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Duke Orthopaedics
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Wheeless' Textbook of Orthopaedics

Accessory Bones of the Foot



- 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.

- 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 nutcracker impingement syndrome.

Accessory bones of the foot: clinical significance.



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Wednesday, October 3, 2012 8:56 pm