The painful accessory navicular

Abstract

The accessory navicular is usually considered a normal anatomic and roentgenographic variant. The term may refer to two distinct patterns. First, a sesamoid bone may be present within the posterior tibial tendon (Type 1); this is anatomically separate from the navicular. Second, an accessory ossification center may be medial to the navicular (Type 2). During postnatal development this is within a cartilaginous mass that is continuous with the cartilage of the navicular. At skeletal maturity the accessory center usually fuses with the navicular to form a curvilinear bone. The Type 2 pattern may be associated with a painful foot, particularly in the athletic adolescent, and should not be arbitrarily dismissed as a roentgenologic variant in the symptomatic patient. The clinical, radiologic, pathologic, and surgical findings in ten cases are reviewed. Roentgenographically the ossicle is triangular or heart-shaped. 99mTc MDP imaging may be of value when the significance of the ossicle is uncertain. Even when the roentgenographic variant is bilateral, increased radionuclide activity occurs only on the symptomatic side. Histologic examination of surgically excised specimens reveals inflammatory chondro-osseous changes in the navicular-accessory navicular synchondrosis compatible with chronic trauma and stress fracture. Nonsurgical treatment with orthotics or cast immobilization produces variable results and resection of the accessory navicular may be the treatment of choice.

Management of Dancers With Symptomatic Accessory Navicular: 2 Case Reports

“…Accessory bones of the foot are anomalies that develop during ossification. 5,24,25,31 Three types of accessory navicular have been described (TABLE 1). The type I accessory navicular is an oval or circular sesamoid located within the posterior tibial tendon (PTT) and is therefore not connected to the navicular tuberosity.…”

“…The type I accessory navicular is an oval or circular sesamoid located within the posterior tibial tendon (PTT) and is therefore not connected to the navicular tuberosity. 5,25,32 The type II accessory is a larger triangular or heart-shaped ossicle connected to the navicular tuberosity by a cartilaginous layer (FIGURE 1). 5,25,32 Portions of the PTT insert on the type II accessory ossicle.…”

“…5,25,32 The type II accessory is a larger triangular or heart-shaped ossicle connected to the navicular tuberosity by a cartilaginous layer (FIGURE 1). 5,25,32 Portions of the PTT insert on the type II accessory ossicle. 32 The type III accessory navicular is a prominent navicular tuberosity referred to as a cornuate navicular.…”

“…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.…”

“…25 However, when trauma or overuse occurs, acute or chronic pain may restrict activity. Although an accessory navicular may spontaneously fuse as the skeleton matures, 25,31,32 surgical excision, with or without rerouting of the PTT, is frequently recommended by orthopaedic surgeons when nonsurgical measures fail. 4,23,25,28 A variety of surgical methods have been used with good results.…”