39: Exostosis and Ossicles - Bennett Flashcards Preview

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Flashcards in 39: Exostosis and Ossicles - Bennett Deck (14)

talar prominence is exaggerated with ...

  • prominence is exaggerated with STJ prontation; reduced with STJ supination
  • talar prominence = produced by head of talus


prominence located just distal to a possible talar head prominence, which is virtually unaffected by subtalar jt motion

navicular prominence

- most commonly due to accessory ossicle

- becomes apparent at age 9-11 radiographically


three typical presentations of navicular prominence

type I: Represents a small ossicle just proximal to the navicular tuberosity, classified as a true sesamoid because it is within the tendon

type II: True accessory scaphoid appears radiographically as an extension of the navicular (its connection to the navicular is represented by a radiolucent zone which measures 1-3 mm.)  The zone may be fibrous, cartilaginous, fibrocartilaginous, or partially osseous.

type III: Represents a true carnuate navicular or enlarged navicular tuberosity.  (May be type II with an osseous bridge.)


sugery options for navicular prominence

type I: removal of ossicle from tendon by tendon splitting approach or reflection of post tib from talonavicular jt capsule and then removing ossicle

type II: excision of mobile fragment using adequate osseous exposure and c-arm.

type III: expose talonavicular jt and supinate subtalar jt to protect talar head. resection of tuberosity following normal contour of bone


what is dorsal bossing?

acquired disorder of the 1st tarsometatarsal joint

- presentation at 1st met-cuneiform jt may be medial or dorsal prominence

- may be secondary to hallux limitus or hallux valgus

- associated with charcot arthropathy


classification of dorsal bossing

type I: dorsal exostosis formation at 1st met cuneiform secondary to intermittent compression of bone. assoc with forefoot valgus plantarflexed 1st ray

type II: 1st met cuneiform exostosis located circumferentially associated with arthritic component. pt may have hx arthritis

type III: dorsal exostosis of 1st met cuneiform with angular malalignment. dorsiflexed = tendon imbalance, hallux limitus; plantarflexed - pes cavus; adducted - hallux abducto valgus

type IV: dorsal exostosis of 1st met cuneiform and involves lis franc's jt. assoc with arthritis w/i tarsometatarsal jt

type V: pseudo exostosis at 1st met cueniform secondary to pes cavus. results in shoe irritation


what is an accessory bone of the foot?

accessory bones of the foot are either normal parts or prominences of the tarsal bones that are abnormally separated from the main structure


review picture

review picture


ossicle located at base of 5th metatarsal

os vesalianum



accessory bone located inferior to peroneal groove of the cuboid

os peroneus

- encompassed w/i tendon of peroneus longus (acutually considered a sesamoid and functions to assist movement of peroneus longus)


accessory boney process located on lateral process of posterior aspect of talus

os trigonum

- usually fuses with talus by age 18

- irritated by FHL



os subfibulare



os subtibiale



accessory sesamoids

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