Do intra-articular knee injuries detected by preoperative MRI affect the clinical management of extensor mechanism ruptures?

OBJECTIVES: We sought to determine the prevalence of intra-articular findings at the time of extensor mechanism injury that required subsequent surgical intervention. DESIGN: Retrospective cohort study. SETTING: Level 1 academic trauma center. PATIENTS/PARTICIPANTS: Sixty-seven knees in 66 nonconsecutive patients (mean age 53.6 years, 95.6% male) with extensor mechanism injury and preoperative magnetic resonance imaging (MRI) before undergoing open primary surgical repair. MAIN OUTCOME MEASUREMENTS: Patellar or quadriceps tendon rupture, high or low injury energy level, and age above or below 45 years were used to stratify patients. The primary outcome was additional surgery for intra-articular injury. Demographics, comorbidities, mechanism and location of injury, and internal derangements based on MRI findings were also collected. RESULTS: Fifty-one knees (76.1%) had quadriceps tendon injury, 13 knees (19.4%) had patellar tendon injury, and 3 knees (4.6%) had both. Thirty-four knees (50.7%) had intra-articular pathology and 3 (4.5%) required additional surgery, including 1 knee (7.7%) with patellar tendon injury and 2 knees (3.9%) with quadriceps tendon injury. Patellar tendon injuries were more commonly associated with cruciate ligament injury (P < .01) and occurred in younger patients (P < .001) than quadriceps tendon injury. CONCLUSIONS: 50.7% of cases with extensor mechanism injury had intra-articular pathology but only 4.5% required additional surgery. The results of our study suggest that preoperative MRI is unlikely to be of significant clinical utility in most extensor mechanism injuries but should be considered in cases of patellar tendon rupture in younger patients where the incidence of concomitant cruciate ligament injury is higher. LEVEL OF EVIDENCE: Diagnostic Level III.