Return to Sport Assessment Following ACL Reconstruction in Adolescent Athletes: Quadriceps Tendon Autograft vs. Hamstring Autograft

Background: Quadriceps tendon soft tissue autograft represents an increasingly popular graft option for ACL reconstruction (ACLR), particularly for adolescents, some of whom have open physes, precluding use of bony graft options. However, there is minimal literature investigating the effects of graft harvest on functional recovery, particularly in this high-risk age group. The purpose of this study was to quantify post-operative return to sport (RTS) testing performance in adolescents 6 months following ACLR with quadriceps tendon autograft (ACLR-Q) versus those with hamstring autograft (ACLR-HS).

Methods: Included athletes were 12-19 years-old, underwent primary ACLR by a single surgeon at a pediatric tertiary care hospital, and performed commonly used RTS assessment between 5-9 months post-operatively. Exclusion criteria were prior ipsilateral or contralateral knee surgery or concomitant procedures other than meniscal repair or meniscectomy. RTS tests included manual muscle strength testing (hamstring, quadriceps, hip abductor, adductor), dynamic balance (Y-balance), and functional hop tests (single-hop, triple-hop, crossover, 6-meter timed hop). Limb Symmetry Index (LSI) was compared with an ACLR-HS control group using chi-square tests, Student’s t-test, and Wilcoxon-Mann-Whitney tests. Propensity score matching was conducted to create matched sub-cohorts and remove meniscus repair rates as a confounder.

Results: An initial cohort of 90 ACLR-Q patients was compared to 54 ACLR-HS patients, with no significant differences in demographic characteristics. Differences in meniscus repair rates, however, prompted use of propensity score matching on age, sex, BMI, meniscectomy, and meniscus repair to produce comparable sub-cohorts (Table 1). The matched cohorts resulted in 67 ACLR-Q and 52 ACLR-HS patients. Hamstring strength deficits were significantly greater in ACLR-HS patients than ACLR-Q patients (-40.5% vs. -5.7%, p<0.001). Quadriceps strength deficits were significantly greater in ACLR-Q patients than ACLR-HS patients (-12.8% vs. 0.4%, p<0.001). ACLR-Q patients had significantly greater hamstring-to-quad ratios for operative knees (p < 0.001). ACLR-Q patients had significantly higher Y-balance composite score deficits than ACLR-HS patients (-2.9% vs. 0.4%, p=0.01). There were no significant differences in hop test performance between groups (Table 2).

Conclusion: Adolescent athletes who underwent ACLR-Q showed significantly greater quadriceps strength deficits (LSI: -13%), but significantly smaller hamstring strength deficits than those who underwent ACLR-HS (LSI: -41%), leading to more favorable HS:Q ratios, but poorer balance performance, in ACLR-Q patients 6 months post-operatively. The degree to which these performance metrics influence eventual athletic performance and ACL graft-tear remains a critical area of continued investigation.