- most common accessory bones
-
os trigonum:
- os tibiale externum (
accessory navicular)
- os peroneum (lateral aspect of cuboid)
- os vesalianum (base of 5th metatarsal)
- less common accessory bones:
- os supratalare (antero-supero aspect of talus)
- os supranaviculare (superior aspect of navicular - seen on lateral)
- processus uncinatus (at intersection of navicula, 2nd and 3rd cuniform)
- os intercuneiforme (between the 1st and 2nd cuniforms)
- pars peronea metatarsalia (1st cuniform and 1st metatarsal)
- cuboides secundarium (proximal-medial aspect of cuboid)
- os talotibiale (anterior tibia)
- os subcalcis (inferior aspect of calcaneus)
- os sustentaculum
- os intermetatarseum (between the 1st and second metatarsal)
- os subfibulare:
- historically, this has been considered to be an accessory ossicle located just below the ditsal fibular epiphysis;
- it is distinguished from a fracture by its smooth borders, and by the fact
that a fracture will preferentially involve the physis;
- there is some recent evidence to suggest that this structure may represent a nonunion of an avulsion frx from the fibula;
- these patients may demonstrate ipsilateral ankle instability and absence of a similar
ossicle on the contra-lateral side of the foot;
- reference:
The symptomatic os subfibulare:
Avulsion fracture of the fibula associated with recurrent instability of the ankle.
EE Berg. JBJS. Vol 73-A. 1991. p 1251-1254.
- Work Up of Suspected Painful Accessory Bone:
-
bone scan:
- increased uptake on bone scan indicates that the lesion is probably symptomatic;
- CT scan:
- helps work up unusual accessory bones and the anatomical imaging will help explain how
they are causing symptoms;
Os Post Peronei and the posterolateral nutcraker impingement syndrome.
I. Callanan et al.
Foot and Ankle International. Vol 19. No 7. July 1998. p 475.
Accessory bones of the foot: clinical significance.
RW Kruse and J Chen.
Military Medicine. Vol 160. 1995. p 464-467.
