Case 21
History:
37 year old female with chronic lateral ankle pain
Findings:
Ankle MRI shows a fibular ossicle or os subfibulare at the distal end of the fibular with pseudo-arthrosis and marrow edema.
Diagnosis:
Os subfibulare
Discussion:
The majority of os subfibulare are usually asymptomatic. The exact cause of symptoms in patients is unclear. In general, accessory ossicles commonly observed in order of frequency of the lower extremity include: tibiale externum, os trigonum and os peroneum. Accessory bones that are rare in the foot include accessory interphalangeus, os peroneum, anamolous os calcaneum and talus, os trignum and os tibiale extenum. When symptomatic they are most often treated with anti-inflammatory. When the pain is recalcitrant, surgical intervention may be required.
References:
- Mellado JM, Ramos A, Salvado E, Camins A, Danus M, Sauri A. Accessory ossicles and sesamoid bones of the ankle and foot: imaging findings, clinical significance and differential diagnosis.Eur Radiol. Suppl. 6:L164-77, Dec. 2003.
- Shands AR Jr. Accessory bones of foot : x-ray study of feet of 1,054 patients. South Med Surg :93:326-34, 1931.
- EE Berg. Associated with recurrent instability of the ankle. The symptomatic os subfibulare. Avulsion fracture of the fibula. 1991;73:1251-1254. J Bone Joint Surg Am.
- TH Bowlus, SF Korman, M Desilvio, and R Climo. Accessory os fibulare avulsion secondary to the inversion ankle injury. J Am Podiatr Med Assoc, Vol. 70, Issue 6, 302-303, June 1, 1980.
