Assessment of the Shank-to-Vertical Angle While Changing Heel Heights Using a Single Inertial Measurement Unit in Individuals with Incomplete Spinal Cord Injury Wearing an Ankle-Foot-Orthosis

Previous research showed that an Inertial Measurement Unit (IMU) on the anterior side of the shank can accurately measure the Shank-to-Vertical Angle (SVA), which is a clinically-used parameter to guide tuning of ankle-foot orthoses (AFOs). However, in this context it is specifically important that differences in the SVA are detected during the tuning process, i.e., when adjusting heel height. This study investigated the validity of the SVA as measured by an IMU and its responsiveness to changes in AFO-footwear combination (AFO-FC) heel height in persons with incomplete spinal cord injury (iSCI). Additionally, the effect of heel height on knee flexion-extension angle and internal moment was evaluated. Twelve persons with an iSCI walked with their own AFO-FC in three different conditions: (1) without a heel wedge (refHH), (2) with 5 mm heel wedge (lowHH) and (3) with 10 mm heel wedge (highHH). Walking was recorded by a single IMU on the anterior side of the shank and a 3D gait analysis (3DGA) simultaneously. To estimate validity, a paired t-test and intraclass correlation coefficient (ICC) between the SVA_IMU and SVA_3DGA were calculated for the refHH. A repeated measures ANOVA was performed to evaluate the differences between the heel heights. A good validity with a mean difference smaller than 1 and an ICC above 0.9 was found for the SVA during midstance phase and at midstance. Significant differences between the heel heights were found for changes in SVA_IMU (p = 0.036) and knee moment (p = 0.020) during the midstance phase and in SVA_IMU (p = 0.042) and SVA_3DGA (p = 0.006) at midstance. Post-hoc analysis revealed a significant difference between the ref and high heel height condition for the SVA_IMU (p = 0.005) and knee moment (p = 0.006) during the midstance phase and for the SVA_IMU (p = 0.010) and SVA_3DGA (p = 0.006) at the instant of midstance. The SVA measured with an IMU is valid and responsive to changing heel heights and equivalent to the gold standard 3DGA. The knee joint angle and knee joint moment showed concomitant changes compared to SVA as a result of changing heel height.

Does user perception affect adherence when wearing biomechanically optimised ankle foot orthosis - footwear combinations: A pilot study

STUDY DESIGN

Pilot study.

BACKGROUND

Ankle foot orthoses (AFOs) and footwear combination (FC) is a commonly prescribed medical device given to children with cerebral palsy (CP) in an attempt to improve their gait. Biomechanically optimising the AFO-FC often requires large adaptations to the sole of the user's footwear. There is currently a dearth of literature regarding the user's perception of wearing biomechanically optimised AFOs and adapted footwear and whether their perception affects their adherence to orthotic treatment.

OBJECTIVE

This study aimed to investigate perception and adherence to wearing an AFO and FC the participants were asked to wear as part of their orthotic prescription. In particular, whether the visibly modified footwear affected the user's adherence to the orthotic treatment.

METHODS

Questionnaire devised for the purpose of this study.

RESULTS

All five participants responded to the questionnaire; reporting a high number of positive responses in relation to function, including; an improvement in the way they walked, improved balance and fewer falls. Conversely, there was a high level of negative responses regarding aesthetics, with all participants reporting they did not like the cosmesis of their AFO-FCs. They were conscious that the modification to their footwear was noticeable and therefore different from their peers, yet they adhered to the treatment and in some cases increased the wearing time.

CONCLUSIONS

This pilot set of questions indicated that cosmesis is an important factor for children who wear AFOs and adapted footwear. It can be concluded that the impact of the adapted AFO-FC on the participants' function outweighed their opinion on the cosmesis of the device.

CLINICAL RELEVANCE

It is vital to understand how orthotic prescriptions affect user adherence. Orthotic prescriptions which are not utilised by the user result in a failed treatment intervention, regardless of the scientific application underpinning them.

Effects of solid ankle-foot orthoses with individualized ankle angles on gait for children with cerebral palsy and equinus

PURPOSE

For children with cerebral palsy (CP) and equinus, the conventional practice of setting the ankle angle in an ankle-foot orthosis (AA-AFO) at 90∘ may not adequately accommodate gastrocnemius length/stiffness. Therefore, this study compared the effects of statically-optimized solid AFOs with individualized AA-AFOs (iAA-AFOs) and conventionally-prescribed AFOs on gait for children with CP and equinus.

METHODS

Ten children with CP and equinus (15 limbs with AFOs), and 15 typically-developing (TD) children participated. For the children with CP, solid AFOs with iAA-AFOs (range = 5∘-25∘ plantarflexion) were compared with their usual AFOs using three-dimensional gait analysis. TD children walked in shoes only. Peak values and Gait Variable Scores (GVS) for joint and segment variables were calculated for stance phase. Responses were categorized using 90% confidence intervals relative to TD data, for each affected leg.

RESULTS

Net responses to iAA-AFOs were positive for 60% of limbs and negative for 40%. Knee variables (GVS and peak extension, flexion, and midstance moment) were most positively affected, and foot-floor angle and vertical ground reaction force were most negatively impacted.

CONCLUSION

Individualized AFO prescription and iAA-AFOs can impact gait biomechanics for some children with equinus, compared to conventionally-prescribed AFOs. Optimizing dynamic alignment for walking may further improve outcomes.