Outcomes Following ACL Reconstruction Using Patellar Tendon Versus Hamstring Tendon Autograft In Adolescent Athletes: An Age, Sex, And Bmi-matched Comparative Cohort Study

Abstract

Objectives: The purpose of this study is to compare the re-tear rates and medium-term functional outcomes in matched cohorts of adolescent athletes who underwent primary anterior cruciate ligament reconstruction (ACLR) with patellar tendon/bone-tendon-bone autograft (BTB) versus hamstring tendon autograft (HS). Methods: An initial cohort of 731 patients, aged 13-19 years, who underwent ACLR-BTB or ACLR-HS between 2003-2015 at a pediatric tertiary care hospital by one of 5 surgeons, was identified through a comprehensive electronic medical record database query. Propensity score matching was performed through a logistic regression model, based on characteristics frequently used by some surgeons to guide graft selection: age, sex, and body mass index (BMI). The resultant cohort of 269 patients allowed for a 1:2 (BTB: HS, 83:186) match. A chart review was performed to identify patient demographics, surgical data, and post-operative outcomes, including ACL re-tear and length of clinical follow-up. Patients were additionally contacted to obtain longer term sport participation and re-injury data that may have been investigated or addressed at outside institutions, as well as to obtain patient reported outcomes (PRO) using validated knee function and activity questionnaires (Pedi-IKDC and HSS-Pedi FABS). Individual questions from the Pedi-IKDC that related to anterior knee pain or kneeling pain were specifically investigated to assess the potential effect of these factors, commonly cited aspects of donor site morbidity associated with BTB grafts, on overall scores within this adolescent population. Results: No significant differences were seen in demographic and clinical characteristics of the two matched graft-based cohorts (overall mean clinical follow-up: 54 months), as listed in Table 1. In the sub-population providing PROs (52% response rate, mean PRO follow up: 81 months), no significant differences were seen in activity level, median Pedi-IKDC scores, or knee pain. BTB patients demonstrated superior scores regarding ability to kneel than HS patients. Rates of ACL graft re-tear were not significantly different between groups, both when calculated based on all possible follow-up methods (ACLR-BTB: 11%; ACLR-HS: 12%; p: 0.72), or amongst patients responding to long-term follow up. Conclusion: Despite previous studies, including large, multi-country registry-based analyses, demonstrating lower re-tear rates following ACLR-BTB than ACLR-HS, the current study, focused exclusively on adolescent cohorts matched for age, sex, and BMI, showed no difference in graft re-tear rates between the two cohorts at medium-term follow-up. Moreover, activity scores and overall functional knee outcome scores appear to be equivalent between these younger graft-based populations, with no suggestion of increased donor site morbidity with BTB autograft, as it relates to knee pain or kneeling ability. For skeletally mature adolescents, graft choice may not influence outcome following ACL reconstruction. Consistent with previous studies, the current study reveals relatively high ACL re-tear rates in adolescents, the sub-population most affected by this common injury. [Table: see text]