Adhesive capsulitis is a problem of chronic inflammation of the shoulder joint capsule. The shoulder capsule is a covering of connective tissue interconnected with shoulder ligaments and tendons. They all help hold the head of the humerus (upper arm bone) in the shoulder socket.
The inflammatory process causes the capsule to thicken and tighten to the point that the extra fold of capsular tissue needed for full motion overhead gets stuck to itself. There is a loss of normal synovial fluid in the joint.
When this happens, the shoulder can no longer slide and glide smoothly through its full range-of-motion. The capsule loses its ability to stretch. The result is the shoulder gets stuck and becomes stiff and painful. In chronic cases, inflammation is gone but it was the first step that got the process started. Treatment is still directed at the joint capsule.
In this study, the use of hyaluronic acid (HA) injections for this problem is compared with traditional physical therapy. Patients were randomly placed in one of two groups: group one received the HA injections along with physical therapy. Group two only went to physical therapy and did NOT get the injections.
Physical therapy consisted of one-hour sessions, three times a week for 12 weeks. Therapeutic exercise along with the use of heat and electric therapy were provided by the physical therapist. The Hyaluronic Acid (HA) injections were placed directly in the shoulder joint once a week for three weeks. HA has been used successfully in the knee; its use in the shoulder is a relatively new treatment approach.
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. 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.
So, what worked better: PT alone or PT plus hyaluronic acid injections? Neither one was more effective than the other in reducing pain, improving motion, or restoring function. The results were equal between the two groups. If this is the case, then the added expense of the injections may not be needed for this condition.
There were some shortcomings in this study though. So before the recommendation to drop the use of hyaluronic acid for shoulder adhesive capsulitis is made, more research is needed to settle some of the questions left unanswered in this study. For example, they did not compare patients receiving injection only to these other two groups.
Fluoroscopy or ultrasound was not used to guide the injections, so it’s possible more accurate injection technique might make a difference. And different stages of adhesive capsulitis may respond differently to treatment making hyaluronic acid a time-specific treatment. And finally, long term results (six months to several years later) should be investigated.