This condition has been observed in multiple family members and has propensity to occur slightly more in females than males. For most individuals this condition is a non-issue and most people who have them never have a problem with them. Over the years when x-raying patients for other problems I will point out that they have an extra bone in their foot and the usual response from the patient is nothing more than a yawn.
Accessory navicular syndrome as it is called can result from a number of causes, excess or overuse syndrome as seen in an athlete. Trauma to the foot as in an ankle sprain or direct trauma to the navicular bone. chronic irritation from shoes rubbing against the extra bone, over time, may cause pain. Excessive pronation which strains the attachment of tibialis posterior muscles into the navicular bone. Keep in mind, the larger the actual accessory bone, the greater the chance of it becoming an issue.
Perhaps the most common of the extra bones in the foot, the accessory navicular bone is estimated to be present in 7 to 19 percent of the population. Zadek and Gold maintained that the bone persisted as a distinct, separate bone in 2 percent of the population. Also be aware that the accessory bone normally fuses completely or incompletely to the navicular. It is this incomplete fusion which allows for micromotion, which, in turn, may cause degenerative changes that can also contribute to the pain.
Typically, accessory navicular syndrome isn?t hard to diagnose. Our podiatrists will examine the lower limb and check the hard prominence, as well as use X-rays to confirm the presence of extra bone tissue. Other diagnostic images may be able to identify inflammation and specific damage to the midfoot. Depending on the severity of your discomfort, conservative measures may be enough to resolve the condition.
Non Surgical Treatment
Although operative treatment, and removal of the accessory navicular is possible, this is not usually indicated at first. Conservative nonoperative treatment is best, the course depending on the severity of the symptoms. When the pain is very severe, which could indicate a fracture, a period of immobilization might be required. This is done by waring a fracture boot, or a cast, which can help the ossicle stay stable, aiding in healing. Immobilization usually lasts between 4 to 6 weeks. Afterwards, physical therapy exercise, or any appropriate home course, should be used to help strengthen the ankle and return the ankle and foot to full range of motion, and have no pain on movement. Sometimes crutches are used when weight bearing is too painful, but it is best to try to bear weight when possible.
Depending upon the severity the non operative or conservative treatment should be maintained for at least 4- 6 months before any surgical intervention. There are 2 surgeries that can be performed depending upon the condition and symptoms. First is simple surgical excision. In this generally the accessory navicular along with its prominence is removed. In this procedure, skin incision is made dorsally to the prominence of accessory navicular. Bone is removed to the point where the medial foot has no bony prominence over the navicular, between the head of the talus and first cuneiform. Symptoms are relieved in 90% of cases. Second is Kindler procedure. In this the ossicle and navicular prominence is excised as in simple excision but along with the posterior tibial tendon advancement. Posterior tibial tendon is split and advanced along the medial side of foot to provide support to longitudinal arch. After surgery 4 week short leg cast, well moulded into the arch with the foot plantigrade is applied. Partial weight bearing till the 8th week and later full weight bearing is allowed. When the cast is being removed can start building up the ROM to counter atrophy and other physical therapy treatment which include stretching and strengthening exercises.