Functional adaptation of articular cartilage from birth to maturity under the influence of loading: a biomechanical analysis.
Authors: Brommer H, Brama P A J, Laasanen M S, Helminen H J, van Weeren P R, Jurvelin J S
Journal: Equine veterinary journal
Summary
# Editorial Summary: Functional Adaptation of Articular Cartilage in Young Horses Brommer and colleagues conducted a biomechanical analysis of cartilage from foals at birth through to mature horses, sampling osteochondral tissue from two distinct loading zones on the proximal phalanx to investigate whether cartilage properties adapt functionally during development. Using indentation testing and ultrasonic measurement techniques, they measured Young's modulus (equilibrium stiffness) and dynamic modulus (viscoelastic properties) across stillborn foals, 5-month-old foals, 18-month-old horses, and mature animals. Fetal cartilage proved biomechanically homogeneous regardless of anatomical location, but by 18 months of age, significant site-dependent differences had emerged—Young's modulus at the low-loading weightbearing site increased gradually with maturation whilst remaining stable at the impact-loading site, and the ratio between sites shifted from approximately 1.0 to 0.5–0.6, mirroring mature horses. Critically, the study demonstrates that functional adaptation is substantially complete by 18 months, meaning the loading environment during early life fundamentally shapes cartilage's long-term biomechanical competence; this finding has profound implications for training protocols and management decisions in young horses, suggesting that optimised joint loading in the first 18 months may be the single most effective preventative strategy against degenerative joint disease later in life.
Read the full abstract on PubMed
Practical Takeaways
- •Early loading and exercise patterns during the first 18 months of life are critical for establishing proper cartilage biomechanical adaptation; inappropriate loading during this window may compromise joint health later
- •Young horses naturally develop site-specific cartilage properties in response to how they are loaded—optimize early-life exercise and training to match functional demands rather than avoiding activity
- •By 18 months, cartilage adaptation is essentially complete, making this a critical period for injury prevention through proper management of loading rather than focusing on older horses
Key Findings
- •Fetal cartilage is biomechanically homogeneous with no site-dependent differences, acting as a 'blank slate' at birth
- •Young's modulus at high-loading Site 1 remains constant throughout maturation, while Site 2 (low-loading) shows gradual significant increase during development
- •Dynamic modulus decreases significantly after birth at both sites, with fetal values higher than post-natal ages
- •Functional adaptation to loading patterns is substantially complete by 18 months of age, with site-dependent biomechanical heterogeneity (ratio 0.5-0.6) comparable to mature horses