Shoulder replacement

Why a shoulder is replaced

The shoulder is a ball and socket joint. The ball is the top of the upper arm bone (humerus) and the socket (glenoid) is part of the shoulder blade. Both are lined with smooth cartilage. When that lining wears away, bone rubs on bone and the joint becomes painful and stiff.

The common reasons are:

• Osteoarthritis, the gradual wearing out of the joint surface.
• Cuff tear arthropathy, arthritis that develops after a large, long-standing rotator cuff tear.
• Inflammatory arthritis, such as rheumatoid arthritis.
• Fractures of the top of the humerus, or their later consequences.

When it is worth considering

A replacement is not a first step. It is considered when pain, particularly pain at night, and loss of everyday function persist despite painkillers, exercise or physiotherapy and, in some people, a steroid injection. X-rays, and sometimes a CT or MRI scan, are used to confirm the extent of the arthritis and to check the bone and the rotator cuff tendons.

The decision is yours. Arthritis of the shoulder is not dangerous, so the question is whether the symptoms are bad enough to justify an operation and its recovery.

The types of replacement

Right shoulder seen from the front, with the bone drawn see-through to show how each implant is fixed. In the reverse design the ball is fixed to the shoulder blade with a plate and screws, and sits in a plastic-lined cup on top of the stem. These are illustrations, not specific implant designs.

Stemmed or stemless

In an anatomic replacement the ball has traditionally been mounted on a stem that runs down inside the humerus. Where the bone is strong enough, it can instead be fixed by a short anchor in the top of the bone, with no stem. This is a stemless replacement. It preserves more of your own bone, and in randomised trials movement, function and the need for further surgery were no different from a stemmed implant over the first few years, although long-term results are still being gathered.¹ It is Mr Wright's preferred design for an anatomic replacement where the bone allows. Bone quality can only be judged for certain during the operation, so a stem is occasionally used instead.

Which type suits you depends on your tendons, the shape of your bone, your age and what you need the arm to do. Mr Wright will explain the reasoning in your case. You can see each design on the 3D shoulder model under "Surgical procedures".

What you can expect from it

Most people get a large and lasting improvement in pain. Movement and strength usually improve, but a replaced shoulder rarely moves like a normal one, and reaching behind the back is often the last movement to return, particularly after a reverse replacement.

Pooled studies with at least ten years of follow-up found that about nine in ten shoulder replacements were still in place at ten years, with benefit to pain and function lasting over that time.² In the UK National Joint Registry, around 4 in every 100 planned shoulder replacements have needed a further operation (revision) by five years. The risk is higher in younger patients, who place greater demands on the joint for longer.³

The operation

• It is usually done under general anaesthetic, often with a nerve block that numbs the arm for several hours afterwards.
• The incision is at the front of the shoulder and the operation takes one to two hours.
• Most people stay in hospital for one or two nights.
• You will wake with your arm in a sling and begin gentle exercises before you go home.

Risks

Most people have no serious complication, but no operation is free of risk. The figures below are averages from large studies. They are a guide, not a prediction for you: your own risk depends on your age, your general health and the type of replacement, and is discussed with you before you decide.

Problems with the shoulder itself

Taking all of them together, published series report a complication of some kind in roughly 10 to 16 in every 100 shoulder replacements.⁴ Many of these are minor or settle without further surgery.

• Infection. Uncommon, but serious if it reaches the implant, when further surgery is usually needed.
• Dislocation or instability of the new joint. This is the most frequent complication after a reverse replacement.⁵
• Fracture of the bone around the implant, during or after surgery. After a reverse replacement this includes stress fractures of the shoulder blade.
• Nerve injury, causing numbness or weakness. This is usually temporary.
• Stiffness, or less movement than hoped for.
• Later failure of the rotator cuff, or loosening of the socket component, after an anatomic replacement. In one large series each affected about 3 in every 100.⁶

Further surgery

About 4 in every 100 replacements are revised within five years.³ Over a lifetime the chance depends strongly on age at the time of surgery: from about 1 in 37 for women aged 85 and over to about 1 in 4 for men in their late fifties.⁷

General medical complications

In a study of more than 58,000 shoulder replacements in England, about 1 in 22 people (4.6 in 100) had a serious medical problem within 90 days. The most frequent were chest infection (about 2 in 100), urinary infection (1 to 2 in 100) and kidney injury (1 in 100). A clot on the lung and heart attack each affected about 3 in 1,000. These risks rise with age and with other medical conditions.⁷

Recovery

The timings below are typical. Yours may differ according to the type of replacement and how the operation went, and you will be given a plan to follow.

Driving and work

Most people are ready to drive at around six to eight weeks, once out of the sling and able to control the car safely; check with your insurer. Desk work is often possible within a few weeks. Manual work takes three months or more, and heavy or repetitive overhead work may not be advisable in the long term.

Looking after the new joint

Swimming, walking, golf and similar activities are generally fine once you have recovered. Heavy lifting and contact sports put the implant at risk and are best avoided.

When to seek help