Is Leg Length Discrepancy Linked To Lower Back Pain?

Have you ever been told or noticed that one of your legs is a bit longer than the other?  Do you have incidences of lower back pain?  These two things could be related.  Most individuals have a small difference in their leg lengths.  For some, the discrepancy is small and negligible and will not be a contributor to lower back pain.  This is usually the case for people if their leg length is less than 5 millimeters.  However, a difference of leg lengths greater than 5 millimeters (1/4 inch) can contribute to lower back pain. If you have a leg length difference of greater than 9 mm, then you have a 6X greater likelihood of having an episode of lower back pain.

Causes
Leg length discrepancies can be caused by poor alignment of the pelvis or simply because one leg is structurally longer than the other.  Regardless of the reason, your body wants to be symmetrical and will do its best to compensate for the length difference.  The greater the leg length difference, the earlier the symptoms will present themselves to the patient.  Specific diagnoses that coincide with leg length discrepancy include: scoliosis, lumbar herniated discs, sacroiliitis, pelvic obliquity, greater trochanteric bursitis, hip arthritis, piriformis syndrome, patellofemoral syndrome and foot pronation.  Other potential causes could be due to an injury (such as a fracture), bone disease, bone tumors, congenital problems (present at birth) or from a neuromuscular problem.

Symptoms

• An obvious observance of one leg being longer than the other
• Affected posture
• Problems with gait (manner of walking)
• Pain in the lower back, hip, ankle or knee

Classifications
Leg length discrepancies can be classified as a structural leg length discrepancy or a functional leg length discrepancy.  A structural leg length discrepancy is a hereditary circumstance that one leg is simply longer than the other leg.  This is determined if the patient’s pelvis and sacroiliac joints are symmetrical and the leg length is simply due to one leg truly being longer than the other.  The best way to determine if a structural leg length discrepancy is present is with an anterior-posterior x-ray of the pelvis.  A clinical alternative is using a tape measure to measure the length of the leg from the hip to the ankle.

Functional leg length discrepancy is diagnosed when there is a torsion or pelvic rotation/obliquity, commonly a sacroiliac joint dysfunction, which causes one leg to function as though it is longer or shorter than the other.  In order to determine if a true structural discrepancy exists, the physical therapist must treat the pelvis and return it to a neutral position before measuring for the leg length discrepancy.  Once the pelvis is symmetrical it is determined if the leg length discrepancy remains or if it goes away, if it goes away it is classified as functional.  If it remains and has a measurable difference, it is a structural leg length discrepancy.

Treatment
Structural leg length discrepancy can be treated with a heel lift in the shorter leg’s shoe, if the leg length is greater than 5 mm.  The use and size of the heel lift is determined by a physical therapist based on how much lift is needed to restore proper lumbopelvic biomechanics. In certain cases, surgical intervention may be needed to either shorten or lengthen the limb. An important component to any surgical procedure to correct leg length discrepancies is physical therapy. Physical therapy  helps to stretch muscles and maintain joint flexibility, which is essential in the healing process.

For a functional leg length discrepancy no heel lift is required, but proper manual therapy techniques and specific therapeutic exercise is needed to treat and normalize pelvic and lower extremity compensations.  The number of treatments needed to hold the pelvis in a symmetrical position is different for each patient based on their presentation and biomechanical dysfunctions in their lower back, pelvis, hip, knee, and foot/ankle.

If you have pain in your lower back or lower extremity and possibly a length discrepancy; the two symptoms could be related.  A good place to start would be a physical therapy evaluation to determine whether you have a leg length discrepancy and if it could be contributing to your lower back pain, hip pain, knee pain, or leg pain.