A gel commonly used in urology and plastic surgery shows promise as a treatment for arthritis in horses, according to a new study from Denmark.
Polyacrylamide hydrogel, which has long been used to reconstruct or augment tissue in human medicine, is a non-degradable gel composed of 97.5 percent water and 2.5 percent polyacrylamide, a highly biocompatible polymer. A 2014 University of Copenhagen study showed that polyacrylamide hydrogel injected into the joints of goats became integrated with the synovial0 membrane, significantly reducing lameness caused by arthritis.
To see whether similar effects occur in horses, the researchers selected 43 with arthritis-related lameness (mild, moderate or severe) diagnosed in only one joint. A polyacrylamide hydrogel product was injected into each arthritic joint and the horse was then rested for two weeks before beginning a tightly controlled progressive exercise program. (The product used in the study is not currently approved by the Food and Drug Administration but is available to veterinarians through a European supplier.)
The researchers gave each horse a follow-up exam to assess lameness at one, three, six, 12 and 24 months after the injection. At the one-month follow-up, 59 percent of the horses showed no lameness, and by the end of the two-year study period, 82.5 percent of the horses were sound and had resumed their previous workload. The largest reduction in lameness in each horse took place between the injection and the first follow-up exam.
The success of a single injection even after two years, the researchers say, is likely due to the integration of the product into the synovial membrane as well as the persistence of the product in the joint fluid to improve lubrication, a process known as “viscosupplementation.” They note that this product integration has also been shown to help treat joint stiffness, a cause of pain in arthritis, in the goat study.
The researchers did not observe any adverse effects in any of the horses over the two-year study period.
References: “Evaluation of a polyacrylamide hydrogel in the treatment of induced osteoarthritis in a goat model: A randomized controlled pilot study,” Osteoarthritis and Cartilage, April 2014; “An international multi-centre prospective study on the efficacy of an intraarticular polyacrylamide hydrogel in horses with osteoarthritis: a 24-month follow-up,” Acta Veterinaria Scandinavica, April 2015
This article first appeared in EQUUS issue #455, August 2015.