Recurrent Instability Episodes and Meniscal or Cartilage Damage After Anterior Cruciate Ligament Injury: A Systematic Review

BACKGROUND: Delayed anterior cruciate ligament (ACL) reconstruction may be associated with increased risk of subsequent knee joint damage and osteoarthritis (OA). The relationship between recurrent instability episodes and meniscal or cartilage damage after first-time ACL injury is unknown. PURPOSE: To assess the association between recurrent knee instability episodes and prevalence of meniscal lesions, cartilage damage, and OA after first-time ACL injury. STUDY DESIGN: Systematic review; Level of evidence, 4. METHODS: Six electronic databases were systematically searched using keywords and Medical Subject Heading terms. Studies selected were of English language, included original data, had a prospective design, and provided an outcome of recurrent instability and meniscal lesions, cartilage damage, or OA after first-time ACL injury. Adjusted odds ratios (ORs) were extracted or unadjusted ORs (95% CI) were calculated. PRISMA guidelines were followed, and 2 independent raters assessed study quality using Downs and Black criteria. RESULTS: Of 905 potentially relevant studies, 7 were included. Sample sizes ranged from 43 to 541, and Downs and Black scores ranged from 2 to 12. Clinical and methodological heterogeneity precluded meta-analysis. Six studies reported a positive association between recurrent instability episodes and medial meniscal damage (OR range, 3.46 [95% CI, 1.24-9.99] to 11.56 [1.37-521.06]). The association between instability episodes and lateral meniscal or cartilage damage was inconsistent. No studies examined the association between instability episodes and OA. CONCLUSION: This systematic review provides preliminary evidence that recurrent instability episodes after first-time ACL injury may be associated with increased odds of medial meniscal damage. This highlights the importance of early diagnosis, education, and treatment for individuals with ACL injury, all of which must include a specific focus on the prevention and management of instability episodes. High-quality, prospective cohort studies are needed that assess the effects of diagnostic and treatment delay, recurrent instability episodes on secondary meniscal and cartilage damage, and OA after an initial ACL injury.