Evaluation of Medial Compartment Knee OA

Principal Investigators: Nicholas J. Giori, MD, PhD and Thomas P. Andriacchi, PhD

Project Category: Arthritis and Osteoporosis - 2003

Objective: The goal of this study is to evaluate the efficacy of a load modifying intervention for treating medial compartmental knee osteoarthritis. The selection of the load modifying intervention (a specially designed shoe) was based on a preliminary study where the shoe reduced the adduction moment at the knee during walking. The shoe is a normal appearing walking shoe that has a variable-stiffness sole (VSS). The material along the lateral aspect of the sole is stiff compared to the material on the medial aspect of the sole. The shoe offers an attractive alternative to other load modifying interventions (unloader braces or wedge inserts) and should improve patient compliance over previous methods.

Research Plan: This study will scientifically test the efficacy of this load modifying intervention by testing the following hypotheses:

1. Functional improvement-based patient ratings (Knee Society, WOMAC, and SF-36 scores) are related to a reduction in the adduction moment during walking. This hypothesis will be tested as follows: Patients will be randomly assigned the VSS or a control shoe and will be tested at entry into the study, one week after wearing the shoe and at one year. Ratings scores will be acquired at entry, at each gait test and at 3 months, 6 months, and one year.

2. The rate of progressive regional thinning of medial compartment articular cartilage over the course of the study period can be correlated with the adduction moment during walking. This hypothesis will be tested by testing the relationship between the adduction moment during walking and cartilage thinning derived from MRI of the articular cartilage at the knee. The MRI will be acquired from the same population described in Hypothesis 1 at entry into the study and at yearly intervals (over a three year period). In addition, radiographic Kellgren-Lawrence osteoarthritis grades will be taken at the same intervals.

Work Accomplished: A study was conducted to evaluate the potential for design interventions using gait to modify the adduction moment during walking. The study was motivated by previous work demonstrating the relationship between the adduction moment during walking and the outcome of treatment for varus gonarthrosis. The knee adduction moments using the intervention shoes showed marked improvement that was related to the mechanical characteristics of the shoe. The study demonstrated the feasibility of conducting a larger prospective study with a VSS design.

Expected Outcome: Finding an effective alternative to surgical intervention for unicompartmental osteoarthritis of the knee that does not involve the expense, bulk, inconvenience, and potential complications of brace use will advance our ability to rehabilitate veterans with this common form of osteoarthritis, and will improve the quality of care we provide to veterans.

Funding Source: Bone & Joint Center

Funding Status: Pending