Long-term follow-up of isolated ACL tears treated without ligament reconstruction

Purpose: The incidence of subsequent meniscal tears and arthritis among patients with isolated ACL tears treated without ligament reconstruction has not been clearly established. The purpose of this study was to (1) compare the risk of subsequent meniscal tears and osteoarthritis (OA) between patients with isolated ACL tears treated without ligament reconstruction and a matched cohort of individuals without ACL tears and (2) examine factors predictive of long-term sequelae after non-operative treatment of isolated ACL tears. Methods: This study compared a population-based incidence cohort of 364 patients with new-onset, isolated ACL tears between 1990 and 2000, to an age and sex-matched cohort of 364 individuals without ACL tears. A chart review was performed to collect information related to the initial injury, treatment, and outcomes. Subjects were retrospectively followed for mean follow-up of 14.3 years (±7.4 years) to determine the development of subsequent meniscal injury, arthritis, or total knee arthroplasty (TKA). Results: Patients treated without ligament reconstruction after ACL tears had a significantly higher risk of secondary meniscal tears (HR 18.0, 95 % CI 9.7, 33.3), arthritis (HR 14.2, 95 % CI 8.0, 25.2), and need of TKA (HR 5.0, 95 % CI 2.1, 12.2) than individuals without ACL tears. Lateral meniscal tear at diagnosis was associated with a higher risk of arthritis (HR 2.7, 95 % CI 1.4, 5.7) and TKA (HR 4.3, 95 % CI 1.3, 13.7). Treatment with meniscectomy was associated with an increased risk of additional meniscal tears (HR 51.5, 95 % CI 10.3, 936.8). Conclusions: Patients treated non-operatively after isolated ACL tears are at a significantly higher risk of secondary meniscal tears, arthritis, and TKA when compared to age and sex-matched subjects without ACL tears. Additionally, baseline lateral meniscal tears were significantly associated with an increased probability of developing arthritis and the need for TKA. This information may be helpful when counselling patients about the natural history of ACL tears treated without ligament reconstruction. Level of evidence: III.