Ankle Osteoarthritis and Its Treatments : Impact on Foot & Ankle Biomechanics

Ankle osteoarthritis is a progressive degenerative joint disease that is characterized by severe pain, loss of autonomy, diminished health-related quality of life, functional disability and diminished physical ability to fulfill occupational duties of life in its end-stage. Current surgical treatments for ankle osteoarthritis are ankle arthrodesis and total ankle replacement. Despite the good pain relief provided by these procedures, patients are still experiencing post-operatively important functional limitations in their activities of the daily living which affect their independency and quality of life. In order to remain capable of performing primary activities of the daily living, those patients have to make functional compensatory adaptations in the ipsilateral adjacent joints that will cause additional degenerative joint disease in those joints.

Currently, the outcome of foot and ankle surgery is primarily based on clinical, radiographic and questionnaire outcomes. However, these outcome measures have been criticized for not being sensitive enough to detect clinically meaningful change in foot function. To tackle these shortcomings, an advanced clinical examination platform integrating pressure-force-kinematic measurement devices was developed and showed its clinical value for the detection of intrinsic foot mobility impairments. Surprisingly, up-to-now, no study has included this integrated use of three-dimensional multi-segment foot models, plantar pressure platform and a force platform to report on the functional outcome of an ankle arthrodesis or a total ankle replacement.

Therefore, a multi-centre study will be conducted with two foot & ankle surgery centres. Both centres are equipped with the same advanced clinical examination platform. It is believed that proposed approach has the potential to provide further insight in the true functional changes related to ankle arthrodesis and total ankle replacement. This may in turn result in improved rehabilitation, less risk for post-operative complications, earlier discharge and quicker resumption of normal activities of the daily living, which would make ankle arthrodesis and total ankle replacement more cost-efficient and could potentially affect thousands of patients each year. Therefore, the hypotheses of the present study are:

• Hypothesis (H1): Subjects with an ankle arthrodesis require a greater reorganization of foot and lower limb kinematic and kinetic patterns to respond to mechanical requirements of level walking compared to subjects with a total ankle replacement.
• Null hypothesis (H0): Subjects with an ankle arthrodesis do not require a greater reorganization of foot and lower limb kinematic and kinetic patterns to respond to mechanical requirements of level walking compared to subjects with a total ankle replacement.