For those who already visited this thread and found it bare, sorry about my tardy start . . . . . a busy week turned into a busy weekend. Also my intent was to start the post with a bunch of gait data for perusal and then I changed tack.
Previously Bruce (Williams) had talked about qualified use of the term “equinus”, I think it was agreed that we should be thinking in terms of ankle and mid tarsal joint (MTJ) dorsiflexion stiffness when talking about related aspects of foot function.
Some off forum discussion concurrently developed with me regarding the use of in-shoe and Mat plantar pressure measurement and augmented 2D computerized video analysis (using 2 synchronized 2D views); essentially what the merits and limitations might be given the paucity of definitive interpretative instruction on this subject and lack of validation of the underlying technology and data we might use for the purpose of understanding a patient lower limb function and improving outcomes by making better treatment decisions.
My thought was to see how those of us using this technology might interpret the function attributed to ankle and MF stiffness and we embarked at the end of Bruce’s thread a token exploration of this, this thread now picks up on the start of this idea.
Perhaps it would be a better initially to consider how those of us with the technology might employ it in a clinically useful way to explore the issue of rear foot stiffness.
I have several ideas – this is the first and I guess, before spending too much time testing it, I am soliciting a reality check.
In terms of clinical evaluation Kevin (Kirby) said “we are not simply measuring the ankle joint dorsiflexion when we measure the plantar foot to the tibia, we are also measuring subtalar, midtarsal and mid foot motion also.”
Because of the limitations (outlined below) in measuring the angle formed between the lateral 5th Ray and fibular in the non weight-bearing foot “in neutral position” I started using the “lunge” test in selected patients to attempt to evaluate and predict ankle function. Again this has been discussed at some length and I cut and paste edited highlights at the end to make this post more complete.
After a bit of testing I found the variance of values I obtained using an inclinometer against the anterior tibia larger than using carefully aligned video camera and measuring angles with software. My opinion was that it is often difficult to decide where the inclinometer rests because of the concave shape of the tibia.
Also I decided to design and fabricate a plinth with an adjustable micro switch wired in series with a visible LED and positioned below the heel to detect the instant of heel rise which again I found reduced the variance in values for a series of trials.
Whilst I feel this allowed me to quantify this tibial excursion over the foot with a good degree of confidence the issue of the flexibility threshold being detected by the heel rising because of MF dorsiflexion rather than ankle dorsiflexion remained unresolved.
I tried adding a synchronized view of the medial segment of the foot to give some qualitative data but this often appeared ambiguous and I wanted to start this thread considering how to improve and interpret lunge test values.
The lunge test is normally performed with the body COM behind the foot and the knee bent. I presume this is done to make balance easier, reduce the likelihood of “lifting the heel” and allow subject to concentrate on slowly advancing the measured knee rather than what is involved otherwise in maximally dorsiflexing ankle to heel raise which can be tricky.
Whilst this works, the limb is not positioned as it would be during the “2nd rocker” with knee straight or slightly flexed and body COM roughly advancing above talo-crural joint.
Although the lunge value makes no claim to represent a true functional gait parameter, the value of what it measures may be compromised if it doesn’t reflect normal gait position. Also, is it an index of things other than ankle stiffness, eg is low lunge value correlation with football injury more a reflection of identifying lateral ankle instability in those with laterally deviated sub-talar joint axis than those with posterior group contractures? (increased plantarflexion moment at mid tarsal joint in those with elevated sub-talar joint supination moment with increasing tendo-achilles force).
I feel that a modified version of the lunge test may fill a gap in our measurement tool box.
What I propose is;
Modify lunge position to mimic gait posture.
Kevin has nicely criticized our pre-existing clinical measurement of ankle flexibility citing lack of discrimination between ankle and mid foot motion. Likewise he criticized the lunge value for similar reasons. Although timing of heel rise is a function of the combination of ankle and MF stiffness, when viewed a kinematic clue it is also a function step length. Everyone with a normally functioning foot has an appropusive gait if they reduce step length which happens if you simply slow down without proportionally reducing cadence.
If we have access to a pressure mat I believe we can exam, possibly quantify ankle and MF stiffness by doing the following:
Stand on mat and record pressure data of stance foot whilst mimicking a step. Incrementally increase step length until heel rise occurs.
View synchronized FMat data with saggital aligned 2D video. Measure tibial excursion against unloading of heel and when present, the increased plantar loading of MF.
I believe this may allow us to separate the 2 motions using pre-existing equipment which many of us already use for other purposes.
Reality check invited
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extra stuff for those unfamiliar with MF function and lunge test.
My ideas on mid foot (MF) function evolved considerably as a result of this forum. I have cut and paste some edited text mostly from Kevin from previous thread on midfoot postion/function to illustrate this.
