Sesamoiditis is inflammation of the sesamoid bones — two small pea-shaped bones embedded in the flexor hallucis brevis tendon under the first metatarsal head at the base of the big toe. It is one of the most common causes of ball-of-foot pain in dancers, sprinters, basketball players, and anyone who spends significant time in high-heeled footwear. Despite its frequency, sesamoiditis is frequently misdiagnosed as plantar fasciitis, Morton’s neuroma, or a metatarsal stress fracture, delaying treatment and allowing progression to the more serious complication of sesamoid fracture or avascular necrosis. At Balance Foot & Ankle in Howell and Bloomfield Hills, MI, Dr. Tom Biernacki, DPM diagnoses and treats sesamoiditis with a comprehensive approach that addresses both symptoms and the underlying biomechanical cause.

What Are the Sesamoid Bones and Why Do They Hurt?

The sesamoid bones are the only bones in the foot not connected directly to another bone via a joint — they are embedded within tendons, functioning like the patella (kneecap) of the big toe. The medial (tibial) and lateral (fibular) sesamoids sit plantar to the first metatarsal head and bear significant compressive force during the push-off phase of gait — approximately three times body weight on each push-off step. Activities that amplify this force — toe raises, sprinting, dancing in relevé, jumping, walking in high heels — repetitively overload the sesamoids and their surrounding soft tissue, producing the inflammatory response we call sesamoiditis. The medial sesamoid is more commonly affected than the lateral because it bears a larger share of the load and is more directly under the first metatarsal head.

Symptoms of Sesamoiditis

Sesamoiditis produces a dull aching or sharp pain directly under the first metatarsal head — the ball of the foot just behind the big toe. In our clinic, the three most consistent findings are point tenderness directly over the sesamoids on plantar palpation, pain that is worse with big toe dorsiflexion (pushing the toe upward), and pain aggravated by walking barefoot on hard surfaces or in thin-soled shoes. Unlike plantar fasciitis, sesamoiditis is not characteristically worse with first steps of the morning — it is more consistently related to activity. Swelling over the ball of the foot is present in acute or moderate cases. Dancers describe pain particularly in relevé; runners describe pain at push-off that improves during warm-up but worsens with mileage.

Diagnosing Sesamoiditis — Ruling Out Fracture First

The critical diagnostic task with sesamoiditis is distinguishing inflammation from a sesamoid fracture — either acute (from a single traumatic event) or stress fracture (from cumulative overload). Standard AP foot X-ray identifies most sesamoid fractures, but the medial sesamoid is naturally bipartite (congenitally split into two pieces) in approximately 10–20% of the population — a finding that is frequently mistaken for a fracture. Comparison X-ray of the opposite foot is helpful: a bipartite sesamoid is typically bilateral and symmetrical; a fracture is typically unilateral with irregular, non-corticated margins. When fracture is suspected despite negative X-ray, MRI is the definitive modality: sesamoid stress fracture shows bone marrow edema; sesamoiditis shows tendon and periosteal inflammation without cortical discontinuity. Bone scan is an older alternative that demonstrates increased uptake in both sesamoiditis and fracture and cannot differentiate the two.

Differential Diagnosis — Other Causes of Big Toe Ball Pain

Several conditions produce pain in the same anatomical region as sesamoiditis and must be distinguished. Hallux valgus (bunion) produces medial prominence and pain at the MTP joint but not directly under the sesamoids. Hallux rigidus (big toe arthritis) causes dorsal MTP joint pain with limited motion and crepitus. Gout — sudden severe pain, warmth, and swelling at the first MTP joint — typically has systemic features and elevated serum uric acid. Turf toe is an acute hyperextension injury to the plantar plate and sesamoid complex with immediate onset of pain after a specific event. Plantar plate tear produces second toe crossover deformity with MTP joint instability. Interdigital neuroma (Morton’s neuroma) causes burning pain in the third and fourth web space rather than directly under the sesamoids. Sesamoid avascular necrosis is a late complication of undertreated sesamoid stress fracture, requiring MRI for diagnosis.

