Radiographic Severity of Arthritis Affects Functional Outcome in Total Ankle Replacement (TAR)

It has been previously demonstrated that radiographic severity of arthritis predicts outcome following knee replacement. In certain circumstances, patients may undergo arthroplasty without severe radiographic disease. An example may be the patient with significant chondral damage unsuccessfully treated with arthroscopy. This patient may proceed to joint replacement when their radiographs would not normally merit such intervention. We investigated whether these findings were also applicable to total ankle replacements (TARs).

We retrospectively reviewed a single-surgeon, single-implant series of 178 TARs in 170 patients. Of them, 124 patients who took part in the hospital joint registry with a minimum 2-year follow-up were included for this study. The radiographic severity of arthritis was graded using the Kellgren-Lawrence classification. Preoperative weight-bearing radiographs were reviewed for severity of arthritis by 2 blinded observers: the first author and an independent colleague from the radiology department. Patients were grouped into 4 subgroups based on degree of severity of radiographic grading for arthritis-A, B, C, and D (for grades 1, 2, 3, and 4 grades, respectively). Data collected included Foot and Ankle Outcome Score (FAOS; pain, function, and stiffness), MOS 36-item Short-Form Health Survey (SF-36) scores, and patient satisfaction scores collected prospectively and at 1 and 2 years postoperation.

Groups were similar in terms of demographic data (P > .1) and preoperative FAOS scores (P > .89) for pain, function and stiffness. Group D had the biggest improvement in all domains of FAOS. This reached significance in each domain when compared to group C. No significant differences were demonstrated in SF-36 scores. Overall, 91.1% of patients in group D were satisfied at 2 years, compared with 50.0% of patients in groups A, B, and C (P < .001). In addition, 93.9% of patients in group D felt that their quality of life had been improved by the surgery, compared to 47% of patients with groups A, B, and C (P < .001). Further, 77.3% of patients from group D said they would have the operation again, vs only 52.2% of patients with grade III or less (P = .014). Patients who were "very satisfied" or "somewhat satisfied" postoperatively had an average Kellgren-Lawrence (KL) grade of 3.9 preoperatively. In contrast the "very dissatisfied" and "somewhat dissatisfied" patients had an average KL grade of 2.9 (P < .05).

Although this study does not explain all of the dissatisfaction in TAR, radiologic severity is an important factor that surgeons must consider when planning how best to treat their patients. There may be a different pathophysiology in this patient group that is not well served by arthroplasty.

Level III, retrospective comparative series.