Loading, lengthening, healing.

Response of the tendon during limb lengthening.

Szöke G, Lee SH, Simpson AH, Prescott J.
University of Edinburgh, Teviot Place, Edinburgh EH8 9AG, Scotland, UK.

J Bone Joint Surg Br. 2005 Apr;87(4):583-7

"Little is known about the increase in length of tendons in postnatal life or of their response to limb lengthening procedures. A study was carried out in ten young and nine adult rabbits in which the tibia was lengthened by 20% at two rates 0.8 mm/day and 1.6 mm/day. The tendon of the flexor digitorum longus (FDL) muscle showed a significant increase in length in response to lengthening of the tibia. The young rabbits exhibited a significantly higher increase in length in the FDL tendon compared with the adults. There was no difference in the amount of lengthening of the FDL tendon at the different rates. Of the increase in length which occurred, 77% was in the proximal half of the tendon. This investigation demonstrated that tendons have the ability to lengthen during limb distraction. This occurred to a greater extent in the young who showed a higher proliferative response, suggesting that there may be less need for formal tendon lengthening in young children."

PMID: 15795216 [PubMed - indexed for MEDLINE]
Link1

Biomechanical properties of tendons during lower-leg lengthening in dogs using the Ilizarov method

B. FinkCorresponding Author Contact Information, a, G. Schwingerb, J. Singera, G. Schmielauc and W. Rüthera

Journal of Biomechanics
Volume 32, Issue 8, August 1999, Pages 763-768

Abstract

Ten dogs were provided with a circular fixator. Segment resection of the fibula and tibial osteotomy in the right lower leg was performed. 5 days after surgery, a lengthening of the right lower leg by 2.5 cm was performed on 6 dogs using a distraction rate of 0.5 mm, twice per day. 3 dogs with leg lengthening and 2 dogs of the control group without leg lengthening were sacrificed at the end of the distraction phase of 25 days and the remaining dogs after another 25 days. Postmortally the tendons of the tibialis anterior, extensor digitorum longus, peroneus longus and the achilles tendon were taken from the operated right side and the left non-operated control side and were examined biomechanically in cyclic tests. The control group without lengthening showed no changes in the biomechanical properties in the tendons of either side nor in those of the unlengthened left side of the operated dogs. In contrast the biomechanical tests revealed a marked decrease of the elastic modulus, an increase of distraction length and an increase of modulus reduction on the lengthened side compared to the non-operated left side.
Link 2

Journal of Bone and Joint Surgery - British Volume, Vol 88-B, Issue 12, 1666-1669.
doi: 10.1302/0301-620X.88B12.17850

Relative ability of young and mature muscles to respond to limb lengthening
T. Shisha, MD, PhD candidate, General Practitioner1; S. Kiss, MD, Orthopaedic Surgeon1; K. Pap, MD, PhD candidate, General Practitioner1; H. Simpson, MD, PhD, DM(Oxon), Professor, Orthopaedic Surgeon2; and G. Szöke, MD, PhD, MSc(Oxon), Assistant Professor, Orthopaedic Surgeon1

"The response of the muscle is critical in determining the functional outcome of limb lengthening. We hypothesised that muscle response would vary with age and therefore studied the response of the muscles during tibial lengthening in ten young and ten mature rabbits. A bromodeoxyuridine technique was used to identify the dividing cells.

The young rabbits demonstrated a significantly greater proliferative response to the distraction stimulus than the mature ones. This was particularly pronounced at the myotendinous junction, but was also evident within the muscle belly.

Younger muscle adapted better to lengthening, suggesting that in patients in whom a large degree of muscle lengthening is required it may be beneficial to carry out this procedure when they are young, in order to achieve the optimal functional result."

Link 3

The preceeding post has the scope to investigate a third possible way through which length of connective tissues can happens.

Since here, most of studies have shown that connective tissue can lengthen through viscoelastic deformation (not true growth, per se); can also elongate as a consequence of micro-failure repairing, that should cause true growth. Is it possible that tissue does elongate without previously causing micro-tears? It would the ideal scenario, since to have micro-tears we do have to go in a dangerous zone, near the major injury evenience.

The above studies seem to suggest that this can actually happens; the mechanism should be cellular proliferation. I have previously posted studies that showed that mechanical strain cause cellular proliferation in connective tissue; but in those studies, despite the cellular proliferation there was no growth in stretched tissues. Actually, the two things seemed unrelated, so much that cellular proliferation was observed in tissue at any degree of stretch, even when the tension was near zero.

