Exploring the Links Between Human Movement, Biomechanics & Gait
Tag: leg length difference
A visual example of the consequences of a leg length discrepancy.
This patient has an anatomical (femoral) discrepancy between three and 5 mm. She has occasional lower back discomfort and also describes being very “aware” of her second and third metatarsals on the left foot during running.
You can clearly see the difference in where patterns on her flip-flops. Note how much more in varus wear on the left side compared to the right. This is most likely in compensation for an increased supination moment on that side. She is constantly trying to lengthen her left side by anteriorly rotated pelvis on that side and supinating her foot and trying to “short” the right side by rotating the pelvis posteriorly and pronating the foot.
With the pelvic rotation present described above (which is what we found in the exam) you can see how she has intermittent low back pain. Combine this with the fact that she runs a daycare and is extremely right-handed and you can see part of the problem.
Leg length discrepancies become clinically important when they resulting in a compensation pattern that no longer works for the patient. Be on the lookout for differences and wear patterns from side to side.
5mm cut off ? MaybeYou are likely to come across hip and knee arthroplasty clients (total joint replacements). When they take a joint out and replace it with a new one, it can be a true challenge to restore leg lengths to equality side to side. Problems often arise down the road once gait is resumed and rehabilitation is completed. It can take time for the leg length discrepancy (LLD) to begin to create compensatory problems. This article seems to suggest that 5mm is the tipping point where gait changes becoming a problem are founded. Other sources will render different numbers, this article found 5mm. The authors found that both over- and underrestoration of leg length/offset showed similar effects on gait and that Gait analysis was able to assess restoration of biomechanics after hip replacement. I would chose to use the word “change” over restore, since the gait analysis is merely showing the deployed strategies and compensations, never the problem. But it is a tool, and gait analysis can be a decent tool to show “change”.*Remember, it is not always a product of true length, it can come from the pelvis posturing and/or from the acetabular orrientation, which can be a postoperative sequella. One cannot over look acetabular inclination, anteversion and femoral component anteversion/retroversion issues.Just remember, before you start making LLD changes with inserts, cork, orthotics etc be sure that you have restored as best as possible, pelvis-hip-spine mechanics because changes here can reflect as a mere leg length discrepancy. And it goes the other way as well, a LLD can cause those changes above.
* Just use your brain and don’t just lift the heel, give them a full sole lift. Heel lifts for this problem are newbie mistakes. Don’t be a newbie.
So a patient presents to your office with a recent history of a L total knee replacement 8 weeks ago AND a recent history of a resurgence of low back pain, supra iliac area on the L side. Hmmmm. Hope the flags went up for you too!
His global lumbar ROM’s were 70/90 flexion with low back discomfort at the lumbo sacral junction, 20/30 extension with lumbosacral discomfort, left lateral bending 10 degrees with increased pain (reproduction); right lateral bending 20 degrees with a pulling sensation on the right. Extension and axial compression of the lumbar spine in left lateral bending reproduced his pain.
Neurologically he had an absent patellar reflex on the left, with diminished sensation over the knee medially and laterally. Muscle strength 5/5 in LE; sl impaired balance in Left single leg standing. There was incomplete extension of the left knee, being at 5 degrees flexion (right side was zero).
He has a right sided leg length deficiency (or a left sided excess!) of 5 mm. Take a look at the tibial lengths in the 1st 3 pictures. See how the left is longer? In the next shot, do you see how the knee cannot completely extend? Can you imagine that the discrepancy would probably be larger if it did?
Now look at the x rays. We drew a line across from the non surgical leg to make things clearer.
Now, think about the mechanics of a longer leg. That leg will usually pronate more in an attempt to shorten the leg, and the opposite side will supinate to attempt to lengthen. Can you see how this would cause clockwise pelvic rotation (in addition to anterior pelvic rotation)? Can you see this patients in the view of the knees from the top? Do you understand that the lumbar spine has very limited rotation (about 5-10 degrees, with more movement superiorly (1) ). Does it make sense that the increased range of motion could effect the disc and facet joints and increase the patients low back pain?
So, how do we fix it? Have you seen the movie “Gattica”? Hmmm….A bit extreme. How about a full length 3mm sole lift to start, along with specific joint manipulation to restore normal motion and some acupuncture to reduce inflammation? We say that is a good start.
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(1) Three-Dimensional In Vivo Measurement of Lumbar Spine Segmental Motion Ruth S. Ochia, PhD, Nozomu Inoue, MD, PhD, Susan M. Renner, MS, Eric P. Lorenz, MS, Tae-Hong Lim, PhD, Gunnar B. Andersson, J. MD, PhD, Howard S. An, MD Spine. 2006;31(15):2073-2078.