MR imaging of synovial disorders of the knee

Synovial membranes line the diarthrodial (movable) joints, bursae, and tendon sheaths of the body. The primary function of this specialized, vascular tissue is to serve as a filter system that lubricates and nourishes the articular structures as well as serving as a shock-absorber. The synovium is affected by a variety of disorders that can be localized to a specific articulation or can be systemic in nature. These include inflammatory, infectious, degenerative, traumatic, or neoplastic categories of disease. Further, MR imaging provides an excellent non-invasive tool for the evaluation of the synovium and synovial-based processes. This article will discuss technical considerations pertinent to the MR imaging evaluation of synovial processes in the knee; will review the synovial and bursal anatomy of the knee as well as the imaging characteristics of general synovial abnormalities and their diagnostic implications. In addition, it will review specific synovial processes and their characteristic MR imaging findings.