Although chiropractors have often been ridiculed for using unequal leg lengths as a diagnostic tool, a recent research paper published in the Annals of Internal Medicine has linked arthritis in the knee to the common trait of having one leg that is longer than the other. Whether or not leg length differential is a direct cause of osteoarthritis isn’t clear, but the findings may allow people to take preventive measures even as early as childhood.
“Most pediatricians adopt a ‘wait and see’ attitude for children with limb misalignment when they’re growing,” said Derek Cooke, Queen’s University adjunct professor and a co-author of the study. “If we can spot factors creating changes in alignment early in bone development, theoretically we could stop or slow down the progression of osteoarthritis.”
The data was collected using x-ray images from more than 3,000 adults aged 50 to 79 who either had knee pain or risk factors for knee osteoarthritis as a part of the Multi Centre Osteoarthritis Study (MOST). Subjects were reassessed after a 30-month period and the researchers found that osteoarthritic changes in the knee were most significant in individuals with pronounced (more than 1 cm) leg length inequality, the shorter leg being most affected.
“Because the condition often goes undiagnosed, many people don’t realize they have a leg length differential until they’re diagnosed with osteoarthritis,” noted the Queen’s University press release on the study.
Evidence about the negative impact of unequal leg lengths has been available for decades but generally ignored or underestimated by the medical community, possibly because leg length checks were so closely associated with chiropractors.
According to a report by J. Philip Gofton, MD in a 1985 issue of the Journal of Rheumatology “Leg length inequality and low back pain go hand in hand.” His research found that a leg length difference of 12.5 mm will cause a lateral tilt of the sacrum of about 4° with a compensatory scoliosis in the lumbar spine. Gofton also demonstrated the biomechanical and clinical problem of leg length disparity and its relationship to hip osteoarthritis.
William F Harvey from Boston University, currently at Tufts Medical Center, was the lead author on the paper.