Association of leg-length inequality with knee osteoarthritis: a cohort study

Ann Intern Med. 2010 Mar 2;152(5):287-95. doi: 10.7326/0003-4819-152-5-201003020-00006.

Abstract

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.

Publication types

  • Multicenter Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aged
  • Disease Progression
  • Female
  • Humans
  • Incidence
  • Leg Length Inequality / complications*
  • Leg Length Inequality / diagnostic imaging
  • Longitudinal Studies
  • Male
  • Middle Aged
  • Osteoarthritis, Knee / complications*
  • Osteoarthritis, Knee / epidemiology
  • Prevalence
  • Radiography
  • Risk Factors