Transverse plane rotations of the hip driving the pronation/supination movement of the foot

Eric:

I can't agree that the "knee is really poor at transmitting transverse plane torque". In the knee extended position, the knee is quite able to transmit torque from the femur to the tibia and fibula. In the flexed knee position, with muscles relaxed, then then the knee will be more compliant within the tranverse plane but will become considerably stiffer with muscle activity from the muscles which cross the knee joint.

In addition, the ligaments and muscles surrounding the hip joint can still generate considerable elastic strain energy in causing transverse plane rotation of the hip when the hip is rotated out of its "neutral position". This elastic strain energy at the hip is the likely cause of abductory twist in certain feet. I have a video of this "elastic tranverse plane hip strain energy effect" from my lecture on abductory twist. I'll see if I can post it up later.

 

And also within them, which is the interesting thing coming from the Nigg data. Pohl's PhD thesis I linked to above is an excellent read.

 

The orientation of the vast majority of the structures of the knee is in the wrong direction to transmit transverse plane moments. Yes, it can after the slop in the joint has been wound up, but there is still a chance for decoupling hip and STJ motion at the joint.

Abductory twist occurs at a different time and under different loads than hip drive is alleged to occur. Hip drive is supposed to be occuring between early stance phase and heel off. Abductory twist occurs after heel off. After heel off, the hip joint will be closer to its end of range of motion where the passive structures will be closer to a stretched position. A more likely explanation is that there is muscular activity slowing external hip rotation over the stance limb, so that it can reverse direction and rotate about the contralateral limb after toe off of the trailing limb. I believe Winter measured tranverse plane rotations and powers. Need to go re-read that.
Eric

 

Eric:

The knee extended position greatly stiffens the transverse plane motions at the knee. I will give you that there is a little bit of "knee joint slop" when the knee is not fully extended. However, in gait I would expect that the knee is actually good, not "really poor", at transmitting transverse plane moments from proximal to distal and from distal to proximal across the knee joint. If this were not true, when the STJ supinated, the femur wouldn't externally rotate and when the STJ pronated, the femur wouldn't internally rotate.:drinks

 

For the record I have no problem with this. My objection is with Brian's labeling of pronation as a symptom and his definition of abnormal pronation. This explains the benefits of elastic coupling:
http://www-personal.umich.edu/~artkuo/Papers/JRSI08.pdf

 

http://journals.humankinetics.com/j...males-and-females-open-and-closed-chain-tasks
http://www.jfootankleres.com/content/1/S1/O15

 

Hey Simon, I've read the abstract and conclusion so far and this looks like a useful paper (mainly because it agrees with much of my thoughts ) We can't do the maths for every patient we see but if we have a intuitive understanding of the nature of the progression of gait in terms of how one segment action affects another then or treatment interventions will realize much getter outcomes. This thread is excellent because learning and investigations following the line of this discussion can only be fruitful in that respect.

Dave

PS this might be a good paper for Howard Dananberg to read since it is considering gait progression perturbations and using those terms.

 

Here you go gentlemen. I knew I'd find it if I kept looking:
http://w4.ub.uni-konstanz.de/cpa/article/viewFile/540/479

 

Brilliant :good:

The lack of time delay is surprising! and the magnitude of change seems to be equal in the mean. However they do seem to say that some coupling in some subjects did exhibit attenuations and the fact that they used subjects that were asymptomatic and non pathological and normal by their definition might suggest that pathology results where the coupling exhibits increased elastic attenuation or indeed increased stiffness between segments. Good Stuff!

Dave Smith

 

This seems to support my steering wheel analogy earlier i.e. if the coupling is to stiff then high peak forces (FTC integral) will cause material damage leading to structural damage. To much elasticity in the system or wear slack will result in a crashed car.

Dave

 

Here is a new video I just produced on YouTube. It demonstrates how elastic strain energy can be stored with internal rotation of the hip joint in the completely relaxed position and how elastic strain energy may accelerate external rotation of the lower extremity. Note that release of the limb causes the stored elastic strain energy within the ligaments and muscles of the hip to be resolved into a rapid external rotation of the thigh, leg and foot. Also note the close kinematic coupling between the thigh and leg at the knee joint. It is mechanically likely that during walking gait, even more elastic strain energy may be stored due to the increased tensile forces within the muscles that cross the hip joint.

