Leg length discrepancies and total joint replacments.

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.

– Dr. Shawn Allen

Leg length and offset differences above 5 mm after total hip arthroplasty are associated with altered gait kinematicsTobias Renkawitz, Tim Weber, Silvia Dullien, Michael Woerner, Sebastian Dendorfer, Joachim Grifka,Markus Weber

Hmmm..What’s going on here? Can you see it?

Welcome to Monday, Folks, and News You Can Use! Sometimes, it’s the subtle things that make all the difference.

Take a look at this patients right leg versus left legs (knees in particular). What do you see?  Can you notice the subtle bend in the right knee?  Can you see how she hyperextends the left? Can you see that she has an anatomical deficiency (Tibial) of the left tibia? This is a common finding if you look for it.

 Noticing subtle changes like these in your examination can make all the difference in your outcomes. This particular patient happens to have right-sided knee pain. On examination (difficult to see from the photos) she has increased amounts of mid foot pronation.  She presented with right sided back pain running from the supra iliac region up along the right lumbar paraspinal’s. You can manipulate this patient forever and her problem is not going to improve until you address the cause.

 Develop keen sense of observation. Become a “student of the obvious”.  Keep your eyes and ears open. Expand your clinical skill set.  Sometimes, when all we have is a hammer, everything starts to look like a nail. 

Falling hard; Using supination to stop the drop.

“One thing, affects all things. One change necessitates global change. The more you know, the more you will see (and understand).  The more you know, see and understand, the more responsible you will and should feel to get it right and the more global your approach should become. If your head does not spin at times with all the issues that need to be juggled, you are likely not seeing all the issues you should be seeing.” -Dr. Allen (from an upcoming CME course)

This is a case that has been looked at before but today with new video. This is a client with a known anatomic short leg on the right (sock-less foot) from a diseased right hip joint.  

In this video, it is clear to see the subconscious brain attempting to lengthen the right leg by right foot strike laterally (in supination) in an attempt to keep the arch and talus as high as possible.  Supination should raise the arch and thus the resting height of the talus, which will functionally lengthen the leg.  This is great for the early stance phase of gait and help to normalize pelvis symmetry, however, it will certainly result in (as seen in this video) a sudden late stance phase pronation event as they move over to the medial foot for toe off. Pronation will occur abruptly and excessively, which can have its own set of biomechanical compensations all the way up the chain, from metatarsal stress responses and plantar fasciitis to hip rotational pathologies.  It will also result in a sudden plummet downwards back into the anatomic short leg as the functional lengthening strategy is aborted out of necessity to move forward.  

This is a case where use of a full length sole lift is imperative at all times. The closer you get to normalizing the functional length, the less you need to worry about controlling pronation with a controlling orthotic (controlling rate and extent of arch drop in many cases). Do not use a heel lift only in these cases, you can see this client is already rushing quickly into forefoot loading from the issues at hand, the last thing you should be doing is plantarflexing the foot-ankle and helping them get to the forefoot even faster !  This will cause toe hammering and gripping and set the client up for further risk to fat pat displacement, abnormal metatarsal loading, challenges to the lumbricals as well as imbalances in the harmony of the long and short flexors and extensors (ie. hammer toes). 

How much do you lift ?  Be patient, go little by little. Give time for adaptation. Gauge the amount on improved function, not trying to match the right and the left precisely, after all the two hips are not the same to begin with. So go with cleaner function over choosing matching equal leg lengths.  Give time for compensatory adaptation, it is going to take time.  

Finally, do not forget that these types of clients will always need therapy and retraining of normal ankle rocker and hip extension mechanics as well as lumbopelvic stability (because they will be most likely be dumping into anterior pelvic tilt and knee flexion during the sudden forefoot loading in the late midstance phase of gait). So ramp up those lower abdominals (especially on the right) !  

