A Novel Serum Biomarker Stress Test for Detection of Early Osteoarthritis
Phase: NA
Conditions: Osteoarthritis
Sponsor: VA Palo Alto Health Care System

Title: A Biomarker Stress Test for Detection of Early Osteoarthritis 
NCT: NCT02593864 
Document Date: 10/2/2019 
 

Study Protocol: 
General Study Plan: Subjects will be assigned a variable-stiffness shoe to wear for 6 months. 
Subjects will have gait testing and an OA stress test (serum collection before and after a 30-minute 
walking activity) at the baseline visit to determine the immediate effects of the shoes on joint 
mechanics and will return at 6 months for a second OA stress test and gait test. 
 
 
Intervention: The intervention shoe is a normal-appearing commercially available athletic shoe 
with a specially designed sole. The lateral aspect of the sole is made of a stiffer material than the 
medial aspect of the sole (lateral sole 1.4 times stiffer than medial sole). Previous studies have 
revealed that a shoe of this kind can reduce medial compartment loading. Patients will be asked to 
use the shoe during their active portion of the day and provide a report of daily usage.  
 
Collection of Serum Samples (OA Stress Test): Subjects will be asked to limit their physical 
activity for 36 hours prior to testing. Tests will begin between 8:00 and 9:00 am, and subjects will 
be required to limit their activity between the time they wake up and the beginning of study 
activities. Blood samples (5mL or 1 teaspoon) will be obtained by trained personnel immediately 
before, immediately after, 0.5, 1.5, 3.5, and 5.5 hours after a 30-minute walking exercise. For the 
walking exercise, subjects will walk at their self-selected speed for 30 minutes on a level surface 
while an activity monitor records the number of steps, cadence, and total distance walked during 
the task. Following the walking exercise, subjects will remain in a seated position with minimal 
physical activity until after the final blood draw. A thin catheter in a vein of the subject’s forearm 
will be used so that only one venipuncture will be required for all blood samples. Blood specimens 
will be centrifuged to separate serum, aliquoted, and frozen to -80oC within 1 hour of collection. 
 
Gait Analysis: Each subject will be tested bilaterally in their own personal walking shoe, a 
constant-stiffness control shoe, and the variable-stiffness intervention shoe, to determine the 
immediate and long-term (6 month) effects of the variable-stiffness shoes on joint mechanics. 
Subjects will be instructed to perform three walking trials at a comfortable speed (normal), slower 
than normal, and faster than normal. A 10-camera optoelectronic system for 3d motion analysis 
(Qualisys Medical AB; Gothenburg, Sweden) will be used to collect marker data. Ground reaction 
force data will be collected using a multi-component force plate placed in the center of the 
walkway (Bertec Corporation; Columbus, OH). All data will be collected at a frequency of 120 
Hz.  
 
The point cluster technique (PCT) marker protocol will be used for gait analysis to measure 
the movements of the underlying femur and tibia. The intersegmental forces and moments at the 
knee will be calculated through an inverse dynamics approach. A link model of the segments of 
interest will be used, assuming the inertial properties for each rigid segment to be lumped at its 
center of mass, symmetry of the segment along the main inertia axis, and negligible angular 
velocity and acceleration along the longitudinal axis. The peak external knee adduction moment 
will be calculated as the maximum moment during stance phase. Average moment values for each 
speed and subject combination will be calculated. Moments will be normalized to bodyweight and 
height (%Bw*Ht) to allow for comparison between subjects. Pain will be quantified at baseline 
and at the time of the 6 month follow-up by Western Ontario and McMaster Universities 
(WOMAC) pain scores. 
 

Statistical Analysis Plan: 
Changes from baseline in peak knee adduction moment and in response of serum levels of 
biomarkers to a mechanical stimulus in an early knee OA population will be tested after 6 months 
of load-modification through variable-stiffness shoe wear. The analysis will test for significant 
differences in the biomarker levels and knee adduction moment between baseline and 6 months. 
Data will be checked for normality, and a paired Student’s T-Test will be used for normally 
distributed data, or a non-parametric alternative such as the paired-sample Wilcoxon Signed Rank 
Test will be used if normality checks show that the data is not normally distributed. Analysis of 
covariance (or non-parametric alternative) may be used to test the influence of potential covariates 
such as pain, age, gender, and BMI.