Citation, DOI & article data
An os subtibiale is a rare, genuine accessory ossicle and normal variant related to the posterior colliculus of the medial malleolus 1. It is present in ~1% of the population 5.
They usually are asymptomatic although they may eventually cause painful syndromes or degenerative changes in response to overuse and trauma.
Normally, the secondary center of ossification of the distal tibia appears during the first year of life. It fuses with the shaft at ~15 years in females and ~17 years in males. The medial malleolus is generally an extension from the distal epiphysis and ossifies in the seventh year.
An accessory bone is formed when the separate epiphysis of the medial malleolus fails to fuse with the distal tibia.
- projects posteriorly, adjacent to the posterior colliculus
- typically measures more than 4 mm
- well-rounded 5
- malleolar fracture (when radiographs are taken following an injury to the ankle) 3, 4
- ossicles related to the anterior colliculus (unfused medial malleolus ossification center)
- present in ~2% of the population 5
- differentiated from other ossicles in this region by its smaller size to os subtibiale, its rounded and well-defined shape, and its anterior position 1,5
- post-traumatic ossification of the deltoid ligament complex 5
- 1. Coral A. The radiology of skeletal elements in the subtibial region: incidence and significance. Skeletal Radiol. 1987;16 (4): 298-303. Pubmed citation
- 2. Coskun N, Yuksel M, Cevener M et-al. Incidence of accessory ossicles and sesamoid bones in the feet: a radiographic study of the Turkish subjects. Surg Radiol Anat. 2009;31 (1): 19-24. Surg Radiol Anat (full text) - doi:10.1007/s00276-008-0383-9 - Pubmed citation
- 3. Park HG, Sim JA, Koh YH. Posterior tibial tendon dysfunction secondary to os subtibiale impingement: a case report. Foot Ankle Int. 2005;26 (2): 184-6. Pubmed citation
- 4. Bellapianta JM, Andrews JR, Ostrander RV. Bilateral os subtibiale and talocalcaneal coalitions in a college soccer player: a case report. J Foot Ankle Surg. 2011;50 (4): 462-5. doi:10.1053/j.jfas.2011.03.016 - Pubmed citation
- 5. Calder JDF. Sporting Injuries to the Foot & Ankle, An Issue of Foot and Ankle Clinics, (The Clinics: Orthopedics). Elsevier. ISBN:B00D9BIPHW. Read it at Google Books - Find it at Amazon