Double-Bundle Anterior Cruciate Ligament Reconstruction Using Hamstring Tendon Hybrid Grafts in Patients Over 40 Years of Age: Comparisons Between Different Age Groups

BACKGROUND: Several recent studies have reported that favorable clinical results and a high level of patient satisfaction can generally be obtained with no increased risk of complications after single-bundle anterior cruciate ligament (ACL) reconstruction performed in patients >40 years of age. However, no studies have yet clarified the age-based differences in clinical outcomes after double-bundle reconstruction. PURPOSE: To compare clinical outcomes after double-bundle ACL reconstruction using hamstring tendon hybrid grafts between patients in 2 different age groups: ≥40 years and <40 years. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A retrospective study was conducted using 96 patients (48 men, 48 women ; mean age, 37 years) who underwent unilateral ACL reconstruction between 2008 and 2011. These patients were divided into 2 groups: group M included patients ≥40 years of age (n = 40 patients), and group Y included patients <40 years of age (n = 56 patients). All patients underwent the same anatomic double-bundle ACL reconstruction procedure. Clinical outcomes were evaluated at 2 years after surgery. Tunnel enlargement was also evaluated by computed digital radiography at 1 week and 2 years after surgery. RESULTS: Mean postoperative side-to-side differences in anterior laxity were 0.5 ± 1.9 mm and 1.2 ± 1.5 mm in groups M and Y, respectively; there was a significant difference between the 2 groups (P = .039). There were no significant differences between the groups in Lysholm knee scores, International Knee Documentation Committee (IKDC) scores, or peak muscle torque of the hamstring. On the other hand, peak muscle torque of the quadriceps was significantly lower in group M (81%) than in group Y (89%) (P = .025). With respect to femoral tunnel enlargement, the posterolateral tunnel in group M was significantly larger than that in group Y on anteroposterior and lateral radiographs (P = .015 and P = .002, respectively). CONCLUSION: Equivalent clinical outcomes were seen between the 2 age groups after double-bundle ACL reconstruction. Postoperative anterior laxity was significantly less in older patients than in younger patients, however, older patients had significantly less quadriceps muscle strength than younger patients. Surgeons should be aware of residual muscle weakness and tunnel enlargement when performing double-bundle ACL reconstruction in older patients.