Magnetic Resonance-Guided Focused Ultrasound for Treatment of Arthritic Pain in a Sheep Model

Introduction: Osteoarthritis (OA) is a significant problem worldwide and within the United States. One in five adults in the USA report having osteoarthritis with one in three people who are obese developing symptoms during their lifetime. Animal models provide clinically relevant ways to study effectiveness of the various treatments of osteoarthritis. Both rodent and non-rodent experimental models mimicking the lesions of OA have been developed using three different methods: spontaneous models, mechanical insult or surgically induced joint instability and extracellular matrix damage or interference in chondrocyte metabolism through substances such as mono-iodoacetate (MIA), collagenase, and steroids [1-2]. Smaller animals are useful because of their ease of use and cost, while larger animals are favorable because of their morphological comparability to humans. The anatomy of the sheep stifle is grossly similar to the knee joint of the human [1]. The OA models in sheep are nearly all surgically induced involving partial or total meniscectomy. Anterior (or cranial) cruciate ligament transection (ACLT) alone is reported to induce quite limited cartilage damage in sheep. Chemically induced OA models generally create an acute model for the study of acute cartilage degradation and joint pain. We found that there was no published report on MIA induced sheep OA models. Our goal was to observe morphological and histological changes using intra-articular injection of MIA to create OA model in the sheep and to test the safety and effectiveness of a novel method to treat OA pain Magnetic resonance-guided focused ultrasound (MRgFUS) which is currently being widely investigated for numerous clinical applications [4].