46-year-old female with right first MTP pain and history of stepping on glass under fourth metatarsal head one month ago. Evaluate for foreign body and osteoarthritis. A marker was placed on the ball of the foot, plantar to the fourth MTP joint of the foot. Just beneath the skin surface adjacent to the marker, is a nonenhancing focus of intermediate signal intensity which is slightly hyperintense to skeletal muscle on T1-weighted images and also hyperintense to skeletal muscle on fat-saturated T2-weighted images, which measures approximately 7 mm in the longitudinal dimension and 7 x 3 mm and the transverse dimension. There is very mild, if any, enhancement of the adjacent soft tissues. The fourth metatarsal and phalanges of the fourth toe appear normal. There is a moderate hallux valgus deformity (metatarsal-phalangeal angle of approximately 30 degrees) with moderate osteoarthritis of the first MTP joint, as seen on recent radiographs. There is associated lateral subluxation of the sesamoid bones relative to their normal location beneath the first metatarsal head and moderate degenerative arthritic changes at the metatarsal-sesamoid articulations. There is low signal intensity within the subcutaneous fat along the medial aspect of the first metatarsal head with enhancement on postcontrast sequences that presumably representing scar tissue. There is a mild synovitis of the first MTP joint.
1. Small cutaneous/subcutaneus focus of intermediate signal intensity within the soft tissues along the plantar aspect of the base of the proximal phalanx. The etiology and significance of this finding is uncertain, but the signal characteristics are atypical for a foreign body. This could represent a focus prior soft tissue injury. If there is strong clinical concern for a foreign body, targeted ultrasound examination is recommended.2. Osteoarthritis and hallux valgus deformity of the first MTP joint.