Keys To Recognizing And Treating Limb Length Discrepancy

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

   The goal of dynamic gait assessment via computer-assisted gait analysis is to identify and reduce torque and stress so the right and left pedal segments spend the same amount of time on the ground, generate the same normal pressure and move with the same speed. It is non-invasive, relevant, repeatable and reliable. It is capable of detecting locomotor events that one cannot observe with the naked eye or time with a stopwatch as well as forces too small or rapid to detect. Gait analysis quantifies and records weight distribution patterns and temporal parameters in a realistic environment (i.e. inside the shoe).

   Perform an initial computer-assisted gait analysis prior to orthotic prescription in order to gauge pre-treatment symmetry or asymmetry, weight distribution patterns, COF and phases of gait. When it comes to assessing symmetry, useful parameters include: stance, single support, propulsion, midstance, heel duration, heel pressure, time speed, center of pressure patterns, etc. Functional limb symmetry or asymmetry following the use of prescription foot orthoses is not predictable with certainty. Accordingly, one should only address this after orthotic realignment.

   After dispensing the orthotic devices and after a period of patient familiarization with their use, usually two weeks, perform a follow-up, computer-assisted gait analysis to assess symmetry and evaluate weight redistribution patterns. More often than not, individuals with functional discrepancies revealed by initial testing will exhibit functional symmetry after the orthotic intervention.

   In some cases, patients who did not exhibit functional symmetry initially now function asymmetrically and require a lift. This may be a result of treatment now rendering the musculoskeletal system unable to compensate pathologically for the discrepancy, in effect rendering it uncompensated. If symmetry is unachievable, this warrants osteopathic, physiatrist, physical therapist or chiropractic referral for further evaluation.

A Guide To The Methodology Of Assessing LLD

In a computer-assisted gait analysis study of 17 individuals with an identified limb length discrepancy and unilateral musculoskeletal symptomatology, the addition of a ¼-inch heel raise to the shorter limb resulted in 50 to 100 percent symptom improvement in all cases.19 Additionally, the average cadence of 48.2 steps per minute on the longer side and 52.3 steps per minute on the shorter side improved to 44.0 steps/minute on the longer limb and 45.0 steps per minute on the shorter limb.

   Customarily, one may place lifts of up to 5/8 inches inside the shoe. Discrepancies greater than ¾ inches will require a tapered extension to the forefoot of approximately half the amount of heel lift required. One may also reduce the heel or remove the shoe insole on the longer limb to achieve symmetry. One may address LLDs up to 7/8 inches in this manner without having to conspicuously alter the short limb shoe.

   To obtain functional symmetry, most individuals respond well to 1/8-inch, ¼-inch or 3/8-inch lifts. It is less common for ½-inch lifts or greater to be necessary to achieve symmetry. In those individuals who do not seem to be able to achieve functional symmetry, even with increasing lift heights, reassessment of sacroiliac and lumbosacral mobility is warranted.

   No matter what size lift is appropriate, begin with either a 1/8-inch or ¼-inch lift, and gradually increase the amount in 1/8-inch increments every few weeks. This is to ensure that adaptive contractures in the hip and low back slowly return to normal function. Physicians may adjunctively employ gentle stretching of this musculature.14

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

Great article!

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