Total shoulder arthroplasty or replacement is the mainstay of treatment for advanced, disabling glenohumeral joint arthritis. Diseased parts of the glenohumeral joint are removed, and the articulation is replaced with plastic and metal components to recreate the normal anatomy of the shoulder joint. Historically, the first shoulder replacement was performed by the French surgeon Dr. Jules Emile Pean, using rubber and platinum implants in a patient with tuberculous arthritis of the shoulder in 1893.¹ Ultimately, the implant was removed after two years due to an infection.¹ The modern era of total shoulder replacement began in the 1950s when Dr. Charles Neer introduced and reported the results of a solid Vitallium arthroplasty implanted for a fracture.² In 1974, Dr. Neer reported the excellent results of a total shoulder replacement implanted for the management of glenohumeral arthritis.³ Since then, there have been significant advancements in the design and technology of total shoulder replacements. Current options include humeral head resurfacing,hemiarthroplasty, anatomic total shoulder arthroplasty, and reverse total shoulder arthroplasty.⁴

Notably, the popularity of total shoulder replacements has grown substantially in recent years.^5,6 In the United States, there were 104,575 primary total shoulder replacements performed in 2017, a number that has increased by 103.7 percent since 2011.⁶ This increase has largely been driven by the drastic increase in the number of reverse total shoulder replacements performed annually, which has grown by 191 percent in this time.⁶ The volume of anatomic total shoulder replacements increased by 38.5 percent in the same period, while the volume of shoulder hemiarthroplasties has decreased by 60.9 percent.⁶

Types of Shoulder Replacements

Shoulder hemiarthroplasty, or a partial shoulder replacement, involves the replacement of the articular surface of the humerus with a metal humeral component.^7,8 Common indications for a hemiarthroplasty are severe glenohumeral arthritis that has failed nonoperative management and non-reconstructible comminuted proximal humerus fractures in younger patients. Specifically, hemiarthroplasty is considered in patients with inadequate glenoid bone stock for a total shoulder replacement and in patients with a diagnosis of avascular necrosis that does not involve the glenoid. Further, it is preferred in younger patients who frequently use the shoulder in high-demand activities and are unwilling to modify their lifestyles to accommodate a total shoulder replacement.⁸ Lastly, in younger patients with severely comminuted fractures that are not re-constructible with open reduction internal fixation, shoulder hemiarthroplasty may be an option.^8,9

Anatomic total shoulder arthroplasty (TSA) involves the replacement of the articular surface of the humerus with a metal humeral component and the resurfacing of the glenoid with a polyethylene component.^10,11 The humeral component may be a stemmed or stemless design. The primary indication for an anatomic TSA is disabling glenohumeral arthritis in a patient for whom nonoperative management has failed. Nonoperative management includes nonsteroidal anti-inflammatory medication (NSAIDs), physical therapy, activity modification, and corticosteroid injections. Possible etiologies of glenohumeral arthritis include osteoarthritis, inflammatory arthritis, and avascular necrosis with glenoid involvement. Contraindications to anatomic TSA include active infection, deltoid or rotator cuff dysfunction, and poor glenoid bone stock. Furthermore, patients younger than fifty years of age are typically cautioned against it, as TSA survival in this population is shown to be significantly worse than in patients over the age of fifty.¹² A recent review demonstrated that the ten-year survivorship of anatomic shoulder replacements, or implant longevity before revision surgery, was 96 percent. However, survivorship depends on the indication for shoulder replacement, as studies have shown that survivorship is worse in patients requiring shoulder arthroplasty for osteonecrosis and posttraumatic arthritis compared to primary glenohumeral arthritis.¹³

Reverse total shoulder arthroplasty is a type of joint replacement that involves switching the natural anatomy of the shoulder joint and includes a convex ball on the glenoid and a concave cup on the humerus with a stem down the medullary canal.¹⁴ With this prosthesis, the center of rotation moves inferiorly and allows the deltoid to gain a mechanical advantage for forward elevation of the arm in the presence of a deficient rotator cuff. Reverse total shoulder arthroplasty is commonly used in patients with cuff tear arthropathy and in elderly patients with three- or four-part proximal humerus fractures. Although utilized in patients with massive rotator cuff tears, the procedure requires an intact deltoid muscle and axillary nerve.¹⁵

