Ankle arthroplasty and ankle arthrodesis: gait analysis compared with normal controls.

BACKGROUND: This study compared patients with isolated end-stage ankle osteoarthritis, after undergoing either total ankle arthroplasty or arthrodesis, using gait analysis and patient-reported outcome measures to elucidate differences between the two treatment options, as compared with a healthy control group.

METHODS: Gait analyses were performed on patients with isolated ankle arthritis more than one year after undergoing either total ankle arthroplasty or arthrodesis during a ten-year period. Validated outcome questionnaire data were obtained. Seventeen patients undergoing total ankle arthroplasty, seventeen patients undergoing arthrodesis, and ten matched control subjects were included for comparison.

RESULTS: Patients who had undergone arthroplasty, when compared with patients who had undergone arthrodesis, demonstrated greater postoperative total sagittal plane motion (18.1° versus 13.7°; p < 0.05), dorsiflexion (11.9° versus 6.8°; p < 0.05), and range of tibial tilt (23.1° versus 19.1°; p < 0.05). Plantar flexion motion was not equivalent to normal in either group. Ankle moments and power in both treatment groups remained significantly lower compared with the control group (p < 0.05 between each treatment group and the control group for both variables). Gait patterns in both treatment groups were not completely normalized. Improvements in patient-reported Ankle Osteoarthritis Scale and Short Form-36 scores were similar for both treatment groups.

CONCLUSIONS: The gait patterns of patients following three-component, mobile-bearing total ankle arthroplasty more closely resembled normal gait when compared with the gait patterns of patients following arthrodesis. Dorsal motion in the sagittal plane was primarily responsible for the differences. Improvement in self-reported clinical outcome scores was similar for both groups. Further investigation is needed to determine why patients who have undergone total ankle arthroplasty do not use the plantar flexion motion in the terminal-stance phase and to explain the limited increase in power generation at toe-off after arthroplasty. Results obtained from this study may be used for future modifications of ankle prostheses and may add to clinicians' ability to inform patients of predicted functional outcomes prior to the treatment of end-stage ankle osteoarthritis.