Detecting And Treating Leg Length Discrepancies

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Detecting And Treating Leg Length Discrepancies
68
Author(s): 
By Mark A. Caselli, DPM, and Edward C. Rzonca, DPM

How To Determine The Amount Of LLD
Once you’ve diagnosed and classified the LLD, you can proceed to quantify the discrepancy by either a direct or indirect method of measurement.
The direct method involves measuring the distance between the anterior superior iliac spine to the medial malleolus. Unfortunately, the direct method is difficult to reproduce and fails to take into account functional LLDs.
The indirect method is superior to the direct method. The indirect method of limb length evaluation involves reducing the pelvic tilt and leveling the sacral base by placing a material of a known thickness under the short leg while the patient is standing. The indirect method is reproducible and accurate in quantifying the amount of leg length discrepancy. In some cases, you may need to confirm the diagnosis with a roentgenograph.

Top Treatment Insights
The treatment for LLD often depends on whether or not symptoms are present. If the body is compensating for a length difference without causing biomechanical stress in other areas, correcting the difference may alter the patient’s body mechanics in such a way as to cause an injury. If the discrepancy is causing symptoms, you do need to address it in order for a full recovery to take place.
Treatment also depends on the classification of the asymmetry. If your patient has a functional asymmetry due to unilateral foot pronation, you can correct it by emphasizing a properly posted orthotic. When it comes to environmental asymmetry secondary to improper foot gear or canted running surfaces, you can recommend new or appropriate foot gear or a change in the geometry of the running surface.
You can use heel lifts to treat structural limb asymmetry. The purpose of the heel lift is to level off the sacral base and correct the compensatory scoliosis caused by the short leg. You can determine the amount of heel lift needed via the indirect method of evaluating a structural shortage. Again, have the patient stand with his or her subtalar joint in neutral. Place a material of known thickness under the short limb until the iliac crests are level. The thickness of the heel lift under the short leg is the amount of the patient’s limb length inequality.
Initially, you want the amount of heel lift to be about half of the anatomic discrepancy because the superstructure is being realigned in a gradual manner. With feedback from the patient, you can determine the final amount of lift that will produce the best results regarding the underlying symptoms. Approximately a 1/4- to 3/8-inch heel lift can fit into the average adult shoe. If more correction is required, the patient may need an addition to the outside of the shoe.

Editor’s Note: This article reflects the views of the authors and is not necessarily the views of the Department of Veterans Affairs of the Hudson Valley Health Care System in Montrose, N.Y.

Dr. Rzonca is a Diplomate of the American Board of Podiatric Orthopedics and Primary Podiatric Medicine. He is a Staff Podiatrist within the VA Hudson Valley Health Care System in Montrose, N.Y.

Dr. Caselli (pictured at right) is a Professor in the Department of Orthopedic Sciences at the New York College of Podiatric Medicine. He is also a Staff Podiatrist within the VA Hudson Valley Health Care System in Montrose, N.Y.




References:

References

1. Baylis WJ, Rzonca EC: Functional and structural limb length discrepancies: evaluation and treatment. Clin Podiatr Med Surg 5(3), 1988.

2. Caborn DNM, Armsey TD II, Grollman L, et al: Running. In Fu FH, Stone DA (eds) Sports Injuries. Philadelphia, Lippincott Williams & Wilkins, 2001. pp 663-669.

3. Fields KB, Craib M: Biomechanics of running and gait. In Sallis RE, Massimino F (eds) Essentials of Sports Medicine. St. Louis, Mosby, 1996. pp 478-486.

4. Julien PH: Sure Footing. Atlanta, Atlanta Foot & Ankle Center, 1998.

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Anonymoussays: September 15, 2010 at 10:29 am

VERY HELPFUL, THANKS

P.Mitchel,C.Ped

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Vincent Van Suchtelensays: March 12, 2011 at 7:35 am

If patient has a verified structural LLD of 6-8 mm, would you recommend orthotic height for the full 6-8 mm or 3-4 mm?

I have heard that many DPM's recommend half the height of LLD? Why or why not?

Thanks for the reply.

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