Feasibility, functionality and comfort of a novel concept Ankle-Foot-Orthosis for equinus foot

A large population of UMND patients suffer from increased passive ankle joint
stiffness and limited active range of motion (RoM) impairing their gait. In
order to improve gait, current ankle-foot-orthoses (AFOs) counteract this so
called equinus foot to neutral position by providing continuous stretch towards
dorsiflexion. These AFOs further increase joint stiffness at the cost of active
RoM. Therefore, we elaborated on a new AFO concept to compensate (instead of
increase) the excessive passive ankle joint stiffness. We have now developed a
first wearable prototype AFO based on this concept, to be tested in our
clinical population of UMND patients.

The objective of this study is to test the feasibility, functionality and
comfort of the AFO as an aid to regain the active RoM of the ankle joint in
UMND patients with equinus foot. Results of the study will be used to further
optimize the AFO design and future study protocols.

Feasibility and functionality will be tested using a within-subject design at
single joint level (i.e. ankle movement only) and at activity level (gait) for
6 conditions: (1) without AFO, (2) with the subject*s current AFO, (3-6) with
the new AFO at 4 levels of stiffness compensation from *no* to *full*
compensation. Overall comfort will be assessed by patient reported outcome
measures (PROMs).

Application of the new AFO in single joint measurements using an instrumented
ankle manipulator and during gait using standard instrumented gait analysis,
electromyography (EMG) and accelerometry .

Subjects visit the LUMC laboratory one day to join the two types of
measurements (single joint level and activity level) for an estimated 60 min.
measurement for each type. First, the subjects have a short physical
examination, fill in a 5 min. questionnaire and participate in the measurements
on single joint level (ankle function experiment of 6 x 15 s for the 6
different conditions while the patients is in seated position). Second, after a
break the subjects join the measurements at activity level (2 min. walk on a
treadmill for each of the 6 conditions) and fill in a 5 min. questionnaire.

Note: In the case the treadmill is not ready to use for the first five
patients, the measurements will be performed by a 5m walking test: Patients
will be asked to walk back and forth along the walkway at comfortable speed for
the 6 different conditions. The main outcome measure (active RoM) will be
measured by an electro-goniometer (Delsys, CE-marked) at lower leg of the
patients synchronized with the EMG system.