Shoulder injections

What is injected, and where

The injection is a corticosteroid, usually mixed with local anaesthetic. This is not the type of steroid used by bodybuilders. Very little reaches the rest of the body.

Some injections are placed by feel in clinic. Others are guided by ultrasound or X-ray, particularly into the ball and socket joint, which is deep.

What to expect from it

• The local anaesthetic may take the pain away within minutes. This wears off after a few hours.
• The steroid starts to work after two to five days and builds over a week or two.

How much relief you get, and for how long, is variable and cannot be predicted in advance. This is true of every injection in this guide, and particularly of injections into the subacromial bursa for rotator cuff pain. Some people get good relief that lasts indefinitely. Many get a few weeks to a few months. Some get little or nothing. Lasting relief is by no means guaranteed.

Those who do best are probably those who use the pain-free period well. With the pain turned down, the shoulder can be moved and strengthened in a way that was not possible before, and it may be this rehabilitation, more than the injection itself, that gives the lasting gain. An injection is therefore most valuable when it breaks a cycle of pain and poor sleep and lets you get on with your exercises, and physiotherapy is best planned to follow it closely.

For some conditions the long-term result is no better with an injection than without: tennis elbow is the clearest example, where injected patients do worse at a year. See the guide to tennis and golfer's elbow.

Hydrodilatation

This is used for frozen shoulder. Under ultrasound or X-ray guidance, a mixture of salt water, local anaesthetic and steroid is injected into the ball and socket joint to stretch the tight capsule. It takes about fifteen minutes. The shoulder feels tight and heavy while the fluid goes in. Physiotherapy starts in the days afterwards to make the most of the gain in movement.

It is one of several effective treatments for frozen shoulder. In a UK trial of 503 patients, physiotherapy with a steroid injection, manipulation under anaesthetic and keyhole release all led to substantial improvement at one year, and none was clearly superior.¹ The options are compared in the frozen shoulder decision aid.

Suprascapular nerve block

The suprascapular nerve runs across the top of the shoulder blade and carries a large share of the pain signals from the shoulder joint and the rotator cuff. Placing local anaesthetic, usually with steroid, around the nerve turns down the pain coming from the shoulder. It does not treat the underlying condition. It is a way of managing pain.

When it is used

For pain that has persisted despite other treatment, particularly where an operation is not suitable or not wanted: arthritis, large rotator cuff tears that cannot be repaired, and some long-running cases of frozen shoulder.

Who does it

• A radiologist, in the radiology department. The injection is guided by ultrasound or CT so the needle can be placed accurately beside the nerve. This is the usual first step.
• A consultant in pain management. Pain specialists perform the same block and can also offer treatments intended to make the effect last longer, described below. Mr Wright will refer you if this seems the better route.

Longer-acting options from a pain specialist

How well it works

In a placebo-controlled trial in 83 people with long-standing shoulder pain from arthritis or degenerative disease, a suprascapular nerve block gave clear improvement in pain and disability at one, four and twelve weeks.² A pooled analysis of eleven trials found it better than a placebo injection and better than physiotherapy alone for pain over twelve weeks, and about as good as an injection into the joint.³ For pulsed radiofrequency the evidence is weaker: the trials are small, and reviews rate the certainty of benefit as low.^4,5

As with the other injections in this guide, the response varies from person to person, and the block is best used as an opportunity for physiotherapy. A block that helps and then wears off can be repeated.

What to expect, and the risks

• It takes ten to fifteen minutes and you go home afterwards. Arrange for someone else to drive.
• The shoulder and upper arm may feel numb, heavy or weak for several hours.
• Bruising and soreness at the injection site for a day or two are common.
• Serious complications are rare. They include infection, lasting irritation of the nerve and, very rarely, a punctured lung (pneumothorax), which causes chest pain and breathlessness and needs urgent attention.
• Where steroid is included, the steroid effects listed under Risks below apply.

Before the injection

Tell the clinician if you:

• have an infection anywhere, or feel unwell
• take blood-thinning medication
• have diabetes
• have had a reaction to steroid or local anaesthetic before
• are due an operation on that shoulder, or a vaccination, in the next few weeks
• are, or might be, pregnant

Risks

• A flare of pain for a day or two as the anaesthetic wears off. This is the commonest side effect. Use simple painkillers and a cold pack.
• Facial flushing for a day or two.
• Raised blood sugar for several days in people with diabetes. Check your levels more often for a week.
• A dimple or pale patch of skin at the injection site. This is uncommon and more likely with injections close to the surface, such as at the elbow or the acromioclavicular joint. It can be permanent.
• Infection in the joint. This is rare but serious.
• Weakening of tendon with repeated injections, which is one reason they are limited in number.
• Allergic reaction. Rare.

Afterwards

• If the arm is numb, arrange for someone else to drive you home.
• Take it easy for one to two days, then return to normal activity and your exercises.
• Avoid heavy lifting and strenuous overhead work for about a week, even if the shoulder feels much better.