Epidemiology
ACL injury rates have increased significantly in paediatric and adolescent populations compared with the adult population 3. Notably, the incidence ranges from 60.9 tears per 100,000 person-years in young adults 1 to 400 tears per 100,000 person-years in adolescents 2. Factors such as surge in youth sport involvement, year-round training, and early specialization contribute to this higher prevalence 4. [PMID:40188407]
An analysis of data from the National Interscholastic Cycling Association (NICA) injury surveillance system (PMID:40103308) revealed 401 injury events among coaches over five seasons, with shoulder/clavicle, head/concussion, and wrist/hand injuries being most common. Notably, there was a significant gender difference in injury patterns, with female coaches sustaining more lower-limb injuries compared to males.
The National Interscholastic Cycling Association (NICA) oversees over 25,000 student athletes in mountain biking, emphasizing the importance of understanding injury patterns in this growing demographic [PMID:34072534].
Common injuries in youth mountain biking include concussion, fracture, dislocation, contusion, and laceration, reflecting the physical demands and risks of the sport [PMID:34072534].
The NICA ISS, comprising 66,588 athlete-years of injury data, offers critical insights into injury trends in youth mountain biking, even during disrupted seasons like those affected by the COVID-19 pandemic [PMID:34072534].
Youth sport participation patterns show a trend towards early specialization in a single sport, which has significant implications for injury risks in growing athletes [PMID:32520903].
The study included 29 athletes with a mean age of 13.9 years, distributed across Tanner stages I (5 patients), II (17 patients), and III (7 patients) [PMID:26996346].
Clinical Presentation
The study by Teramoto et al. (PMID:40103308) highlighted that female coaches experienced a significantly higher rate of lower-limb injuries (33.3%) compared to male coaches (17.9%), while male coaches had a higher incidence of upper-limb injuries (62.9% vs. 51.5%).
The knee, being a critical joint in many sports, frequently manifests symptoms of overuse and potential osteochondrosis in skeletally immature athletes due to repetitive stress [PMID:32520903].
The study highlights the necessity of transphyseal techniques in managing ACL injuries in skeletally immature patients to minimize complications like growth disturbances [PMID:26996346].
Management
Autografts ensure high success rates and avoid immunogenic reactions but come with disadvantages like harvesting issues and donor-site morbidity 14. Allografts, while avoiding donor-site issues and simplifying rehabilitation, carry risks of disease transmission and slower integration, though these risks are minimized with current methods 14. [PMID:40188407]
Educating athletes, parents, and coaches about the benefits of varied sporting activities over single sport specialization can mitigate injury risks, including those related to osteochondrosis [PMID:32520903].
Twenty-nine skeletally immature athletes underwent transphyseal ACLR with autografts and allografts, achieving high return rates to prior sports levels (100% initially, 76% at latest follow-up) [PMID:26996346]. However, graft failure occurred in 16.7% of patients, with a higher incidence in allograft recipients (37.5% vs 9% for autografts). Additionally, 16.7% sustained contralateral ACL injuries [PMID:26996346].
Complications
Several investigations have described higher allograft rupture rates, particularly in younger patients 1516. This study aims to compare clinical outcomes and failure rates between autograft and allograft ACL reconstructions in young, athletic patients [PMID:40188407]
Among the injuries reported in the NICA injury surveillance system (PMID:40103308), fractures were the most frequent diagnosis (27.1% of non-head injuries), followed closely by concussions (18.0% of all injury events), indicating these as significant complications in this population.
Post-ACLR, 4 patients developed Harris growth arrest lines, and one patient exhibited genu valgum deformity, which spontaneously corrected over time [PMID:26996346].
Prognosis & Follow-up
The study focuses on assessing clinical outcomes through validated questionnaires as primary outcomes and evaluating the rate of return to sports and timing of any graft failure as secondary outcomes [PMID:40188407]
There is a growing body of evidence suggesting that early specialization could lead to increased long-term joint health complications, necessitating thorough follow-up assessments [PMID:32520903].
At a mean follow-up of 4 years, patients demonstrated high functional scores (IKDC: 91.8, Cincinnati: 93.0, Lysholm: 91.5) and minimal knee instability (mean KT-1000 side-to-side difference: 0.4 mm) [PMID:26996346].
Special Populations
The immature skeleton is more susceptible to the detrimental effects of repetitive stress from specialized sports, highlighting the need for tailored management approaches [PMID:32520903].
References
1 Screpis D, De Berardinis L, Qordja F, Piovan G, Giannini E, Gigante AP et al.. Comparison of autograft and allograft outcomes in adolescent ACL reconstruction: a propensity score analysis. European journal of orthopaedic surgery & traumatology : orthopedie traumatologie 2025. link 2 Teramoto M, Cushman DM, Ehn M, Provance A, Johnson LA, Egbert J et al.. Injury epidemiology of youth cross-country mountain biking coaches: analysis of data from the National Interscholastic Cycling Association injury surveillance system. Research in sports medicine (Print) 2025. link 3 Ehn M, Teramoto M, Cushman DM, Saad K, Willick S. The National Interscholastic Cycling Association (NICA) Mountain Biking Injury Surveillance System (ISS): Analysis of 66,588 Student Athlete-Years of Injury Data. International journal of environmental research and public health 2021. link 4 Lansdown DA, Rugg CM, Feeley BT, Pandya NK. Single Sport Specialization in the Skeletally Immature Athlete: Current Concepts. The Journal of the American Academy of Orthopaedic Surgeons 2020. link 5 Larson CM, Heikes CS, Ellingson CI, Wulf CA, Giveans MR, Stone RM et al.. Allograft and Autograft Transphyseal Anterior Cruciate Ligament Reconstruction in Skeletally Immature Patients: Outcomes and Complications. Arthroscopy : the journal of arthroscopic & related surgery : official publication of the Arthroscopy Association of North America and the International Arthroscopy Association 2016. link