Background

Hallux rigidus is a degenerative condition of the first metatarsophalangeal joint (MTPJ) of the great toe, which can result in significant pain and stiffness. Treatment using joint replacement, either by means of hemiarthroplasty or total arthroplasty of the metatarsophalangeal joint is becoming an increasingly popular option for patients with severe disease.

Worldwide, total ankle replacement is being more frequently offered as an alternative to ankle fusion. Most reports in the literature come from single centres with surgery performed by ‘high volume’ foot and ankle surgeons. We describe the New Zealand experience with the Scandinavian Total Ankle Replacement (STAR).

Fifty-two STARs in 49 patients were implanted between September 1998 and May 2005. Eleven surgeons performed between one and thirteen of the operations. Of the 49 patients five were deceased and five refused to participate in the study. The average age at surgery was 64.9 years (range 46-80). There were 26 males and 13 females. The average follow up was 58.2 months. Of the 41 ankles available for review 11 had been revised or fused (27%) at an average of 42 months post surgery. Of the remaining 30 intact ankles recent radiographs were available on all ankles. Of the retained primary ankles, the mean Oxford ankle score was 25.6. This scale has a range from 12, for an asymptomatic ankle, to 60. The mean WOMAC score was 18.9, the SF-12 PH 42 and the SF-12 MH 54. The scores were substantially worse for the group who had been revised or arthrodesed. Perioperative x-ray findings demonstrated intraoperative malleolar fracture occurred in seven patients including one with a complete saw cut transection of the medial malleolus and one who had sustained fractures of both malleoli. The tibial component was undersised in five patients and the talus oversized in at least three patients.

Of the 11 revision cases, two were bearing exchanges only. Nine involved either a major revision procedure or tibiotalocalcaneal arthrodesis for subsidence of malaligned components usually in the presence of peri-implant fracture. Of the unrevised cases, the latest x-rays did not demonstrate any significant osteolysis or increased lucent lines. Five cases demonstrated subtle talar or tibial component subsidence when compared with earlier radiographs. Despite overall satisfactory outcomes in the majority of patients the perioperative complication rate and revision rate in infrequent users is concerning. There may be implant and instrumentation elements, which also contribute to these suboptimal outcomes.

Level of evidence IV, retrospective review.

Worldwide, total ankle replacement is being offered more often as an alternative to ankle fusion. Most reports in the literature come from single centers with surgery performed by ‘high volume’ foot and ankle surgeons. We describe the New Zealand experience with the Scandinavian Total Ankle Replacement (STAR).

Ethical approval was gained for the study. Using the national joint register we identified all STARs performed in New Zealand. Patients were contacted by mail and consented to participate in the study. We retrospectively reviewed patient notes and x-rays. Patients were asked to complete and return an Oxford Ankle Score, WOMAC score, and SF-12.

Fifty two STARs were implanted in 49 patients between 1998 and 2005. Eleven surgeons performed between one and 13 operations. Forty one STARs in 39 patients were available for follow-up at an average of 58 months. Eight STARs had been revised (19.5%) at an average of 22 months post surgery. In patients with the implant still in-situ the average oxford score was 24.9, WOMACs core 17.3, SF-12 physical component 44.1, and SF-12 mental component 54. X-rays were available for review in 30 ankles. Most components were implanted in a good position. Intra-operative malleolar fracture was noted in six ankles. The tibial component was undersized in 5 patients and the talar component was oversized in three patients. Two cases of talar subsidence and 3 cases of tibial subsidence (one requiring revision) were noted on follow-up x-rays.

In New Zealand, the Scandinavian Total Ankle Replacement has a high revision rate at five years’ post surgery. A significant number of intra-operative malleolar fractures and component mal-sizing was noted. Patients who have not required revision mostly report acceptable ankle specific, and quality of life outcomes.