Updated: Nov 14, 2021
On the blog today, not only are we going to talk about frozen shoulder (adhesive capsulitis) but we're also going to talk about laser dosing. Don't fall asleep on me. I know that sounds really boring right up front, but I think you'll find this interesting because it helps to answer some of the questions I get from doctors quite frequently, like "how often should I treat? Is it once a week? Is it seven days a week, twice a day? How long should my laser treatments be? 30 minutes? Is it two minutes? What about the power levels?"
If you've had those questions than read on as we go into a very interesting study. These researchers have done us a huge favor. The study I'm referring to today is titled "Efficacy of high-intensity laser therapy in patients with adhesive capsulitis: a sham-controlled randomized controlled trial." This was published in 2020 in Lasers in Medical Science. I'm going to go ahead and spoil the ending for you. They say that all groups had good improvements in their range of motion, but the patients that received the active laser treatment had better results in pain and quality of life, but not better results in terms of disability or function. They went into this with a hypothesis that they were going to see good pain relief, as well as improvement in range of motion and reduction of stiffness, and they didn't see all of that. So, when I saw those results, I thought, you know, that's not too unusual to not necessarily see the full benefits. Obviously, they still got good reduction of pain in this sham controlled trial, which is great. But then when I started looking into their parameters and exactly what they did and how they did it, I thought, ah, there is a learning point here for those of us who are looking for more information about dosing laser effectively.
Before I get into the setup for this particular study, just a quick recap on adhesive capsulitis. Adhesive capsulitis is a fibrosis process that happens in the shoulder. It typically follows some kind of overuse injury or a mild sprain/strain, sometimes a rotator cuff tear, or tendonitis. And what happens is that chronic inflammation starts this fibrotic process around the GH and AC joints. You will find a decreased volume of the glenoid capsule, and the patient will start to lose that range of motion.
Many cases, it's one particular range of motion. For example, patients can still internally rotate just fine, but the external rotation is limited, or the abduction is limited, and it tends to be progressive. It tends to get worse over a period of time. Isn't super common, but it's in about 3 to 5% of the population. So you're definitely going to see it in practice if you deal with orthopedic injuries at all. The thing is, your diabetic patients are going to be much more likely to encounter this, especially after a minor injury to the shoulder. About 20% of people with diabetes will experience frozen shoulder, and we have more and more people every year that are becoming diabetic.
Now a lot of cases of adhesive capsulitis will do quite well with conservative care, especially physical therapy and chiropractic, exercise home plans, things like that. But even if people don't do anything, it's often a self-limiting process. So patients can expect to see some pretty good improvement but not until after two to three years, which is a long time to wait. However, about 40% of patients will have ongoing pain and dysfunction, stiffness, and reduced range of motion, even after the three-year period. Whenever you have patients that have reduced range of motion, stiffness, and pain, they're going to use that body part less, which means it's going to get weaker. And if it goes on for years, you're talking about progressive weakness and then you're going to be more prone to rotator, cuff tears, strain, sprain injuries.
It is not unusual to see one of these problems, maybe just a minor tendonitis problem, develop into adhesive capsulitis and then turn into major rotator cuff tears, and now the person has to get the shoulder replaced and they could have resolved it non-surgically if they'd gotten good conservative care much earlier.
Laser Therapy for Adhesive Capsulitis
So these researchers went at this with the idea of, "let's see if high-intensity laser therapy can be a good addition to a conservative care plan so that we can get patients better quicker."
Quick side note here. We're not talking about surgical laser. We're not talking about damaging any tissues. We're talking about high intensity laser and class four laser therapy, which works the same in the same mechanisms that cold laser or low-level laser therapy does. It just operates at a higher power level, which means most cases you end up with shorter treatments in the five-to-10-minute range instead of the 30-to-45-minute range. For more about this go here.
About the Study
So the researchers set up this study to treat the adhesive capsulitis patients five days a week for three weeks, and all the patients got an exercise program supervised by the same PT. And then half of the participants got real laser, and half the participants got a sham laser treatment.
It was really a pretty, well-designed pretty robust study. And what caught my eye right off the bat was that they were treating these patients five days a week. I thought, that's a little unusual for an exercise-based plan and definitely not the norm for what we see with laser therapy; three times a week or twice a week is usually more common with these studies. So this could be interesting, right?
Then I got into the exact method of application that they used for the laser. They use a 1064nm laser, which has been well proven to have good therapeutic effects in tissues. And the device they used went up to 15 Watts. They applied between eight and 12 Watts on a single shoulder for 15 minutes, at a dosage rate of 100 J/cm2. Now, if you've heard me discuss research on the podcast before, or you've read any of my blog posts, all that information should be raising some questions in your mind. 15 minutes of very high intensity laser on a medium body part like the shoulder is pretty intense. If you were talking about a low-level laser at half a watt, that sounds about right. But this study used much greater power and a dosage at a hundred joules per centimeter squared. That is a very high dose. The WALT dosing guidelines usually says between five and 10 joules per centimeter squared.
So we're talking a 10 times greater dose than what is normally recommended. Now don't get me wrong, I'm not being hard on these researchers or saying they did anything wrong. We only find out new information by researchers who are willing to push the envelope and find the limits and find which parameters work. Well, these guys did a very high dose five days a week, Monday, Tuesday, Wednesday, Thursday, Friday, along with exercises, and then reevaluated at the end.
Laser Therapy Dose Response
Now, you know what? This actually worked out pretty well, because patients experienced improved range of motion, less stiffness and reduced pain. The laser therapy group, the ones that got real laser, had much less pain and higher quality of life scores as well. But the improved range of motion and stiffness was no different from the sham group to the real laser group.
To some degree, this atypical method worked, but if you know about how laser therapy works, then you know it works by stimulating improvement in the tissue health, producing better circulation, better oxygenation, and better cellular metabolism. If laser therapy works via those mechanisms to produce pain relief, then these patients should have also seen better range of motion gains above the sham treatment group.
So what was going on with this particular setup? Well, in my opinion, three days a week is typically going to be enough. Five days a week with a high intensity laser with an extremely high dose doesn't give the tissues time to recover. It does help to reduce nociceptive action, which means pain reduction for these patients, but not necessarily healing. This is a case of doing too much laser and, you know, I think as clinicians, that's an easy thing to do because we want to help people. We want to help them now, and quickly, but in most cases, five days a week is going to be too much for most conditions.
Think about exercise therapy. You can give the patient some things to do for mobility at home on their off days. But in many cases, you want to be two to three times a week for an exercise plan. And the same goes for laser therapy. Two to three times a week is often about right, because it gives the tissue some downtime and time in which they can heal and recover and improve tissue health in-between the application of exercise and laser therapy.
Also, the very high dose obviously helped with reducing pain, but maybe the researchers would have seen better pain relief as well as better range of motion improvements with a lower dose. (To learn more about dosing, check out our instant-access course here.) Now again, they didn't do anything wrong. Actually, the patients came out doing much better with laser than they did without getting laser. Laser Therapy Institute exists to provide fine-tuned laser therapy protocols, settings, treatment plans, frequency, how long the treatments are, how to even apply the laser, what patterns should be used.
Laser Therapy Settings and Protocols
Studies like this are exactly why we are able to have those protocols because research shows us what effective and ineffective protocols look like. We know from clinical experience how patients present and how laser therapy can power their improvement. If you want to learn more about our protocols, you can contact us and tell us more about your clinic and what you're looking to do with laser therapy. We offer a large variety of training options that can be customized to fit your and your patients' needs.