This study from Korea has two unique features. First, it may be the only one so far comparing results of treatment for shoulder adhesive capsulitis between steroid injections and hyaluronic acid. And second, the authors used ultrasound instead of fluoroscopy (real-time X-rays) to guide the injections.
Many adults (mostly women) between the ages of 40 and 60 years of age develop adhesive capsulitis. You may be more familiar with the term “frozen shoulder” to describe this condition that causes shoulder pain and stiffness.
The terms frozen shoulder and adhesive capsulitis are often used interchangeably. In other words, the two terms describe the same painful, stiff condition of the shoulder no matter what causes it. But frozen shoulder and adhesive capsulitis are actually two separate conditions.
A more accurate way to look at this is to refer to true adhesive capsulitis (affecting the joint capsule) as a primary adhesive capsulitis. As the name suggests, adhesive capsulitis affects the fibrous ligaments that surround the shoulder forming the capsule. The condition referred to as a frozen shoulder usually doesn’t involve the capsule.
Secondary adhesive capsulitis (or true frozen shoulder) might have some joint capsule changes but the shoulder stiffness is really coming from something outside the joint. Some of the conditions associated with secondary adhesive capsulitis include rotator cuff tears, biceps tendinitis, and arthritis. In either condition, the normally loose parts of the joint capsule stick together. This seriously limits the shoulder’s ability to move, and causes the shoulder to “freeze.”
There are two separate schools of thought regarding treatment for adhesive capsulitis. Some experts suggest a home-based approach because eventually the problem corrects itself. Patients use pain relievers, moist heat, and simple exercises to keep the joint moving. Others recommend direct treatment to make sure patients regain normal motion and function.
Most experts agree that severe painful limitations of motion should be treated by a physical therapist. For patients with persistent pain, pain-relieving medications and steroid injections are commonly used in addition to physical therapy. But steroid injections have some disadvantages and some patients either don’t want them or can’t tolerate them. That’s when hyaluronic injections may be used instead.
Hyaluronic acid is a normal part of the matrix that makes up cartilage. It has two distinct properties that make it so important for smooth joint motion. It is both viscous (slippery) and elastic. The viscosity allows the tissue to release and spread out energy. The elasticity allows for temporary energy storage. Together, these two properties protect the joint, help provide joint gliding action (especially during slow movement), and act as a shock absorber during faster movements.
Some experts think hyaluronic acid (HA) injected into the shoulder has some additional benefits. They suggest that the HA reduces inflammation of the synovium (lubricating fluid inside the joint). It also has a direct effect on the pressure inside the joint to separate the joint capsule where it is stuck together. Hyaluronic acid may be protective of the joint cartilage and prevent the formation of adhesions that keep the capsule from the smooth gliding action needed for normal shoulder motion.
The question naturally arises — which works better: steroid or hyaluronic acid injections? To find out, the authors of this study divided 90 patients with adhesive capsulitis into two groups. The first group received a series of three steroid injections (spread out over six weeks’ time) into the shoulder.
The second group was injected with hyaluronic acid with the same frequency (one injection every two weeks for a total of three injections over six weeks’ time). Ultrasound (instead of the usual fluoroscopy) was used to guide the needle into the joint. The main advantage of ultrasound over fluoroscopy is that it doesn’t expose the patient to unnecessary radiation. That is important when using a series of injections with the potential for repeated radiation exposure.
Results were measured using pain intensity, shoulder joint motion, and function. Everyone in both groups was evaluated using these measures before treatment and again two weeks and six weeks after treatment. They didn’t find much difference in outcomes between the two treatment techniques.
Everyone in both groups had less pain, better motion, and improved function. These improvements were observed at the two week follow-up and maintained through the six-week check-up. The only difference was greater passive external shoulder rotation with the hyaluronic acid injections. This might have occurred because the pressure from the hyaluronic acid opened up the joint space, which is needed to increase external rotation.
The authors concluded by saying that hyaluronic acid injections delivered with careful placement using ultrasound may be just as effective as steroid injections. In fact, there may be some added advantages. The patients receiving hyaluronic injection via ultrasound are not exposed to radiation. They are not affected by the potential negative consequences of steroids (e.g., thinning and weakening of the soft tissues, skin color change). They even get some extra rotational motion.
For patients who cannot tolerate steroid injections (or who don’t want them), hyaluronic acid injection may be a good alternative treatment approach. Likewise, patients with other problems that affect the soft tissues such as diabetes, hyaluronic acid injections may be a better choice.