This article contains information about shoulder pain, sourced from a study that was published in Lasers in Medical Science in August of 2020. The title of the study is Efficacy of High-Intensity Laser Therapy in Patients with Adhesive Capsulitis: A Sham-Controlled Randomized Controlled Trial.
The high-intensity laser therapy we are talking about does not refer to surgical lasers or any super heating of the tissues. We are merely describing a therapeutic laser that works the same as cold lasers; the difference is that it works at a higher rate and provides a higher dose of light than the low-intensity lasers. For example, instead of having a half a watt of power like Class 3 lasers offer, Class 4 lasers can go up to 10, 20, or 30 Watts of power or even higher. They can typically accomplish the same results in a shorter duration. So, instead of a 45-minute treatment, you can expect around 10 minutes. In this study, the researchers used this high-intensity laser therapy on patients with adhesive capsulitis (or, as it is more commonly known, "frozen shoulder").
Adhesive capsulitis is a unique disorder because it does not happen anywhere else in the body. It is a product of the way the shoulder joint moves and responds to injury. It occurs when a shoulder is either overused or engages in too much repetitive motion, or if it suffers a sprain or a strain injury. This frozen shoulder process then sets in because the shoulder will start developing fibrosis around the joint (meaning fibrous tissue starts to form in the shoulder joint). As this continues, its range of motion will continuously decrease. It starts to become more painful and stiff. It prevents you from being able to reach as high as you had before, or it limits your ability to reach behind yourself. Certain motions become painful while other motions do not seem to be much of a problem. Unfortunately, many people experience the pain and lack of mobility described in this paragraph.
Approximately 3 -5% of the population suffer from a frozen shoulder. However, it is much more common in people with diabetes—an estimated 20% of all diabetics will have frozen shoulder. This is believed to be due to the fact that diabetic patients do not have the ability to heal and recover as well as non-diabetics. Diabetics also tend to have more inflammation, which, from what we know, is a significant driver of adhesive capsulitis. Inflammation rapidly stimulates the formation of fibrous tissue. If you have diabetes, you need to be aware that a minor injury could turn into something like frozen shoulder syndrome because of this.
What happens after you have frozen shoulder? Many cases seem to resolve in 2-3 years, but about 40% of patients tend to have persistent pain and stiffness for much longer than 3 years. So, it can be a long-lasting and life-altering disorder. This does not mean that your shoulder will be rendered unusable for the rest of your life, but it certainly means you could be limited in some activities like, for example, golfing or tennis, or maybe even things like playing with the grandkids. These limitations are why most people pursue some form of treatment. Fortunately, in many cases, conservative care can work well. Most physical therapists have good protocols for working with frozen shoulder, and they can help resolve the issue. If it does not help, though, there are a few other options, such as injections or surgical alternatives. However, those are somewhat risky and usually not advised—at least not until you have exhausted all your conservative, non-invasive care options.
The non-invasive care option that the researchers of the aforementioned paper wanted to explore was high-intensity laser therapy. They were wondering if laser is a good solution for the conservative care of frozen shoulder patients. They approached the study with the hypothesis that laser therapy would help reduce the pain, improve the stiffness, and increase the range of motion of frozen-shoulder patients who participated in the study. They also put the participants through a standard physical therapy mobilization program. The program was designed to increase shoulder mobility and decrease shoulder pain.
The study was conducted with one group both performing the exercises and receiving laser therapy; the other group served as the control group: Although they also performed the exercises, they only received sham laser therapy treatments (fake laser treatments) so that they could control for the placebo effect. The researchers went through the effort of trying to eliminate that effect by having a real laser therapy treatment group and a fake laser therapy treatment group.
Every participant was treated 5 days a week for 3 weeks. At the end of the 3 weeks, all the participants experienced improvements in both their ranges of motion and in their pain levels. Yet, the group that received real laser treatments had significantly less pain than the patients in the control group. What is somewhat surprising is that the range of motion and the stiffness were about the same for both groups. So, even though the group that received laser therapy experienced less pain, laser did not appear to produce any improvements in mobility.
Upon first reading the study, we were surprised. How did they have less pain but did not have functional improvement? To answer this, let's dig into the techniques that these researchers used.
**Before going any further, we want to point out that this is not a criticism of the researcher's technique. It is absolutely critical in science that, when things end up not working as well as we anticipated, we use that information to help us better understand which approaches are effective and which are not.**
These researchers found that, by using laser therapy, patients experienced more relief from their frozen-shoulder pain than the patients who did not receive laser therapy. But why didn't laser also help improve their range of motion? The patients were treated 5 times per week. They were treated on Monday, Tuesday, Wednesday, Thursday, and Friday. Based on extensive clinical experience, it is evident that patients do not typically need to be treated every day. Receiving daily treatments does not allow much time for the tissues to rest and recover and improve. It's like going to the gym: When you lift weights, you get better results by working out a muscle group a couples times a week. You don't get those good results if you work the same muscle group every day back to back because that does not allow those muscles time to rest and recover. This is one potential explanation as to why the laser patients did not experience more improvements in their ranges of motion than the control group did.
Next, we'll look at how they applied the treatments. These researchers used a fairly high-powered laser in the 8-12 watt range. They treated the injured shoulder for 15 minutes. When delivering a treatment with a high-powered device, 15 minutes is a very long time. And they did that every day. The recommended dosages are between 5 and 10 joules per centimeter squared. They delivered 100 joules per centimeter squared—that is 10x higher than the recommended dose. So, not only did they treat 5 days per week, but they also treated for a long time per treatment at a rate of power 10 times higher than normal.
The way in which they applied the treatments is probably why the laser patients felt such a significant reduction in pain: By delivering a very high dose, you can overwhelm the pain sensors, reducing the perception of pain. However, because the tissues were not given much recovery time in between their high-dose treatments, the fibrous tissues in their frozen shoulders did not recover to the point at which they could see functional improvement in the shoulder. Although it is speculation on our part, we believe it is safe to suggest that they were treated too often and with too high of a dose. Did they do these patients any harm? No. That is one of the great things about laser therapy! Even if practitioners do not use high-precision protocols, patients can still benefit from the treatments. Even if the power, dose, or treatment frequency is too high, patients will not be negatively impacted. Ultimately, when patients experience pain relief, they should also experience improvements in functionality. If that does not happen, as it did not in this study, we think it is worth asking why, as we have here.
Takeaway: When treating frozen shoulder, laser therapy can be a great tool, but you will also want to also implement interventions like exercise or physical therapy. If you receive treatments from the correct type of equipment, with the right dosage, the right treatment plan, and the right treatment frequency, you should experience noticeable benefits from laser. That is what you will find at LTI Clinics! Our members use well-designed, clinically proven treatment plans along with high-quality equipment and technique.
If you are dealing with adhesive capsulitis (frozen shoulder), or if your current treatment plan is not really producing good results, we recommend you give laser a try. Do not let this go on for years! Regain that range of motion now so that you feel and function better. Additionally, if you correct this sooner than later, you will save yourself from losing more strength in that shoulder. When you lose strength in the shoulder—especially in the rotator cuff muscles—you become increasingly likely to have a rotator cuff injury. That injury, on top of adhesive capsulitis, means you are more likely to end up in the surgeon's office. Prevent all that by finding a laser clinic near you instead!