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Leg Length Inequality and Hip Osteoarthritis in the Multicenter Osteoarthritis Study and the Osteoarthritis Initiative

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Kim C1, Nevitt M2, Guermazi A3, Niu J1, Clancy M1, Tolstykh I2, Jungmann PM4, Lane NE5, Segal NA6, Harvey WF7, Lewis CE8, Felson DT1,9. Arthritis Rheumatol. 2018 Apr 26. doi: 10.1002/art.40537. [Epub ahead of print]

Abstract

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1 Clinical Epidemiolgy Research and Training Unit, Boston University School of Medicine.

2 Department of Epidemiology and Biostatistics, University of California San Francisco.

3 Quantitative Imaging Center, Department of Radiology, Boston University School of Medicine.

4 Department of Neuroradiology, University Hospital Zurich, University of Zurich, Switzerland.

5 Department of Rheumatology, University of California, Davis.

6 Department of Rehabilitation Medicine, University of Kansas Medical Center, Kansas City, KS.

7 Department of Rheumatology, Tufts Medical Center.

8 Division of Preventative Medicine, University of Alabama, Birmingham.

9 NIHR Manchester Musculoskeletal Biomedical Research Centre, University of Manchester.

Abstract

OBJECTIVE: Studies suggest that persons with a 2 cm shorter limb have an increased risk of knee osteoarthritis (OA) in that limb. We examined whether leg length inequality (LLI) confers an increased risk of hip OA.

METHODS: Using long limb radiographs from MOST and the Osteoarthritis Initiative, we measured LLI and scored hip radiographs which were obtained at baseline and 3-5 year follow-up. We examined the association of >1 cm LLI and >2 cm of LLI with radiographic hip OA cross-sectionally and longitudinally, assessing risk in shorter limbs and longer limbs compared with limbs with no LLI. We carried out logistic regression analyses with GEE and adjusted for age, sex, BMI, height and cohort of origin.

RESULTS: In MOST, we studied 1,966 subjects and in OAI 2,617 subjects. 12% of persons had LLI of >1 cm and 1% had LLI of >2 cm. For LLI >1 cm, the adjusted OR for prevalent hip OA in the shorter leg was 1.47 (95% CI 1.07-2.02) and for LLI >2 cm, it was 2.15 (95%CI 0.87-5.34). For LLI >1 cm, the odds of incident hip OA in the shorter leg was 1.39 (95%CI 0.81-2.39) while for LLI >2 cm, the odds in the shorter leg was 4.20 (95%CI 1.26 - 14.03), We found no increased risk of hip OA in longer limbs.

CONCLUSION: Our findings suggest that, like knee OA, limbs at least 2 cm shorter are at increased risk of hip OA.