Knee injuries, such as those to the meniscus or anterior cruciate ligament (ACL), are common in the military due to lower-extremity demands placed on soldiers. These injuries are difficult to heal and predispose soldiers to the development of osteoarthritis (OA), which can limit their function and quality of life. Surgery is not always the preferred course of treatment, and is not completely effective in preventing post-traumatic OA when performed. It is hypothesized that the acute inflammatory reaction to these injuries plays a role in the development of OA via exposure of synoviocytes to noxious stimuli.

The primary objective of this study is to evaluate the biochemical and cellular composition of hemarthroses after acute knee injuries. Secondarily, we seek to create a platelet-rich plasma (PRP) product using hemarthroses collected after aspiration and characterize the biochemical and cellular composition of the product. This study will provide the preliminary data needed to design, fund, and implement a future interventional study, which will use the PRP product in a clinical trial for acute knee soft-tissue injuries.