Imaging of the symptomatic type II accessory navicular bone

Abstract

Accessory ossicles of the foot are commonly mistaken for fractures. The accessory navicular is one of the most common accessory ossicles of the foot. There is a higher incidence in women and the finding might be bilateral in 50-90%. This entity is usually asymptomatic, although populations with medial foot pain have a higher prevalence. Three types of accessory navicular bone have been described. The type II accessory navicular is the most commonly symptomatic variant with localized chronic or acute on chronic medial foot pain and tenderness with associated inflammation of overlying soft tissues. Plain radiographic identification of the accessory navicular is insufficient to attribute symptomatology. Ultrasound allows for comparison with the asymptomatic side and localization of pain. Bone scintigraphy has a high sensitivity but positive findings lack specificity. Magnetic resonance imaging is of high diagnostic value for demonstrating both bone marrow and soft tissue oedema.

Os Subfibulare: A case report of painful fibular accessory ossicle

“…Accessory bones that are rare in the foot include accessory interphalangeus, os peroneum, anamolous os calcaneum and talus, os trignum and os tibiale extenum. [1][2][3][4][5][6] Os peroneum can fracture following an inversion and may mimic sport injury. 7 An accessory, distal focus of epiphyseal ossification may develop in either malleolus.…”

Magnetic resonance imaging in adolescent symptomatic navicular tuberosity

“…The results of this study indicate that symptomatic navicular in adolescence is described by an edema-like bone marrow pattern on MR image regardless of whether an accessory navicular is present or not, and that alleviation of the symptom is proportional to the diminish of the edema-like bone marrow pattern. The edema-like bone marrow pattern has been typically shown for symptomatic type II accessory navicular bones, in which the both sides of the synchondrosis present this pattern (9)(10)(11) . In the present study, there were three patients who did not have accessory navicular bones (cases 4, 5 and 8) but still showed an edema-like bone marrow pattern on the navicular tuberosity.…”

“…resonance (MR) images of symptomatic type II (synchondrosis type) accessory navicular bone showed an "edema-like bone marrow pattern" (9)(10)(11). Edema-like MR abnormality was also reported in the posterior tibial tendon in adults with flatfoot (12,13).…”

Management of Dancers With Symptomatic Accessory Navicular: 2 Case Reports

“…Of the 3 types, the type II accessory navicular is most commonly associated with medial foot pain. 5,25,32,33 Several authors have theorized that this may be due to the altered insertion of the PTT on the accessory navicular ossicle. 5,25 In addition, repetitive forces applied by the PTT could potentially produce stress on the synchondrosis, resulting in pain and tenderness in the medial foot region.…”