Gait analysis in ankle osteoarthritis and total ankle replacement

BACKGROUND: Little information is available about gait changes in ankle osteoarthritis and total ankle replacement, and also about total ankle replacement patients' rehabilitation in the first year after surgery. METHODS: Thirty subjects were included in this study: 15 unilateral post-traumatic ankle osteoarthritis patients and 15 age-/gender-matched control subjects. Patients were followed prospectively: preoperatively, at 3, 6, 9, and 12 months after total ankle replacement. The clinical-functional level was assessed by the American Orthopaedic Foot and Ankle Society ankle and the Short-Form-36 health survey score. 3D ankle-hindfoot kinematic-kinetic analysis was performed using a motion analysis and a two-plate force-platform system. Statistics included repeated measures analysis of variances, independent sample and paired Student's t-tests (significance alpha=0.05). FINDINGS: Compared to normal subjects, ankle osteoarthritis caused significant reduction of the American Orthopaedic Foot and Ankle Society and Short-Form-36 score. In gait analysis, ankle osteoarthritis showed a significant deficiency in six of seven spatiotemporal variables, a decrease of the tri-planar ankle movement, a decrease of the second active maximal vertical and the maximal medial ground reaction force, a reduction of the sagittal and transverse ankle joint moments, a reduction of the ankle joint power. Three months after total ankle replacement surgery patients experienced a worsening of gait. At 12 months follow-up, all spatiotemporal variables were not different from the normal subjects (full rehabilitation); in six of 11 kinematic and kinetic variables there was a partial rehabilitation. INTERPRETATION: This study provides data for the clinical-biomechanical understanding of the normal, arthritic, and total ankle replacement treated ankle during walking and the first year of rehabilitation.