Firstly finding a good alternative to my college day “Rootian” concepts of mid tarsal joint (MTJ) locking mechanisms from 20 years ago, Kevin Kirby truncated nicely Nestor et Al’s recent and well regarded work with;
“The MTJ may have only one true instantaneous axis of rotation at any one time during its motion. This instantaneous axis of motion has multiple possible spatial locations depending not only on the internal morphology of the foot but also the internal forces and external forces generated across the MTJ. In other words, the MTJ is not a highly constrained joint, as is the subtalar joint, and may be moved in nearly any direction depending on how forces are acting across it. The subtalar joint, on the other hand, is a highly constrained joint, that will move along nearly the same joint axis regardless of how direction and point of application of the external forces acting across it”.
He then gave us his excellent lecture notes on MF function and included these examples:
Foot A: Foot with low forefoot dorsiflexion stiffness will allow increased forefoot dorsiflexion motion for a given increase in magnitude of GRF on plantar forefoot.
Heel-off will be delayed since insufficient internal forefoot plantarflexion moments are developed during late midstance to resist forefoot dorsiflexion
Foot B: Foot with medium forefoot dorsiflexion stiffness will allow average forefoot dorsiflexion motion for a given increase in magnitude of GRF
Heel-off will be normal since sufficient internal forefoot plantarflexion moments are developed during late midstance to prevent excessive arch flattening
Foot C: Foot with high forefoot dorsiflexion stiffness will allow decreased forefoot dorsiflexion motion for a given increase in magnitude of GRF on plantar forefoot
Heel-off will be early since sufficient internal forefoot plantarflexion moments are developed early in stance phase so that the early restriction of forefoot dorsiflexion causes an early heel-off
During clinical exam for “ankle joint dorsiflexion” in feet with different forefoot dorsiflexion stiffness…..
Increase in forefoot dorsiflexion stiffness results in decrease in “ankle joint dorsiflexion” since forefoot dorsiflexes less on rearfoot for a given force exerted on the forefoot by examiner
This of course raises the question
Is standard measurement technique for ankle joint dorsiflexion measuring dorsiflexion of talus to tibia or is it actually measuring forefoot dorsiflexion relative to rearfoot?
Kevin goes on to say;
Effects of increase in forefoot dorsiflexion stiffness during weightbearing activities:
– Arch of foot becomes higher during walking/standing
– Heel off occurs earlier during stance phase of walking
– Achilles tendon tensile force is increased for a given apparent ankle joint dorsiflexion angle
– GRF forefoot will be greater at middle of midstance
Adding bony issues to the equation: The dorsal-plantar thickness of the midtarsal-midfoot articulations would be one factor that would affect forefoot dorsiflexion stiffness for the medial-lateral MTJ axis. Increased dorsal-plantar thickness of the midtarsal-midfoot joints would tend to increase forefoot dorsiflexion stiffness.
Also of relevance: The center of pressure (CoP) will tend to more anteriorly located in the foot with increased forefoot dorsiflexion stiffness due to its increased internal resistance to forefoot dorsiflexion, all other factors being equal. Kevin
From Craig (Payne):
1. Patient stands against wall with about 10cm between foot and wall.
2. Have them move one foot back a foot's distance behind the other
3. Bend knee of front limb until knee touchs wall - keep heel on ground.
4a. If knee cannot touch wall without heel coming off ground, move foot closer to wall --> repeat
4b. If knee can touch wall without heel coming off ground, move foot further away from wall --> repeat
5. Keep repeating 4 until can just touch knee to wall and heel stays on ground.
6. Measure either:
a) Distance between wall and great toe (<9-10cm is considered restricted)
b) The angle made by anterior tibia to vertical (<35-38 degrees is restricted)
(see discussion in other thread on reasoning behind actual values)
I do test when issuing/dispensing foot orthoses with them standing on foot orthoses and always add a heel raise (usually only ~3mm is enough) if they can not get to 35-38 degrees.
I first learnt of the lunge test when Kim Bennell published their reliability study:
Bennell K et al: Intra-rater and Inter-tester reliability of a weightbearing lunge measure of anbkle dorsiflexion. Australian Physiotherapy 24(2)211-217 1998
I promptly ignored it becasue of my (and the professions) mindset of the time .... ie the test was not done with the STJ in neutral, allegedly increasing the range.
After that a number of things influenced my thinking:
1. We started to wake up re the "mindset"
2. Numerous podiatrists and, especially, physiotherapists anecdotally started to comment on how useful the lunge test was (even though it was not done STJ neutral)
3. I started to understand more about the concepts of "range of motion" vs "stiffness"
4. We did our research on the 10 degrees of ankle dorsiflexion being considered normal (...it not)
5. A number of clinicians were beginning to make throw away lines like - "if your orthoses does not work, then add a heel raise' - this was based on their good clinical experience, but where I come from, we have to do better.
6. Pope et al (1998) showed the lunge test was prospectively predictive of injury in army recruits and Gabbe et al (2004) showed an association with lunge and football injuries.
At the end of the day, a clinical decision had to be made when adding a heel raise to a foot orthoses if the calf muscles are tight. We can not use the standard measurement and 10 degrees. Taking the work of Pape et al (1998) and Gabbe et al (2004) we now testing a protocol that involves doing the lunge test while standing on foot orthoses - if the tibia can not get to 35-38 degrees, a heel raise (usually only 3mm) is added. Some of the work suggests that 9-10cm distance between the wall and foot as a cut off point - the problematic nature is that all shorter people will have less than that, so I prefer the tibial angle part of the measurement.
