Frozen shoulder is the layperson's term for a medical condition called adhesive capsulitis. What is it? Well, the answer to that question is not entirely clear. There's inflammation of the tissues in and around the shoulder joint that leads to fibrosis (scarring). The result is the joint gets stuck and can't move smoothly anymore. Painful and limited shoulder motion are the two main characteristics of this condition.
What causes it? That's not entirely clear either. Sometimes it just seems to come on without any reason. In other cases, it's linked with diabetes, stroke, heart attack, or some other systemic illness. In this article, physiotherapists review the condition and offer us some insights into what's currently known about the pathology, diagnosis, treatment, and natural history. Natural history refers to what happens in this condition over time. For example, in many patients, it seems to clear up on it's own over time.
There are different ways to classify or describe adhesive capsulitis. One method divides the condition into two separate categories: pimary (cause unknown) and secondary (linked with trauma or a systemic disorder). Patients with secondary frozen shoulder are further divided into two more groups based on which part of the joint is affected (intrinsic or inside the joint and extrinsic, which is outside the joint).
Physiotherapists may use a different classification scheme altogether. This one is based on the patient's irritability level (low, moderate, high). For example, someone with high irritability has pain that limits motion and function. Someone with low irritability may have slightly restricted motion with stiffness, but no pain. For patients with primary adhesive capsulitis, the natural history is one in which the patient begins with high irritability. As the condition gets better, the level of irritability goes down to moderate, and then low.
What's happening inside the joint? In other words, what's the pathologic process causing these symptoms? Here, there is more recent information to offer. New techniques of cellular analysis have shown scientists that there is both an active inflammatory process and chronic inflammation with the formation of fibrosis as an end-product. Yet in some patients, there's no evidence of inflammation, but rather nerve cells are found inside the joint.
Surgeons can attest to the fact that there's definitely scarring in and around the joint. They see it when they do open incision or closed arthroscopic surgery. Surgically releasing the fibrotic tissue restores motion immediately. Sometimes they see inflammation around the tendons and lining of the joint. Therapists perform stretching and joint mobilization to help these patients.
What's the natural history of adhesive capsulitis? Experts differ on how they view this. Some say it occurs in three stages, while others see four distinct stages. Either way it's described, there's an initial period of pain, then stiffness (the frozen part), then recovery or the thawing phase. Sometimes the stiff, frozen stage is divided into the process of freezing and then the frozen phase.
Because the condition gradually gets better, it is considered self-limiting. The whole process takes anywhere from 12 to 18 months to go through the main stages. But at least half of the patients say they still have stiffness and loss of motion for years. So, what can be done about this condition? And what works best?
Many studies have been done looking at various types of nonoperative treatments such as acupuncture, nerve blocks, steroid injections, joint mobilization and/or manipulation, exercise, and antiinflammatory drugs. It's difficult to compare and summarize the results because each study was done with different tests, measures, and definitions of treatment success. Is success measured by the return of full, normal motion? Is that even reasonable for this condition? It may be more realistic to see if patients end up with improved, but functional motion.
If patients get better in a year's time, is treatment even needed? If treatment is provided, when's the best time for it? Is there some point in time when antiinflammatories work best (or better than other choices)? If physiotherapy is the treatment of choice, how often should the patient see the therapist? What treatment techniques should the therapist use? Is it the same for each patient? There are many unanswered questions yet to be studied.
At the very least, it's clear that teaching the patient about the process and what to expect is important. They should be prepared for the fact that this is not a quick and easy problem to solve. A couple of Advil and a few exercises aren't the answer. A consistent, daily program of exercises to relieve symptoms and restore motion is important -- especially during the phase when increased blood supply to the area in response to pain sets up a fibrosis response (scar tissue formation). These fibrovascular inflammatory soft tissue changes are present in all patients with rotator cuff injuries linked with adhesive capsulitis.
Muscles stretch easier when they are warmed up. So, before starting a program of flexibility exercises, patients are encouraged to apply some form of moist heat before and during stretching. The therapist will help each patient determine how to stretch in a way that won't overload the tissues and cause increased irritability. Frequency, intensity, and duration of exercise are calculated based on the patient's irritability classification.
Assessment of irritability for classification purposes starts with a sleep history. Can the patient sleep through the night? Can the patient lie on that side and for how long? Both of these measures are indicators of irritability. A second way to determine level of irritability is to see if the primary problem is pain or stiffness. Stiffness is a sign of fibrosis. Pain is an indication that there is the fibrovascular inflammatory process going on. And finally, is the patient getting better, staying the same, or getting worse? Knowing how irritated the tissues are helps the therapist plan patient care.
The authors provide some detailed guidelines for how exercises should be done based on the patient's irritability classification. For example, if the goal is to change how the joint perceives input, then low-intensity, short-duration range-of-motion may be best. The result will be to decrease pain and muscle guarding with the net effect of increasing shoulder and arm motion. A very helpful table outlining treatment strategies for each level of irritability is provided.
Since this is an article written by physiotherapists, the discussion of how to perform exercises for each irritability level is a major focus. This approach may be new to some people who have never heard of it before. What works and doesn't work seems to parallel what's happening at the cellular level of the connective tissue during each phase from freezing to frozen to thawing. Studies show that too much stretching too soon in the process can result in worse results.
Evidence from research on the role of joint mobilization is also presented. Joint mobilization is a way to move the joint surfaces to increase motion. The technique involves some sliding and gliding of the shoulder joint in a variety of different directions. Which way to go is determined by areas of movement restriction. All joint mobilizations are followed up with an active home program of stretching. Although joint mobilization has some positive benefits, it's not clear that this treatment technique is better than some other methods of working with the patient.
If the proposed rehabilitation program using levels of irritability as a guideline fails to improve patient symptoms to his or her satisfaction, then surgery may be advised. Under anesthesia, the surgeon may manipulate (move) the shoulder. With the muscles around the shoulder completely relaxed, the surgeon can put the shoulder through its full range-of-motion, breaking any adhesions present in all directions.
There are some potential problems with manipulation such as fractures or dislocations. It's not a good procedure for anyone with bone loss or who can't perform the necessary follow-up program of exercises. Open incision surgery isn't really done on a frozen shoulder. The surgeon may go into the joint using an arthroscope and release the joint capsule This isn't always the best option since bleeding into the joint from this procedure can cause the formation of more scar tissue.
When we step back and look at all the research that's been done with short- to long-term results reported, it's still not entirely clear what approach or approaches works best. Most patients get the best results in the first three months no matter what kind of treatment is applied. Steroid injections seem to have a good benefit in the first three weeks. It's likely that pain relief early on allows the patient to move the shoulder and thereby regain range of motion and function quickly.
Should everyone have these injections routinely to speed up recovery and reduce overall costs? Probably not. A more common sense approach would be to save steroid injections for patients who don't show improvement (or who continue to get worse) after the first three weeks even with physiotherapy.
The authors conclude that despite the fact that adhesive capsulitis is a fairly common problem, there isn't a clear path in treatment to help the patient recover. Using a rehab program based on levels of irritability applies the right amount of stress on the soft tissues of the shoulder while stretching the same tissues. Patients can be taught how to do these exercises at home for the long duration of the problem. The result hoped for is reduced pain, improved movement, and return of function. With satisfactory results from this type of program, patients may not have to have surgery.
Martin J. Kelley, PT, DPT, OCS, et al. Frozen Shoulder: Evidence and Proposed Model Guiding Rehabilitation.In Journal of Orthopaedic & Sports Physiotherapy. February 2009. Vol. 39. No. 1. Pp. 135-148.