Abstract
Accessory ossicles of the foot and ankle are normal variants of bone development that usually remain asymptomatic. However, they may be involved in various disorders and become a source of pain such as in fractures, dislocations, degenerative changes, osteonecrosis, osteoarthritis, osteochondral lesions, avascular necrosis, and irritation or impingement of adjacent soft tissues. Hence, during the assessment of the situations above, knowledge about these little-known ossicles could be very important to reach the correct diagnosis. Recent studies in the literature have mostly focused on the most frequent 9-12 accessory bones. In this review, 24 types of accessory ossicle are described. These ossicles are accessory navicular bone, os peroneum, os trigonum, os intermetatarseum, os vesalianum. os subfibulare, os subtibiale, os calcaneus secundarius, os calcanei accessorium, os supratalare, os sustentaculi, os talotibiale, os tali accessorium, talus secundarius, os subcalcis, os cuboideum secundarium, os supranaviculare, os infranaviculare, os paracuneiforme, os intercuneiforme, os cuneometatarsale I tibiale, os cuneometatarsale plantare, os cuneo–I metatarsale-II dorsale, and os aponeurosis plantaris. The clinical importance of these bones should be known thoroughly to reduce unnecessary orthopedic consultations and misdiagnosis. This article describes the clinical importance of the accessory ossicles and their possible pathological conditions. Understanding the possible disorders of the accessory ossicles of the foot and ankle can provide a more accurate diagnostic process.
Highlights
BackgroundAccessory ossicles around the foot and ankle are common skeletal variations
Numerous accessory ossicles of the foot and ankle are described in the current literature
For e.g., the accessory navicular bone is known as tibiale externum, prehallux, os supranavicular, talonaviculare ossicle, and Pirie’s bone [2]
Summary
Accessory ossicles around the foot and ankle are common skeletal variations. They are usually derived from the failure of union of secondary ossification centers adjacent to the main bony mass. Differential diagnosis between talus secundarius and talus accessorius can usually be made radiographically It may be confused with the more common os subfibulare or os tali accessorium, but the latter is located on the medial side of the talus and the former represents an accessory ossification centre just under the tip of the lateral malleolus [40]. The bone was associated with scalloping of the inferior margins of the calcaneus and cuboid bones at their articulation, without the involvement of the navicular Knowledge of this rare accessory ossicle, together with the foresight to obtain radiographs before MRI, could prevent this type of confusions [43].
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