Table 2 Prevalence, clinical significance, and differential diagnosis of the most common types of variants and accessory ossicles in the forefoot
Ossicle | Prevalence | Clinical significance | Differential diagnosis | |
|---|---|---|---|---|
Hallucal sesamoids | Multipartite (gen medial) | 2.7–33.5% bilateral—22–85% | Potential sesamoiditis (osteoarthritis—osteonecrosis) | Sesamoid fracture (multipartite) |
Absence | rare | |||
Lesser metatarsal sesamoids | 2nd digit | 0.4% | Asymptomatic (Infection from surrounding soft tissues) | – |
3rd digit | 0.2% | |||
4th digit | 0.1% | |||
5th digit | 4.3% | |||
Interphalangeal joint sesamoids | 2–13% ossified 73% nodule in cadaver series | Interposition in joint dislocation. Limitation to joint mobility and painful callosity have been reported | – | |
Os vesalianum | 0.1 to 1% | Very rarely a source of pathology Painful conditions similar to the os peroneum syndrome have been reported | Avulsion fractures of the apophysis and base of the fifth metatarsal | |
Os intermetatarseum | 1.2–10% | Pain on palpation of the dorsum of the foot (superficial and deep peroneal nerves compression) | Small fractures of the base of the second metatarsal in Lisfranc fracture—dislocations | |