Symptomatic Patient With Two Separate Accessory Navicular Bones

Abstract

We present the case of a symptomatic patient with two separate accessory navicular bones, a novel finding that does not fall within current classification standards. Furthermore, there is a paucity of current literature with regard to the management of symptomatic cases. Accessory navicular bones, sometimes referred to as os naviculare, are ossicles that can occur in multiple configurations and are considered developmental anomalies. The accessory navicular is an accessory bone found on the medial side of the navicular bone of the foot. While often asymptomatic, they can occasionally lead to clinically significant pain and/or deformity that can cause patients to seek out treatment and sometimes surgical correction. Diagnosis relies on clinical suspicion and imaging studies. A nine-year-old female patient presented initially with complaints of sharp pain over the medial side of her left foot, after which X-rays were obtained that demonstrated an accessory navicular bone. Upon diagnosis, conservative measures were implemented, including placing the patient in a short-leg cast with limited activity. After a failed trial of conservative measures, the patient underwent surgical excision of the accessory navicular bone, with imaging and intraoperative findings of two separate accessory navicular bones, a unique finding in patients with accessory navicular bones. During the six-week follow-up, the patient improved with no new complaints or concerns and was informed she could begin weight-bearing as tolerated with two crutches; she was then weaned from the crutches and returned to normal activity. In the current case, we followed the same route of treatment used to treat a single accessory navicular bone, utilizing first non-surgical interventions and then ultimately surgical excision after continual pain despite conservative measures. This case highlights the promising outcome for a patient with two separate accessory navicular bones when following the guidelines for the treatment of a single accessory navicular bone.

Keywords: accessory navicular bone; bipartite os naviculare; geist classification; os naviculare treatment; surgical excision.

Figure 1. Preoperative foot and ankle radiographs

A) Anterior-posterior (AP) view X-ray of the left foot demonstrating avulsed ossification center (yellow arrow) and possible second ossification center at the time of initial presentation; B) Oblique view X-ray of the left foot at the time of initial injury demonstrating fractured navicular ossification center (yellow arrow).

Figure 2. Repeat preoperative foot and ankle radiographs.

A) Oblique view X-ray of the left foot, six months post-injury, demonstrating two distinct ossification centers (yellow arrow); B) Anterior-posterior (AP) view of the left foot, six months post-injury, demonstrating two distinct ossification centers (yellow arrow); C) Lateral view X-ray of the left foot. Ossicles are occluded by the remainder of the foot.

Figure 3. Intraoperative foot and ankle radiograph

Intraoperative anterior-posterior (AP) view X-ray of the left foot following excision of the ossicles, demonstrating complete excision of the ossicles and no new osseous abnormalities.