Surgical Techniques for Shoulder Replacements

The most common surgical approach for a shoulder replacement is the deltopectoral approach.¹⁶ However, other surgical approaches, such as the anterosuperior approach, have been described and utilized with excellent results as well.¹⁶ The deltopectoral approach uses the interval between the deltoid laterally and pectoralis major medially (video 8.1). An 8- to 10-centimeter linear incision is drawn just lateral to the coracoid process, down the deltopectoral groove, and toward the deltoid tuberosity of the humerus. Following superficial dissection, the interval between the deltoid, innervated by the axillary nerve; and the pectoralis major muscles, innervated by the medial and lateral pectoral nerve, is identified and dissected.¹⁷

It should be noted that the deltopectoral approach to shoulder arthroplasty requires mobilization of the subscapularis tendon in order to provide adequate exposure. Several techniques, including subscapularis tenotomy, subscapularis peel, and lesser tuberosity osteotomy, have been developed for management of the subscapularis.^18,19 While the subscapularis tenotomy is an intra-tendinous division of the subscapularis, and the subscapularis peel is a detachment of the subscapularis tendon from its insertion on the lesser tuberosity, the lesser tuberosity osteotomy was designed to decrease the risk of injury to the subscapularis by relying on bone-to-bone healing. While studies suggest similar clinical outcomes between these techniques, each technique requires the repair of the subscapularis. Therefore, careful attention to subscapularis function postoperatively should be noted.^19,20

Postoperative Physical Examination

Thorough physical examinations during postoperative visits are essential in assessing the status of the total shoulder replacement. The examiner should assess wound healing and ensure that there is no erythema, edema, or other signs of inflammation that may indicate an underlying surgical site infection. Infection is a particularly devastating complication of shoulder replacements, with an occurrence of 2.9 percent after reverse shoulder replacements and 0.51 percent after anatomic total shoulder replacements.²¹ This difference has been attributed to a variety of factors, such as the increased dead space in reverse total shoulder replacement due to the absent rotator cuff, older patient age, more comorbidities, and higher likelihood of prior shoulder surgery in patients undergoing reverse total shoulder replacements.²¹ Additional signs of infection following shoulder replacements include a stiff and painful shoulder, and inflammatory markers should be obtained if clinical suspicion is high. However, it is important to note that inflammatory markers may not be elevated in the setting of Cutibacterium acnes (C. acnes) infection.²² C. acnes has notably emerged as a common cause of infection following shoulder surgery.

It is important to carefully examine for signs of instability following anatomic and reverse total shoulder replacement. In a recent review article, Bohsali et al. noted that the overall rates of instability following anatomic and reverse total shoulder replacement were 1 percent and 5 percent, respectively.²¹ However, instability rates vary based on patient-related factors, surgical technique, implant design, and surgical indication. Therefore, for example, studies have reported the instability rate following reverse total shoulder arthroplasty to be as high as 31 percent.²¹ Signs of anterior shoulder instability on physical examination include anterior shoulder pain, weakness of subscapularis strength, and increased active or passive external rotation. Mechanical symptoms or a deformity may be present as well. On the other hand, signs of posterior shoulder instability on history and physical examination include the sudden onset of posterior glenohumeral joint pain and a loss or decrease of external rotation.²³

In the immediate postoperative period, the focus should be on reducing pain and inflammation; maintaining range of motion in the wrist, hand, and elbow; and allowing only passive range of motion of the shoulder. After the patient meets surgeon-specific passive range-of-motion goals, the patient gradually begins active range of motion, with the goal of progressive improvement and strengthening. Range-of-motion goals following shoulder replacement depend on both patient-specific and surgeon-specific factors. Kiet et al. reviewed and compared range of motion at minimum two-year follow-up following both anatomic and reverse total shoulder replacement in one hundred patients.²⁴ In their cohort of anatomic total shoulder replacements, they found an average forward elevation of 144 degrees, abduction of 136 degrees, external rotation of 53 degrees, and internal rotation to L2. In their cohort of reverse shoulder replacements, they found an average forward elevation of 136 degrees, abduction of 129 degrees, external rotation of 38 degrees, and internal rotation to L2. The only significant difference between the two groups was improved external rotation in the anatomic shoulder replacement cohort. Furthermore, deficits in internal rotation are often noted following a reverse total shoulder replacement, with patients reporting difficulty in performing activities of daily living, including washing their backs or closing their bras.²⁵ Overall, however, patients do achieve excellent pain relief and improvement in range-of-motion outcomes in terms of shoulder flexion, abduction, external rotation, and internal rotation following both anatomic and reverse total shoulder replacement (video 8.2; figure 8.1).

