Co-Principal Investigators: Nicholas J. Giori, MD, PhD and Thomas P. Andriacchi, PhD 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: 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. 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. We have found thus far that the variable stiffness sole shoes do reduce knee adduction moment at all walking speeds compared to the control shoes at the initial fitting of the shoe and at six months of shoe use. In fact, the effect of the special shoe is enhanced at the six month time period, indicating that as the variable stiffness sole shoe wears in, it becomes more effective. We have also found reductions in WOMAC scores that are statistically significant in the variable stiffness sole group after three and six months of shoe use while there was no statistically significant reduction in the control group. We are in the process of collecting one-year data. 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. Publications Song Y, Greve J, Koo S, Giori NJ: MR Imaging and 3-D Articular Cartilage Thickness Mapping of a Mechanically Loaded Knee Joint With and Without Meniscectomy. Trans Orthop Res Soc 51:38, 2005. Haemer JM, Wang MJ, Giori NJ: Resection of one leaf following horizontal meniscus tears is biomechanically comparable to resection of both leaves. American Society of Biomechanics Northwest Biomechanics Symposium, Seattle, May 13-14, 2005. Song Y, Greve J, Carter DR, Koo S, Giori NJ: Articular cartilage MR imaging and thickness mapping of a loaded knee joint before and after meniscectomy. Osteoarthritis and Cartilage 2006 14(8):728-37. Haemer JM, Wang MJ, Carter DR, Giori NJ: Benefit of Single Leaf Resection for Horizontal Meniscus Tear in an Ovine Model. Clin Orthop in press. Accepted for publication on Oct 25, 2006. Haemer JM, Wang MJ, Giori NJ: Biomechanical Assessment of Single- versus Double- Leaf Resection Following Horizontal Meniscus Tear. Proc 73rd Ann Mtg American Academy of Orthopedic Surgeons, Chicago, IL, 73:157, 2006. Haemer JM, Giori NJ: A finite element method for articular cartilage mechanics from MRI of loaded joints. Proc 52nd Ann Mtg Orthopedic Research Society, Chicago, IL, 52:81, 2006. Song Y, Greve J, Carter DR, Giori NJ: MR measurement of cartilage deformation in a cyclically loaded intact knee joint. Proc 52nd Ann Mtg Orthopedic Research Society, Chicago, IL, 52:1519, 2006. Song Y, Greve J, Carter DR, Giori NJ: Time Dependent Deformational Behavior of Cyclically Loaded Articular Cartilage in a Meniscectomized Knee Joint. 2006 ASME Summer Bioengineering Conference, Amelia Island, FL, June 21-25, 2006. Song Y, Greve J, Gold GE, Carter DR, Giori NJ: Cartilage nominal strain correlates with GAG content and shear modulus in meniscectomized joints. Proc 53rd Ann Mtg Orthopaedic Research Society, San Diego, CA, 53:692, 2007. Haemer JM, Song Y, Carter DR, Giori NJ: Quantification of changes in cartilage mechanics after meniscectomy with MRI and FEA of cyclically loaded joints. Proc 53rd Annual Meeting of the Orthopaedic Research Society, San Diego, CA, 53:620, 2007. Funding Source: Department of Veterans Affairs - Merit Review
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