The human body has magnificent intelligence to monitor, maintain, and repair itself 24/7. These complex, biological functions are the result of millions of years of evolution and of course play a major role in the survival and thriving of our species.
But even nature has its faults. When it comes to injury repair, the body’s repair mechanisms can inadvertently create a new set of problems.
When you sustain tissue damage, whether from sudden trauma such as spraining your ankle or gradual trauma such as a cumulative/repetitive tendinous strain or joint wear and tear, your body initiates a cascade of events to heal the injured tissue.
First, clotting factors appear and thicken the blood to stop any bleeding (hemostasis). This is a complex chain reaction that involves many types of substances, each with a specific role. Some clotting factors make blood vessel walls more permeable, allowing fluids to exit around the area and accumulate into the extracellular (outside the cells) spaces. This is why edema, or swelling occurs following an injury. The purpose of swelling to quarantine the injury site by creating a wall of pressure around it. The swelling also contains noxious substances (“the inflammatory soup”) such as substance p and arachidonic acid that produce pain and therefore discourage movement, protecting against further damage.
While this is happening, cells called fibroblasts start laying down a net of protein fibers called fibrin around the damaged tissue, which could be skin, muscle, bone or organ.
This fibrous net catches red blood cells, which stack up and form a fibrous blood clot, plugging damaged blood vessels and filling in the space formed by the injury. The fibrous clot gradually contracts, hardens and pulls damaged tissues together. The blood clot material eventually thins out, falls off, and may even be picked off by the person. Underneath, the reparative collagen fibers remain, forming what we call scar tissue.
You can observe this process if the injury is superficial such as a gash in the skin, but this process also happens in ligament, tendon, muscle and bone tissue injuries where there is no damage to the skin above. If it was a paper cut, you may not see a scar, but if it was a gash/laceration, when it finally heals you will see a scar.
Upon close inspection, the scar is lighter in color, feels harder, and is raised. Now imagine this scar tissue in the ligaments and tendons of a healed sprained ankle, knee or shoulder where there is movement and proximity to other structures such as bone, muscle, bursae, and nerves.
Unlike the scar tissue of a skin gash, which does not take much physical stress to it, ligaments and tendons by nature are subject to frequent movement and stress (bearing a load). They are components of all joints in your body, and the function of joints is movement and generating force. So, excess scar tissue in deeper muscle, ligaments and tendons present potential problems, described next.
Going back to the repair process, as the fibroblasts continue to lay down strands of collagen, they do so in a random, criss-crossed pattern forming the scar tissue. It’s tough and dense, which is good for repairing, but can also pose a problem in a couple of ways.
First, the criss-cross pattern of scar tissue makes it less elastic (stretchable). So after it heals, and the area is later subject to substantial stress, the scar tissue will give, and you’ll have a re-injury. This explains why boxers easily get flesh cuts after getting hit in the right spot—it’s an area of scar tissue from a previous cut that “broke” upon absorbing stress forces. Fibrosis is a term that describes pathological scar tissue; i.e. abnormal scar tissue deposition that causes disease/dysfunction such as pain and restricted movement.
Second, the very dense nature of scar tissue can cause pain receptors to bunch up around it, as they cannot penetrate it. This makes the injury site sensitive after healing completes, and contributes to the pain becoming chronic (recurring). Small, focalized areas of pain are called trigger points, as they can trigger pain in other areas when pressed.
Third, scar tissue build up constricts blood vessels, which compromises waste removal from the area and inhibit oxygen delivery to the area. In some cases, this results in chronic, low-grade inflammation, which contributes to pain sensation.
Fourth, the body may try to stabilize scar tissue by calcifying it. Calcium ions in the blood deposit on the scar tissue, hardening it and making it have rougher edges, which can cause restricted and painful movement. This is common in chronic shoulder injuries.
The bottom line is that scar tissue is essential to healing, but due to the aforementioned reasons it may also lead to pain chronicity, whether it is an acute onset sprain/strain injury; a cumulative strain such as tennis elbow; or pain from tissue degeneration such as hip osteoarthritis.
So how does one fix chronic pain caused by excess scar tissue build up?
