Hamstring graft remodelling after ACL reconstruction is slower in paediatric population compared to adults.

PURPOSE: Anterior cruciate ligament (ACL) injuries are increasing in children and adolescents and reconstruction (ACLR) is now frequently performed in this population. Paediatric patients remain at higher risk of reinjury, possibly due to delayed graft remodelling. The current study aims to compare magnetic resonance imaging (MRI)-based graft remodelling between paediatric and adult populations at 1 year postoperatively. METHODS: We conducted a single-centre comparative pilot study including a prospectively collected cohort of 52 paediatric and 59 adult patients undergoing ACLR with a semitendinosus autograft folded in four (ST4) without additional lateral extra-articular tenodesis (LET). MRI was performed at 12 months postoperatively. Graft maturation was assessed using the signal-to-noise quotient (SNQ) and Howell scores. Tibial tunnel widening (TTW) and patient-reported outcome measures (PROMs) were also collected. RESULTS: The mean adjusted SNQ was significantly higher (p < 0.001) in paediatric patients (5.1; 95% confidence interval [CI] [4.3-5.9]) than in adults (1.5; 95% CI [0.9-2.2]), indicating slower remodelling. The Howell classification confirmed less mature grafts in children, with a predominance of Grade II. TTW was observed in similar proportions in both groups. PROMs were favourable and comparable in both groups. One paediatric patient experienced a graft rupture at 6 months, following premature return to pivoting sport. CONCLUSION: At 1-year post-ACLR, paediatric patients show delayed graft remodelling compared to adults. This slower biological incorporation may contribute to higher reinjury rates in young athletes and supports the need for prolonged rehabilitation and careful return to high-risk sports. LEVEL OF EVIDENCE: Level II.