A limb length difference starts to be become significant around 3mm. With a leg length discrepancy of 6mm the mere shifting from one side of the body to another plus the added stress of sport can cause the equivalent of a 2cm difference.
Sports such as cycling, skiing, rugby will produce a significant difference in function causing muscle and joint fatigue.
During running, forces of up to 3 times body weight are transmitted through the feet and the lower limb, when performing sports that involve leaping and jumping these forces can reach 7 or 8 times body weight.
Leg length discrepancy can either be anatomical or physiological.
Anatomical difference is due to actual measured differences in leg length caused by natural growth retardation.
Physiological leg length results when some other body structure affects leg length e.g scoliosis, muscle imbalance, infection, flat feet, trauma.
Depending on the magnitude of the discrepancy the body can often adapt itself and function quite normally, however, for many the altered mechanics required to compensate can result in:
- Lower back pain
- Iliotibilal band syndrome
- Hip pain
Podiatrists are trained to identify leg length discrepancies.
Treatment can involve a combination of:
- Altering footwear with raises along the entire length of the under side of footwear
- Stretching and strengthening exercises, muscle re-balance