How common leg length differences can go undetected, affecting athletic performance and physical well being.
Leg length differences in people can lead to abnormal sideways curves in the spine or scoliosis. Screening for scoliosis has been mandated to perform in the middle schools, girls in 7th grade and boys in 8th grade. Unfortunately, according to the Standards for Scoliosis Screening in California Public Schools 2007, a student is referred for a medical screening if the following results are found:
- More than 1/2″ difference in height of iliac crests when standing.
- Significant shoulder height asymmetry and/or elevated scapula (shoulder blade) of more than 1”.
- Prominence of the thoracic ribs or lumbar (low back) area, but specifically to more than a 7 degree curve or greater than a 10 millimeter hump.
As you can see, leg length differences less than 1/2″ are not considered important to report and these differences can certainly affect athletic performance. Even if the junior is sent to the physician for a medical evaluation, it is common for physicians to note that any scoliosis curve less than 10 degrees has a minimal chance to progress and may not refer the student for corrective exercises. If the student does happen to be referred for corrective exercises, these exercises typically revolve only around the spine or trunk, leg length monitoring or correction may not be performed.
Another key issue with finding and controlling leg length differences is that all our bones grow at a different rate especially during puberty when bone growth is rapid. Screening just in the middle schools ages will not help those students that have late growth spurts even into their late high school or early college years. Leg length differences should be assessed during any physical screening, prior to starting any athletic or fitness program or every 2 to 3 months on juniors during their growth spurts, especially if they are participating in sports. Unfortunately, many fitness screening programs that are utilized do not include leg length assessments.
When assessing leg length differences, care must be taken to also screen for abnormal foot mechanics (flat foot on one side and high arch on the other), limitations in the muscles and soft tissue flexibility/mobility of the legs (calf, hamstring, quadriceps, iliotibial band, etc.) and abnormal rotations of the pelvis all of which can create or hide leg length differences. If a person has had a previous injury to their ankle, knee or hip, they might have injured the growth plates in a bone, which will slow down the growth of that bone.
Fixing leg length differences depends on whether they are structural, meaning one bone is physically longer than the other or functional, meaning the pelvis has rotated or possibly the feet have different arch heights.
True structural leg length differences can only be fixed by placing a lift in or on the sole of a person’s shoe. The lift must be placed under the entire foot and not just the heel. Placing the lift under just the heel can shift your center of gravity to far forward and it will also allow for the person’s calf muscle to shorten.
Functional leg length differences must be addressed by specifically correcting the area or areas where there are physical deficits. Rotations of the pelvis bones (iliac) are common and can be corrected by your physical therapist. Just correcting the pelvis bone rotation and not addressing the reason why the pelvis bone rotated (muscle/soft tissue tightness and poor trunk or core strength/stabilization) will not lead to a long term solution. If the leg length is attributed to abnormal foot mechanics or arch heights/shapes, then orthotics will be very beneficial in correcting these problems.
Correcting leg length differences have been one of the significant keys in enhancing athletic performance while decreasing pain and weakness in our patients.