June 7, 2021
What is frozen shoulder?
Frozen shoulder is a shoulder pain condition where there is significant loss of motion of the shoulder joint accompanied by stiffness. The shoulder joint is surrounded by the strong capsule and the main problem in this condition is believed to be the tightening of this capsule. The resulting pain is generally deep seated and poorly localised. It may be constant or present only at night when lying on the affected side. All movements of the joint are affected, especially the ones involving reaching straight up and rotation of joint such as while reaching behind the back.
Frozen shoulder is seen more commonly in women, especially between the ages of 40-60 years. Non-dominant side is more commonly involved, although in 20% to 30% of individuals both sides may be affected. Diabetics have five times more chances of developing this condition and about 30% of people with frozen shoulder have diabetes. Patients with overactive or underactive thyroid or those with shoulder immobilisation (such as after a fracture or stroke) are also at higher risk for developing frozen shoulder.
What is capsular hydrodistention?
Hydrodistention or dilatation or hydrodilatation is a non-surgical procedure aimed at stretching of the tight shoulder joint capsule. This is achieved by injecting saline or a mixture of saline, steroids and local anaesthetics under ultrasound or x-ray guidance. Ultrasound guidance is preferred as it is quicker, can be performed in the OPD and does not involve any radiation exposure. This procedure is an alternative to a surgical procedure – manipulation under anaesthesia (MUA), with some studies indicating better results with hydrodistention.
How is capsular hydrodistention performed?
I perform this procedure under ultrasound guidance in a sitting or lying position. The injection area is cleaned with antiseptic solutions. Ultrasound scan is performed to identify the shoulder joint, its capsule and plan the best pathway into the joint. Local anaesthetic is used to numb the injection site. A fine needle is introduced onto the surface of the shoulder joint under ultrasound guidance. A solution containing saline, local anaesthetic and steroid is then injected below the capsule. As the injection mixture is given, the capsule can be seen lifting off the joint. Once the injection is complete the needle is removed and a small dressing is placed over the injection site. The procedure takes about 20- 30 minutes to complete.
How does capsular hydrodistention work?
Hydrodistension is thought to have a mechanical effect of opening up the joint and releasing sticky adhesions within the joint, although the exact mechanism of action is debated. With stretching, the pressure inside the joint is reduced and the shoulder volume is increased. These effects can help in reducing pain, stiffness and improving the range of motion.
There is research evidence supporting better outcomes with the combination of hydrodilatation with steroids and physiotherapy, compared to either of the modalities when used alone. Hydrodistension results are comparable or better to the surgical procedure manipulation-under-anaesthesia (MUA), although the risks are less. Diabetic patients with frozen shoulder have inferior outcomes and in these hydrodilatation is likely to be more beneficial. In case of incomplete recovery these patients can be considered for repeat injections.
The option of steroid injections directly into the joint is preferred over the oral steroid as they are associated with fewer side effects. Some studies have found that oral steroids are as much as 5 times more likely to give the typical steroid side effects one hears of, compared to the one-off joint injection. Also, the lack of long-term benefits makes oral steroids a less attractive option in this condition.