Abstract
BACKGROUND: It is recognized that patients suffering rupture of the anterior cruciate ligament (ACL) are prone to accelerated osteoarthritis (OA), thus, this patient group is at increased risk of undergoing knee replacement (KR) at a younger age compared to the general population. There are limited data directly determining the risk of KR in ACL-injured patients. The purpose of this study is to estimate the risk of undergoing KR in patients with a history of primary ACL injury (ACLi). STUDY DESIGN: Systematic review. METHODS: A systematic literature search with keywords and MeSH terms was performed using PubMed and Cochrane Library. We identified all studies reporting KR as an outcome in individuals with primary ACLi. Individuals with concomitant and secondary intra-articular injuries were included. A modified version of the Coleman Methodology Score (CMS) was used to evaluate the quality of the included studies. The risk was estimated by using the total number of ACL-injured patients and the total number of KRs within this cohort, consisting of both patients with reconstruction and patients with non-operative treatment. RESULTS: A total of 152 390 ACL-injured patients and a total of 1071 KRs were assembled from 5 prospective and 7 retrospective studies, which revealed a mean modified CMS of 70. Mean follow-up time was 16 years (ranging from 4.6 to 30 years). Mean age among the patients was 29.8 years. Estimated risk of undergoing KR after ACLi was 0.7 % with values between 0.54 % and 9.5 % among the included studies. CONCLUSION: This systematic review suggests an estimated risk of KR among ACL-injured patients to be 0.7 %. Our findings are based on the results from the included studies, which, to some degree, showed divergence. The discrepancy may be due to variability in several factors, both research variables and patient factors, including follow-up time, sample size, subsequent injuries, obesity, sex, age and activity level. No consensus about OA development after ACLi has been established, however, OA is a common topic in the conversation between the doctor and the patient. This data may be helpful for physicians and clinicians when informing patients about the long-term risk of symptomatic OA, eventually requiring KR.