The tarsal navicular bone is a bone in the midfoot. The bone can be a site of midfoot pain when either a fracture or another condition affecting the bone has occurred. It can case a variety of conditions ranging from arthritis or joint space narrowing to having an extra bone known as an accessory navicular.
Fracture/Stress Fracture
The navicular can fracture as an avulsion fracture, body or tuberosity fracture, or stress fracture. An avulsion fracture of the tarsal navicular bone can occur when the posterior tibialis tendon becomes sprained. An avulsion fracture occurs when the tendon pulls off a piece of bone. Treatments range from immobilization in a cast to surgery.
Navicular body or tuberosity fractures usually result due to impaction mechanisms. This type of fracture occurs through either the body or the tuberosity of the bone and has an association with other mid-tarsal joint injuries. Treatments range from a non-operative cast for 6 weeks to surgery to reduce the occurrence of arthritis.
Stress fractures of the navicular occur commonly in runners and basketball players due to increased fatigue of the bone. These fractures may not appear on an x-ray and may require further imaging with CT scan or MRI to make the diagnosis. Treatment consists of 6 weeks of non-weight bearing in a short leg cast. When non-operative treatments fail, surgery may prove necessary.
Calcaneonavicular Coalition
The calcaneonavicular coalition is a type of tarsal coalition. A coalition is a congenital connection between two bones. The connection can consist of bone, cartilage or fibrous tissue. The calcaneonavicular coalition occurs between the calcaneus or heel bone and the navicular bone. The symptoms include stiffness and pain, typically bilateral. The coalition is best seen on CT scan or MRI, as well as X-rays.
Not all coalitions require treatment. Some remain asymptomatic throughout the patient's life. Casting can help reduce pain and muscle spasm. If casting fails, then surgery presents another option.
Kohler Disease
Kohler disease is a pediatric condition of the navicular where avascular necrosis or death of part of the bone has occurred. The disease appears most commonly in boys starting at the age of four, and may result due to a compression of the bone. Pain, swelling and limpness are the common symptoms of presentation. The overall prognosis of the disease remains very good with symptoms resolving within 15 months of onset typically. Treatment consists of casting with a short leg walking cast to help relieve symptoms. Surgery is never indicated.
Accessory Navicular
An accessory navicular is an extra bone fragment fused or not fused to the navicular bone. It occurs in approximately 12% of the population according to the "AAOS Comprehensive Orthopaedic Review" by Dr. Jay Lieberman of UCONN orthopaedics. It usually proves asymptomatic, but can become painful in some individuals. The treatment includes using orthotic devices to reduce the pressure on this bony prominence, a short leg cast or surgical excision of the bone.
References
- Wheeless' Textbook of Orthopaedics: Tarsal Navicular
- "AAOS Comprehensive Orthoapedic Review"; Dr. Jay Lieberman; 2008.