It may well be that 35-38 degrees as the cut of point is not correct, but we had to make a 'judgement call' and start somewhere - I suspect that its in the "ballpark"
Gabbe BJ, Finch CF, Wajswelner H, Bennell KL. Predictors of lower extremity injuries at the community level of Australian football.Clin J Sport Med. 2004 Mar;14(2):56-63.
Rodney Pope, Rob Herbert and John Kirwan: Effect of ankle dorsiflexion range and pre-exercise calf muscle stretching on injury risk in Army recruits. Australian Physiotherapy 44(3)165-172
We have found no correlation between the value obtained for traditional non-weightbearing ankle joint ROM and the weightbearing lunge test ROM.
A 3mm heel raise moves most people past the 35-38 degrees. Shannon Munteanu has done a whole lot of trig calculations on this - I will see if he can reply.
Why is this test used, and what are its benefits against other measures of equinus?
1. It has been shown to prospectively predict injury (how many other clinical tests do that?)
2. It is related to dynamic function (how many other clinical tests do that?)
3. It may be predictive of orthotic outcomes (how many other clinical tests do that?)
How many of the clinical tests do you use that meet those 3 criteria ... or even just one of them? None?
Craig, please explain the mechanical reasons behind always adding a 3 mm heel lift to these patients when they have, for example, 33 degrees on the lunge test but their ankle joint is never dorsiflexed more than about 10 degrees during walking gait and they are not involved in running activities.
Kevin, these same people who don't run, can't avoid inclines (escalators/slopes) and can't avoid descending steps or gutters.
This undoubtedly quashes the magic '10 degree figure' that many believe and are side-tracked about. The other thing is that why do we assume that the sedentary don't hurry for a few steps during an intermittent but urgent activity (late for a pedestrian crossing; catching bus etc.)
The whole point of the lunge is not a magic minimum figure/angle. It provides information about (a) symmetry (My advice is not to be too concerned about 10, 12, 33 or 35 degrees. The most important benchmark (in unilateral conditions) is the contra-lateral lunge reading.) and (b) ankle joint health and whether stretching is appropriate or inappropriate.
I cannot fathom how one can fully understand the ankle joint in terms of complete diagnoses, prognosis and when to refer on, without first understanding and utilizing the lunge test.
Kevin, how do you test for anterior ankle impingement(AAI)? I guess the classic AAI involves bone on bone and can be viewed in a lateral xray film. But the more common, under-diagnosed, misunderstood variety of AAI involves non-osseous structures.
There is a huge difference in how one should treat an ankle equinus on the basis of end-feel. Physiologically, end-range dorsi-flexion is limited by posterior ankle joint structures. Pathologically, this is limited by anterior structures. Although most musculo-skeletal practitioners prescribe stretching for every equinus, to do so with an anteriorly impinging ankle does not make sense.
As for an internally deranged ankle, I am confident the lunge test will be restricted on the ipsilateral side, and that the end-feel restriction will not be posterior to the joint; hence I disagree that the lunge has no place in testing for such pathology.
The other thing, is that if used properly, the lunge test can determine whether the inferior tib/fib joint and/or syndesmosis is relevant in ankle joint hypomobility. I have presented this in Craig's presence, and have yet to fill in the research blanks.
But I will stick to my foolish conclusion that "I cannot fathom how one can fully understand the ankle joint in terms of complete diagnoses, prognosis and when to refer on, without first understanding and utilizing the lunge test". I did not suggest foot nor lower extremity; simply the ankle joint.
I would be interested to see how you test and treat AAI without the functional weightbearing dorsi-flexion lunge test.
To answer your question, I use a weightbearing stress dorsiflexion radiographic projections of the ankle to diagnose "anterior ankle impingement".
If you can only rely on radiology to detect/diagnose anterior ankle impingement, you are only picking up the classic osseous bone-to-bone variety; and I agree that this is one solitary pathology.
However, you are not picking up the more common variety that accompanies many ankle conditions from a sprain to post-ORIF-immobilisation. The soft-tissue underpinning of anterior-ankle-impingement is a detrimental adjunct that will slow recovery; invariably will not respond to dorsi-flexion stretching; and be aggravated by fast walking, and/or slow walking up-hill or down stairs.
I stand by my comment that "I cannot fathom how one can fully understand the ankle joint in terms of complete diagnoses, prognosis and when to refer on, without first understanding and utilizing the lunge test." Because if the practitioner misses a soft-tissue anterior ankle impingement, the diagnosis is not complete; the prescribed exercise(s) (eg. dorsi-flexion stretching) can be counter-productive; the prognosis is overestimated and referring back to a specialist is often delayed.
In relation to "changed statements", how did you infer that I meant that if a "clinician does not use the lunge test that he or she can not properly diagnose and treat mechanically-based conditions of the foot and lower extremity."