Prevalence of Tibiofemoral Osteoarthritis 15 Years After Nonoperative Treatment of Anterior Cruciate Ligament Injury: A Prospective Cohort Study.

BACKGROUND: The occurrence of osteoarthritis (OA), associated meniscal injuries, meniscectomy, and patient-related measures for patients treated nonoperatively after anterior cruciate ligament (ACL) injuries have not been well described in the literature in terms of natural history. HYPOTHESIS: Patients with ACL injury can achieve a low occurrence of tibiofemoral OA and good knee function when treated without ACL reconstruction. STUDY DESIGN: Cohort study (prognosis); Level of evidence, 2. METHODS: One hundred consecutive patients with an acute, complete ACL injury were observed for 15 years. All patients were primarily treated with activity modification and without ACL reconstruction. To achieve improved functional stability, supervised physical therapy was initiated early after injury. The patients were examined using anteroposterior weightbearing radiography. The Knee injury and Osteoarthritis Outcome Score (KOOS) was used to quantify knee-related symptoms and knee function. RESULTS: Seventy-nine patients consented to radiographic examination and 93 completed the KOOS questionnaire. Thirteen patients (16%), all of whom were among the 35 patients whose knees were meniscectomized, developed radiographic tibiofemoral OA. In contrast, none of the remaining nonmeniscectomized and radiographed knees developed OA (n = 44) (P < .0001). Sixty-three patients (68%) had an asymptomatic knee. Twenty-two patients (23%) had undergone ACL reconstruction with a mean time of 4 years after injury. CONCLUSION: The study had a favorable long-term outcome regarding incidence of radiographic knee OA, knee function and symptoms, and need for ACL reconstruction. Although risk factors for posttraumatic OA are multifactorial, the primary risk factor that stood out in this study was if a meniscectomy had been performed. Early activity modification and neuromuscular knee rehabilitation might also have been related to the low prevalence of radiographic knee OA. In patients with ACL injury willing to moderate activity level to avoid reinjury, initial treatment without ACL reconstruction should be considered.