Shoulder Joint Replacements - what a GP needs to know

Shoulder arthroplasty, shoulder hemiarthroplasty

The surgical replacement of the shoulder joint is much less common and much less advanced than replacement of the hip or knee joints. The shoulder is a ball and socket joint like the hip but a much shallower socket gives a much wider range of movement with much less stability. It is also a more complex joint.

Shoulder joint replacement is usually performed for osteoarthritis, rheumatoid arthritis or where there has been damage from trauma. It permits elevation of the arm up to the horizontal but no higher. Hemiarthroplasty where only the head of the humerus is replaced is a satisfactory treatment¹ for a fractured neck of humerus especially in the elderly.

Only about 5,000 operations a year are performed in the UK. Although it is the 3rd commonest joint replacement it may be difficult to find an orthopaedic surgeon who does such surgery.

The per capita rate of shoulder replacement compared with the USA² is approximately one-tenth for total replacement and one-fifth for hemiarthroplasty.

Patients with rheumatoid arthritis often have very poor bone that makes the operation technically difficult. However, in one study of rheumatoid patients the survival of the prosthesis³ after 8 years was 92%.

The component that replaces the head of the humerus is made of an alloy based on cobalt and chromium. It comes in various sizes and can be a single piece or a modular unit.

The component that replaces the glenoid depression is made of ultrahigh density polyethylene. Some varieties have a metal tray but totally plastic versions are more common.

The surgeon may replace just the humeral head in a hemiarthroplasty or both the humeral head and the glenoid in a total shoulder replacement. The components are held in place by either acrylic bone cement (cemented) or bone ingrowth (cementless). The surrounding muscles and tendons provide stability for the prosthesis as with the normal shoulder.

A well-planned rehabilitation programme is essential for success.⁴ Therapy begins very soon after surgery. A physiotherapist will start gentle, passive range of movement exercises. Stay in hospital is usually 2 or 3 days.

Here is some advice following discharge:

• Wear the sling every night for at least the first month.
• Do not use the arm to push up in bed or from a chair.
• Follow the exercise programme diligently. Do the exercises 4 or 5 times a day for a month or more.
• Do not overdo it! Early overuse of the shoulder may result in restricted movement later.
• Do not lift anything heavier than a cup of tea or coffee for the first 6 weeks after surgery.
• Do not do any contact sports or heavy lifting for at least 6 months.

These will be carried out in secondary care. As well as plain x-ray of the shoulder, CT is useful. Most patients are over 60 years old. For the elderly and infirm FBC, U&E, LFTs, CXR, ECG and spirometry will all be required but usually arranged by Secondary Care in the pre-operative assessment.

The patient may have rheumatoid arthritis and this can complicate operative risk and post-operative rehabilitation.
The patient is also likely to be elderly and so my have other diseases too.

Complications after shoulder replacement surgery are less frequent than with other joint replacements. Infection, intraoperative fracture of the upper humerus or postoperative fractures, postoperative instability and loosening of the glenoid component are the most common complications. Advances in surgical techniques and prosthetic innovations are helping to reduce the occurrence of complications.

• Infection of the implant requires⁵ revision.
• Damage can occur to nerves or vessels in the area. The nerves may just be bruised and recover with time.
• Pulmonary embolism can occur after shoulder replacement but it is much less common than after prosthesis of the lower limb.
• As is so often the case, complications are fewer in the hands of the more experienced surgeons and those who do the most cases.^6,7

• About 10% of shoulder joint replacements fail completely.
• The best results are in older patients who had surgery for osteoarthritis as they give the joints less stress. A survey found that of patients given hemiarthroplasty 82% were functional after 10 years and 75% after 20 years. For total shoulder arthroplasty the figures were 97% at 10 years and 84% at 20 years.⁸ Younger patients fare worse and 30% develop loosening of the joint.
• Preoperative planning, attention to anatomy, and an ideal rehabilitation programme are the keys to success.
• Paraplegics put a great deal of stress on their upper limbs but a group of female paraplegics who have received joint replacement⁹ seem to have done well.
• The improvement in the quality of life after such surgery¹⁰ is as good as for hip replacement or coronary artery bypass grafting.

Much of the literature is from the USA where experience of the procedure is much greater. It may be questioned if their good results are repeated elsewhere, especially as it tends to be centres of excellence that publish their results. A paper from Wigan,¹¹ examining the results of 124 shoulder arthroplasties for osteoarthritis in 113 patients found a 10 years survival of 86% with no difference between total and partial arthroplasty. Pain and function were much improved.

It is a general rule that revision arthroplasty is significantly more complex than the original operation and this holds for shoulder replacement as much as any other joint. Component revisions, excluding humeral head revision for salvage, provide the best results, whereas soft-tissue reconstructions can be expected to yield poorer results overall.¹²