The Ideal Approach to Ensure Proper Soft Tissue Healing, Minimize Scar Tissue and Prevent Chronicity
The best defense is a good offense: immediately after an injury, follow the standard methods of treatment: apply cold directly to the area; add some compression, elevate the area if possible to help prevent excessive swelling/edema, and rest the injured area for at least two days. If the pain is unbearable, you can take over-the-counter anti-inflammatory medications (non-steroidal anti-inflammatories like Tylenol and Ibuprofen) but I recommend trying to just stick with ice if you can, and tough it out.
As the acuteness subsides, you can introduce passive movement of the injured area. This stresses the ligaments and tendons just enough which causes the fibroblasts to lay down the scar tissue collagen fibers in a more organized fashion, which will result in better healing/ quality of healed structures.
Then, perhaps on the third day do active movements of the injured area, then a week later, active-resistance movements (weights, resistance bands, swimming pool) to stress the structures in a controlled fashion, encouraging quality remodeling of scar tissue. You may need assistance from a rehab specialist to gauge how much resistance to use, and when.
And finally and ideally, your injury will be 100% healed, without loss of strength or range-of-motion.
What to Try if You Did Not Rehabilitate Your Injury Properly and Have Chronic Pain and/or Stiffness
But what if you didn’t do all of this, and now your pain is chronic, a year after the injury or onset of pain? Scar tissue could be the main culprit: limiting mobility, getting re-injured, attracting pain-sensing nerve endings (forming trigger points), and constricting arterial, venous and lymph flow to and from the injury site causing chronic, low-grade inflammation.
Will heat do the job? Heat such as that delivered by a hotpack vasodilates blood vessels close to the skin. If you use an infrared heat lamp, you could treat deeper areas such as the hip. This may help your chronic injury feel better, as more circulation means more oxygen, nutrients, proteins and other substances that benefit cells. But heat doesn’t do much to that hard, rigid scar tissue. Heat offers temporary relief.
Will electrical stim (TENS) help? Devices like TENS that deliver an electrical current to the skin transcutaneously (through the skin) can be helpful in temporarily reducing pain perception, but they do nothing to address scar tissue.
Will pulsed EMF help? Pulsed EMF uses magnetic fields to generate pulses of electromagnetic energy. PEMF has been used since the 1950s to help heal broken bones. Scientists know that biological tissue reacts to electromagnetic fields. They affect cell membrane permeability and gene expression, which can have beneficial effects such as reducing inflammation and synthesizing functional proteins. PEMF may make chronic pain feel better, but it does not have any therapeutic effect on scar tissue itself.
Will therapeutic ultrasound help scar tissue? Ultrasound (not the kind used for imaging) is the delivery of high frequency sound waves through the body to generate heat. Ultrasound is popular for treating deep joint structures, particularly the shoulder (glenohumeral joint), hip and knee joints. Unlike topically-applied heat, ultrasound heats from the inside of the body. Sound, physically, is reverberating pressure waves traveling through a medium. When the ultrasound waves pass through the skin and strike something of higher density; i.e. tendons, ligaments or bone, it generates heat, just as rubbing your skin really hard will generate heat. The pressure waves of the ultrasound may be strong enough to loosen some of the scar tissue fibers as well, making it a good choice for treating chronic joint pain.
Will massage therapy help? It can, depending on the nature of the scar tissue. It’s most effective in reducing fibrosis if started during the sub-acute phase, and continuing past the remodeling phase of tissue healing. Massage is known for its soothing/relaxing effect, but it is also appropriate for soft tissue injuries, particularly myofascial release/ trigger point release, deep tissue massage, instrument-assisted soft tissue therapy, and Active Release technique. These methods are more accurately described as “soft tissue mobilization” techniques and involve placing pressure into areas of scar tissue to break them up, stretch them as they are being laid down by fibroblasts, or to separate scar tissue adhesions—points where scar tissue binds to other structures.
There is another modality that is not well-known to most people that has a high success rate in treating chronic tendinopathies due to scar tissue fibrosis: extracorporeal shockwave therapy (ESWT), or shockwave for short. Shockwave uses pulsed, high energy acoustic (sound) waves delivered right through the skin to physically break apart/ thin out underlying scar tissue. You may have heard of how doctors can dissolve kidney stones using a machine that sends waves through the skin all the way to the kidney stone, without surgery, called lithotripsy. This is precisely extracorporeal (meaning “outside the body”) shockwave therapy.
Shockwave treatment is often described as “ultrasound on steroids” since it uses sound pressure waves, but at a lower frequency and higher energy. Think of thunder, clapping hands, and a jet breaking the sound barrier.
