Sinus tarsi and canalis tarsi syndromes. A post-traumatic entity

Abstract

The post-traumatic sinus tarsi syndrome is a clinical entity induced by supination trauma of the hindfoot. In pathomorphological terms this is due neither to a ligament rupture nor to an osteochondral lesion. Clinically, local pain in the sinus tarsi is associated with pain during supination or pronation, pain during walking, especially on uneven ground, and ‘giving way’ without signs of mechanical instability. A more severe variant of this syndrome, in which the patient complains of pain on the medial aspect of the hindfoot in conjunction with the typical pain of the sinus tarsi syndrome is described. This medial symptom complex has been identified as the ‘canalis tarsi syndrome’. Injection of a steroid and local anaesthetic agent into the sinus tarsi or tarsal canal will relieve the pain if the underlying pathology is that of a tarsi syndrome, depending on which side the injection is given. An arthrogram of the subtalar joint in a patient with a confirmed sinus tarsi syndrome demonstrates a sac-like anterior bulge of the capsule. Performed on a non-pathological sinus tarsi, this procedure would demonstrate a corrugated appearance of the capsule anteriorly, without this anterior protrusion. At the Medical School in Hannover, 95 patients with a sinus tarsi syndrome were assessed between 1981 and 1989. In all patients a conservative regime of repeated injections (six or fewer) of a steroid and local anaesthetic agent into the sinus tarsi was applied. In addition, three of these patients were identified as having a canalis tarsi syndrome, and injections were simultaneously given into their tarsal canals. Most of the patients ( n =78) had complete resolution of their symptoms with the conservative regimen, including one patient identified as having both sinus tarsi and canalis tarsi syndromes. In 17 patients surgical exploration was subsequently performed because the conservative regime had failed, and 14 patients in this latter group had complete resolution of symptoms after a single surgical procedure, a modified O'Connor technique, including two patients with tarsal canal excision. There were three moderate results after primary surgery, and in one of these patients the symptoms abated after further surgery. Retrospectively, the remaining two patients with moderate outcomes were reassessed and were found to have radiographic evidence of subtalar arthritis (CT scan); it was therefore thought that the original diagnosis of sinus tarsi syndrome was probably incorrect. In conclusion it is postulated that: (i) sinus tarsi syndrome is an underdiagnosed entity; (ii) modification of the surgical treatment of the sinus tarsi syndrome is advocated where indicated; (iii) a variant of the sinus tarsi syndrome, the canalis tarsi syndrome, occurring in conjunction with the sinus tarsi syndrome or as a single entity is described.