Tuning ankle foot orthoses using a standardized protocol

Ankle-foot-orthoses (AFOs) are commonly prescribed to improve the walking ability of patients with neurological diseases. However, the AFO effectiveness depends on several factors, of which alignment of the AFO is highly important. Optimal alignment is achieved by making fine adjustments to the AFO footwear combination (AFO-FC), which is often referred to as tuning. In clinical practice, the tuning process is performed by observation of gait (observational gait analysis) and alignment is optimized by trial and error. However, observational gait analysis has shown to be ineffective and unreliable, and could therefore result in incorrect AFO alignment. Moreover, incorrect AFO alignment can result in a suboptimal walking pattern and the development of pressure sores, which negatively affects the patient’s walking ability, satisfaction and treatment adherence. Furthermore, inadequate AFO tuning may influence the clinical process, as it could result in more tuning adjustments and more return visits before reaching optimal alignment. An alternative to observational gait analysis is 2D gait analysis using cameras and a force plate or the use of Inertial Measurement Units (IMUs) and/or pressure plate. With 2D gait analysis, the ground reaction force vector can be displayed in a video (force vector overlay), visualizing the GRF in relation to the joints. IMUs can measure movements of body segments and joints, while the pressure plate can measure the GRF in relation to the footprint. With the use of these measuremnt instruments, AFO alignment can be quatified more objectively. However, the use of a standardized protocol for AFO tuning has never been investigated.
Objective: Investigate the use of a standardized protocol for AFO tuning.
- Investigate the effect of wedges under the heel and forefoot on the GRF in relation to the knee joint
- Investigate the effect of wedges under the heel and forefoot on knee angle and knee moment
- Investigate the effect of wedges under the heel and forefoot on the Shank-to-Vertical Angle
- Validate the use of force vector overlay to estimate the GRF in relation to the knee joint centre
- Validate the use of IMUs to estimate the knee angle
- Validate the use of a pressure plate to estimate the GRF in relation to the footprint
- Estimate the inter-rater reliability of the assessment of the GRF in relation to the knee joint

The GRF in relation to the knee joint, knee angle and moment and the SVA change when wegdes are placed under the heel and forefoot. Furthermore, these parameters and changes can be measured accurately with force vector overlay (2D gait analysis), IMUs and/or a pressure plate.

Measurements will be performed at one measurement day.

AFO tuning following a standarized protocol using wedges under the heel and forefoot.