When a shockwave enters living tissue and encounters changes in tissue density or impedance (such as from fat to muscle) it will either be reflected, refracted, transmitted or dissipated just like any other wave. According to the site Shockwave Therapy Education, energy is released at these interfaces of different impedance values, creating compression and shear loads on the surface of the material with the greater impedance (mostly scar tissue, tendons, and ligaments), like very tiny explosions.
The energy released by shockwaves causes microtrauma (tissue destruction), which triggers the reparative process: new blood vessels form (neovascularization) and fibroblasts secrete collagen fibers in a more organized fashion, replacing the old, disorganized scar tissue. Blood flow improves, and the old, chronic injury undergoes new healing and heals more completely the second time around. The restructuring of collagen fibers results in less nociceptors than when fibrosis was present, and the result, after a brief soreness following the microtrauma, is less pain.
Conditions Extracorporeal Shockwave Therapy is used to treat include:
- Plantar fascitis
- Epicondylitis
- Trochanteric bursitis
- Dupruyten’s contracture
- Carpal tunnel syndrome
- Achilles, patellar and other tendinopathies
- Post surgical scar tissue fibrosis
Below are video fluoroscopy images of ESWT breaking apart a calcaneous (heel) bone spur:
TYPES OF SHOCKWAVE MACHINES
There are two, main types of shockwave machines, ballistic and piezoelectric. In a ballistic machine, a small pellet is accelerated back and forth inside a metal tube by strong electromagnets or by compressed air. When the pellet strikes inside the end of the metal tube (strikeplate), it produces a radial shockwave. This type of shockwave is considered low-energy, as the shockwave dissipates and expands radially as it enters and travels through tissue.
A piezoelectric machine uses an array of tiny crystals at the end of a concave treatment head. An electric current is passed through the crystals, which causes them to quickly expand and contract, generating pulsed acoustic pressure waves. A silicone cone attachment is affixed to the treatment head to conduct, focus and direct the shockwaves produced by the tiny crystals.
The shape of the cone attachment and the output voltage determine the depth to which the soundwave travel. Piezoelectric machines are considered high-energy, as the acoustic wave is focused into a small area and does not dissipate much. These machines therefore are used with more caution.
BOTTOM LINE:
Scar tissue is like biological “glue” the body uses to repair injuries to itself, but it can cause problems long after the injury heals. Scar tissue fibrosis is a mass of hardened protein strands laid down haphazardly by fibroblasts at the injury site. It is often a factor in chronic musculoskeletal pain. It develops in injuries, such as shoulder and knee strains, and is worse if the injury is not properly treated/ rehabilitated. Scar tissue perpetuates chronic pain by inhibiting proper movement of soft tissue structures– tendons, ligaments, fascia and muscles, which can cause abrasion to adjacent tissues; inhibit vascular flow to the area; and cause sensory nerve endings to bunch together. Extracorporeal Shockwave Therapy (ESWT) is a treatment that uses high-energy pressure waves to break down scar tissue fibrosis so that new, organized fibers can replace it; abrasion and congestion are reduced, and movement and strength are improved. It is a highly-effective modality for tendinopathies and similar musculoskeletal diseases, with some studies finding an 80% success rate.
For more a more in-depth explanation of how extracorporeal shockwave therapy works, watch my interview with Dr. Ulyss Bidkaram, a chiropractor who uses ESWT in his practice:
REFERENCES:
Shockwave Education
http://www.shockwavetherapy.education/index.php/theory/biological-effects
Angela Notarnicola and Biagio Moretti. The biological effects of extracorporeal shock wave therapy (eswt) on tendon tissue. Muscles Ligaments Tendons J. 2012 Jan-Mar; 2(1): 33–37.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3666498/
Semra Aktürk,1,* Arzu Kaya, et al. Comparision of the effectiveness of ESWT and ultrasound treatments in myofascial pain syndrome: randomized, sham-controlled study, J Phys Ther Sci. 2018 Mar; 30(3): 448–453.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5857456/
Image credits:
https://www.biodermis.com/what-are-the-stages-of-wound-healing-s/221.htm
http://www.shockwavetherapy.education/index.php/theory/biological-effects
https://www.verywellhealth.com/what-is-rice-190446
https://www.pediagenosis.com/2019/10/exercises-for-range-of-motion-and.html
https://www.verywellhealth.com/what-is-rice-190446
