By Dr. Murray Heber, DC, BSc(Kin), CSCS, CCSS(C) resident
Head Chiropractor - Performance Enhancement Team - Bobsleigh Canada Skeleton 

Symptoms:

Sinus tarsi syndrome often presents with pain along the top and/or outside of the foot and ankle. The pain is often described as a sharp pinching sensation when the foot is dorsiflexed such as when walking up stairs. Patients with sinus tarsi syndrome commonly complain of hindfoot instability while walking on uneven ground.

Anatomy:

The sinus tarsi is located over the anterolateral ankle and is palpable as the soft indentation just in front of the lateral malleolus. The space created in the tarsal sinus contains nerve endings, fat, joint capsule, arterial anastomoses and five ligaments. The etiology of sinus tarsi syndrome has been a matter of debate over the past few decades, however it appears that the prevailing theory is that thickening of the joint capsule occurs as a result of scar tissue deposition. This thickening of the joint capsule makes it susceptible to pinching between the bones in the ankle. Once it gets pinched it becomes inflamed and is more likely to get pinched again.

Sinus tarsi syndrome is a common development following ankle inversion sprains that were never treated or rehabilitated properly. It has been shown that the structures of the sinus tarsi play an integral role in ankle proprioception and stability. After an inversion ankle sprain, the sensory receptors that are responsible for proprioception are damaged and if not treated appropriately may not heal and regain their pre-injury ability to sense changes in ankle position. If this happens, the ankle become unstable, resulting in more ankle sprains and occasionally a feeling of unsteadiness when walking on uneven surfaces. Furthermore, the natural healing process of an ankle sprain may result in thickening of the joint capsule which then predisposes to developing a sinus tarsi syndrome.

Treatment:

Conservative treatment for sinus tarsi syndrome involves decreasing any inflammation present in the ankle, decreasing the tension and thickening of the joint capsule and finally restoration of proper ankle proprioception is necessary. This is achieved through the use the RICE principal to decrease inflammation as well as soft tissue techniques such as ART®, Graston®, and medical acupuncture as well as ankle rehabilitation to restore proprioception.