The navicular is one of the small bones of the foot collectively known as the tarsal bones. It is an important component of the anatomy of the foot as it acts as the keystone bone of the medial arch of the foot and bears the majority of the load applied to the tarsal complex during weight bearing. Biomechanical and vascular factors make it susceptible to stress facture and there’s a region in the centre of the bone that gets relatively poor blood supply, giving it an increased risk of stress injury and delayed healing or non-union.
Stress fractures of the navicular usually start at the top of the bone and then extend further into the bone if the athlete keeps playing. The pain may start gradually, without any mechanism of injury. It often starts as a nagging, dull ache with activity that is relieved by rest. This pain becomes more constant if the athlete keeps loading the bone. Sometimes the athlete can localise the pain to the midfoot but the symptoms are often vague with the pain poorly localised. A high index of suspicion is needed for this injury as diagnosis is often delayed making it even harder to treat. Tenderness over the navicular in a place on the foot called the N spot is the most common sign and there may be pain in the foot when hopping.
Initial x-rays are often normal unless the stress fracture is old and advanced imaging is usually needed. MRI, CT scan and bone scan all have their strength and weaknesses for the diagnosis of navicular stress injury. MRI is often used first as it can pick up other associated soft tissue injuries but a negative MRI does not always rule out a navicular stress fracture and a fine cut CT scan may also be needed to see the fracture line.
Navicular stress fractures can be managed non-operatively initially but there are some that do better with immediate surgical management. All stress reactions and stress fractures of the navicular that are managed non-operatively need at least 6-8 weeks of strict non-weight bearing due to the high risk of delayed healing and non-union. Once healing has occurred, a progressive rehabilitation program is needed with a graduated return to activity once all clinical outcomes have been achieved. Times frames for return to full play after diagnosis of a navicular stress fracture are between 4 to 6 months irrespective of which type of management is used. It is also important to assess for risk factors for bone stress injury in the athlete and correct any predisposing factors.
If you have sustained a foot injury that has resulted in significant pain or a limp, a consultation at Shire Sports Medicine can be beneficial for you to get an accurate diagnosis, to help guide management of your condition and to ensure the prevention of further complications.