Oh, and do not forget that left arm swing will be all distorted since it pairs with this right limp challenge. Leave those therapeutic issues to the end, they will not change until they see more equal functional leg lengths. This is why we say never (ok, almost never) retrain arm swing until you know you have two closely symmetrical lower limbs. Otherwise you will be teaching them to compensate on an already faulty motor compensation. Remember, to get proper anti-phasic gait, or better put, to slow the tendency towards spinal protective phasic gait, you need the pelvic and shoulder “girdles” to cooperate. When you get it right, opposite arm and leg will swing together in same pendulum direction, and this will be matched and set up by an antiphasic gait.

One last thing, rushing to the right forefoot will force an early departure off that right limb during gait, which will have to be caught by the left quad to dampen the premature load on the left. They will also likely have a left frontal plane pelvis drift which will also have to be addressed at some point or concurrently. This could set up a cross over gait in some folks, so watch for that as well.

“One thing, affects all things. One change necessitates global change. The more you know, the more you will see (and understand).  The more you know, see and understand, the more responsible you will and should feel to get it right and the more global your approach should become. If your head does not spin at times with all the issues that need to be juggled, you are likely not seeing all the issues you should be seeing.” -Dr. Allen (from an upcoming CME course)

Shawn Allen, one of the gait guys.

Difference between adult and infant gait compensation.

We highly doubt the infants compensated to the point of “recovering symmetrical gait”. It just isn’t possible seeing as there was frank asymmetry in leg length. However, it is quite possible they accomodated quicker with a more reasonable compensation, that MAY have appeared to have less limp. We did not do the study, but over a beer we might guess that the investigators might agree that our verbiage is closer to accurate. None the less, cool stuff to cogitate. We are very appreciative of this study, there is something to take from this study.

“The stability of a system affects how it will handle a perturbation: The system may compensate for the perturbation or not. This study examined how 14-month-old infants-notoriously unstable walkers-and adults cope with a perturbation to walking. We attached a platform to one of participants’ shoes, forcing them to walk with one elongated leg. At first, the platform shoe caused both age groups to slow down and limp, and caused infants to misstep and fall. But after a few trials, infants altered their gait to compensate for the platform shoe whereas adults did not; infants recovered symmetrical gait whereas adults continued to limp. Apparently, adult walking was stable enough to cope with the perturbation, but infants risked falling if they did not compensate. Compensation depends on the interplay of multiple factors: The availability of a compensatory response, the cost of compensation, and the stability of the system being perturbed.”- From the Cole et all study (reference below)

– thoughts by Shawn Allen


Infant Behav Dev. 2014 Aug;37(3):305-14. doi: 10.1016/j.infbeh.2014.04.006. Epub 2014 May 20.Coping with asymmetry: how infants and adults walk with one elongated leg.Cole WG1, Gill SV2, Vereijken B3, Adolph KE4.


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.

The Gait Guys. Increasing your gait literacy with each and every post. If you liked this post, please send it to someone else for them to enjoy and learn. 

(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.

Podcast #18: Treadmills, ‘Shrooms & Santa

If you do not split a gut laughing by the time the band plays there is something wrong with you ! Who says gait stuff isn’t entertaining !
Perhaps our best podcast to date ? You decide.

Permalink URL

itunes link:


Topics: Treadmills, neuroreceptors, foot types, hip biomechanixcs, gait cycle

Neuroscience piece link:


1. from Eric on our FB page:

a. Had a 9yr old girl for a shoe fitting recently. She had a forefoot valgus, with a rearfoot that is neutral or slightly varus. Fairly high arch and rigid Midfoot for a child that age as well. usually a child’s foot is super flexible so this makes me wonder if it’s a compensation for a true FF varus. How do I tell if he has an anatomic FF valgus vs a compensated version?

b. I asked Blaise Dubois his opinion on Treadmill vs outdoor running and he mentioned that the literature indicates TM’s aren’t much different than outdoor. He cites (Wank 1998). To me, running feels completely different and I can’t run nearly as efficiently on a TM as outdoor. i know some people are the opposite, which i subscribe to specificity of training.

the question i have is what basis do you use for your opinion on different motor patterns? i agree with you, but the literature seems to disagree. this is a piece from cybex so of course it will be “pro-treadmill”, but they quote several studies that concur with Wank… http://media.cybexintl.com/cybexinstitute/research/Truth_on_Fit_Apr10.pdf

hope i’m not sending too many questions. i figure you can ignore them if you have too many from other listeners.

