluded. Physician clinical notes were reviewed, recording detailed information regarding the presenting symptoms and physical exam findings. Pre-operative demographic information and intraoperative findings were evaluated. Poor outcomes were defined as a need for revision, complications, post-operative range of motion (ROM) of less than 110 degrees of knee flexion, and extensor lag greater than 5 degrees. Parametric continuous data was presented as mean(SD) and p values were calculated by performing T tests. Nonparametric continuous data was also presented as mean(SD) for easier interpretation and p values were calculated by performing Mann- Whitney tests. P values less than 0.05 were deemed significant. All statistical analyses were done using R Studio (Version 4.1.2, Vienna, Austria). Results: There were 235 patients who met the inclusion criteria. Patients had an average age of 59 (13.3) years at time of surgery consistent of predominantly males (90.2%). The mean BMI for this cohort was 32.1(6.34). The most common surgical procedure was Transosseous fixation (81.5%) followed by suture anchors (16%) and simple sutures (2.6%). The most common mechanism of injury was trauma (57.6%) followed by spontaneous injury (39.8%). On post-operative physical exam, 18.4% of patients experienced loss of range of motion, 15.4% experienced extension lag, 9.52% had post-operative complications, and 4.7% underwent revision. Three sets of logistic regressions were run for subgroups of poor outcomes showing BMI (OR, 1.07, 95% CI, 1.01 – 1.14) and Age (OR, 1.05, 95% CI, 1.02 – 1.08) were significantly associated with loss of range of motion. Post-operative extension lag was also associated with greater BMI (OR, 1.63, 95% CI, 1.17 – 2.91). Complications were found to be significantly associated with patients found to have pre-operative tendon degeneration via MRI (OR, 4.74, 95% CI, 1.65 – 14.67) and those who were current smokers (OR, 7.84, 95% CI, 2.32 – 27.12). Amount of retraction, degree of pre-operative osteoarthritis, retinacular involvement, tear thickness and location were not significantly associated with poor outcomes. Conclusions: This study demonstrates that patient specific characteristics can play a significant role in outcomes following quadriceps tendon repair. Advanced age, BMI, tendon degeneration and current smokers are all at risk for poor outcomes following quadriceps tendon repair.