Sesamoidopathy: The Tiny Bones Under the Big Toe That Cause Big Problems

What are the sesamoids?

The sesamoids are two small bones embedded in the tendons beneath the first metatarsal head - right under the base of the big toe. They act as a pulley system for the flexor hallucis brevis and help absorb the enormous forces generated during push-off.

Sesamoidopathy is an umbrella term covering inflammation, stress reaction, stress fracture, or avascular necrosis of these bones. The pain is localised to the plantar surface directly under the big toe joint.

What runners feel

• Focal pain under the ball of the foot at the base of the big toe
• Worsening with forefoot loading - running, barefoot walking, stairs
• Possible swelling and bruising if a fracture is involved
• Particularly bad on hard surfaces and in thin-soled shoes

Distinguishing sesamoiditis from a fracture

An X-ray is essential. The sesamoids are naturally bipartite (in two pieces) in about 10–30% of people, which can mimic a fracture. MRI is the most reliable way to identify a stress fracture or avascular necrosis.

If a fracture is present, the approach changes significantly - partial weight-bearing, walking boot, and a longer recovery timeline.

What helps

1. Offloading - the priority

A dancer's pad (foam donut pad) placed around, not under, the sesamoid reduces direct pressure. A stiff-soled shoe or carbon plate reduces flexion at the joint. These are immediate interventions.

2. Footwear adjustment

Zero-drop or thin-soled shoes are major aggravators. A cushioned heel (to shift weight back) and a rigid forefoot (to reduce toe extension load) are helpful.

3. Gait modification

Heel-strike or midfoot strike patterns reduce the push-off load on the sesamoids. Running cadence increase helps.

4. Intrinsic foot strengthening (pain-free only)

Towel scrunches and toe curls - but only if they don't provoke sesamoid pain.

5. Calf and hip strengthening

Distributes load away from the forefoot.

Timeline

4–6 weeks for mild sesamoiditis. Stress fractures: 6–12 weeks in a boot followed by gradual return. Avascular necrosis may require surgical consultation.

Running during recovery is possible with adequate offloading if pain remains low. Full forefoot loading should be avoided until pain-free.