Alleviation of Osteoarthritis-Induced Pain and Motor Deficits in Rats by a Novel Device for the Intramuscular Insertion of Cog Polydioxanone Filament

The importance of skeletal muscles in the development of osteoarthritis (OA) is known. However, in OA, strengthening the muscle is arduous process. This study investigated the effects of muscle enhancement and support therapy (MEST), a novel device for the intramuscular insertion of cog polydioxanone filament intended to hold and stimulate surrounding muscles, on OA-induced symptoms. In our results, the MEST attenuated OA-induced pain and mobility limitations, as evidenced by increases in withdrawal thresholds, rearing duration and travelled distance in an open cage, and fall latency from rotarod. It further restored atrophic rectus femoris muscle (RFM) in OA animals by increasing mass, decreasing nucleus density, and increasing the cross-sectional area of muscle fibers. Decreased collagen and insulin-like growth factor 1 levels in OA animals were restored without affecting the interleukin-6 and tumor necrosis factor-alpha levels in RFM. No evidence of structural improvement in the knee was observed via computed tomography after MEST. These results suggest that MEST in the quadriceps is effective for relieving pain and motor impairment in knee OA animals by restoring atrophic muscles, providing a novel therapeutic strategy for OA symptom management.