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I'm new to this forum and come with an old burning question. Along the lines of the previous post questioning the true origin of the calcaneal spur, I question the true origin of first-step pain (the subjective phenomenon of intense heel pain upon walking following periods of off-loading which quickly lessens with each step- AKA post-static dyskinesia). It is commonly associated with plantar fasciitis. I doubt that this pain is coming from the plantar fascia, but rather the intrinsic muscles. It seems to me that injured dense fibrous tissue (plantar fascia) would not behave this way. However, I can see how a painful tendonous insertion (the intrinsics) would have less traction pain as the muscle belly stretches. This could could occur with a few steps as the contractile/non-contractile elements elongate. We see this morning stiffness with Achilles tendonitis as well. Any thoughts? Any references?
Nick
Last edited by Admin : 11th August 2005 at 01:11 PM.
Reason: Added link to other thread
I think we really have no true idea. Several hypotheses have been advanced that all have some biological plausibility, but I not sure how any can be tested, so it will almost always be one of conjecture.
__________________
Craig Payne
Department of Podiatry
La Trobe University
Melbourne, Australia http://www.latrobe.edu.au/podiatry
__________________________________________________ ___________________________________ God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.
The views expressed above are those of the author and not that of La Trobe University This is where I am, where are you?
Sorry, I don't think there are any real references - just passing comments made in a number of publications etc. But they tend to center around three:
1. The relatively plantarflexed position adopted by the foot during sleep/rest --> soft tissues contact --> upon first step --> pain until usual tissue "length" restored.
2. During rest inflammatory "fluids" accumulate --> bulk in tissues --> more pain on first step until "dissipates"
3. Neural tension issues.
__________________
Craig Payne
Department of Podiatry
La Trobe University
Melbourne, Australia http://www.latrobe.edu.au/podiatry
__________________________________________________ ___________________________________ God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.
The views expressed above are those of the author and not that of La Trobe University This is where I am, where are you?
Could you share some of these hypotheses?? I have been unable to find direct references on the topic.
Thanks,
Nick
One of the earliest references on the ability of the plantar fascia to stretch under load was done here in California over 40 years ago (Wright DG, Rennels DC: A study of the elastic properties of plantar fascia. JBJS, 46 (A):482-492, 1964). I previously worked with the author, Gilbert Wright, MD, who was a practicing foot orthopedist here in Sacramento up until a few years ago when he retired.
All viscoelastic tissues, including the plantar fascia, will undergo a phenomenon called creep response which is where, when the tissue is subjected to a constant load over time, the tissue continues to deform, or "creep", as it approaches a deformation plateau. Therefore, with a plantar fasciitis night splint, the plantar fascia will elongate over time as a steady forefoot dorsiflexion moment is applied to the foot.
In addition, all viscoelastic tissues will also undergo a phenomenon called the stress-relaxation response when they are subjected to constant deformation. A tissue stretched to a given length, and then held at that length, develops an initial resistance to deformation, or stress, which will then decrease in magnitude, or "relax", over time. Again, if the foot is placed in a rigid night splint that holds the foot in a 90 degree angle relative to the ankle, then the stress (i.e. internal force resisting elongation) within the plantar fascia will be initially much greater than in the morning before the brace is removed.
One other interesting mechanical phenomenon of viscoelastic tissues is that these tissues are strain-rate dependent. This means that as the strain rate is increased, then the tissue becomes stiffer (more steeply sloped stress/strain curve) and the peak stress is higher and occurs sooner than with the slower strain rate (Whiting, W.C. and R. F. Zernicke: Biomechanics of Musculoskeletal Injury. Human Kinetics, Champaign, IL, 1998, p. 77).
These well-documented mechanical characteristics of bone, ligament, muscle and tendon very neatly explain the clinical observation of "first step pain" or "post-static dyskinesia" in patients with plantar fasciitis and the therapeutic results of plantar fasciitis night splints in treating "first step pain".
