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Leg-Length Difference in the Elderly: How Much Is a Problem?

After an artificial hip replacement, patients sometimes notice a slight but annoying difference between the length of their legs. This difference in length can change the way a person walks. It can also make walking more difficult, requiring more effort. However, the amount of difference that begins to cause problems in an elderly person hasn't been firmly established. Researchers recently set out to find the answer.

They tested 44 men and women who ranged from age 55 to 86. Participants who were selected for the study had less than 1 cm of difference between the length of their legs. None of them had significant neurological, orthopedic, pulmonary, or cardiac problems.

The researchers added crepe shoe lifts to the participants' shoes to mimic the effect of different leg lengths. Then the participants were monitored while walking on a treadmill. The researchers randomly varied the height of the shoe lifts for each participant at 0, 2, 3, and 4 cm. At each height, participants were checked for heart rate, muscle activity, the amount of oxygen they used, and the how much air they exchanged. They were also asked to rate the amount of effort they felt they were exerting.

The researchers found that 2 cm of leg-length difference had a considerable effect on how much oxygen was consumed and how much effort participants felt they were exerting. Between 2 and 3 cm of difference in leg length made a big difference in most of the factors that were tested. This led researchers to conclude that elderly patients with significant cardiac, pulmonary, or musculoskeletal problems might have trouble walking with even 2 cm of difference in leg length.

References: Burke Gurney, PhD, et al. Effects of Limb-Length Discrepancy on Gait Economy and Lower-Extremity Muscle Activity in Older Adults. In The Journal of Bone and Joint Surgery. June 2001. Vol. 83-A. No. 6. Pp. 907-915.

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