Having different leg lengths is not a cause for alarm, in fact it is a fairly common occurrence. Researchers estimate that 40 to 70 percent of the population has one slightly shorter leg.

Although having different leg lengths is normal, it can be a problem for certain groups of people. For example, in athletes, a small difference in leg length can make a big difference in their performance.

Depending on how great the difference is, and what physical condition they are in, elderly people may have a problem with different leg lengths. Researchers attempted to determine how much discrepancy could become a problem using a set of 44 healthy participants age 55 to 86. Small shoe lifts of varying heights were placed in the participants' shoes. Then they walked on a treadmill. Heart rate, muscle activity, oxygen use, and air exchange were monitored.

The researchers found that a 2 cm difference in leg length had a considerable effect on oxygen use and on how hard the walkers felt they were working. Between 2 and 3 cm of difference in leg length made a big difference in most of the factors measured.

The researchers concluded that elderly patients with significant cardiac, pulmonary, or musculoskeletal problems might have trouble walking with even 2 cm of difference in leg length.

It's not uncommon for total hip arthroplasty or other surgical procedures to result in one shorter leg. Fortunately, this does not occur with the direct anterior approach to total hip replacement . The use of a specialized X-ray machine known as a fluoroscope allows the surgeon to see the placement of the component parts of the hip prosthesis in real time and to make adjustments immediately. This assures accurate placement of the hip implant and equal leg lengths before leaving the operating room. Different leg lengths would be rare with this approach.