Accessory Ossicles of the Foot and Ankle: Disorders and a Review of the Literature

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.

Removal of Painful Os Paracuneiforme: A Case Report

“…Some types of accessory bones associated with the medial cuneiform have been described. 1,2 Os cuneometatarsale 1 tibiale occurs near the medial aspect of the metatarsocuneiform joint, whereas the tibialis anterior (tendon) sesamoid is located in the tibialis anterior tendon near the tendon insertion on the anterior inferior corner of the medial cuneiform. Os cuneo-1 metatarsale-1 plantare occurs on the plantar aspect of the first metatarsocuneiform joint.…”

“…Os paracuneiforme (OPC) is an extremely rare accessory bone that is located either medial to the medial cuneiform or to the naviculocuneiform joint. 1,2 Although this bone often appears on the list of accessory ossicles, few reported cases are available in the literature, [3][4][5] and its incidence is unclear. OPC can cause symptoms that require surgical treatment.…”

Maximum standardized uptake value of foot SPECT/CT using Tc-99m HDP in patients with accessory navicular bone as a predictor of surgical treatment

“…CT = computed tomography, SPECT/CT = single-photon emission computed tomography/CT, VOI = volume of interest. [6,7]…”

“…ANB can be classified into 3 types according to the Geist classification. [6,7] Type I ANB is a sesamoid bone within the tibialis posterior tendon which is not directly connected to the navicular. Type II ANB, actually, is a secondary ossification center of the navicular tuberosity which is connected to the navicular by cartilage (synchondrosis).…”

Normal Anatomy and Traumatic Injury of the Midtarsal (Chopart) Joint Complex: An Imaging Primer

“…Although small fragments may be merely incidental, larger fragments can form a pseudarthrosis with the anterior calcaneus or posterolateral navicular and may be associated with instability, degenerative change, and chronic pain (Fig 22) (49). Fracture nonunion may be difficult to distinguish from an os calcaneus secundarius, an accessory ossification, which can also be symptomatic owing to instability (50).…”