Clinical study on total hip arthroplasty patients with instrumented shoes

Total hip arthroplasty (THA) is a successful surgical procedure to treat
orthopedic osteoarthritis. Studying the differences in movement during various
activities of daily living before and after total hip replacement is important
for the follow up of the patients. Clinicians use different questionnaires
filled out by patients that have been standardized to assess and compare the
patient's pain and functional capacity. These questionnaires as well as gait
velocity show significant improvement after THA (Vissers et al, 2011). This
clinical evaluation is not based on objective physical measurements and does
not provide information about the movement patterns underlying the functional
capacity. This information is however clinically important and can currently
only be obtained in a fully equipped gait laboratory. Instrumented force shoes
(IFS) can quantify gait velocity, step time and length, ground reaction forces
and the position of the center of pressure during walking and therefore can be
used to quantify the gait pattern in an outpatient setting.

The first aim of this study is to investigate whether the IFS is a sufficiently
sensitive instrument to show differences in mobility performance between before
and after THA. The second objective is to investigate how mobility
characteristics, as measured with the IFS, relate to global functional
parameters gait velocity and questionnaire outcomes (HHS, WOMAC-FC).

Prospective cohort study with two measurement sessions: pre-operative and 6-8
months post-operative.
Patients undergoing THA will be measured before and 6-8 months after the
operation. Both measurements include 3 functional mobility tasks while the
subject is wearing instrumented force shoes (IFS). In the first task, the
subject is instructed to walk several times through the corridor from the
beginning to the predefined endpoint. Subsequently, the subject is asked to
stand and sit in a chair with arms folded across the chest 5 consecutive times.
The third task is to ascend and descend a total of 5 steps of a stair. Before
and after each measurement a Visual Analogue Scale (VAS) will be used to score
pain in the hip. Besides the VAS, after each measurement the Harris Hip Score
(HHS) and the Functional capacity part of the Traditional Western Ontario and
McMaster Universities osteoarthritis index (WOMAC-FC) will be administered.

There is no risk associated with participating in the measurments. Each
measurement will take about 40 minutes and will be planned during a regular
clinic visit. There is no direct benefit for the patient. However, future
patients shall benefit from the results because functional mobility performance
before/after THA can be assessed quantitatively in a clinical setting, which
can help the orthopedic surgeon in the future to evaluate the effect of THA.