Influence of autological growth factors on activation of regenerative processes of the superficial digital flexor tendon of horses

Injury of the superficial digital flexor tendon is known for slow and functionally incomplete recovery, which is a problem in the equestrian horse farming. In the clinical studies, we used platelet-rich plasma, obtained from horse blood, and a specially designed scheme of rehabilitation after physical loads for the treatment of injuries of the superficial digital flexor tendon of horses. We analyzed four clinical cases of injuries of the superficial digital flexor of horses, of which 3 cases were treated using platelet-rich plasma, injected under ultrasound-diagnostic control, and one case that was treated without its administration. Ultrasound studies of the superficial digital flexor tendon revealed the following changes: increase in the volume of the tendon, damage to the fiber structure, and absence of fibrosity on the longitudinal images, and hypo-echogenic or anechogenic structure on transverse and longitudinal images. The results of the platelet-rich-plasma treatment of the horses were compared with the control (without utilization of platelet-rich plasma). As seen on the ultrasound images during the intermediate-control stage (2.5–4.0 months after injury), the horses that had received injection of platelet-rich plasma and had undergone the complex of physical exercises were forming new fibers of the superficial digital flexor tendon, which had distinct structure and alignment. This indicated the process of their physiological development. Four and a half months after being injured, the horse that had only received a symptomatic treatment combined with a complex of rehabilitating physical loads had poorly structured fibers in the damaged area, with their disordered alignment, as revealed by the longitudinal images. This suggested the formation of a scar. Transverse images showed the anechogenic areas of the injury suffered by this horse. The method of preparing and administration of platelet-rich plasma is relatively cheap, given the equipment and a qualification of a veterinary doctor. Taking into account its identified efficacy for recovery of the superficial digital flexor tendon, it would be promising to conduct further clinical trials using platelet-rich plasma for treating other injured tendons of horses, which can notably increase the quality of recovered connective tissues.