Increased Graft Diameter and Quadrupled Versus Tripled Hamstring Tendon Autograft are Associated With Improved Graft Survival in Double‐Bundle Anterior Cruciate Ligament Reconstruction

PURPOSE: To compare graft survival and clinical outcomes between patients who underwent double-bundle anterior cruciate ligament reconstruction using quadrupled versus tripled hamstring tendon (HT) grafts and to investigate factors associated with graft failure. METHODS: Propensity score matching was performed at a 1:2 ratio between patients who underwent primary double-bundle anterior cruciate ligament reconstruction with a quadruple HT autograft (Group Q) and those who received a triple HT autograft (Group T) between 2014 and 2020, including patients with a minimum follow-up of 2 years. The same triple- or quadruple-strand configuration was used for both the anteromedial (AM) and posterolateral bundles within each group. Propensity score matching was performed using the following covariates: age, sex, body mass index, time interval from injury to surgery, and Tegner activity scale. Primary outcome was graft failure rate in both groups during the follow-up period. Graft diameter of the AM and posterolateral bundles were compared between the groups. Patient-reported outcomes, including the International Knee Documentation Committee subjective score, Lysholm score, Knee injury and Osteoarthritis Outcome Score subscales, and Tegner activity scale, were compared between the two groups both preoperatively and postoperatively. Follow-up magnetic resonance imaging was routinely performed between 6 and 12 months postoperatively to evaluate graft status prior to return to sports activity (Group Q 7.8 ± 5.6 months vs Group T 7.7 ± 4.8 months; P = .871). The Kaplan-Meier analysis was conducted to compare graft survival between the 2 groups. Multivariable logistic regression analysis was performed to identify factors associated with graft failure. RESULTS: Forty-five pairs (Group Q = 45, Group T = 90) were identified using 1:2 propensity score matching. Demographic factors did not differ significantly between the groups, and all matching variables achieved adequate covariate balance (absolute standardized mean differences < 0.1). There was no significant difference in follow-up duration between Group Q (37.3 ± 12.0 months) and Group T (39.6 ± 17.6 months; P = .261). In Group Q, graft failure occurred in 1 (2.2%) patient, whereas in Group T, graft failure occurred in 14 (15.6%) patients (P = .020). Graft diameter of the AM bundle was 8.2 ± 0.6 mm in Group Q and 7.2 ± 0.6 mm in Group T (P < .001). Graft diameter of the posterolateral bundle was 6.3 ± 0.5 mm in Group Q and 5.7 ± 0.5 mm in Group T (P < .001). Postoperative patient-reported outcomes were comparable between the two groups, except for the Lysholm score (Group Q 92.1 ± 9.3 vs Group T 94.4 ± 6.2, P = .049). The Kaplan-Meier analysis showed better graft survival in Group Q. (P = .027) The AM bundle graft diameter was significantly associated with graft failure (Odds ratio 0.233; 95% confidence interval 0.062-0.869; P = .030). CONCLUSIONS: In double-bundle anterior cruciate ligament reconstruction using HT autografts, quadrupled grafts showed significantly lower graft failure rates compared with tripled grafts. A larger graft diameter, particularly in the AM bundle, was independently associated with improved graft survival. LEVEL OF EVIDENCE: Level III, retrospective comparative case series.