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Association of Leg-Length Inequality With Knee Osteoarthritis: A Cohort Study

William F. Harvey, MD, MSc; Mei Yang, PhD; Theodore D.V. Cooke, MA, MB, BChir; Neil A. Segal, MD, MS; Nancy Lane, MD; Cora E. Lewis, MD, MSPH; and David T. Felson, MD, MPH
[+] Article and Author Information

From Boston University School of Medicine and Tufts Medical Center, Boston, Massachusetts; Queen's University, Kingston, Ontario, Canada; University of Iowa, Iowa City, Iowa; University of California at Davis, Davis, California; and University of Alabama, Birmingham, Alabama.


Acknowledgment: The authors thank the participants and staff of MOST and the staff of the Boston University Clinical Epidemiology Research and Training Unit, who assisted in coordinating the radiography.

Grant Support: By grants from the National Institute on Aging (U01-AG-18820, 18832, 18947, and 19069) and the National Institute of Arthritis and Musculoskeletal and Skin Diseases (K24-AR-048841), National Institutes of Health, and by the American College of Rheumatology Research and Education Foundation's Clinical Investigator Fellowship Award.

Potential Conflicts of Interest: Disclosures can be viewed at www.acponline.org/authors/icmje/ConflictOfInterestForms.do?msNum=M09-1311.

Reproducible Research Statement:Study protocol and statistical code: Available from Dr. Harvey (e-mail, wharvey@tuftsmedicalcenter.org). Data set: Some data used in this project will be released to the public in early 2010 as a documented analytic data set (http://most.ucsf.edu).

Requests for Single Reprints: William F. Harvey, MD, MSc, Tufts Medical Center, 800 Washington Street, Box 406, Boston, MA 02111; e-mail, wharvey@tuftsmedicalcenter.org.

Current Author Addresses: Dr. Harvey: Tufts Medical Center, 800 Washington Street, Box 406, Boston, MA 02111.

Drs. Yang and Felson: Boston University Clinical Epidemiology and Training Unit, 650 Albany Street, Suite 200, Boston, MA 02118.

Dr. Cooke: Queen's University, 797 Princess Street, Suite 404, Kingston, Ontario K7L 1G1, Canada.

Dr. Segal: Department of Orthopedics and Rehabilitation, University of Iowa, 200 Hawkins Drive, 0728 JPP, Iowa City, IA 52242-1088.

Dr. Lane: Aging Center, Medicine and Rheumatology, University of California at Davis Medical Center, 4800 2nd Avenue, Suite 2600, Sacramento, CA 95817.

Dr. Lewis: University of Alabama, 1717 11th Avenue South, Suite 614, Birmingham, AL 35205.

Author Contributions: Conception and design: W.F. Harvey, N. Segal, N. Lane, D.T. Felson.

Analysis and interpretation of the data: W.F. Harvey, M. Yang, T.D.V. Cooke, N. Lane, D.T. Felson.

Drafting of the article: W.F. Harvey, N. Segal, N. Lane.

Critical revision of the article for important intellectual content: W.F. Harvey, N. Segal, N. Lane, C.E. Lewis, D.T. Felson.

Final approval of the article: W.F. Harvey, T.D.V. Cooke, N. Segal, N. Lane, C.E. Lewis, D.T. Felson.

Provision of study materials or patients: C.E. Lewis.

Statistical expertise: W.F. Harvey, M. Yang, N. Lane.

Obtaining of funding: C.E. Lewis, D.T. Felson.

Administrative, technical, or logistic support: C.E. Lewis, D.T. Felson.

Collection and assembly of data: W.F. Harvey, M. Yang, N. Segal, N. Lane, C.E. Lewis, D.T. Felson.


Ann Intern Med. 2010;152(5):287-295. doi:10.7326/0003-4819-152-5-201003020-00006
Text Size: A A A

Background: Leg-length inequality is common in the general population and may accelerate development of knee osteoarthritis.

Objective: To determine whether leg-length inequality is associated with prevalent, incident, and progressive knee osteoarthritis.

Design: Prospective observational cohort study.

Setting: Population samples from Birmingham, Alabama, and Iowa City, Iowa.

Patients: 3026 participants aged 50 to 79 years with or at high risk for knee osteoarthritis.

Measurements: The exposure was leg-length inequality, measured by full-limb radiography. The outcomes were prevalent, incident, and progressive knee osteoarthritis. Radiographic osteoarthritis was defined as Kellgren and Lawrence grade 2 or greater, and symptomatic osteoarthritis was defined as radiographic disease in a consistently painful knee.

Results: Compared with leg-length inequality less than 1 cm, leg-length inequality of 1 cm or more was associated with prevalent radiographic (53% vs. 36%; odds ratio [OR], 1.9 [95% CI, 1.5 to 2.4]) and symptomatic (30% vs. 17%; OR, 2.0 [CI, 1.6 to 2.6]) osteoarthritis in the shorter leg, incident symptomatic osteoarthritis in the shorter leg (15% vs. 9%; OR, 1.7 [CI, 1.2 to 2.4]) and the longer leg (13% vs. 9%; OR, 1.5 [CI, 1.0 to 2.1]), and increased odds of progressive osteoarthritis in the shorter leg (29% vs. 24%; OR, 1.3 [CI, 1.0 to 1.7]).

Limitations: Duration of follow-up may not be long enough to adequately identify cases of incidence and progression. Measurements of leg length, including radiography, are subject to measurement error, which could result in misclassification.

Conclusion: Radiographic leg-length inequality was associated with prevalent, incident symptomatic, and progressive knee osteoarthritis. Leg-length inequality is a potentially modifiable risk factor for knee osteoarthritis.

Primary Funding Source: National Institute on Aging.

Figures

Grahic Jump Location
Figure 1.
Diagram of a bilateral standing full-limb radiograph.

A. Measurements of leg-length inequality. B. Mechanical axis alignment.

Grahic Jump Location
Grahic Jump Location
Figure 2.
Associations of LLI and knee OA.

LLI = leg-length inequality; OA = osteoarthritis; OR = odds ratio.

Grahic Jump Location

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Comments

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Leg measurement helpful
Posted on June 11, 2010
Morton Linder
No Affiliation
Conflict of Interest: None Declared

Dear Dr. Harvey, I read with great interest your article about measuring leg lengths via radiographic images. It brought back many memories of my years in Medical School, and my many years of practice before I retired.

Over 50 years ago, while in Medical School i Utrecht, the Netherlands, I was taught to carefully measure both leg lengths at the bony landmarks with a simple tape measure. Inequality of more than one cm. was usually treted with a shoe wedge at the short leg side. Oftentimes, this simple DX and Rx relieved the pains at the low back, hips, and/or knees. This was helpful many dozens of times during my years in practice.

Keep up the good work.

Conflict of Interest:

None declared

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Summary for Patients

Unequal Leg Length and Knee Osteoarthritis

The summary below is from the full report titled “Association of Leg-Length Inequality With Knee Osteoarthritis. A Cohort Study.” It is in the 2 March 2010 issue of Annals of Internal Medicine (volume 152, pages 287-295). The authors are W.F. Harvey, M. Yang, T.D.V. Cooke, N.A. Segal, N. Lane, C.E. Lewis, and D.T. Felson.

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