Abstract
Category:
Ankle, Ankle Arthritis, Basic Sciences/Biologics, Hindfoot
Introduction/Purpose:
Several studies on the effect on gait of total ankle arthroplasty (TAA) have demonstrated significant functional improvement post-operatively, compared to the patients’ preoperative function. While there are many post-operative studies showing abnormalities of gait in patients who have had ankle arthrodesis, there are very limited published data in ankle fusion which compare post-operative gait to the patients’ own preoperative function. Moreover, there are no published correlation of those gait changes with patient reported outcomes.
Methods:
Twenty-six consecutive ankle arthrodesis patients were prospectively studied, with pre- and post-operative three- dimensional gait analysis. Kinematic data were collected at 100 Hz with a twelve-camera digital Vicon motion capture system, and two OR6-5 AMTI force plates. Patients walked barefoot at a self-selected speed over a 10-meter walkway. A minimum 20 gait cycles were used for averaging and statistical analysis for temporal-spatial and kinematic parameters and a minimum of five force plate readings for kinetic parameters. Gait parameters were collected for both operated and unaffected limbs (i.e. control). Demographic data were compiled. Prospectively collected patient-reported outcomes included SF-36, VAS, AOFAS scores, which were repeated annually postoperatively.
Results:
Mean age was 56 (19 – 80) years, BMI 29.7 (18.6 - 45.6), and follow-up 21.9 (12 - 69) months. There were multiple objective parameters of gait which showed statistically significant functional improvements compared to preoperative performance.
Temporal-spatial: Improvements were detected in walking speed, step length and cadence; single and double limb support time. Kinematic parameters: Increase in maximum plantarflexion, decrease in maximum dorsiflexion, but total sagittal range of motion was not diminished, and slightly increased (mean 1.8 degrees). The preservation of total sagittal motion after arthrodesis suggested either precise postoperative compensation by the hindfoot, or that most of the preoperative motion was already occurring in the surrounding hindfoot joints. Kinetic parameters: Improvement in ankle moment and hip power were detected. Patient reported outcomes (table)
Conclusion:
Ankle arthrodesis improves gait in end-stage arthritis, as demonstrated by statistically significant improvements in multiple, objective parameters. Moreover, the increase in sagittal plane motion of the hindfoot, presumed in the literature to be compensatory to the arthrodesis, was shown to be present pre-operatively, as well, suggesting it is also an effect of tibiotalar stiffness due to end-stage arthritis. Improvements in gait corresponded to clinical improvements as well, as demonstrated by improvements in patient reported outcomes in this population. Biomechanical improvements corresponded to clinical outcomes.