Sesamoiditis & Sesamoid Fracture 2026 | Podiatrist

The sesamoid pathology spectrum ranges from early inflammation (sesamoiditis) through stress fracture to avascular necrosis (AVN) -- these represent stages of progressively severe sesamoid injury, and distinguishing them determines both the prognosis and treatment approach. Sesamoiditis (earliest and most common): inflammation of the sesamoid bone and its surrounding soft tissues (the flexor hallucis brevis tendons, joint capsule, and bursae) without discrete fracture or bone death; it is a reactive stress response to overloading; MRI findings: bone marrow edema within an intact sesamoid (high signal on STIR, low signal on T1); the sesamoid is structurally intact; prognosis: excellent with offloading; heals with appropriate conservative management in 6-10 weeks; Sesamoid stress fracture: a fatigue fracture through the sesamoid bone caused by repetitive cyclic loading; the tibial (medial) sesamoid is affected more commonly than the fibular (lateral) sesamoid; the fracture runs transversely through the sesamoid; MRI findings: a fracture line through the sesamoid with surrounding bone marrow edema; X-ray: the fracture may be visible but is often confused with a bipartite sesamoid (a normal variant in which the sesamoid has two segments separated by a smooth cartilaginous interval -- the bipartite sesamoid has smooth, corticated edges, while a fracture has irregular, non-corticated edges); prognosis: healing is slower than sesamoiditis (3-4 months in a walking boot); some sesamoid fractures develop fibrous union (scar tissue) rather than bony union; fibrous union may be asymptomatic or persistently painful; Sesamoid avascular necrosis (AVN): the blood supply to the sesamoid is disrupted, causing bone death; the sesamoid cannot heal without a blood supply; causes: trauma (acute disruption of the feeding vessels), prior corticosteroid injection (fat necrosis of the vascular supply), repetitive stress that progressively compromises the microvascular supply; X-ray findings: the sesamoid appears dense (sclerotic) and fragmented; the normal homogeneous trabecular pattern is replaced by irregular dense fragments; MRI: absent enhancement on gadolinium-enhanced sequences (no blood flow); T1 signal loss throughout the sesamoid without the patchy edema pattern of stress fracture; prognosis: the avascular sesamoid cannot recover its blood supply and will not heal with conservative management; sesamoidectomy is often ultimately required for AVN with persistent pain.

A bipartite sesamoid is a normal developmental variant in which the sesamoid bone develops from two separate ossification centers that fail to fuse -- it is present in approximately 10-30% of people (bilateral in 25% of cases) and is almost always asymptomatic; it is the most common diagnostic pitfall in sesamoid evaluation and is frequently misidentified as a fracture on plain X-ray. The developmental anatomy: during skeletal development, the sesamoid bones ossify from a single ossification center in most people; in approximately 10-30%, the tibial (medial) sesamoid ossifies from two centers that remain separate -- this is the bipartite sesamoid; the fibular (lateral) sesamoid is bipartite in approximately 1-2% of people; the bipartite sesamoid is a structural variant with smooth, well-corticated margins at the interface between the two segments; the intervening cartilage (synchondrosis) is smooth and regular; Radiographic distinction from fracture: bipartite sesamoid: smooth, rounded, well-corticated edges at the interface between the two halves; the margins are sclerotic (dense) because they represent normal bone cortex; the edges fit together with a smooth contour; the overall sesamoid size may be slightly larger than average; sesamoid fracture: irregular, jagged, non-corticated fracture margins; the edges are not sclerotic (fresh fracture edges lack cortication); the two fragments often have an acute triangular configuration rather than a rounded interface; comparison views of the opposite foot are helpful -- if the opposite sesamoid is also bipartite with identical morphology, the finding in the symptomatic foot is likely a bipartite variant; Why it matters clinically: a bipartite sesamoid that becomes symptomatic (from the synchondrosis being stressed, typically after an ankle sprain or increase in activity) can cause pain that mimics a sesamoid fracture; MRI distinguishes the two: in a symptomatic bipartite sesamoid, edema is present at the synchondrosis interface; in a fracture, edema surrounds a fracture line through otherwise normal-appearing bone; treatment of a symptomatic bipartite sesamoid: identical to sesamoiditis -- offloading with a dancer's pad or sesamoid relief orthotic; walking boot for 4-6 weeks for acute inflammation; the synchondrosis may be injected with corticosteroid for persistent pain; surgery (excision of one fragment or the entire bipartite sesamoid) is reserved for refractory cases after 6 months of conservative management.