[Posterior ankle impingement syndrome: a retrospective study in 21 cases treated surgically]

The purpose of this work was to describe the posterior ankle impingement syndrome and to present a retrospective analysis of results after surgical treatment in 21 patients with a mean five years follow-up.

Twenty-one patients with a posterior ankle impingement syndrome underwent surgery between 1991 and 1999. There were 17 men and four women, mean age 33 years (18-45); 71% practiced sports, half at the competition level. For 71% of the patients, there was an acute fracture with nonunion of the posterior process of the talus; a microtrauma context was identified in 29%. The physical examination revealed pain at passive forced plantar flexion in 94% of patients with limping during exercise in 88%. Plain x-rays showed a long tail on the talus in 87% of the patients, a short tail in 9%, and a trigone bone in 4%. The posterior malleolus (or third tibial malleolus) was remodeled in 9%. Other examinations performed preoperatively completed the topographic analysis: 99Tc bone scintigraphy, computed tomography with 2D reconstruction and horizontal slices, MRI. The patients were placed in the ventral prone position for surgery via a para-achilles approach, medial in ten patients and lateral in eleven. Bone resection with combined arthrolysis of the subtalar and tibiotalar joints was performed in 20 patients (17 with nonunion of the posterior talar process, one with a trigone bone, two with malformed callus of the posterior malleolus). A soft tissue procedure was also performed in three patients (resection of a synovial cyst in one, tenosynovectomy of the long flexor of the great toe in two).

All patients were reviewed clinically and radiographically (plain x-rays). The AOFAS score was determined. There were no cases of infection. Mean follow-up was five years (range 3-10). Results were excellent with a mean Kitaoka score of 90/100, varying with cause and type of procedure performed. Only one patient was dissatisfied (Kitaoka score 67/100); this patient presented residual dysesthesia in the territory of the posterior tibial nerve. In 90% of the patients, there was no sign of degeneration of the peritalar joints (two patients exhibited minimal remodeling of the posterior subtalar joint). 90% of the patients were satisfied or very satisfied.

The posterior ankle impingement syndrome includes several pathological entities with similar clinical expression. It involves both bony and soft tissue elements in the posterior peritalar region. Repeated or acute forced plantar flexion is the main cause. Complementary explorations (bone scintigraphy, CT, MRI) besides standard radiography, are indispensable to obtain a definitive diagnosis and demonstrate the functional and mechanical impairment. Surgical treatment is simple via a posterior approach (posterolateral or posteromedial)) and in our hands has provided very good results without arthritic consequences at mid-term.