Associated tears of the lateral meniscus in anterior cruciate ligament injuries: risk factors for different tear patterns

Background: The pattern of lateral meniscus tears observed in anterior cruciate ligament (ACL)-injured subjects varies greatly and determines subsequent management. Certain tear patterns with major biomechanical consequences should be repaired in a timely manner. Knowledge about risk factors for such tears may help to identify patients in the early posttraumatic phase and subsequently may improve clinical results. Methods: A database of 268 patients undergoing primary ACL reconstruction was used to identify all patients with isolated ACL tears and patients with an associated tear of the lateral meniscus. Patients who underwent surgery >6 months after the injury were excluded. Based on the arthroscopic appearance of the lateral meniscus, patients were assorted to one of three groups: 'no tear,' 'minor tear,' and 'major tear.' Tear patterns defined as major included root tears, complete radial tears, and unstable longitudinal tears including bucket-handle tears. Univariate analysis was performed by comparing the three groups with regard to gender, age, height, weight, BMI, type of injury (high-impact sport, low-impact sport, and not sports related), and mechanism of injury (non-contact vs. contact). Multivariate logistic regression was carried out to identify independent risk factors for minor and major meniscal tears and to calculate odds ratios (OR). Results: Two hundred fifteen patients met the inclusion and exclusion criteria. Of those, 56% had isolated ACL tears, 27% had associated minor tears, and 17% had associated major tears of the lateral meniscus. Univariate analysis revealed significant differences between the three groups for gender (p = 0.002), age groups (p = 0.026), and mechanism of injury (p < 0.001). A contact injury mechanism was a risk factor for minor tears (OR: 4.28) and major tears (OR: 18.49). Additional risk factors for major tears were male gender (OR: 7.38) and age <30 years (OR: 5.85). Conclusion: Male patients, patients <30 years, and particularly patients who sustained a contact injury have a high risk for an associated major lateral meniscus tear. Special attention is therefore necessary in those patients and early referral to magnetic resonance imaging and/or arthroscopy is recommended to allow meniscus repair in a timely manner.