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Tibial Sesamoid of the Hallux

os sesamoideum tibiale hallucis

The medial (tibial) sesamoid of the hallux is the larger of the two sesamoids embedded in the flexor hallucis brevis tendons beneath the first metatarsal head. The medial sesamoid is on the tibial side of the first MTP joint and bears approximately 40-50% of forefoot load. It articulates with the medial crista of the first metatarsal head and is held in place by the sesamoid ligament complex.

Region: Foot & Ankle

Clinical Relevance

Clinical Notes

The tibial sesamoid is the primary pathological sesamoid in hallux valgus, where the first metatarsal drifts medially while the sesamoids remain in their fibular groove, producing the sesamoid lateralisation characteristic of valgus deformity. Sesamoiditis, stress fractures, and avascular necrosis of the tibial sesamoid produce plantar first MTP pain in dancers and runners. Tibial sesamoidectomy is performed for refractory sesamoid pathology but risks cock-up first toe deformity from imbalance of the hallux sesamoid complex.

Pathology

Common Injuries & Conditions

Tibial Sesamoid Stress Fracture in Dancers

Repetitive demi-pointe loading produces stress fracture of the tibial sesamoid with plantar first MTP pain worsened by push-off; MRI demonstrates linear signal through the sesamoid with marrow oedema, and treatment includes offloading with a dancer's pad, protected weight-bearing, and a graduated return to dance activity.