Anterior Cruciate Ligament Transection and Synovial Fluid Lavage in a Rodent Model to Study Joint Inflammation and Posttraumatic Osteoarthritis

Osteoarthritis (OA) is a joint disease characterized by chronic pain and currently has no cure. A subset of OA, posttraumatic osteoarthritis (PTOA), can occur after a joint injury. The knee is one of the most affected joints, and among knee injuries, injuries to the ACL are among the most common. Symptomatic OA, which is accompanied by changes to the joint such as cartilage degradation and osteophyte formation, can develop years after the initial injury, but early joint changes can be detected shortly after. Inflammation is considered one of the contributing factors in PTOA development, and the pro-inflammatory mediators produced in response to an injury can catalyze PTOA development. In animal models, surgically injuring structures in the knee is a widely used method of OA induction, and a common surgical technique is an ACL transection (ACLT). The purpose of this study is to describe our ACLT technique for the induction of OA, as well as methods to monitor joint inflammation and quantify OA severity. To assess inflammation post-surgery, we describe a technique for measuring knee edema as well as a technique for harvesting and analyzing knee synovial fluid. To evaluate the long-term joint changes associated with OA, we present a semi-quantitative scoring system we developed to evaluate OA severity via microCT imaging.