This alleged problem is widely discussed in medical literature and it is re assuring to know that the attitude of the medical profession towards the “shorter leg” has evolved over the years.
After neglecting this diagnosis for years, doctors started to prescribe heel wedges for every case of tilted pelvis, and routinely, their diagnosis rested on the observation of the posterosuperior iliac spine. Although the immediate results were good, in the long term, they were disappointing.
Realizing that something was amiss, orthopedic surgeons will tell you that there is no need to correct a “shorter leg” under 1.5 to 2cm. To think that dentists work on a precision of microns…One would hope, that precision in regards to LLD, is a must!
Leg Length Discrepancy Measurement
The first thing to know is that all classical measures are false: pubis to malleoli, greater trochanter to malleoli or iliac crest to malleoli. An articulacy constrain, such as a slight valgus of one foot and a varus on the other foot, will cause one side of the pelvis to rotate forward relative to the opposite side.
To assume that a difference in leg length means that there is an actual difference in the length of the bones (femur and/or tibia) is most of the time a mistake. Most often what we are seeing is an apparent, or functional LLD. This is usually the result of disharmonic feet.
Leg Length Discrepancy and X-Rays
The orthogonal projection in X-Rays does not take into consideration the rotary pivot and the heights of the femurs. A simple articulary constraint (asymmetrical feet) can cause an X-Ray to show a difference of several millimeters. Unless you know for certain that the length of one of your legs is different than the other, you should be skeptical of shoe lifts as the first line of treatment for injuries.
What should be used?
The most accurate and reliable technique of measure is frontal teleradiography of a subject in the standing position.
The angle between the feet should be of 30 degrees. The angle of the radiography tube should be of 15 degrees. And the patient should not be pressed against the plate.
To be accurate, it should be performed at a distance of 4 meters away from the body by measuring the diaphysis of each bone.
If any doubts remain with respect to possible rotations. The measurements should be from the base of the greater trochanter to the inter-condylicus incisures. Unfortunately, it is rarely done this way.
What are the causes of Leg Length Discrepancy ?
Leaving aside genetic and traumatic factors, the two legs should grow symmetrically. To believe that the two legs could grow at different rates would suggest that there is two different types of growth hormones. In fact, asymmetries observed in growth period are linked to postural disequilibrium described in Delpeche’s law: “ Any increased pressure on a limb will slow the growth of that limb” the opposite is also true, “any decrease in pressure will stimulate growth”.
Leg Length Discrepancy and children
In children, most cases of short leg are linked to excessive pressure on the lower limbs caused by a postural disequilibrium. It is important to be aware of your child’s posture habits, as they could be creating an imbalance that will cause them grief in the future. The first thing to do is to reprogram the postural system. By inducing permanent equilibrium, asymmetrical pressure will be reduced. When in doubt, refer to a Posturologist near you.
Symptoms of leg length discrepancy:
1) Meniscus ruptures
2) Herniated disk DDD
3) Lower back pain
4) Coxarthrosis (exposure of the femoral head)
7) Hip pain, always on the side of the short leg.
The Posturepro Team