A Difference in Leg Lengths Could Indicate Pattern for Osteoarthritis

Newswise — A leg length difference of as little as two centimeters (about 4/5s of an inch) is definitely associated with knee and hip osteoarthritis, according to research presented this week at the American College of Rheumatology Annual Scientific Meeting in Washington, DC.

To examine the relationship between leg length inequality and knee and/or hip osteoarthritis, researchers conducted the first large community-based study with 3,161 participants enrolled in the Johnston County Osteoarthritis Project, North Carolina. Within this group, 6.4% had legs of different lengths, with equal frequency in men and women and in blacks and whites.

Compared to people with equal leg lengths, those with two or more centimeters of difference in the length of their legs were more likely to have osteoarthritis in their right hip or, most often, their left or right knee, and were more likely to have more severe disease. Surprisingly, the location of the disease did not appear to be driven by which was the longer or shorter limb, although right hip osteoarthritis was more common when the left leg was longer than when the right leg was longer.

Researchers are now exploring whether leg length variances can actually predict who will get osteoarthritis before it happens or whose osteoarthritis will get worse.

"Recognizing that leg length inequality has a significant association with hip and particularly knee osteoarthritis opens the door to more studies on whether leg length variances might cause the development and progression of the disease," indicates Joanne M. Jordan, MD, MPH, Associate Professor of Medicine and Orthopaedics at University of North Carolina, Thurston Arthritis Research Center, Chapel Hill, North Carolina, and the senior investigator in the study. "The findings from this study may help us predict who may develop osteoarthritis and who may have symptoms that worsen or have a potential risk of increased disability. Studies to test whether correction of leg length inequality with orthotics or shoe lifts can prevent the onset of osteoarthritis, or its progression, would be a logical next step."

The American College of Rheumatology is the professional organization for rheumatologists and health professionals who share a dedication to healing, preventing disability and curing arthritis and related rheumatic and musculoskeletal diseases. For more information on the ACR's annual meeting, see http://www.rheumatology.org/annual.

Presentation Number: 672

Relationship of Limb Length Inequality with Hip and Knee Osteoarthritis

Yvonne M. Golightly1, Kelli D. Allen1, Jordan B. Renner2, Charles G. Helmick3, Joanne M. Jordan2. 1Durham Veterans Affairs Medical Center, Durham, NC; 2University of North Carolina at Chapel Hill, Chapel Hill, NC; 3Centers for Disease Control and Prevention, Atlanta, GA

Objective: This study examined the relationship of limb length inequality (LLI) with hip and knee osteoarthritis (OA) in a large, population-based sample.

Methods: The total study group comprised 3166 participants enrolled in the Johnston County Osteoarthritis Project, including 837 (26.4%) with radiographic hip OA, 948 (30.0%) with radiographic knee OA, and 210 (6.4%) with LLI. The presence of radiographic OA was defined as Kellgren/Lawrence (K/L) grade >2, and LLI was defined as a 2.0 cm or greater difference between limbs. We further categorized radiographic OA severity as mild for a K/L grade of 2 and moderate-to-severe for K/L grade 3 and 4. Chi-square tests were used to examine the relationship of LLI with radiographic hip and knee OA. Fisher's exact test was used to examine the relationship of LLI with radiographic OA severity. Among participants with LLI, we used Chi-square tests to compare the presence of hip or knee OA in the shorter vs. longer limb. Multiple logistic regression models were used to examine the relationship of hip and knee OA to LLI, while controlling for age, gender, race, body mass index, and history of hip or knee problems (joint injury, fracture, surgery, or congenital anomalies).

Results: Participants with LLI were more likely than those without LLI to have hip OA (32.5% vs. 26.1%, p<0.044) and knee OA (45.3% vs. 29.0%, p<0.001). LLI was associated with a greater likelihood of right hip OA, right knee OA, and left knee OA (p<0.05), but not left hip OA. Among subjects with radiographic right knee, left knee, and right hip OA, there were no significant relationships between radiographic severity (mild vs. moderate-to-severe) and LLI. However, among participants with left hip OA, those with moderate-to-severe OA were statistically more likely to have LLI than those with mild OA (p=0.013). Among participants with LLI, there were no statistically significant differences in the prevalence of radiographic hip or knee OA in the longer vs. shorter limb. In multiple logistic regression models, knee OA was significantly associated with presence of LLI (OR = 1.74, p=0.001), but there was no significant relationship between hip OA and LLI (OR = 1.22, p = 0.221).

Conclusion: LLI was significantly associated with both hip and knee OA, but the relationship was stronger for knee OA. Future research should examine the relationship of LLI to hip or knee OA incidence and progression over time, as well as the relationship of LLI and symptom severity (pain and function) in individuals with hip or knee OA.

Disclosure Block: Y.M. Golightly, None

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