Assessing LLD And Whether Shoe Lifts Can Have An Impact

Author(s): 
David Levine, DPM, CPed

While most of the published research on leg length discrepancy (LLD) focuses on surgical intervention, conservative care may be helpful in this regard. Accordingly, this author discusses the assessment of LLD and how shoe lifts can be beneficial.

When it comes to leg length discrepancies (LLDs), the literature has infrequently described a practical approach — namely conservative use of footwear as part of the solution — although etiologies and surgical treatments have been well documented. The majority of the LLD literature is geared toward surgical intervention, perhaps because quantifying the efficacy of conservative treatment is fairly subjective. There are so many variables to consider, including the activity level of the person, the body type and the way to truly assess the amount of difference present.

   While the causes of LLDs are divided into functional and structural etiologies, the simple fact remains that the person who has a LLD is functioning every day and every step with one leg longer than the other. Add scoliosis into the equation or a pelvic tilt, and significant asymmetry results. Regardless of the cause, treatment should start conservatively.

   We see clues on a daily basis as to the prevalence of LLD. In fact, it is estimated that 1 to 2 percent of adolescents and 50 percent of people over 60 have a LLD.1 Asymmetric structural findings, such as asymmetric hallux limitus, are the first clue to indicate that a LLD may be present. Over time with feet having to compensate for the leg length inequality, one foot will be forced to pronate more than the other. This constant driving of the first ray into the ground, whether this is on the longer or shorter side, will contribute to an early breakdown of the first metatarsophalangeal joint (MPJ). That is not to say that every hallux limitus is the result of a LLD but if hallux limitus is an asymmetric finding and it is not traumatically induced, looking for a LLD is simple, quick and worthwhile.

   If one is planning surgery, identifying this difference preoperatively becomes especially important in ensuring a satisfactory outcome. If one does not identify and address the LLD sufficiently, it is quite possible to see either rapid recurrence of the problem or a failed procedure.

   Leg length discrepancy could result in recurrent bunion deformities, failed hallux limitus surgery, Charcot arthropathy, reconstructive rearfoot or ankle surgery, and many other difficult to explain phenomena. These are just the podiatric implications. These do not include hip and knee joint replacements, spinal fusions and other lower extremity problems that are common to the general population.

   A clear analogy is the front end of a car. If it is not aligned properly, the car will constantly pull to one side. When this occurs, repair is needed. Unfortunately, our patients do not always realize they need repair and continue to function and cause further damage. In less severe cases, maybe only the front tires will wear unevenly. However, if one just replaces the tires, this is analogous to treating only the symptoms. After several hundred miles, the same exact thing can happen again.

   Another analogy is the foundation of a building where symmetry is critical. You would never want to build upward on a crooked foundation. That would be a cause for instability, breakdown and disaster. The bottom line is that mechanical symmetry is critical for a machine to run smoothly and efficiently, or for a building to be stable. This is no less important for the human body.

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