Association of all-inside versus double-bundle anterior cruciate ligament reconstruction with a study-defined composite patient-acceptable knee state at long-term follow-up in patients aged 18–39 years

All-inside (AI) and double-bundle (DB) anterior cruciate ligament reconstruction (ACLR) are widely used techniques with distinct technical rationales. Whether surgical technique is associated with long-term patient-acceptable outcome in young adult patients remains uncertain. This retrospective comparative cohort study included patients aged 18–39 years who underwent primary ACL reconstruction using an autologous hamstring tendon graft with either an all-inside single-bundle or double-bundle technique and had long-term follow-up. The primary endpoint was a study-defined composite patient-acceptable knee state at approximately 10 years, requiring simultaneous achievement of the published PASS thresholds for the IKDC-SKF and KOOS-QOL. Multivariable regression models were adjusted for age, sex, body mass index, baseline IKDC-SKF score, preinjury Tegner score, injury-to-surgery interval, meniscal pathology, high-grade cartilage lesion, and follow-up duration. The final analysis included 192 patients: 100 in the AI group and 92 in the DB group. The measured baseline distributions were broadly comparable, although high-grade cartilage lesions were more frequent in the double-bundle group. The composite patient-acceptable knee state was achieved by 63.0% of patients after AI reconstruction and 67.4% after DB reconstruction. All-inside reconstruction was not associated with a higher likelihood of achieving the composite endpoint compared with double-bundle reconstruction (adjusted odds ratio, 0.76; 95% confidence interval, 0.40–1.44; p =0.402). Adjusted differences in 10-year IKDC-SKF and KOOS-QOL scores were small. All-inside reconstruction was also not significantly associated with IKDC-SKF PASS, KOOS-QOL PASS, or IKDC-SKF deterioration from 2 to 10 years. Firth bias-reduced sensitivity analyses yielded closely similar estimates and did not materially alter the interpretation of any binary outcome. Exploratory analyses identified associations involving body mass index, meniscal pathology, high-grade cartilage lesions, and injury-to-surgery interval. In patients aged 18–39 years undergoing primary ACLR, AI reconstruction did not demonstrate a clear adjusted advantage over DB reconstruction for achieving a composite patient-acceptable knee state at approximately 10 years. The findings should be interpreted as a comparison of long-term patient-reported acceptability and do not address possible differences in objective knee stability or other structural outcomes between the techniques.