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
Sorry, I don't think there are any real references - just passing comments made in a number of publications etc. But they tend to center around three:
1. The relatively plantarflexed position adopted by the foot during sleep/rest --> soft tissues contact --> upon first step --> pain until usual tissue "length" restored.
2. During rest inflammatory "fluids" accumulate --> bulk in tissues --> more pain on first step until "dissipates"
3. Neural tension issues.
To this I would now add another 4th one suggested by Paul Conneely:
4. Muscle tone is at it lowest in the morning --> less muscular support --> more strain on plantar fascia first thing in AM
__________________
Craig Payne
Department of Podiatry
La Trobe University
Melbourne, Australia http://www.latrobe.edu.au/podiatry
__________________________________________________ ___________________________________ God put me on this earth to accomplish a certain number of things - right now I am so far behind, I will never die.
The views expressed above are those of the author and not that of La Trobe University This is where I am, where are you?
To this I would now add another 4th one suggested by Paul Conneely:
4. Muscle tone is at it lowest in the morning --> less muscular support --> more strain on plantar fascia first thing in AM
Craig,
I suspect lost tone is not regained in a few steps- after which patients typically report lessening of the pain. The answer must be consistent with the fact that the pain can be "walked off" in a few steps. The tissue dynamics suggested by Kevin don't seem to align with this as well. Creep takes longer.
I question if the phenomenon is related to tearing of adhesions within the fascia, or re-tearing microtears that have partially healed. It could be similiar to having a scab on the skin anterior to the knee- the first few knee bends of the day are very painful until the scab is broken, it re-seals, and the next morning the cycle continues.
I suspect lost tone is not regained in a few steps- after which patients typically report lessening of the pain. The answer must be consistent with the fact that the pain can be "walked off" in a few steps. The tissue dynamics suggested by Kevin don't seem to align with this as well. Creep takes longer.
Nick,
You say that "creep takes longer". How long do you think that a flat, and thin ligament that is approximately 7-9" long, being subjected to 150-250 pounds of tensile force with each step will take to stretch 2-3 mm at approximately 33 degrees Celsius?? I would guess that this would take about 5-15 minutes, which is exactly what patients report as the duration of their post-static pain.
How do you know "creep takes longer"????
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
You say that "creep takes longer". How long do you think that a flat, and thin ligament that is approximately 7-9" long, being subjected to 150-250 pounds of tensile force with each step will take to stretch 2-3 mm at approximately 33 degrees Celsius?? I would guess that this would take about 5-15 minutes, which is exactly what patients report as the duration of their post-static pain.
How do you know "creep takes longer"????
Kevin,
The majority of patients tell me that the pain begins to lessen noticibly in 10 or less steps, not after 5-15 minutes of walking. I had PF, and found the same to be true.
As I understand it, creep is a phenomenon that occurs after a sustained stretch. I agree that it explains the response to night splints, but I doubt that it explains the first-step response.
The majority of patients tell me that the pain begins to lessen noticibly in 10 or less steps, not after 5-15 minutes of walking. I had PF, and found the same to be true.
As I understand it, creep is a phenomenon that occurs after a sustained stretch. I agree that it explains the response to night splints, but I doubt that it explains the first-step response.
Nick
Nick,
Creep or stress-relaxation can occur with even one cycle of loading. In experiments on biological tissues, most researchers will "pre-condition" the specimen since the initial loading response is different than the 10th. Therefore, for "first step pain", the first step likely produces the most stress, the second a little less, the third a little less, and so on, until the stress is at a sub-pain threshold level. This is exactly what patients describe and what you would expect to find in material testing of a ligament or tendon, if you performed this experiement yourself.
What known mechanism of biological tissues would make you tend to think that "creep takes longer"? Please provide a reference.
__________________
Sincerely,
Kevin
**************************************************
Kevin A. Kirby, DPM
Adjunct Associate Professor
Department of Applied Biomechanics
California School of Podiatric Medicine at Samuel Merritt College
First-Step Pain
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