AUGUST 2014 |฀Volume฀37฀•฀Number฀8 541 n trauma update Acute Fractures of the Tarsal Navicular Andrew J. Rosenbaum, MD; Richard L. Uhl, MD; John A. DiPreta, MD I njuries of the tarsal bones re- sult in significant long-term morbidity, adversely impacting overall outcome and long-term function in polytraumatized patients. 1 Despite their associa- tion with high-energy trauma, injuries of the tarsal bones are often subtle and frequently only diagnosed on a delayed basis. 2 Midfoot fractures, which are rare, are most commonly as- sociated with motor vehicle collisions. 3,4 However, these fractures are being seen with increasing frequency, a find- ing attributed to enhancements in automobile safety leading to improved survival of patients with significant foot injuries. 5,6 The most frequently in- jured lesser tarsal bone is the navicular, a vital component of the foot’s medial column and an active participant in the transverse tarsal locking mechanism. Avulsion, tuber- osity, and body fractures have been described. Body fractures, although less common than avulsion and tuberosity types, are more severe and most often associated with high-energy mechanisms. In addition to acute injuries, stress fractures of the tarsal navicular have been described and can also have devastating consequences, including avascular necrosis. 7,8 Neither the adverse out- comes following fracture nor the biomechanical significance of the navicular can be refuted. However, there is little literature devoted to these injuries. This article provides an overview of acute fractures of the navicular, reviewing the relevant anatomy and biomechanics, the classifi- cation and presentation, and the indications for and outcomes following both conservative and operative interventions. ANATOMY The navicular derives its name from its resemblance to a small boat, as suggested by its concave proximal articu- lar surface. The bone articu- lates distally with the 3 cu- neiforms, proximally with the talar head, and laterally with the cuboid (Figures 1-2). It is located in the uppermost por- tion of the medial longitudinal arch of the foot, acting as the keystone of the arch (Figure 3). 2 The body of the navicular is a 6-sided, horseshoe-shaped disk. The navicular’s distal articulation with the cunei- forms is via 3 facets that share a common synovial cavity. Its medial surface slopes posteri- orly, ending in the tuberosity. Plantar and dorsal ligaments reinforce each articulation, with further stability provided by the posterior tibial tendon and plantar calcaneonavicular (spring) ligament, which in- sert distally and medially on the tuberosity, as well as the The authors are from the Division of Orthopaedic Surgery, Albany Medi- cal Center, Albany, New York. The authors have no relevant financial relationships to disclose. Correspondence should be addressed to: Richard L. Uhl, MD, Division of Orthopaedic Surgery, Albany Medical Center, 1367 Washington Ave, Ste 202, Albany, NY 12206 (uhlr@aol.com). doi: 10.3928/01477447-20140728-07 Abstract: The tarsal navicular plays an integral role in hind- foot motion and gait, and is the keystone of the foot’s medial longitudinal arch. As such, injuries to the navicular can be devastating. Acute avulsion, tuberosity, and body fractures have been described. Fractures of the body result from high- energy trauma and are often seen in conjunction with addi- tional ipsilateral foot injuries. Plain radiographs are the gold standard for diagnosis, with computed tomography helpful in the presence of intra-articular fracture extension. Non- operative treatment is reserved for avulsion injuries and non- displaced body fractures. Open reduction and internal fixation must be performed for all other types, as failure to achieve an anatomic reduction can impede proper locomotion. Com- plications following operative intervention include pain, stiff- ness, posttraumatic arthritis, avascular necrosis, nonunion, and hindfoot deformity. [Orthopedics. 2014; 37(8):541-546.]