Keys To Recognizing And Treating Limb Length Discrepancy
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
Lifts are not forever. What is appropriate at the onset of treatment may not be what is required six months later. Periodic evaluation is necessary. Once the patient has achieved symmetry, perform a computer-assisted gait analysis in two to three months to reassess. It has been my observation that functional LLDs in most individuals tend to reduce over time with treatment. This may be due to assimilation of the lift action into the musculoskeletal functional framework, thereby in some cases obviating the need for a lift at all. If the need for the lift is still apparent at the time of the first follow-up computer-assisted gait analysis, reassess it in six months and periodically thereafter.
The bottom line is when a patient states, “Fifteen years ago, my doctor told me my right leg is shorter so I have a lift built into all my shoes,” that lift is not doing the same thing now as it did at the initial prescription. Many times, I have found it is either too much, too little, not needed or on the wrong side.
Limb length discrepancy is a common musculoskeletal deficiency with widespread untoward effects. Historic methods to statically assess its presence do not address or take into consideration its dynamic requirements. Computer-assisted gait analysis is a non-invasive, objective, relevant, reliable clinical method to identify, quantify and manage functional asymmetry.
Dr. D’Amico is a Professor and Past Chairman in the Division of Orthopedics at the New York College of Podiatric Medicine. He is a Diplomate of the American Board of Podiatric Medicine, a Fellow of the American College of Foot and Ankle Orthopedics, and a Fellow of the American Academy of Podiatric Sports Medicine. Dr. D’Amico is in private practice in New York City.