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:

• 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.
• 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

• Severe pain and disability associated with radiological changes not responsive to non-surgical treatment.
• Shoulder joint replacement is usually performed for osteoarthritis, rheumatoid arthritis or where there has been damage due to trauma. It may sometimes be used in recurrent shoulder instability.¹
• Hemiarthroplasty is a satisfactory treatment for a fractured proximal end of humerus.² It may also be used in avascular necrosis of the humeral head and in arthropathy following rotator cuff rupture.³ However, total joint replacement may lead to better outcome in most other situations.^4,5

Epidemiology

• Only about 5000 operations a year are performed in the UK.
• It is the third commonest joint replacement.

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 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.⁶

The anaesthetic

• The anaesthetist should discuss the options with the patient at the pre-operative assessment.
• The procedure can be done under either a general anaesthetic or using a regional block. These can also be combined as the regional block provides excellent post-operative analgesia.

The surgical procedure

• The shoulder is approached from either the front (deltopectoral), or from the side (deltoid split).
• The choice of prosthesis depends on the condition of the joint surfaces and on the anatomy and functional condition of the rotator cuff.³
• The damaged humeral head is removed, or is sometimes just resurfaced. In this case, a 'cap' is placed over the humeral head and not all of the bone is removed.⁶
• 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.⁷
• 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 use of bone cement is dictated by the quality of the patient's bone stock, but is routinely used when a fracture is being treated.⁶
• The glenoid component is 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.

NICE guidelines and joint arthroplasty⁸

• The NICE guidelines on the care and management of adults with osteoarthritis state that referral for joint arthroplasty should be considered for people with joint symptoms (pain, stiffness and reduced function) that:
  • Reduce their quality of life
  • Have not responded to non-surgical treatment
• Referral should be made before there is prolonged and established functional limitation and severe pain. A patient's age, gender, smoking status, weight and comorbidities should not be barriers to referral.

Postoperative care and rehabilitation

• A well-planned rehabilitation programme is essential for success.³
• 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. In the deltopectoral approach the subscapularis tendon is either surgically divided or elevated with a lesser tuberosity osteotomy. Range of movement allowed will depend on the adequacy of fixation.
• Hospital stay varies from 2 to 5 days and is dependant on patient co morbidities.
• Advice following discharge usually includes:
  • 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 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.

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
• Intraoperative fracture of the upper humerus
• 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)⁹
• Infection of the implant (this usually requires revision)^10,11
• Postoperative fractures of the upper humerus
• Postoperative shoulder instability (dislocation, subluxation)¹²
• Loosening of the glenoid component/glenoid component failure^12,13

Advances in surgical techniques and prosthetic innovations are helping to reduce the occurrence of complications. Complications are fewer in the hands of the more experienced surgeons and those who do the most cases.^14,15

Prognosis

• 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.
• One study found that of patients who underwent hemiarthroplasty, 82% were still 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.¹⁶
• Outcome is best for an experienced surgeon who performs high volumes of shoulder arthroplasty or hemiarthroplasty operations.^14,15
• 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 post-operatively.¹

Revision arthroplasty

• 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.
• The outcome of the revision tends to depend on the indication for the procedure.¹⁷
• In one study in the UK, the commonest cause for revision in hemiarthroplasty was glenoid pain, and in arthroplasty was glenoid loosening.¹⁸

Document references

1. Wheeless' Textbook of Orthopaedics; Arthroplasty of the Shoulder
2. Robinson CM, Page RS, Hill RM, et al; Primary hemiarthroplasty for treatment of proximal humeral fractures. J Bone Joint Surg Am. 2003 Jul;85-A(7):1215-23. [abstract]
3. Caniggia M, Fornara P, Franci M, et al; Shoulder arthroplasty. Indications, contraindications and complications. Panminerva Med. 1999 Dec;41(4):341-9. [abstract]
4. Bryant D, Litchfield R, Sandow M, et al; A comparison of pain, strength, range of motion, and functional outcomes after hemiarthroplasty and total shoulder arthroplasty in patients with osteoarthritis of the shoulder. A systematic review and meta-analysis. J Bone Joint Surg Am. 2005 Sep;87(9):1947-56. [abstract]
5. Rispoli DM, Sperling JW, Athwal GS, et al; Humeral head replacement for the treatment of osteoarthritis. J Bone Joint Surg Am. 2006 Dec;88(12):2637-44. [abstract]
6. Arthritis UK, Shoulder and elbow surgery.
7. Wheeless' Textbook of Orthopaedics; Hemiarthroplasty of the Shoulder
8. Osteoarthritis, NICE Clinical Guideline (January 2008); The care and management of osteoarthritis in adults
9. Lyman S, Sherman S, Carter TI, et al; Prevalence and risk factors for symptomatic thromboembolic events after shoulder arthroplasty. Clin Orthop Relat Res. 2006 Jul;448:152-6. [abstract]
10. Jerosch J, Schneppenheim M; Management of infected shoulder replacement. Arch Orthop Trauma Surg. 2003 Jun;123(5):209-14. Epub 2003 Apr 26. [abstract]
11. Coste JS, Reig S, Trojani C, et al; The management of infection in arthroplasty of the shoulder. J Bone Joint Surg Br. 2004 Jan;86(1):65-9. [abstract]
12. Wheeless' Textbook of Orthopaedics; Complications of Shoulder Arthroplasty
13. Matsen FA 3rd, Clinton J, Lynch J, et al; Glenoid component failure in total shoulder arthroplasty. J Bone Joint Surg Am. 2008 Apr;90(4):885-96. [abstract]
14. Jain N, Pietrobon R, Hocker S, et al; The relationship between surgeon and hospital volume and outcomes for shoulder arthroplasty. J Bone Joint Surg Am. 2004 Mar;86-A(3):496-505. [abstract]
15. Hammond JW, Queale WS, Kim TK, et al; Surgeon experience and clinical and economic outcomes for shoulder arthroplasty. J Bone Joint Surg Am. 2003 Dec;85-A(12):2318-24. [abstract]
16. Sperling JW, Cofield RH, Rowland CM; Minimum fifteen-year follow-up of Neer hemiarthroplasty and total shoulder arthroplasty in patients aged fifty years or younger. J Shoulder Elbow Surg. 2004 Nov-Dec;13(6):604-13. [abstract]
17. Dines JS, Fealy S, Strauss EJ, et al; Outcomes analysis of revision total shoulder replacement. J Bone Joint Surg Am. 2006 Jul;88(7):1494-500. [abstract]
18. Haines JF, Trail IA, Nuttall D, et al; The results of arthroplasty in osteoarthritis of the shoulder. J Bone Joint Surg Br. 2006 Apr;88(4):496-501. [abstract]

Acknowledgements