Factors associated with outcome after subtalar arthrodesis

Abstract

Objectives: To evaluate radiographic and functional outcomes after subtalar arthrodesis and to identify patient factors associated with poor outcome.

Design: Retrospective study.

Setting: Two academic hospitals.

Patients: Eighty-eight patients with primary or secondary osteoarthritis treated between 1995 and 2002.

Intervention: Primary subtalar arthrodesis.

Main outcome measurements: Radiographic outcome was assessed by determining union rates. Functional outcome was assessed through self-administered questionnaires (Short Form-36, Short Musculoskeletal Function Assessment, and the AAOS Foot and Ankle Instrument).

Results: After adjusting for age and sex smokers were 3.8 times more likely to go on to nonunion than nonsmokers (P < 0.05). As patients aged, there was a higher likelihood of nonunion if they also smoked (P < 0.05). Of patients undergoing subtalar bone block distraction arthrodesis 95% went on to union compared with 65% of patients treated with an in situ subtalar arthrodesis without bone graft (P < 0.05). There was a trend for higher rates of union if a bone graft was used among patients treated with an in situ subtalar arthrodesis. Diabetic patients were 18.7 times more likely to have a malunion (P < 0.05). As a group, patients who have undergone subtalar arthrodesis can expect significantly worse functional outcomes compared with the Canadian and American normative populations. The poorest functional outcomes were observed among patients with diabetes. A trend for poorer outcome in bodily pain and general health (Short Form-36) was seen in workers' compensation patients.

Conclusions: Certain patient variables are associated with poorer outcomes after subtalar fusion. The results of this study will enable surgeons to provide better information to patients in preoperative discussions with respect to patient expectations, outcomes, and the success of surgery.