Disorders of the hallux sesamoid complex: MR features.

Numerous painful conditions can affect the first metatarsophalangeal-sesamoid joint complex. Symptoms can be of sudden or insidious onset, and be of acute or chronic duration. Although conventional radiography is recognized as the initial diagnostic procedure for these symptoms, there is often a need to proceed to MR imaging. MR imaging is sensitive and can be utilized in the investigation of the hallux sesamoid complex to differentiate soft tissue from osseous pathology. Synovitis, tendonitis, and bursitis can be distinguished from bony abnormalities such as sesamoid fracture, avascular necrosis, and osteomyelitis. An understanding of MR imaging features and techniques will result in the highest diagnostic yield. Early and accurate diagnosis of sesamoid complex disorders can guide the physician to the appropriate clinical management and prevent potentially harmful longstanding joint dysfunction.