Comparison of Anterior Cruciate Ligament Tears Treated Nonoperatively Versus With Reconstruction: Risk of Subsequent Surgery.

BACKGROUND: Anterior cruciate ligament (ACL) tears can be devastating injuries, leading to joint instability, meniscal tears, and subsequent arthritis. It is unknown whether ACL reconstruction (ACLR) alters the natural history of joint degeneration in the ACL-deficient knee compared with nonoperative treatment, and few studies have examined outcomes in middle-aged patients. PURPOSE: The objective of this study was to compare the midterm risk of subsequent ipsilateral knee surgery in middle-aged patients after an ACL injury treated with initial conservative (nonoperative) management (CM) versus ACLR (operative management [OM]) within 6 months of the diagnosis. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: We performed an electronic database search from 2011 to 2012 for all patients aged 35 to 55 years with an initial diagnosis of magnetic resonance imaging-confirmed ACL tear. Patients who elected CM and those who underwent ACLR within 6 months of the diagnosis (OM) were identified. Index patient and clinical characteristics were collected from the health record. All patients were longitudinally observed until August 31, 2017. The primary outcome was subsequent ipsilateral knee surgeries, and secondary outcomes included contralateral knee surgeries, deep surgical-site infections, and venous thrombotic events. RESULTS: The mean follow-up was 4.8 ± 0.6 years. The CM group included 463 patients (40.2%) and the OM group included 690 patients (59.8%). The mean ages were 43.9 ± 5.7 years and 42.7 ± 5.3 years for patients in the CM and OM groups, respectively (P < .001). Obesity and smoking were significantly more common in the CM group. During the follow-up, 180 patients (38.9%) in the CM group underwent subsequent ipsilateral knee surgery compared with 73 (10.6%) patients in the OM group (P < .001). The mean time to the first ipsilateral procedure was 0.9 ± 1.1 years in the CM and 2 ± 1.5 years in the OM group (P < .001). Delayed ipsilateral ACLRs were performed in 81 patients in the CM group (17.5%); non-ACLR ipsilateral knee surgeries were performed in 156 patients in the CM group (33.7%). Contralateral knee surgery rates were similar. In a regression model, after controlling for age, sex, the Charlson Comorbidity Index score, and smoking status, it was found that normal body mass index and CM group were risk factors for undergoing subsequent knee surgery or ipsilateral non-ACLR surgery. CONCLUSION: Excluding delayed ACLR, subsequent ipsilateral knee surgeries were more common and occurred earlier in middle-aged patients with nonoperatively managed ACL tears compared with patients managed with reconstruction.