Tarsal coalition describes the complete or partial union of two or more bones in the foot.
This developmental fusion is commonly symptomatic when partially fused, leading to the pseudo-joint (cartilaginous or fibrous union) undergoing increased mechanical stress. This in turn leads to stress responses within the bones and ‘joint’ which may lead to the development of early osteoarthritis.
The following case demonstrates the utility of ultrasound to identify a fibrous midfoot coalition between the calcaneus and navicular.
Fibrous bridge between the Calcaneus and Navicular
MRI demonstrating the coalition
Hyperemia of the pseudo joint
A previous MRI of the patient clearly demonstrates the coalition and associated bone stress response, which was missed by the reporting radiologist at an alternative imaging practice.
Ultrasound is a reliable tool in identifying bony coalitions, with the mantra of ‘scan where the patient is sore’ often yielding excellent results.