Keys To Recognizing And Treating Limb Length Discrepancy

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Author(s): 
Joseph C. D’Amico, DPM, DABPO

   Other authors feel that the commonly occurring 1 to 1.5 cm discrepancies do not lead to symptoms and may not need treatment.5 However, discrepancies as small as 1 cm have been associated with back pain and plantar fasciitis.32,39 Harvey and associates, in a study of 3,026 subjects with radiographically confirmed LLD, determined that those with 1 cm discrepancies were more likely to develop knee pain and osteoarthritis on the shorter limb.40 In those with 2 cm or greater discrepancies, pain and osteoarthritis were present bilaterally. Additionally, this study points out that LLDs as small as 5 mm may be associated with increased odds of prevalent symptomatic knee osteoarthritis. It is because of this and the documented prevalence of osteoarthritis in the hip on the longer limb that some authors contend that any LLD should receive treatment.40,41

   As I mentioned earlier, even minor discrepancies may result in major problems when the musculoskeletal system is placed in stress situations. A basic tenet in a biomechanics-based medical practice is that excessive loads, whether they are brief, high impact, loading or cumulative stresses, have the potential to cause structural damage to all facets of the musculoskeletal system. In any case, the ideal situation for all individuals is for both limbs to be of equal length and function symmetrically. Specifically, there should be normal application of pressure for the normal duration of time applied equally through each limb at each phase of the walking or running cycles.

What You Should Know About Functional Symmetry

A level pelvis does not ensure symmetrical function. Equal limb length does not ensure functional symmetry. An individual with a structural LLD may function symmetrically while some individuals with equal length of the extremities may function asymmetrically. Computer-assisted gait analysis may help determine this with in-shoe pressure transducers capable of measuring time, pressure and direction of force.19,42

   It is one thing to measure limb length either clinically or radiographically, and couple the findings with symptomatology and observational gait analysis. However, it is another story to be able to identify and assess symmetry where it matters most: in action. Life is movement and the locomotor system is designed just for that purpose (i.e. to transport the individual to a desired destination in the mot efficient fashion utilizing the least expenditure of energy). Symmetrical function lowers energy requirements and improves efficiency. With the population today living longer, more active lifestyles, it is imperative for patients to maintain the ability to walk without pain. This starts with optimum symmetrical lower extremity alignment and function.

How To Assess And Obtain Functional Symmetry

The first step in assessing and obtaining functional symmetry is to negate all untoward musculoskeletal influences and deficiencies. This includes identification and neutralization of all abnormal pronatory influences and malalignment. This may entail any or all of the following interventions: prescription of foot orthoses; identification and stretching of posterior group contractures (equinus influences); improving restricted ranges of motion, especially in the hip, knee, ankle and subtalar joints; strengthening of weak musculature; strengthening of joint stabilizers in individuals with ligamentous laxity; weight reduction (when appropriate); evaluation and remediation of inappropriate footwear, etc.

   After addressing these factors, one can assess symmetry functionally. In my early years in practice, I would equalize limb length based on clinical and radiographic measurements as well as sacral leveling. Computer-assisted gait analysis taught me that leveling the pelvis or equalizing limb length may in fact create pedal and limb imbalances during gait. This manifests via asymmetrical plantar pressures as well as temporal parameter disturbances.

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Stanley Beekmansays: June 8, 2014 at 11:23 pm

Great article!

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