 

Kevin,
You need to eliminate gravity as the mechanism for return. With internal leg rotation, the femur is lifted off of the table. A force couple is created by gravity and upward force at the head of the femur from the acetabulum. You don't get the same effect with external rotation, especially if you allow for "cheek motion". Of course, it depends on where the center of hip range of motion is. You can rotate the leg to a point where you will stretch the ligaments, and then you you will get some elastic return. There is a range within the total hip range of motion where there will be minimal or no stretch of the ligaments.

Eric

 

I agree that the knee, when wound up, can transmit torque. The question I have is should it transmit torque. Can the knee stand the repetitive trauma of twisting (to wind up) at the same time that is bearing loads that can be greater than body weight. The knee is not designed well to transmit torque from the pelvis to supinate the STJ.

Just because, in a live person, you see STJ supination at the same time as you see femoral external rotation, does not mean that moment to create that motion is transmitted across the knee. If you choose to internally rotate your femur relative to the ground, you can use hip musculature to move the femur and lower leg musculature to move the tibia. I would bet that most people would choose to do this because it would start to get uncomfortable, at the knee, if they didn't use both sets of muscles.

Eric

 

Transverse plane moments acting on the lower extremity may be generated from multiple sources.

1. Transverse plane moments acting on the lower extremity may be generated by leg and/or foot muscles that cause subtalar joint (STJ) supination or STJ pronation moments during weightbearing activities. For example, contractile activity of the posterior tibial muscle will cause an STJ supination moment that will tend to internally rotate the foot relative to the leg and externally rotate the leg and femur relative to the ground. In addition, contractile activity of the peroneus brevis muscle will cause an STJ pronation moment that will tend to externally rotate the foot relative to the leg and internally rotate the leg and femur relative to the ground.

2. Transverse plane moments acting on the lower extremity may be generated by hip and thigh muscles which cross the hip joint and cause either an femoral internal rotation moment or an femoral external rotation moment. For example, contractile activity of the gluteus maximus muscle will cause a femoral external rotation moment which will tend to externally rotate the femur relative to the pelvis and externally rotate the leg relative to the ground. In addition, contractile activity of the anterior fibers of the gluteus medius and gluteus minimus muscles will cause a femoral internal rotation moment which will tend to internally rotate the femur relative to the pelvis and internally rotate the leg relative to the ground.

3. Transverse plane moments acting on the lower extremity may be generated by muscular actions and movement originating above the hip joint. For example, while standing on one leg, if the arms are accelerated across the body from right to left (i.e. in the motion similar to swinging a baseball or cricket bat), the transverse plane accelerations and decelerations created by these upper extremity and torso movements will cause a "free moment" (see video below) that will tend to cause transverse plane moments to be exerted on the lower extremity.

The summation of these transverse plane moments, whether they occur from above the pelvis or across the hip joint (i.e. superior to the knee joint) or from within the leg and foot (i.e. inferior to the knee joint) will tend to not only rotate the whole lower extremity, but will also tend to generate transverse plane moments at the knee joint. If the knee joint is more compliant within the transverse plane, then relatively more transverse plane motion will occur between the femur and tibia than if the knee joint is stiff within the transverse plane.

Mechanical factors that determine the transverse plane stiffness of the knee are likely the knee joint angle within the sagittal plane (e.g. fully extended is more stiff), knee ligamentous tensile stiffness and integrity (i.e. anterior and posterior cruciate, medial and lateral collateral ligament, posterior capsular ligaments), medial and lateral meniscal shape and integrity (i.e. torn menisci will make knee less stiff), muscle-tendon tensile forces acting across the knee joint (i.e. increased muscle contractile activity across the knee joint will make knee more stiff within the transverse plane) and compressive forces acting within the knee (i.e. increased compressive forces will tend to increase frictional forces within the knee which will increase the transverse plane stiffness of the knee).

To say that the extrinsic foot muscles or foot orthoses are the most important factors in producing transverse plane rotations at the knee or that hip joint rotators are the most important in producing transverse plane rotations at the knee is only partially correct. There are a multiple of factors, acting both superior and inferior to the knee joint that may affect transverse plane rotational moments and motion at the knee. Further research is necessary to determine which factors are the most important in normal and abnormal biomechanical function of the limb.

http://www.ux1.eiu.edu/~cfje/2440/Hip-muscles.pdf

 

Actually it was this one I was thinking of: http://www.gaitposture.com/article/S0966-6362(00)00082-5/abstract

 

From unpromising beginnings I think this has turned into a valuable and educational thread- many thanks:drinks

 

Here is one of Chris Nester's papers where he measures the kinematic coupling between the leg and foot at the ankle joint. At the end of the paper he mentions van Langelaan's concept of "talar delay" which is consistent with the model that there is some "slack" within the ankle joint within the transverse plane that can allow significant tranverse plane motions between the tibia and talus during weightbearing activities.

