Assessing LLD And Whether Shoe Lifts Can Have An Impact

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Author(s): 
David Levine, DPM, CPed

   There are many specialties that are forced to deal with LLDs. We as podiatrists often deal with the condition in the form of heel lifts in the shoe or heel lifts that one can add to orthotic devices. This is often inadequate and unsuccessful in fully addressing what the patient actually needs. Physical therapists and chiropractors will often try and address discrepancies with adjustment of the hips and spine. Although this can work well, it may only be temporary, sometimes lasting until the patient gets up from the exam table. Then there are differences of opinion from time to time. Some specialists believe that regular adjustment will address it adequately but others see this only as practice management.

   Orthopedists and neurosurgeons see LLDs in their practices regularly. However, they may not feel the need to treat or even look for discrepancies unless the difference is large or the cause of symptoms is obvious. Often the orthopedist’s best intervention is on the operating table in the form of sizing joint implants properly. Unfortunately, the table or even the radiographic view does not always correlate with the way a person functions. When a patient is supine, scoliosis or pelvic tilt issues may not be as easy to appreciate. The key is assessing how the person functions.

   With the high frequency of joint implantation surgery occurring in the baby boomer age group, checking for LLDs should become a routine part of a biomechanical examination. Often when a patient needs a joint replacement, the affected limb has gone through changes over the years. For example, sometimes when knee replacement is necessary, the affected lower extremity may exhibit genu valgum or varum, which might be asymmetric. Once the joint is replaced, that limb may then be rectus but the other limb might not be. Structurally, the bony segments may measure the same but may not be in the same plane of function.

How To Test For Leg Length Discrepancy

There are simple quick diagnostic tests that one can perform when suspicious of a leg length discrepancy. The literature reports that there is a lack of intratester and intertester consistency, making it difficult to arrive at a definitive amount. There is a sensible solution to this problem. Let the patient decide if there is a significant difference and how much of that difference needs to be addressed. If you suspect a LLD and you are wrong, your patient will tell you. If you are right, the patient will thank you. This will all happen within a week or two at the most. This approach is also a cost effective way of approaching the problem.

   First, have your patients stand in front of you in a relaxed position without shoes on. Talk to them for a bit as you assess their posture and the position in which they are most comfortable standing. If you see a pelvic tilt or a slant to the belt line, this will serve as supportive evidence.

   Then see if their posture changes. For example, some people constantly shift from one foot to the other while others may favor standing on one foot more than the other. When the latter is the case, this is often a clue to which side is shorter. Due to gravity, it is easier to go downhill and stand on the shorter limb than it is to go uphill and stand on the longer side.

   Additionally, if someone does have a leg length discrepancy, he or she is probably not comfortable standing for too long without constantly changing position. They will find themselves consistently changing feet for support. It is all about symmetry. If the legs are equal in length and the foundation stable, using both feet and legs for equal balance will be more comfortable.

   Palpating the anterior superior iliac spine and the pelvic crests is helpful, but not if the patient is obese. In obese patients, those bony landmarks are obscured, making it difficult to objectively assess them. Having the patient supine with knees bent will allow you to see if the femoral or tibial segments differ in length. You can always measure these segments but this is too subjective to be effective or reliable. Measuring also does not take scoliosis or other pelvic issues into account.

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