J Biomech Eng. 2025 Dec 12:1-21. doi: 10.1115/1.4070647. Online ahead of print.
ABSTRACT
Anterior cruciate ligament (ACL) reconstruction in pediatric patients has a higher graft failure rate compared to adults. Restoring joint stability and reducing graft failure is essential. However, how graft biomechanical properties change with age and affect reconstruction outcomes remains unclear. This study investigated the biomechanical development of porcine flexor tendons across skeletal growth and evaluated how graft size and stiffness influence knee biomechanics in a pediatric porcine model. Flexor tendons (n = 57) were harvested from pigs at 0.5, 1.5, 5, and 9 months of age to measure cross-sectional area (CSA), stiffness, and failure load. ACLs in nine early adolescent porcine knees were reconstructed using both 1.5- and 5-month-old (1.5mo and 5mo) grafts and tested under anterior-posterior, compressive, and varus-valgus loading at 40° flexion using a robotic system. ACL and graft forces were calculated using the principle of superposition, and in situ properties were derived from force-displacement curves. Tendon CSA, stiffness, and failure load increased with age, and stiffness associated with CSA. The CSA of 5mo tendons was 57% greater than that of 1.5mo tendons, but stiffness increased only 20%. ACL reconstruction with 5mo grafts resulted in 29% less anterior-posterior tibial translation and 44% higher graft force compared to 1.5mo grafts. In situ stiffness of 5mo grafts was 51% higher than 1.5mo grafts. These findings highlight the differences between tendon size and biomechanical development, which together contribute to the improvements in joint function following ACL reconstruction.
PMID:41385220 | DOI:10.1115/1.4070647
