Evidence suggests that shockwave therapy might improve the performance of platelet-rich plasma in treating tendon and ligament injuries in horses.
American researchers based their findings on a laboratory experiment in which they compared the release of growth factors from platelet-rich plasma exposed to shockwave therapy to those found in control samples.
Platelet-rich plasma is a biomaterial obtained from the blood of the individual being treated. The processed plasma, when injected into the site of an injury, releases high concentrations of growth factors which aid in healing and the natural formation of new blood vessels. An attractive feature is that it can be deployed as a straightforward stall-side treatment using one of many commercial available devices or kits.
Shockwave therapy is a popular method for treating musculoskeletal injuries in the horse. Pulses from the shockwave unit are transmitted into tissues and stimulate healing of the targeted structure.
It has been shown to improve the rate of healing in horses with some ligament problems. The way it works is not yet fully understood, but it triggers cell-specific responses to promote healing.
It has been suggested that greater growth-factor release would hasten the healing process, and that a combination of shockwave therapy and treatment with platelet-rich plasma could promote healing in injured tendons and ligaments in horses.
Kathryn Seabaugh, Merrilee Thoresen and Steeve Giguère ran a lab experiment to see if shockwaves applied to platelet-rich plasma samples increased the concentration of transforming growth factor-β1 (TGF-β1) and platelet-derived growth factor ββ (PDGF-ββ) released from the platelets.
They used platelet-rich plasma derived from six Quarter Horse mares for their experiment.
The platelet-rich plasma from each horse was exposed to one of four different treatments before the growth factors were measured.
There was a positive control, in which the platelet-rich plasma was exposed to a freeze-thaw cycle. There was a negative control, in which the blood-derived product received no special treatment. Other samples were exposed to shockwaves using a standard probe providing medium-density energy, while other samples were exposed to shockwaves using a power probe, which delivered higher-density energy.
The growth factors were measured after the treatment using commercially available kits.
Seabaugh and her colleagues, writing in the journal Frontiers in Veterinary Science, reported that concentrations of TGF-β1 and PDGF-ββ in the platelet-rich plasma that underwent a freeze-thaw cycle were significantly increased compared with all other treatments.
The study team said that while this could be interpreted as a freeze/thaw cycle being a better therapeutic option when using platelet-rich plasma, it ruled it out its use as a stallside treatment. It has also been suggested that a freeze/thaw cycle resulted in the platelets breaking down, which may be undesirable, rather than activating them. This break-down would explain the high concentrations of growth factors found.
However, the news was better for shockwave therapy. Both shockwave treatments resulted in significantly increased TGF-β1 concentrations, which were up 46% after exposure using the standard probe and 33% for the power probe, when compared with the negative control.
Shockwave using the standard probe increased PDGF-ββ concentrations by 219% and shockwave using the power probe increased them by 190% when compared with the negative control.
The findings, they said, suggested that the combination therapy of local platelet-rich plasma injection followed by shockwave therapy may stimulate release of growth factors from platelets after they have been injected into the injury area.
The combination therapy might result in synergism of two methods previously used individually for tendon and ligament injuries in horses, they said.
“This study provides useful information for equine veterinarians but does have limitations,” they added, pondering whether veterinarians were comfortable transferring the findings of the laboratory experiment into animals.
The study team said the results, in their view, supported the use of shockwave therapy in combination with platelet-rich plasma for the treatment of tendon and ligament injuries in horses.
Seabaugh is with the Department of Clinical Sciences at Colorado State University; Thoresen and Giguère are with the Department of Large Animal Medicine at the University of Georgia.
Extracorporeal Shockwave Therapy Increases Growth Factor Release from Equine Platelet-Rich Plasma In Vitro
Kathryn A. Seabaugh, Merrilee Thoresen and Steeve Giguère.
Front. Vet. Sci., 07 December 2017 | https://doi.org/10.3389/fvets.2017.00205