Shoulder joint replacements

Anatomical total shoulder arthroplasty is the gold standard shoulder replacement procedure for patients with an intact rotator cuff and sufficient glenoid bone to accommodate prosthetic glenoid implant and offers reliable patient satisfaction, excellent implant longevity, and a low incidence of complications.¹

Patients with shoulder joint disease may have shoulder pain accompanied by functional limitation and a reduced quality of life. The humeral head may degenerate as a result of a range of conditions, particularly osteoarthritis, rheumatoid arthritis or avascular necrosis. The whole or only part of the articular surface of the humeral head may be affected.²

Conservative treatments for shoulder joint problems include physiotherapy, drug treatments (eg, pain relief and topical or oral non-steroidal anti-inflammatory drugs) and corticosteroid injections. Patients not responding to conservative treatments may require surgery, which may be either shoulder arthroplasty using a stemmed humeral head prosthesis, or fusion of the joint.²

The surgical replacement of the shoulder joint is the third most common joint replacement after replacement of the hip and knee joints. Like the hip, the shoulder is a ball and socket joint. However, the shoulder 'socket' is much more shallow to allow a greater range of movement at the cost of bony stability.

Shoulder joint replacement can be:^{3 4}

• Shoulder resurfacing arthroplasty (replacement of only the damaged joint surfaces, with minimal bone resection) is recommended by the National Institute for Health and Care Excellence (NICE) as an appropriate treatment option.²

• Partial: one articular surface is replaced, the humeral head; also known as shoulder hemiarthroplasty.

• Total: both articular surfaces are replaced by prostheses; also known as shoulder arthroplasty. Improved long-term results have increased the use of total shoulder prostheses.⁵

• Reverse: both articular surfaces are replaced but with the 'ball' on the glenoid and the 'cup', or 'socket', on the humerus. This is to medialise the joint centre of rotation in order to maximise the lever arm of the deltoid muscle in rotator cuff deficiency.

Indications

Shoulder replacement constitutes the gold standard treatment for severe shoulder diseases, including osteoarthritis, rheumatoid arthritis, complex fractures, avascular necrosis and rotator cuff arthropathy.⁶

In reverse shoulder replacement, the ball is placed on the socket side of the joint, which is the opposite of its natural position. The socket is then placed on the arm side where it is supported by a metal stem in the humerus. In a standard shoulder replacement, the metal ball attaches to the upper part of the humerus and the new plastic socket attaches to the shoulder blade, which more closely follows the normal anatomy. Reverse shoulder replacement should be considered in arthroplasty situations with rotator cuff disease, deformity, bone loss, and instability as part of the diagnosis.⁷

Shoulder joint replacements epidemiology

The number of shoulder replacement procedures in England, Wales and Northern Ireland has significantly increased since 2012. There were approximately 2,500 shoulder replacements carried out in England, Wales and Northern Ireland in 2012; by 2019 this number had increased to almost 7,800, but dropped to 5,500 in 2021.⁸

Pre-operative assessment

• The patient may have rheumatoid arthritis and this can complicate operative risk and postoperative rehabilitation.

• The patient is also likely to be elderly and so may have other health problems.

• Any potential source of infection should be dealt with prior to arthroplasty, with special care given to dentition.

• Good pre-operative assessment is needed to assess surgical risk and is usually carried out in secondary care.

• Patients should be advised that the outcome of surgery should be pain reduction and improved movement. However, movement of the shoulder may still be restricted.

• The range of movement of the shoulder commonly achieved allows the arm to be raised to a height where the elbow is level with the shoulder but not above this.

NICE guidelines and joint arthroplasty⁹

Consider referring people with shoulder osteoarthritis for joint replacement if joint symptoms (such as pain, stiffness, reduced function or progressive joint deformity) are substantially impacting their quality of life, and non-surgical management (eg, exercise, weight loss, pain relief) is ineffective or unsuitable.

Use clinical assessment when deciding to refer someone for joint replacement, instead of systems that numerically score severity of disease.

Do not exclude people with osteoarthritis from referral for joint replacement because of age, gender, smoking, comorbidities, or overweight or obesity. However, the risks of joint replacement can vary depending on these factors.

Procedures for primary elective shoulder replacement¹⁰

• If glenoid bone is adequate, offer conventional total shoulder replacement to people having primary elective shoulder replacement for osteoarthritis with no rotator cuff tear.

• NICE are unable to provide any recommendations for shoulder replacement for pain and functional loss for people with a previous proximal humeral fracture, and have made a recommendation for research in this area.

The options for anaesthesia and analgesia with people having primary elective shoulder replacement include general anaesthesia, regional anaesthesia, local infiltration analgesia and nerve blocks.

Postoperative care and rehabilitation¹⁰

A well-planned rehabilitation programme is essential for success. Therapy should begin very soon after surgery. A physiotherapist will start gentle, passive and active assisted range of movement exercises. The safe range of movement will depend on the type of surgical approach.

Complications

Complications after shoulder replacement surgery are less frequent than with other joint replacements. Complications can include:

• Anaesthetic complications.

• Damage to nearby nerves or blood vessels intra-operatively.

• Intra-operative fracture of the upper humerus.

• Rotator cuff tears.

• Wound infection.

• Thromboembolic complications (thromboembolic complications were less common than after prosthesis of the lower limb in one study but the percentage of pulmonary embolism was higher).

• Infection of the implant (this usually requires revision).

• Postoperative fractures of the upper humerus.

• Postoperative shoulder instability (dislocation, subluxation).¹¹

• Loosening of the glenoid component/glenoid component failure.¹¹

Prognosis

• The prognosis will depend on the underlying condition, age, general health and comorbidities.

• The best results are in older patients who had surgery for osteoarthritis, as they give the joints less stress. Younger patients tend to fare worse and may develop loosening of the joint.

• Pre-operative planning, attention to anatomy, and an optimum rehabilitation programme are the keys to success.

• Improvement in function can continue for up to 18 months postoperatively.¹²

The most common causes of revision surgery after reverse total shoulder arthroplasty are: prosthetic instability (38%), infection (22%), humeral problems (21%) including loosening, unscrewing and fracture, and problems of glenoid loosening (13%). Complications leading to reoperation are often multiple and it is not uncommon for patients to be reoperated several times due to the persistence of the same complication, failure to diagnose associated complications, or onset of an additional complication.¹³