2. On the Hip Bio Pt 6 you mention ext rot leg to gain leg length.  This one has been racking my brain.  I could see how this could happen if the person supinates the foot at the same time, but is there some other external rotating mechanism occurring in the hip that would cause this lengthening?  Thanks,Ryan


Hi Gait Guys,

I am a chiropractor in South Africa, and find gait, biomechanics and running fascinating…I’m hoping to become a true gait geek one day.Reading your blog has taught me so much, you guys seem to look at gait from every angle and don’t take things at face value.

I would like to find out about your Shoe Fit Certification Program. Can people from outside the USA complete the course? Would I be able to take the exam online? and would it give me any creditation in South Africa

 Hope to hear from you soon.

 Regards, Claire

3. I have been watching your video’s on you tube.  I have a cavus foot in which I have had severe nerve pain, why is the high arch caused by nerve pain?

And would any of your exercises help with my nerve pain


4. Hi guys,
Found your youtube channel. Very interesting stuff. Have started reading up on the whole gait cycle. Its very interesting.
I have a quick question that I hope that you can help me with:
Are you aware of any correlation of hip impingement (cam/pincer) in terms of having an irregular gait cycle?
I am suffering from both CAM & PINCER impingement in my right hip. Had surgery in January, but they did not shave sufficiently off the bone, so going back to surgery soon.
I am therefore interested in seeing how surgery possible could help me with bettering my walk and strain on my lower back / leg / foot. And also in terms of looking into some theory on how to retrain myself in walking cycles.
The problem is, that this kind of rehab/research is not available here in Denmark. So would appreciate if you are aware of any research on the above, and would be able to point me in the direction of that.
Thank you – and keep those great videos coming. 🙂
Terje (Denmark)

More on Leg Length Discrepancies

Hi Guys,

I hope you guys are well?

I have a question I hope you can help me with?

Last week I assessed an entire football team, and over 90% have some sort of Leg Length Discrepancy (LLD). I am working with the physiotherapist to improve their weaknesses, including using sole lifts.

My question is if it’s a tibial short leg, then a lift with align the knee and hip. But a lift in a leg with a short femur will align the pelvis but raise the knee higher than the other side. Would you still insert a sole raise, and if not, what would you do?

Kind Regards



Hi Luke

Yes, you are correct in your assumption of the change in mechanics, and yes, most often, we prescribe a sole lift, if a lift is indicated. Keep in mind that if they are asymptomatic and test out well, a lift may not be indicated. Hope that helps. You can also search LLD on the blog; we have written extensively on it: http://thegaitguys.tumblr.com

Remember sole lifts will correct the LLD but it could shift the pelvis off further…….many LLDs are from pelvic asymmetry and core weakness, this encompasses hip rotation differences which is a typical response to the core and pelvis that is distorted. 
merely forcing a change at the Sole does not mean you are making the positive change at the top……however it may in some cases……you have to determine that with your evaluations.

Most folks legs are of symmetrical length……..the changes at the top (core / pelvis/ hip) is what throws the apparent length off.

i wish i had a good answer for your great insight……..but it is about
1- making the right changes……..so that all parts are in cooperation for the restoration change
2- that you are directing change and not a further body compensattion to the compensation you have forced…….(if it is in fact a forced compensation and not the correction you are hoping for)….. time and re-evals will determine this
3- after restoration and strengthenging you must quickly wean off the lifts from them
4- you are speaking of tibial and femoral short………those are structural short LLDs , make sure you know if you are dealing with functional or structural shortness

Hope that Helps

Ivo and Shawn