Scar tissue? To break or not to break?

I have dove into this topic before but I’ll give a bit of background into my reasoning for going into it. Imagine someone you cared for was recommended to have surgery. The surgery had to be done with the person awake and was extremely painful. Out of curiosity you look into the research and find studies that state the surgery is a waste of time and has no proof of actually being effective. How would you feel? I’ve been aware that manual therapy is very unlikely to create any change but there was a tipping point. I over saw a therapist working with a young patient, probably not even 12 years old. Their parent was in the room and they had a particular issue they wanted to address. The therapist then stated the patient probably has scar tissue and it needs to be broken down manually. I watched the child in tears for what seemed like a good 5-10 minutes. Even if you could show me that there was evidence for that technique and method I would still consider it abuse as there are alternatives. I can go along with the use of various treatment techniques in conjunction with evidence based approaches. What I refuse to go along with is bulls%^t theories with zero significant evidence that are used to justify and cause pain to people without appropriate information. If a therapist wants to say “this is going to hurt, but my personal theory despite the lack of any evidence is that it will help break down scar tissue” then go for it, but watch out for litigation. I am here to help people with pain, not to cause it.

The human body is a marvel of nature. We often underestimate how robust and resilient the body can be. The body can adapt over time in terms of structure but can anything be changed in a short amount of time? When we discuss how manual therapy effects the tissue there are many who believe that manual forces can deform tissue or change structure. Let’s take a look at this from what has been shown to be the potential force applied from manual therapy.

First let’s take a look at the amount of force that can be applied in terms of compression and shearing. In order to determine if this is possible we must determine two main things: how much force is physically possible from manual therapy and how much force is needed to deform tissue. If more force is needed then it’s impossible, if a therapist can produce more force then it’s possible. I like to look at things at a relatively objective way in order to reduce my own bias.

Manual therapy in one study showed to have a maximal compressive force of 450PSI (3N/mm2) while the shear force was at roughly 55% at 250PSI (1.7 N/mm2). This means they applied a downward force to the patient of 450, while moving the fist along the tissue they were able to apply 50% of that to shear which is the force that would be theoretically responsible for shearing and breaking tissue. When compared to the force needed to cause microtears in connetive tissue being 10,000-30,000 PSI it would not make sense to think that type of force could deform tissue (3). The sheer force plausible from manual therapy is 250PSI, which is still below the vertical load tolerance of the line alba (abdominal) scar tissue (480 PSI) by 50%.

One study looked at tissue tolerance of line alba to horizontal load has shown to be 1450PSI (10N/mm2) and 1000PSI (6.9N/mm2) in scar tissue. The vertical load tolerance was 650PSI (4.5N/mm2) for linea alba and 480PSI (3.3N/mm2) for the scar tissue (1). Again these two forms of scar tissue had anywhere from 2 to 5 times the strength that could be applied from manual therapy.

A much older study seems to confirm the strength of connective tissue. This study looked at the tensile strength of the tensor fascia lata which showed to be 7000 PSI at a specific gravity of 1.3, compared to steel at 45000PSI with a specific gravity of 7.8. This means that based on strength to density ratio that steel is only 6% stronger than connective tissue. This makes sense as the IT band has shown to only deform 2.5% under 10,000 PSI and would then be regarded as having a similar strength to steel when looking at strength to density, with steel being much more dense of course

Another study looked at the tensile strength of 70 day old scar tissue on the skin in pigs(4). The strength was measured at roughly 850PSI. So say you had surgery two months ago, that scar tissue is already 3.5 times stronger than what a manual therapist can produce, the body is amazing in terms of these adaptive healing properties. This again is much lower than the demonstrated maximal shear force of 205PSI mentioned previously.

The tensile strength of healthy human skin much like leather is around 2000PSI. This would make sense as soft tissue release techniques can’t create enough force to shear skin. Since the tensile strength of most connective tissue far exceeds the plausible force that can be created manually, it can be concluded that manual force can’t create enough force to shear things such as scar tissue. Otherwise any force that would be enough to deform most scar tissue would most likely be pretty much enough to shear the skin right off your body, which is probably not what you hope to happen during your treatment.

From Chaudry et al.: “Our calculations reveal that the dense tissues of plantar fascia and fascia lata require very large forces—far outside the human physiologic range—to produce even 1% compression and 1% shear. However, softer tissues, such as superficial nasal fascia, deform under strong forces that may be at the upper bounds of physiologic limits”

The superficial nasal fascia is simply the thin skin on the inside of your nose. So the very thin layer of tissue inside your nose may be possible to deform if someone put their maximal force into it. Just imagine someone putting their full weight into their thumb up your nose, that would be the only possible situation where full force may actually deform tissue, and also cause some bleeding as well.

The other conundrum I am unsure of is even if it were all possible there are still a few questions. If one breaks up tissue then one increases inflammation, which may not necessarily be bad but also not ideal as inflammation can contribute to other issues. The other concern is, if someone just broke human tissue, guess what the body will do? That’s right, lay down some fresh scar tissue to repair the tissue that the body previously laid down. Imagine tearing down your house right after renovation it, doesn’t seem sensible to me.

Lastly, I’ll leave you with this; if human connective tissue can be broken from the pressure of a thumb then what would squatting a few hundred pounds do to tissue? Once at parallel and squatting 2.5 times body weight a powerlifter has a compressive force on the knee joint is 8000N, which is again far greater than manual therapy can create(4). Luckily the patellar tendon can handle 10000-15000 N, the body is awesome isn’t it?

So it seems that the plausibility of breaking scar tissue down manually is highly unlikely unless someone is digging their fist into your nose. Even scar tissue only two months old is far too strong to be broken. The human body is strong, it adapts, and it can be simply remodeled by someone’s hands or a tool, if they did there would likely be a lot of blood and tearing of skin.

As always I would love to see any research that shows otherwise. So far I have been shown a case study where the scar tissue was remodeled for a single person, the treatment also included aggressive stretching which seems more likely to have any effect. The other studies look at rat tissue, an animal that has such a short lifespan likely has healing mechanisms much different than our own.

Thanks for reading, Vitas

1- Chaudhry, H. Schleip, R. et al. “ Three-Dimensional Mathematical Model for Deformation…” J Am Osteo Assoc. Aug 2008.

2- Hollinsky, C. Sandberg, S. “Measurement of the tensile strength of the ventral…” Clin Biomech. Jan 2007.

3- Gratz, C. “Tensile strength and elasticity tests on the tensor fascia lata”. J Bone Joint Surg. 1931

4- Corr, D. Hart, D. “Biomechanics of Scar Tissue and Uninjured Skin”. Adv Wound Care. 2013