Medically reviewed by Dr. Tom Biernacki, DPM — Board-Certified Podiatric Surgeon — Balance Foot & Ankle, Howell & Bloomfield Hills, MI. Last updated April 2026.

Pain under the big toe joint from sesamoid pathology presents a diagnostic challenge: is the irregularity on X-ray a fracture, a bipartite sesamoid (a normal anatomic variant), sesamoiditis, or avascular necrosis? Getting the diagnosis right determines treatment — a fracture requires protected weight-bearing and possible surgical intervention, while a bipartite sesamoid needs only activity modification and orthotics.

Anatomy of the Sesamoids

Two sesamoid bones — the medial (tibial) and lateral (fibular) sesamoids — are embedded within the flexor hallucis brevis tendons beneath the first metatarsal head. They function as pulleys that increase the mechanical advantage of the flexor hallucis longus, absorb impact forces under the first metatarsophalangeal joint, and protect the flexor hallucis longus tendon from direct compression. Together they bear up to three times body weight during push-off.

The medial sesamoid is larger, bears more load, and is fractured approximately twice as often as the lateral sesamoid. Both sesamoids are susceptible to stress fractures in high-impact athletes — runners, dancers, basketball players — who repeatedly load the forefoot.

Bipartite Sesamoid: A Normal Variant

Approximately 10–30% of people have a bipartite medial sesamoid — a sesamoid that developed as two separate ossification centers rather than fusing into a single bone. Bipartite sesamoids are bilateral in roughly 85% of cases where they occur. They are typically asymptomatic and discovered incidentally on X-ray.

Distinguishing features on plain radiograph: bipartite sesamoids have smooth, rounded, corticated (well-defined white border) edges at the division. The two fragments fit together like puzzle pieces with rounded margins. In contrast, an acute sesamoid fracture shows irregular, sharp, non-corticated fracture edges with an angular appearance.

Sesamoid Fractures: Acute vs. Stress

Acute sesamoid fractures result from direct trauma — typically a hyperextension injury of the great toe (landing from a jump, stubbing the toe) or direct impact. Stress fractures develop gradually from repetitive loading without adequate recovery, typically presenting with insidious onset forefoot pain that worsens with activity over weeks.

Acute fractures show sharp, irregular edges on X-ray without sclerosis. Stress fractures may initially appear radiographically occult (invisible on plain X-ray) for 2–4 weeks; MRI shows bone marrow edema and fracture line earlier. Sesamoid fractures often occur through a bipartite sesamoid, creating a “fractured bipartite” — distinguishable from an unfractured bipartite by bone marrow edema on MRI at the fracture site.

Sesamoiditis and Avascular Necrosis

Sesamoiditis is an inflammatory condition of the sesamoid-tendon complex without discrete fracture, presenting with diffuse tenderness under the first metatarsal head and pain with great toe extension. X-rays and MRI may be normal or show mild reactive changes. Avascular necrosis (osteonecrosis) of the sesamoid results from disruption of the blood supply, most commonly following fracture or corticosteroid injection. MRI shows low signal on T1 (loss of fatty marrow) at the involved sesamoid.

Imaging Workup for Sesamoid Pain

Initial evaluation includes weight-bearing foot X-rays including an axial (sesamoid) view, which projects the sesamoids free of the metatarsal head. MRI is the gold standard for differentiating fracture from bipartite sesamoid and for detecting stress fracture, avascular necrosis, and adjacent soft tissue pathology. Bone scan can confirm increased activity at a stress fracture or sesamoiditis but lacks the anatomic detail of MRI. CT scan best evaluates fracture healing and cortical bridging during recovery.

Treatment: Conservative vs. Surgical

Most sesamoid fractures and sesamoiditis are treated non-operatively with a stiff-soled shoe, sesamoid padding, custom orthotics with a sesamoid cutout, and activity modification. Acute fractures may require a short-leg cast or boot for 6–8 weeks. Stress fractures typically require 8–12 weeks of protected weight-bearing.

Surgical intervention is reserved for fractures that fail to heal after 3–6 months of conservative care, avascular necrosis with structural collapse, or sesamoiditis refractory to all conservative measures. Sesamoidectomy — surgical removal of the problematic sesamoid — can relieve pain in carefully selected patients, though it alters great toe mechanics and carries a risk of transfer metatarsalgia.

At Balance Foot & Ankle, Dr. Biernacki evaluates sesamoid pain with weight-bearing X-rays and MRI at both Bloomfield Hills and Howell offices, providing accurate diagnosis and individualized treatment. Call (810) 206-1402 for an evaluation.

Sesamoid Fracture vs. Bipartite Sesamoid — Expert Diagnosis

Distinguishing a fractured sesamoid from a naturally bipartite (two-piece) sesamoid requires expert evaluation. Our podiatrists use advanced imaging, clinical testing, and bone scans to make the correct diagnosis and provide targeted treatment for your big toe pain.

View Our Foot Treatment Options | Book Your Appointment | Call (810) 206-1402

Clinical References

1. Richardson EG. Hallucal sesamoid pain: causes and surgical treatment. Journal of the American Academy of Orthopaedic Surgeons. 1999;7(4):270-278.
2. Dedmond BT, et al. The hallucal sesamoid complex. Journal of the American Academy of Orthopaedic Surgeons. 2006;14(13):745-753.
3. Cohen BE. Hallux sesamoid disorders. Foot and Ankle Clinics. 2009;14(1):91-104.

Dr. Tom Biernacki, DPM

Dr. Tom Biernacki, DPM is a double board-certified podiatrist and foot & ankle surgeon at Balance Foot & Ankle Specialists in Southeast Michigan. With over a decade of clinical experience, he specializes in heel pain, bunions, diabetic foot care, sports injuries, and minimally invasive surgery. Dr. Biernacki is a member of the APMA and ACFAS, and his patient education content on MichiganFootDoctors.com and YouTube has reached over one million views.