Whether an accessory navicular bone (ANB) can grow back after surgical removal is a major concern for patients considering the procedure. The ANB is a common congenital foot variation that often remains asymptomatic. When this extra bone causes pain and inflammation—known as Accessory Navicular Syndrome—surgical excision is considered after conservative treatments fail. Understanding the accessory bone’s nature and the surgical technique clarifies the low probability of true regrowth.
What is an Accessory Navicular Bone?
The accessory navicular is an extra piece of bone or cartilage located on the inner side of the foot, just above the arch, near the tarsal navicular bone. This ossicle is a congenital variation present from birth. It is found in approximately 4% to 21% of the population, but most individuals never experience symptoms.
The posterior tibial tendon (PTP), which supports the foot’s arch, attaches directly to the accessory bone. When the foot is strained, the PTP pulls on the ANB, causing irritation or inflammation in the surrounding tissues and the tendon itself, leading to Accessory Navicular Syndrome. Symptoms often appear during adolescence as the foot bones mature, manifesting as a painful, visible prominence on the midfoot. Pain is typically aggravated by physical activity or irritation from footwear.
The Goal of Surgical Removal
When non-surgical options like orthotics or immobilization fail to provide lasting relief, surgical intervention is recommended. The standard approach is the Kidner procedure, or a modification of it. The goal of this surgery is twofold: complete excision of the accessory bone and stabilization of the posterior tibial tendon.
The surgeon removes the accessory ossicle, eliminating the source of chronic irritation and inflammation. The PTP, which was attached to the excised bone, is then detached and securely reattached to the main navicular bone. This reattachment restores the PTP’s function in supporting the arch and prevents the tendon from becoming lax. The procedure aims to restore the foot’s anatomy and function, leading to long-term pain relief.
Can the Bone Truly Regrow?
True regrowth of a completely excised accessory navicular bone is extremely rare, especially in adults. The process of bone formation, or osteogenesis, is not typically triggered in a way that would regenerate an entirely new, separate bone structure after the area has been meticulously cleared. The tissue removed is usually a separate ossification center or a cartilaginous component that has failed to fuse with the main navicular bone.
If a patient experiences recurrent pain mimicking the original symptoms, it is almost always attributed to factors other than the accessory bone growing back. One possible cause is the incomplete initial removal of the cartilaginous component, which is a greater risk in adolescents whose bones are still developing and may not be fully hardened. Another rare cause is heterotopic ossification, which is the abnormal formation of bone in soft tissues where bone should not exist; this is a distinct process from the accessory bone regenerating.
The most common reason for persistent or recurrent pain relates to the soft tissue structures, particularly the posterior tibial tendon. Residual symptoms or a failure in the PTP repair can mimic the original pain, especially if the foot has an underlying flatfoot (pes planovalgus) or hindfoot valgus deformity. These structural issues place increased tension on the reattached PTP, leading to its degeneration and renewed pain, which is often misinterpreted as the bone having returned.
Ensuring Long-Term Functional Recovery
The ultimate success of the surgery is measured by the proper healing and functioning of the foot’s arch support system, not just the absence of the accessory bone. Post-operative care is highly important and typically involves a period of non-weight-bearing immobilization in a cast or boot for several weeks. This initial phase allows the surgical site to heal and permits the reattached posterior tibial tendon to securely integrate with the main navicular bone.
Following immobilization, a gradual transition to partial and then full weight-bearing is initiated, often with the aid of a physical therapist. Physical therapy is crucial for regaining strength, flexibility, and proper function in the foot and ankle, particularly for strengthening the PTP. Full recovery and a return to unrestricted activity can take several months, sometimes up to six months or a year, depending on the individual and the complexity of the initial surgery. Patient adherence to the rehabilitation protocol is crucial to ensure the PTP heals correctly and achieves long-term stability.