Ankle arthrodesis is a common operation with published fusion rates ranging from 62–100%. The literature documents the difficulties of obtaining arthrodesis in certain patients for example with neuroarthropathy, but the risk of non union related to deformity, bone quality, bone defects and systemic disease has not previously been reported.

Between 2002 and 2006 we performed an ankle arthrodesis in 154 patients, and analyzed these patients retrospectively to delineate categories of risk factors for achieving arthrodesis. From this analysis we devised a preoperative radiographic scoring system to grade complexity of pre-operative ankle arthrodesis. The scoring system is based upon 5 categories; size and plane of deformity, presence and size of bone defects, presence and area of avascular necrosis, site of previous fracture in post-traumatic arthritis and predisposing condition causing the arthritis. Each category has potential scores of 1–5, apart from the latter which is scored up to 6, with higher scores being more severe. The grade of complexity is derived from a cumulative score from all 5 categories.

Statistical analysis revealed good intra and inter- observer correlation. Multivariate regression analysis demonstrated that this scoring system correlates with the techniques used for arthrodesis as well as outcome. This study demonstrated that if the method of arthrodesis is altered according to the relative risk of non –union then there is no significant difference in outcome between patients of high and low risk for non-union

We present a new scoring system for severity of pre-operative condition in ankle arthrodesis patients and introduce an algorithm for surgical correction based upon this pre-operative scoring system. The surgical techniques for the arthrodesis are presented, ranging from simple screw fixation to more complex bone grafting techniques, bone stimulation and alternative methods of fixation.