Did the superficial digital flexor tendon lesions just happen?

Superficial digital flexor tendon (SDFT) injuries can arise by intrinsic (overstrain) or extrinsic (penetrations, lacerations) damage. Overstrain injury can occur either by sudden overextension of the metacarpophalangeal joint, which overcomes the strength of the tendon, or, more commonly, following a preceding phase of tendon degeneration. As the SDFT is operating very close to its functional limit, any deterioration in its mechanical properties will markedly increase the risk of clinical tendonitis. In young, immature tendon, loading appears to have a stimulatory effect for matrix production whereas after skeletal maturity this effect appears to be largely lost. In the adult, gross mechanical properties do not differ significantly with age or exercise, but show a high variance, suggesting some horses are more resistant to injury than others. The collagen fibril crimp angle and length show a regional reduction in the central core with exercise and age, both acting synergistically, whereas, in the matrix, regional differences in collagen fibril diameter were seen in longterm exercised older horses, but not in short-term exercised, younger, horses ...