Intra-articular findings in primary and revision anterior cruciate ligament reconstruction surgery: a comparison of the MOON and MARS study groups.

BACKGROUND At the time of anterior cruciate ligament (ACL) reconstruction, there are usually concurrent meniscal and articular cartilage injuries. It is unclear if there is a significant difference between intra-articular injuries at the time of a primary ACL reconstruction compared with revision ACL reconstruction. PURPOSE To compare the meniscal and articular cartilage injuries found at the time of primary and revision ACL reconstruction surgery and to determine associations between primary and revision surgery and specific intra-articular findings. STUDY DESIGN Cohort study (prevalence); Level of evidence, 2. METHODS Primary and revision ACL surgeries were identified from the Multicenter Orthopedic Outcomes Network (MOON) and Multicenter ACL Revision Study (MARS) study groups, respectively, from January 1, 2007 to November 1, 2008. Demographic data on individual patients were analyzed including age, body mass index (BMI), and gender. Intra-articular findings including the presence of medial or lateral meniscal tears and chondral damage to articular surfaces were analyzed for each patient. Comparisons of intra-articular findings at the time of surgery for the 2 groups were analyzed. Chondral damage in the medial and lateral compartments was analyzed considering previous meniscal tear as a possible confounder. RESULTS There were 508 patients undergoing primary ACL reconstruction and 281 patients undergoing revision ACL reconstruction who were identified for inclusion. There were no differences in the mean age, BMI, and gender in the 2 study groups. There was a decreased odds ratio (OR) of new untreated lateral meniscal tears (OR, 0.54; P < .01) but not of medial meniscal tears (OR, 0.86; P = .39) in revision compared with primary ACL reconstruction. There was an increased OR of Outerbridge grade 3 and 4 articular cartilage injury in revision compared with primary ACL reconstruction in the lateral compartment (OR, 1.73; P = .04) and in the patellar-trochlear compartment (OR, 1.70; P = .04) but not in the medial compartment (OR, 1.33; P = .23). There was an increased OR of Outerbridge grade 3 and 4 articular cartilage injury in patients from both groups having a prior medial meniscectomy on the medial femoral condyle (OR, 1.44; P < .01) and on the medial tibial plateau (OR, 1.63; P < .01). There was an increased OR of Outerbridge grade 3 and 4 articular cartilage injury in patients from both groups having a prior lateral meniscectomy on the lateral femoral condyle (OR, 1.65; P < .01) and on the lateral tibial plateau (OR, 1.56; P < .01). CONCLUSION Meniscal tears are a common finding in both primary and revision ACL reconstruction. These results show a decreased OR of new untreated lateral meniscal tears in revision compared with primary ACL reconstruction. A previous medial or lateral meniscectomy increases the OR of articular cartilage damage in the medial or lateral compartments, respectively. Even when controlling for meniscus status, there is an increased OR in revision compared with primary ACL reconstruction of significant lateral compartment and patellar-trochlear chondral damage but not medial compartment chondral damage.