 

Just thought I'd chime in. I am a unilateral trans-tibial amputee. I have a transverse plane rotator in my setup. it allows for approximately 10 degrees of internal and 10 degrees of external rotation.


I can engage the rotator and externally rotate my affected limb by swinging my arms more vigorously and rotating my shoulders back and forth in the transverse plane. Also narrowing the base of my gait by abducting my affected hip will increase external rotation in late stance. Without these actions there is minimal rotation in my affected leg.

The rotator needs to be fairly loose to do this. If i try to rotate my leg with the rotator tightened up i Quickly get pain in my stump. When i was first given a rotator it took a little practice to learn how to do this. Its also very laborious to walk without a rotator. Walking without a rotator means taking shorter steps. With a rotator i can relax and bounce along. It is a vastly superior way to walk than walking without rotation.

 

Peter
Thanks for your input, can you elaborate on your prosthetic leg set up. you say

Is the rotator in the ankle joint? Is there a flexion unit in the ankle joint? are these terms familiar and are they in your prosthesis? Endolite Multiflex Ankles [flexion unit] and Otto Bock Torsion Adapters [torsion unit]) or do you know the model you are fitted with?.

Many thanks Dave Smith

 

I have a college park true step foot. It is supposed to have transverse rotation built into the foot by using rubber bushings around the pins that hold the components together. I find this mechanism provides almost nonexistent rotation maybe the bushings are too firm.

I have an Otto Bock Torsion Adapter fitted on the shaft that replaces the tibia. It allows the foot to abduct and adduct in relation to the socket.


My foot has around ten degrees of dorsiflexion. I would like a little more but the problem is there is very little resistance to the first 5 degrees of dorsiflexion so i tend to fall into knee flexion until i encounter resistance then i have to push down hard on my forefoot to get more doriflexion. This allows me to dely my heel lift so i can get a bit more hip extension. I like to walk with roughly the same amount of hip extension on both legs.


Thanks for your interest.

 

Ok so just to be clear when you say external rotation you are talking about the limb motion relative to the ground and not the hip joint motion. I.E. in normal gait the hip joint will usually be internally rotating while the leg externally rotates. (when in closed chain / stance phase)

 

Now, as Eric has pointed out during the stance phase and contralateral swing thru, the hip could internally rotate without and transmitted torque to the femur. This seems unlikely since there are passive ligamentous connections that will have a certain stiffness at all times, however the force they transmit could be relatively insignificant in terms of total forces and moments.
The amount or magnitude of torque transmitted by soft tissues will depend greatly on the real anatomical position of the hip compared to the standard reference position. So if there is an external femoral torsion and the subject chooses to walk with the knee straight ahead then this would mean that the hip start position would be internally rotated and therefore the ligaments would exert much more external torque on the femur during internal rotation of the hip during contralateral swing thru, especially as the pelvis passes the neutral position i.e. facing in the direction of progression.
Therefore Peter if you did have an external femoral torsion, i.e. with the foot straight ahead then there is not much internal hip rotation RoM available but loads of external hip RoM available, then you would need much more play in your tibial torsion adapter. This play will reduce the rotational shear forces due to friction in the stump socket and so reduce pathologies and symptoms due to that.
This translates to possible wear and tear in the normal knee as torsional stress is increased in the normal leg that does not have much transverse play in the ankle or a compliant supination RoM.

Dave

 

In the subject who has an external femoral torsion and also has a pronated foot posture in stance then it is far more likely that the pelvic rotation resulting in internal hip rotation of the stance leg will also cause supination moments at the STJ since all the play is used up and the relevant ligaments are more likely to be more greatly strained and so have greater elastic tension due to the coupling force effect of GRF and CoM inertia. In this case I would expect that this would result in a perturbation to forward progression since it is difficult for the pelvis to rotate about the hip and so if the step length is shortened then pelvic rotation is less and so there is less restricting or perturbating tension in joint ligaments.

Therefore peter, as you have found with the torsion adapter as you allow more play in the device then forward progression becomes easier.

