Absence of the medial sesamoid bone associated with metatarsophalangeal pain.

Pain at the first metatarsophalangeal (MTP) joint can result from inflammation, chondromalacia, flexor hallucis brevis tendinitis, osteochondritis dessecans, fracture of a sesamoid bone, avascular necrosis of sesamoids, inflamed bursae, intractable keratoses, infection, sesamoiditis, gout arthropathy, and rheumatoid arthritis. Congenital absence of a sesamoid bone is extremely rare. We present a 17-year-old male patient with pain at the plantar aspect of the right MTP joint associated with congenital absence of the medial sesamoid. There was tenderness and the range of motion was minimally restricted. He described the pain as necessitating changes in his social life. On radiographs, the medial hallucial sesamoid was absent on the right side. The MTP joint was also evaluated using magnetic resonance imaging (MRI). A metatarsal pad was prescribed and the patient was satisfied with the treatment at the 2 months follow-up period. MRI revealed no pathological tissue at the medial sesamoid site. Hallucial sesamoids absorb pressure, reduce friction, protect the tendons, act like a fulcrum to increase the mechanical force of the tendons, and provide a dynamic function to the great toe by elevating first metatarsal head. Congenital absence of these bones is very rare but we must consider it in a patient with MTP joint pain.