Conservative Treatment for Sesamoiditis

Conservative treatment resolves the majority of sesamoiditis cases when implemented consistently. The foundational treatment is sesamoid offloading: a dancer’s pad (a U-shaped, donut-holed pad that surrounds the sesamoid without placing pressure directly on it) is placed inside the shoe to redirect plantar pressure away from the first metatarsal head. Combined with a stiff-soled shoe that limits big toe dorsiflexion and thus reduces sesamoid compression during push-off, this offloading strategy allows healing of the inflamed periosteal and tendinous tissue. Custom functional orthotics with a first metatarsal cut-out and sesamoid accommodation are the long-term solution for patients with underlying pes planus (flat foot) or hallux abducto valgus that increases medial sesamoid load. MLS Class IV laser therapy accelerates soft tissue healing and reduces the inflammation cycle in recalcitrant cases. Activity modification — particularly eliminating high-heeled footwear, dance activities, and barefoot walking on hard surfaces — for a minimum 6–8 weeks is essential and the most frequently skipped component of treatment.

Cortisone Injection for Sesamoiditis

Cortisone injection into the first MTP joint or sesamoid sheath is an effective adjunct for moderate-to-severe sesamoiditis that is not responding to offloading and activity modification alone. Injection under ultrasound guidance ensures accurate depot placement adjacent to the inflamed sesamoid without direct injection into the tendon substance (which risks tendon weakening). Injection reduces acute inflammation within 3–5 days, providing a therapeutic window during which offloading can begin to address the mechanical cause. Repeated injections are avoided because multiple cortisone injections into the sesamoid region have been associated with sesamoid osteonecrosis (avascular necrosis) — a serious complication requiring surgical sesamoidectomy. No more than 2–3 injections per sesamoid over the lifetime of conservative management is the general guideline.

Surgical Options — When Conservative Care Fails

Surgical intervention is indicated for sesamoiditis that has failed 6–12 months of comprehensive conservative management, confirmed sesamoid stress fracture with non-union, or sesamoid avascular necrosis. Sesamoidectomy — surgical removal of the affected sesamoid — is the definitive procedure. Isolated medial sesamoidectomy has good long-term outcomes when proper surgical technique is used, including careful preservation of the flexor hallucis brevis tendon insertion to prevent the development of hallux valgus (bunion) or cock-up deformity from loss of medial sesamoid function. Removal of both sesamoids is avoided whenever possible due to the high rate of post-surgical deformity when the entire sesamoid mechanism is disrupted. Recovery from sesamoidectomy involves 4–6 weeks in a post-operative shoe followed by progressive return to athletic footwear at 8–12 weeks.

Red Flags — When to Seek Urgent Evaluation

Seek same-day podiatric evaluation if: you had a sudden, traumatic onset of severe big toe ball pain (possible acute sesamoid fracture or turf toe requiring immobilization); the area under the first metatarsal head is warm, red, and swollen without a clear injury (possible gout requiring urgent uric acid testing and medication); you are a diabetic patient with any pressure-related skin breakdown or ulceration under the ball of the foot; or you have been treating sesamoiditis conservatively for more than 6 months without significant improvement (possible undiagnosed sesamoid stress fracture requiring MRI).

Sesamoiditis Treatment at Balance Foot & Ankle — Michigan

Dr. Tom Biernacki, DPM evaluates sesamoiditis with in-office X-ray, comparison views to assess bipartite anatomy, musculoskeletal ultrasound for tendon and soft tissue assessment, and MRI coordination for suspected stress fracture. Conservative management including dancer’s pad fitting, custom orthotic fabrication with sesamoid accommodation, cortisone injection under ultrasound guidance, and MLS laser therapy are all available at the same visit. Appointments at our Howell office (4330 E Grand River Ave, Howell MI 48843) and Bloomfield Hills office (43494 Woodward Ave #208, Bloomfield Hills MI 48302). Call (810) 206-1402 or

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