Thanks for this useful and practical example of how varying stiffness in the leg segment joints changes forward progression in gait.

Regards Dave

 

Thats correct.

 

Hello everyone,

I'm a podiatry student from Belgium.
I'm writing a paper about the flatfoot and its consequences on the ankle, knee and hip, the biomechanical effects + the effects on the muscles, and ligaments around those articulations.
I hope some people can help me a bit further with some usefull literature?

I thanks a lot,
Kind regards,
Tine

 

Phew! how many years will you devote to writing this paper, I would say, focus your area of investigation.

Regards Dave Smith

 

A very simple concept convoluted into an enigmatic brain-teaser!

A very simple experiment quickly resolves this discussion:

Standing, barefooted, rotate your pelvis (on the transverse/horizontal plane) clockwise. As you do this, look at the motion in your left foot. What motion is occurring in the STJ. Right! Pronation.

Now rotate your pelvis counter clockwise. Look at the motion occurring in the right foot. Pronation!

No fuss, no muss. That is the link between the pelvis and foot.

Just food for thought.

 

Sometimes, it is more complex than the simple explanation. If you don't look at the ankle when you ask the subject who is rotating their pelvis, you might miss the obvious contraction of the peroneal muscles and the posterior tibial muscle. When you rotate your pelvis clockwise, and you see the right leg rotate externally, relative to the foot, you have to ask what is the source of the moment that causes the external rotation of the leg relative to the foot. There are multiple possible sources. One source of moment to cause leg external rotation is the posterior tibial muscle. If the muscle is contracting you cannot conclude that the leg motion is caused by the hip motion.

Something that is also missed the simple example above is how torques is transmitted from the pelvis to the foot. When you do a seated range of motion exam of the femur relative to the pelvis, there is very little resistance to the motion up until you reach the end of range of motion where the ligaments become tight. In the middle of range of motion the ligaments are not transmitting torque between the pelvis and the femur. In the middle of range of motion it is possible for the muscles to transmit torque from the pelvis to the femur. However, the hip muscles that externally rotate the femur simultaneously rotate the hip. (Newton's third law for angular motion: for every action there is an equal and opposite reaction.) Looking at the right hip from above, a moment from the hip that would tend to externally rotate the femur relative to the foot would cause a moment that would tend to cause a counter clockwise moment on the pelvis. This counter clockwise moment, on the pelvis, would tend to slow the clockwise rotation of the pelvis that would be occurring during gait. However, this would not work in static stance in the "experiment" described above. What is the source of moment that is rotating the pelvis in the first place?

The above is a great illustration of the problems created by just doing positional analysis and not examining the forces that are causing the changes in position. The above "experiment" starts in static stance and then the pelvis is moved. The pelvis does not just magically move. Forces and moments have to be applied to the pelvis. You could make the case that moments from the STJ that cause internal, or external, motion of the leg is what is contributing to the pelvis motion. Of course, there is also the hip musculature that contributes to pelvis motion. It is possible to rotate the pelvis without the STJ muscles, but you can move it farther if you use the STJ muscles. The positional changes seen in the "experiment" are correlations and not causations.

Eric

 

Hi Eric,

Question - are you saying that muscular activity basically controls pronation/supination during stance phase? And if so, what would you expect the isometric activity of the tibialis anterior and peroneal longus to be, during midstance/propulsion stance phase, in a person with a flexible pes planus foot?

Brian

 

Motion of any joint is determined by the net moment acting at that joint. At the STJ ground reaction force will contribute a moment proportional to the distance from the center of pressure under the foot and the location of the transverse plane projection of the STJ axis. Sometimes the ground will create a supination moment and other times the ground will create a pronation moment. Muscles, when contracting will also contribute a moment to the joint.

In most feet the ground will create a pronation mmoent, most of the time. People can choose to activate their posterior tibial muscle to resist that pronation moment. It is possible to walk holding the foot inverted so that the first met head does not touch the ground. That would not be a "normal" gait but within the range of possible gaits that a normal foot could do. The muscles will contribute to the motions seen.

During the stance phase of gait, I would not expect there to be isometirc contraction of those muscles. With motion, the length of those muscles would change.

 

Our viewpoints are very different. But what it all comes down to is what makes sense to you.

Inman and Closes' hip to foot paradigm has been consistently validated in my research and it works for me clinically.

This thread has been very informative and enjoyable. Appreciate your input.