ACL Reconstruction in Skeletally Immature Patients: Does Graft Retear and Complication Rates Differ Based on Surgical Technique? A Systematic Review

BACKGROUND: Despite exponential increases in studies regarding ACL reconstruction (ACLR) in pediatric patients in the last two decades, there remains a dearth of comparative studies designed to elucidate the optimal technique(s) for this active, high-risk sub-population. HYPOTHESIS/PURPOSE: The purpose was to compare the rates of ACL re-tear, contralateral ACL tear, complications, and return-to-sport (RTS) between categories of ACLR techniques in skeletally immature patients. The hypothesis was that complication rates would be similar between techniques, while ACL re-tear rates would be higher in transphyseal (adolescent) ACLR than physeal-sparing (pediatric) ACLR. METHODS: A literature search indexed from the earliest available date to January 5, 2021 was performed using the PubMed/MEDLINE, Embase, and Cochrane databases for relevant journal articles with standard inclusion/exclusion criteria utilized for systematic reviews. Further exclusions were investigations of ACL repair, revision ACLR, and ACLR with allograft or BTB autograft. Cohorts of adolescent patients undergoing transphyseal ACLR were distinguished from those of pediatric patients undergoing physeal-sparing techniques, which were further sub-classified as all-epiphyseal (AE), iliotibial band (ITB)/modified Macintosh, and partial transphyseal (PTP). Transphyseal ACLR was further classified based on graft type (hamstring vs. quadriceps autograft). Meta-analysis for each outcome incidence rate was conducted within each subgroup and overall using a random-effects generalized linear mixed model with logit link. RESULTS: 44 studies published between 2001 and 2021 from 15 different peer-reviewed journals were included. The mean age of the adolescent/transphyseal group was 13.4 years (range, 11.0-14.8), compared to 12.3 years (range, 11.0-14.8) in the pediatric/physeal-sparing group (All-Epiphyseal, 12.6 years; ITB, 11.5 years; PTP, 12.6 years). Mean duration of follow-up was reported in 93.2% of the studies and was 4.0 years (range, 1.6-10.6 years). ACL re-tear, contralateral ACL tear, complications, and RTS were not significantly different between transphyseal and physeal-sparing techniques (all p>0.05) (Table 1). ITB demonstrated significantly lower complications (2.9%) than other physeal-sparing techniques (AE, 10.8%; PTP, 15.3%, p=0.005) and the lowest ACL re-tear rate (AE, 10.1%; ITB, 6.9%; PTP, 7.5%, p=0.20), though this difference was not significant. CONCLUSIONS: Unlike the findings of some single-center analyses, when the breadth of pediatric ACLR literature was analyzed in pooled fashion, no differences were seen between the clinical results of younger pediatric patients undergoing physeal-sparing ACLR and relatively older skeletally immature adolescents undergoing transphyseal ACLR. Amongst physeal-sparing techniques, the ITB/modified-Macintosh ACLR appears to have the lowest retear rate and a significantly lower complication rate than all-epiphyseal and partial-transphyseal ACLR.