Table 3 Pathological conditions associated with sesamoids and accessory ossicles of the foot and radiological clues to diagnose them
From: Sesamoids and accessory ossicles of the foot: anatomical variability and related pathology
Pathologies | Radiological clues |
|---|---|
Trauma (fracture) | Irregular bony fragment with poorly corticated margins; evidence of displacement; presence of a donor site; soft tissue swelling |
Sesamoiditis | Bone marrow oedema isolated to the sesamoid without changes in the metatarsal head on MRI; no increase in sclerosis on CT; increased uptake on 99mTc-MDP bone scan |
Osteonecrosis | Increased sclerosis on CT; bone marrow oedema pattern (early) or diffusely decreased signal (late) on MRI |
Infection (osteomyelitis) | Cortical destruction and adjacent soft tissue inflammation on radiograph (late stage disease); T2 hyperintensity of the marrow with corresponding T1 hypointensity, in addition to signs of inflammation in the surrounding soft tissues on non-enhanced MRI; intraosseous enhancement on contrast-enhanced MRI; possible fluid-equivalent signal changes with peripheral enhancement representing intraosseous and soft tissue abscess formation |
Degenerative disease (osteoarthritis) | Joint space loss, subchondral sclerosis and cysts, and osteophytes formation on radiograph; cartilage loss, signal changes suggestive of bone marrow and soft tissue changes on MRI; sclerosis and fragmentation on CT |
Posterior ankle impingement syndrome | Presence or absence of os trigonum, soft tissue swelling and infiltration of fat on radiograph; fractures or fragmentation, and degeneration at the synchondrosis on CT; intrinsic osseous pathology and associated synovitis/tenosynovitis on MRI |
Painful os peroneum syndrome | Presence of os peroneum, displacement from its normal location, fracture or distraction of a bipartite sesamoid on radiography and CT; tendinosis and abnormal bone marrow signal within the ossicle and the adjacent osseous structures on MRI; tendon tears |
Painful accessory navicular | Always type II; degenerative changes at the synchondrosis and abnormal osseous density on CT; increased uptake on technetium bone scan; abnormal signal within the ossicle in the synchondrosis and navicular tubercle, within the adjacent soft tissues and in the posterior tibial tendon on MRI |
Painful os intermetatarseum | Increased radiotracer uptake on scintigraphy |