The talonavicular (TN) joint allows for hindfoot motion in all planes. Loss of TN motion results in loss of complex hindfoot circumduction. Therefore, it is essential to retain the TN function as it has a protective function for the adjacent joints. Loss of TN motion leads to adjacent joint degeneration (DJD). Retaining even a small amount of motion is thought to protect the adjacent joint function. Because of its extensive range of motion, the TN joint is also known as the “coxa pedis.”
There is a 3-point bending force on the navicular (see diagram), which can result in a Frank fracture or an occult (stress) fracture.
The principle that guides treatment is the removal of bending forces or stresses. Therefore we use external immobilization like a cast or a removable orthosis.
2. Nonoperative care
A functional boot can be used for support and immobilization. The advantage of a boot over casting is that the boot can be removed for personal hygiene.
Weight-bearing should be avoided while there is pain and swelling. The boot can be removed for daily hindfoot circumduction. As healing progresses, protective weight-bearing is allowed in the boot. The patient can then be progressed from the boot to cushioned running shoes.
Return to sports is allowed when pain and swelling subside (after three months) and there is evidence of healing on plain x-rays.