Results of this study suggested that exercise on an underwater treadmill is useful for increasing the ROM of various joints of horses during rehabilitation and that the depth of water affects the amount of flexion and extension of joints.

Objective Develop a non-terminal animal model of acute joint injury that demonstrates clinical and morphological evidence of early post-traumatic osteoarthritis (PTOA). Methods An osteochondral (OC) fragment was created arthroscopically in one metacarpophalangeal (MCP) joint of 11 horses and the contralateral joint was sham operated. Eleven additional horses served as unoperated controls. Every 2 weeks, force plate analysis, flexion response, joint circumference, and synovial effusion scores were recorded. At weeks 0 and 16, radiographs (all horses) and arthroscopic videos (OC injured and sham joints) were graded. At week 16, synovium and cartilage biopsies were taken arthroscopically from OC injured and sham joints for histologic evaluation and the OC fragment was removed. Results Osteochondral fragments were successfully created and horses were free of clinical lameness after fragment removal. Forelimb gait asymmetry was observed at week 2 (P=0.0012), while joint circumference (P<0.0001) and effusion scores (P<0.0001) were increased in injured limbs compared to baseline from weeks 2 to 16. Positive flexion response of injured limbs was noted at multiple time points. Capsular enthesophytes were seen radiographically in injured limbs. Articular cartilage damage was demonstrated arthroscopically as mild wear-lines and histologically as superficial zone chondrocyte death accompanied by mild proliferation. Synovial hyperemia and fibrosis were present at the site of OC injury. Conclusion Acute OC injury to the MCP joint resulted in clinical, imaging, and histologic changes in cartilage and synovium characteristic of early PTOA. This model will be useful for defining biomarkers of early osteoarthritis and for monitoring response to therapy and surgery.

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Purpose: Exosomes are small nanosized extracellular membrane vesicles produced within multivesicular bodies of the late endocytic compartment of hematopoietic and non-hematopoietic cells. Exosomes have immunoregulatory activities in animal models of inflammatory and autoimmune disease. Osteoarthritis (OA) is mainly characterized by the degradation of the cartilaginous extracellular matrix (ECM), resulting in a progressive loss of the articular cartilage. The cascade of proinflammatory and catabolic events is primarily induced by interleukin 1 beta (IL-1b) that ultimately leads to the release of ECM molecules like proteoglycans. Whether exosomes are of value for the treatment of OA remains, however, unclear. Here, we evaluated the possible early protective versus suppressive effects of exosomes on the release and contents of glycosaminoglycans (GAG) in human OA cartilage explants treated (or not) with IL-1b, either concomitantly or sequentially, and relative to the application of autologous conditioned serum (ACS), a component used in OA patients. Methods: Human OA cartilage explants (Mankin score ¼ 7-9) were obtained from patients undergoing total knee arthroplasty and placed in serum-free medium. In order to study the component-induced protective, suppressive, or deleterious effects on cartilage metabolic processes, the following experimental groups were evaluated: Group 1: explants treated with total serum, serum without exosomes (final