So, instead than cellular proliferation, there could be some other process activated by stretches that could cause CT growth.

Here you are another abstrac on this topic:

Cyclic tensile strain upregulates collagen synthesis in isolated tendon fascicles.

Screen HR, Shelton JC, Bader DL, Lee DA.
Biochem Biophys Res Commun. 2005 Oct 21;336(2):424-9.

"Mechanical stimulation has been implicated as an important regulatory factor in tendon homeostasis. In this study, a custom-designed tensile loading system was used to apply controlled mechanical stimulation to isolated tendon fascicles, in order to examine the effects of 5% cyclic tensile strain at 1 Hz on cell proliferation and matrix synthesis. Sample viability and gross structural composition were maintained over a 24 h loading period. Data demonstrated no statistically significant differences in cell proliferation or glycosaminoglycan production, however, collagen synthesis was upregulated with the application of cyclic tensile strain over the 24 h period. Moreover, a greater proportion of the newly synthesised matrix was retained within the sample after loading. These data provide evidence of altered anabolic activity within tendon in response to mechanical stimuli, and suggest the importance of cyclic tensile loading for the maintenance of the collagen hierarchy within tendon."
Strain and collagen

What does that mean in English? :) This is all extremely esoteric.

Do they mean the stresses/mechanical stimuli causes the body to release growth hormones in the specific regions where the stress is applied that then causes tissue growth?

No it’s not about growth hormone. What they are saying is that cyclical strain at high frequence (1 hz = 1 straing each second) caused production of new collagenous tissue, cellular proliferation and matrix syinthesis.

Shortly said, new tissue in the stretched tendon.

Cyclical strain, hm. So kinda like JAI stretches or quick Jelq strokes? If cyclic straining is the way to go it would appear that hanging/extenders is ineffective.

“These data provide evidence of altered anabolic activity within tendon in response to mechanical stimuli.”
That’s what made me think of some kind of hormone being release in the area. But what does it mean? Anabolic activity within the tendon?

JAI stretches are an example of cyclical stretches, for sure, altough they were inteded primarily to avoid the kik-back reflex. JAI have to be done in a controlled manner, where with cyclical strethces the goal is somewhat the adverse: they want to cause many little breaks in the tissue.

The frequency is also higher: once or more per second. I had the intention to try a fast stretches routine to see what I could give, but I couldn’t because my shoulders hurt.

Anabolic activity just means that the amount of tissue was augmenting, like it was a man that was eating more and growing more.

This is interesting stuff. But isn’t there a risk of only creating a stronger/tougher penis by producing more collagenous tissue?

Right Dicko. We don’t know if these new tissue was used to make the tendon longer, stronger or both things. This study doesn’t say anything about the length of the tendon after the cyclic stretching, was longer and/or more pliable (in formal terms, if his elastic modulus was decreased).

But, even in the case that the new tissue created by cyclic strains made the tendon stronger, we could lengthen this new tissue through the low tension-long time approach, I think.

How permanent is this newly created tissue?

I think they will last long, Gjurob, but I haven’t any study to backup this guess.

It really explains how repetitive stress injury takes place though. I now all kinds of people, as I’m sure others do who have joints that pop out of place constantly because they have been so over-stretched and over-stressed that the ligaments and connective tissues are permanently stretched to the point they will never heal - and consequently hold the joints in place again without surgery to shorten the elongated tissues. Since these are the same type of fibers we are working with its relevant for sure.

I swear your in the rehabilitation business Marinera. I like a more aggressive approach than you, but I like how you put intelligent, relevant science into your thinking.

The penis is big business, I can’t see why there aren’t studies about the actual penis itself. If I had that level of intelligence and influence I wouldn’t hesitate.

No, I’m not in the rehabilitation field, H2H. Firegoat is, I think.

I think marinera is an engineer :D

Marinera you have convinced me to give light hanging for many sets a day a try and I was wondering how much weight would you suggest I use for the next few months?

What you should check into is Prolotherapy. This is medical technique that when applied ends up with joints that will hold together again. It restarts the healing process and causes the ligaments to go through the 4 phases of healing, that ends with ligaments returning to their normal and original length tightening the joints again. This is obviously something we want to avoid in PE.