Short Leg Syndrome
Leg length inequality is estimated to plague over eighty percent of the population. When a spine loses its ability to properly compensate for this structural fault, serious problems develop over time. A short leg can lead to osteoarthritis, spinal disc degeneration, and pain from the legs to the head. A short leg coupled with these symptoms is broadly called "Short Leg Syndrome".
A person with a short leg will follow specific trends in pain. Commonly it is mild low back pain beginning after standing or walking a short time (15 to 30 minutes) which gets worse the longer a person is on their feet and gets better is they can sit down.
When one leg is shorter than the other it unlevels the base of the spine. Since the spine (and upper body) is like a tower built on this base it becomes unlevel as well. When the spine tilts over to the side the muscles have to tighten up to keep it from falling over. These muscles begin to get tired. This is where the pain comes from. If the muscles are strong and in top condition they can stand the strain longer without pain which can delay onset. The actual tilt level difference doesn’t have to be much. As little as 5 mm (about 1/4") can offset the upper body enough to create the stress on the muscles.
A “Short Leg Syndrome” should be broken into one of three specific categories.
Anatomical Short Leg
About 5 % of the time a short leg is due to a congenital or developmental defect. Another small percentage of short legs are the result of leg fractures or surgeries. For these types of short legs, a heel lift or arch support should be prescribed.
Structural Short Leg
Without the historical background of trauma or surgery the cause can be the cumulative effect of all the lower extremity parts - bones, knee joints, ankles, feet - being different lengths when subjected to gravity (standing up).
This is a structural difference which can be measured by an x-ray; taken while the patient is standing up.
Functional Short Leg
The most common cause of leg length inequality is pelvic or spinal misalignment that causes what is known as a "functional" short leg. Twisting of the pelvis occur frequently as a result of strain or injury. Foot problems such as fallen arches can also cause a short leg.
This does not show a measurable difference on an x-ray. The case history is more important.
Generally, restoration of mobility through physical therapy and manipulation is enough to correct this.