A patient has an anatomic short leg when one leg is shorter than the other anatomically and does not simply appear to be shorter due to surrounding anatomy. The most common cause is hip replacements.
A functional short leg occurs when one leg appears to be shorter than the other but is not actually shorter than the other. The surrounding anatomy just makes the leg appear shorter.
Short leg syndrome has many compensation mechanisms. Commonly, the short leg will have an anterior innominate rotation on the same side. This works to extend the length of the short leg to create some semblance of homeostasis. The long leg typically has a posterior innominate rotation on the same side, in an effort to balance the length discrepancy between the legs.
The sacral base is almost always inferior on the side of the short leg. This is another mechanism the body uses to attempt to compensate.
On exam, the pelvis commonly shifts to the side of the long leg in patients with leg length discrepancy.
On the side of the short leg, the lumbar spine commonly side bends away. The lumbar spine will also rotate toward the side of the short leg. These structural findings commonly occur as the body compensates for the leg length discrepancy in an effort for the body to maintain balance.
If an anatomic short leg is suspected after osteopathic manipulative treatment has been performed to correct relevant somatic dysfunctions, then a standing X-Ray is warranted. The height of the femoral heads is measured; if there is a difference of more than 5 mm then consider using a heel lift.
Many times, the leg length discrepancy is due to a functional short leg, and lots of progress can be made with Osteopathic manipulation. Once somatic dysfunctions of the lower spine, innominates, and sacrum is corrected an anatomic short leg can be investigated further.
Patients who are elderly, fragile, arthritic, osteoporotic or in acute pain, start with 1/16th of an inch and increase by increments of 1/16th of an inch every two weeks. If a patient has a hip replacement or another sudden change in leg length, then it is acceptable to replace the entire amount of length discrepancy right away. Stop when one-half to three-quarters of the discrepancy is replaced.
Patients who are young, flexible, fit or otherwise healthy can have their leg length discrepancy replaced more rapidly. Apply 1/8th of an inch every two weeks until ½-3/4th of the discrepancy is replaced.
The maximum height that can be applied inside the shoe is a fourth of an inch. An extra fourth can be applied to the outside of the shoe.
The maximum heel lift that is possible is a ½”. If more lift is needed then the lift should be applied from heel to toe to prevent pelvic shift on the opposite side.
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