Leg-length inequality is a potentially modifiable risk factor for knee osteoarthritis, say authors of a study that found that radiographic leg-length inequality was associated with prevalent, incident symptomatic, and progressive knee osteoarthritis.

In a study involving 3,026 participants aged 50 to 79 years with or at high risk for knee osteoarthritis, leg-length inequality was measured by full-limb radiography. The outcomes were prevalent, incident, and progressive knee osteoarthritis.

Compared with leg-length inequality less than 1 cm, leg-length inequality of 1 cm or more was associated with prevalent radiographic and symptomatic osteoarthritis in the shorter leg, incident symptomatic osteoarthritis in the shorter leg and the longer leg, and increased odds of progressive osteoarthritis in the shorter leg.

The authors say that the 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, they added.

The study appears in the March 2 issue of Annals of Internal Medicine.

Any of the PTs at ECRC Physical Therapy can help with the assessment of leg length differences, determining if the difference is due to structural differences [as when a leg bone is previously broken] or other biomechanical dysfunctions that can appear to look like a leg length discrepancy.