Page 62 - Maximizing the efficacy of ankle foot orthoses in children with cerebral palsy

62
Chapter III
A limitation of the study is the calculation of the SVA, which was expressed in the global sagittal plane. Although the SVA was calculated according to methods used in other research and in clinical (2D) settings, it may have introduced a small underestimation of the SVA. Another limitation is poor fitting of the AFOs to some subjects, enabling compensation to the AFO-FC manipulations. This is supported by the results on the Shank-to-AFO angle, which decreased with increasing heel height, indicating that the lower leg was pushed more into the dorsal shell of the AFO when heel height increased. Moreover, the AFO may have been lifted inside the shoe, therewith affecting joint flexion-extension angles and moments.
Our results indicate that the SVA is responsive to AFO-FC heel height manipulations in young healthy adults walking with bilateral rigid AFOs. An increase in SVA was accompanied by increased joint flexion angles and internal net extension moments, especially at the knee joint. Whereas the SVA was not responsive to changes in footplate stiffness, the stiff footplate increased the internal ankle plantar flexion moment, and an interaction effect of heel height and footplate stiffness showed an opposite effect of the stiff footplate on the internal knee extensor moment in the low and high heel height conditions. These findings emphasize the consideration of footplate characteristics in the tuning process. In conclusion, the SVA may serve as a parameter to evaluate AFO-FC tuning, which has to be elaborated on in the clinical target population.