Positive Pressure Treadmill Walking for Individuals With Knee Pathology

Study Overview
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Brief Summary
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Our goal is to compare the serum biomarker changes of joint disease that occur in response to partially off-loaded (50%) walking exercise to regular (100%) walking exercise while on a Lower Body Positive Pressure (LBPP) treadmill. Secondly we are determining the relationship between changes in the concentration of these serum biomarkers and participant reported knee pain while walking on a LBPP treadmill.

Detailed Description
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The morphology and composition of healthy mature articular cartilage is optimized to its primary function of load transfer and distribution. In the osteoarthritic state however, homeostasis of the knee joint is significantly altered, such that as load is placed on the joint there is progressive worsening of cartilage damage over time. Altered joint mechanics and intra-articular biological processes are thought to play pivotal roles in the initial breakdown and potentiation of cartilage damage which is the hallmark finding in knee OA leading to knee pain. Walking or running with weight support on a lower-body positive-pressure (LBPP) treadmill is a novel training and rehabilitation modality for individuals with lower extremity pathologies due to its ability to limit pain. This treadmill provides a controlled off-loading of the lower extremities with significant benefit being shown after 12 weeks of training in overweight individuals with knee OA on knee pain, function and muscle strength. Although this methodology alters the joint mechanics, the intra-articular biological effect on joint disease remains unknown. A recent study from our laboratory compared walking exercise on a regular treadmill at a defined speed with and without rest breaks in 27 participants with knee OA and demonstrated that one-hour rest breaks had significant benefits. This conclusion was based on reduction in knee joint contact force and decreased levels of a serum marker commonly associated with cartilage degradation (cartilage oligomeric matrix protein, COMP) at 45 minutes of walking. This investigation assessed patterns of walking, but the impact of varying knee joint contact force, such as by walking on a LBPP treadmill on the biological profiles of joint disease is not known. The present study will establish the conditions and parameters for a future longer-term clinical trial that aims to individualize the amount of joint loading during LBPP treadmill training in participants with knee OA based on their biomarker profile. Objective 1: Compare the serum biomarker changes of joint disease that occur in response to partially off-loaded (50%) walking exercise to regular (100%) walking exercise while on a LBPP treadmill. Objective 2: Determine the relationship between changes in the concentration of these serum biomarkers and participant reported knee pain while walking on a LBPP treadmill.

Official Title
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The Effects of Anti-Gravity Treadmill Walking In Individuals With Knee Osteoarthritis

Conditions
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Knee Osteoarthritis

Intervention / Treatment
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* Other: Anti-Gravity Treadmill


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age > 50 years Diagnosis of unilateral or bilateral knee osteoarthritis Clinical AND/OR radiographic knee osteoarthritis. Exclusion Criteria: Age < 50 years History of lower extremity total joint arthroplasty Current cardiovascular disease or hypertension that is uncontrolled History of neurological disorder that effects lower extremity function (i.e., stroke, peripheral neuropathy, multiple sclerosis, Parkinson's disease) Current ankle or hip pain Currently pregnant for female participants Weight over 400 lbs (181.4 kg), height less than 4'8 (142 cm) or over 6'4 (193 cm), 18.5 (47 cm) hip width, or 58 (147 cm) hip circumference

Ages Eligible for Study
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Minimum Age: 50 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Interventional Model Description: Individuals with knee osteoarthritis will walk 45 minutes on a treadmill at 100% full body weight loading
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: 100% body weight walking<br>Individuals with knee osteoarthritis will walk 45 minutes on a treadmill at 100% full body weight loading | Other: Anti-Gravity Treadmill<br>* Treadmill in which the body weight percent placed on the lower extremities can be controlled<br>|
| Other: 50% body weight walking<br>Individuals with knee osteoarthritis will walk 45 minutes on a treadmill at 50% full body weight loading | Other: Anti-Gravity Treadmill<br>* Treadmill in which the body weight percent placed on the lower extremities can be controlled<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Cartilage oligomeric matrix protein serum concentration | Serum (blood) marker concentration | baseline, and 45 minutes of walking | 
| Change in Knee Joint Pain | Numeric pain rating scale (NPRS). Higher scores on this scale indicate higher pain | baseline, and 45 minutes of walking | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in Inflammatory cytokine (IL-6, IL-1B and TNF-A) concentration | Serum (blood) marker concentration | baseline, and 45 minutes of walking |