The Scar Tissue Myth & Manual Therapy

Scar tissue has been demonized in the sports medicine world as the cause of many myofascial pain syndromes. Shoulder and knee pain, among others, are often attributed to scar tissue formed after a previous injury with treatments geared towards the breakup of said tissue. Is scar tissue really the cause of these pain syndromes and can it be broken down by manual therapy? Or is there another way manual therapy works? This blog post will discuss the scar tissue myth and also explain how manual therapy works. 

If you’ve had some sort of myofascial pain in the last 10 years, chances are someone told you (massage therapist, physical therapist, chiropractic, athletic trainer, your dog, etc.) that fascial adhesions or scar tissue were the culprit of your pain. The practitioner then claims to break up the evil scar tissue using their hands (Active Release Technique, pin and stretch), tools (Instrument-Assisted Soft Tissue Mobilizataion/Graston), or maybe even a foam roller. The problem is that research suggests that the amount of force needed to elongate these tissues far exceeds what is possible for the practitioner to generate.

For reference, a female giraffe weighs about 828 kg... that's a lot of pressure. 

For reference, a female giraffe weighs about 828 kg... that's a lot of pressure. 

The iliotibial band (tissue on the side of your thigh) and the plantar fascia (tissue on the bottom of your foot) are two fascial bands that are subjected to manual therapy to “break up adhesions and scar tissue.” However, research suggests that a load of 9075 N (925 kg) would be needed to cause 1% compression and 1% shear for the iliotibial band, while a load of 8359 N (852 kg) would be needed for the same effect in the plantar fascia.  That’s 2040 and 1879 pounds of pressure to cause 1% compression of the tissue for the iliotibial band and plantar fascia, respectively! 

And I think we would all agree that we would need to cause more than 1% compression and shear to have any “real” effect on the dysfunctional tissue. But if we feel better after a manual therapy session, something had to happen. So what is going on if we aren’t blasting scar tissue? 

Well, the benefit of manual therapy seems to be through the stimulation of mechanical receptors, also called mechanoreceptors.  

Here are a few of the common mechanical receptors in the body. 

Here are a few of the common mechanical receptors in the body. 

While the stimulation of golgi tendon organs would seem to make the most sense with what is experienced during manual therapy, the golgi tendon organ seems to only be stimulated with active contraction of the muscle. The ruffini and interstitial receptors actually seem to the be the receptors most likely stimulated by manual therapy. 

The stimulation of these mechanical receptors in the body alters the message to the central nervous system (the brain and spinal cord). The new sensory information can then allow the brain and spinal cord to alter the tone in the targeted tissue, resulting in the decrease in muscle tightness often experienced. The ruffini and interstitial receptors also have an inhibitory effect on nociceptors (receptors that alert your body to danger). Thus manual therapy both decreases pain as well as alters tissue tone. 

You might be asking why does the mechanism behind manual therapy matters if it works? Well, it changes how you would approach treating musculoskeletal issues using manual therapy. If the goal is to stimulate mechanical receptors and not break up scar tissue, you can generally use less force (limiting the possibility of soft tissue damage), resulting in decreased post-treatment soreness and faster return to play.

Does that mean that there isn’t a time and place for deep manual therapy or using an aggressive foam roller (ie. the rumble roller)? Not necessarily. The mechanical receptors can alter their sensitivity which means that more force may be needed to stimulate them. It also means that some days a gentle stretch could work and another day the rumble roller might be needed. 

The point is that you will have to find how “sensitive” your receptors are at the time, which will influence which treatment strategy you will use. 

 

References: 

Bialosky, Joel E., Mark D. Bishop, Don D. Price, Michael E. Robinson, and Steven Z. George. "The Mechanisms of Manual Therapy in the Treatment of Musculoskeletal Pain: A Comprehensive Model." Manual Therapy 14.5 (2009): 531-38.

Chaudhry, Hans, Robert Schleip, Zhiming Ji, Bruce Bukiet, Miriam Maney, and Thomas Findley. "Three-Dimensional Mathematical Model for Deformation of Human Fasciae in Manual Therapy." The Journal of the American Osteopathic Association J Am Osteopath Assoc 108.8 (2008): 379

Schleip, Robert. "Fascial Plasticity – a New Neurobiological Explanation: Part 1." Journal of Bodywork and Movement Therapies 7.1 (2003): 11-19.