Rates and Risk Factors for Failure of Surgical Repair of the Knee Extensor Mechanism

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Abstract

Objectives: To evaluate rates and risk factors for failed surgical repair of the knee extensor mechanism. Design: Retrospective cohort study. Setting: Academic medical center. Patients/Participants: Two hundred ninety-four patients and a total of 303 extensor mechanism repairs were included. This encompassed 113 quadriceps tendon repairs (QTR), 112 fracture repairs (FR), and 68 patellar tendon repairs (PTR). Main Outcome Measurement: Repair failure. Results: There were 6 failures (5%) in the QTR group, 21 failures (17%) in the FR group, and 2 failures (3%) in the PTR group. The difference in failure rates between the groups was significant (P = 0.001), but the rate of revision fixation or repair was not (P = 0.315). In the QTR group, a history of inflammatory arthritis was found to be significantly different between patients who had repair failure and patients who did not (P = 0.014) with a relative risk for failure of 17.8 (confidence interval 4.5–70.4). In the FR group, patient age (P = 0.001) and comorbid diabetes mellitus (P = 0.046) were found to be significantly different between patients with and without repair failure in univariate analysis, but only patient age (P = 0.005) was significant in multiple logistic regression analysis. The relative risk for FR failure was 6.6 (confidence interval 2.3–18.3) for age greater than 60. No risk factors for failure were identified in the PTR group. Conclusions: Overall, patients with fractures were more likely experience repair failure than patients with tendon injuries, but all patients underwent similar rates of reoperation. Inflammatory arthritis in patients with QTRs and older patient age in FRs are risk factors for repair failure. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.