Special Considerations

Subscapularis function should be assessed during postoperative physical examinations due to the mobilization of the subscapularis during the procedure. This is particularly important following anatomic total shoulder replacement. The subscapularis can be tested through the lift off test, belly press test, and passive external rotation at the side. Notably, shoulder pain, weakness of internal rotation, and increased passive external rotation at the side may be suggestive of a subscapularis rupture.²¹

The examiner should carefully palpate the acromion and scapular spine in a patient following a reverse total shoulder replacement. The origin of the deltoid includes the lateral third of the clavicle, acromion, and scapular spine. Due to the design of the reverse total shoulder replacement, which increases the deltoid abduction moment arm and increases deltoid tension, these altered kinematics may precipitate insufficiency fractures in the acromion and scapular spine.²⁶ The rate of these fractures has been estimated at 1 percent following reverse shoulder replacement.²¹ These patients present with generally atraumatic point tenderness over the scapular spine, or wherever the insufficiency fracture is located.

Key Terminology

Anatomic Total Shoulder Arthroplasty

Replacement of the articular surface of the humeral head and glenoid with man-made components. Typically used in patients with debilitating glenohumeral arthritis after failure of conservative measures. Requires intact rotator cuff. ↵

Deltopectoral Approach

Common operative approach to the shoulder using the interval between the deltoid laterally and pectoralis major medially. Used in the exposure for shoulder replacements, proximal humerus fractures, and more. ↵

Hemiarthroplasty

Partial shoulder replacement involving the replacement of the proximal humerus with a man-made component. Commonly used for glenohumeral arthritis for which nonoperative management has failed and non-reconstructible comminuted proximal humerus fractures in younger patients. ↵

Humeral Head Resurfacing

Replacement of the articular surface of the humeral head with a non-stemmed implant. ↵

Lesser Tuberosity Osteotomy

Operative technique that involves cutting the lesser tuberosity of the humerus while maintaining the insertion of the subscapularis tendon in order to provide adequate exposure to the glenohumeral joint during the deltopectoral approach to shoulder replacement. ↵

Reverse Total Shoulder Arthroplasty

Type of shoulder replacement that switches the natural anatomy of the shoulder joint so that a half-sphere is affixed to the glenoid and the humerus receives a cup, typically with a stem down the medullary canal. Lengthens the deltoid to gain a mechanical advantage for forward elevation of the arm in the presence of a deficient rotator cuff. Commonly used in patients with cuff tear arthropathy and in elderly patients with three- or four-part proximal humerus fractures. ↵

Subscapularis Peel

Operative technique involving detachment of the subscapularis tendon from its insertion on the lesser tuberosity in order to provide adequate exposure to the glenohumeral joint during the deltopectoral approach to shoulder replacement. ↵

Subscapularis Tenotomy

Operative technique involving intra-tendinous division of the subscapularis in order to provide adequate exposure to the glenohumeral joint during the deltopectoral approach to shoulder replacement. ↵

Total Shoulder Arthroplasty or Replacement

Operative procedure involving the removal of diseased parts of the glenohumeral joint and replacing the articulation with manufactured components to restore mobility of the shoulder joint and reduce pain. ↵

 References

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3. Neer CS, 2nd. Replacement arthroplasty for glenohumeral osteoarthritis. J Bone Joint Surg Am. 1974;56(1):1-13. ↵

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19. Levine WN, Munoz J, Hsu S, et al. Subscapularis tenotomy versus lesser tuberosity osteotomy during total shoulder arthroplasty for primary osteoarthritis: a prospective, randomized controlled trial. J Shoulder Elbow Surg. 2019;28(3):407-414. ↵

20. Louie PK, Levy DM, Bach BB, Nicholson GP, Romeo AA. Subscapularis tenotomy versus lesser tuberosity osteotomy for total shoulder arthroplasty: a systematic review. Am J Orthop (Belle Mead NJ). 2017;46(2):E131-E138. ↵

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24. Kiet TK, Feeley BT, Naimark M, et al. Outcomes after shoulder replacement: comparison between reverse and anatomic total shoulder arthroplasty. J Shoulder Elbow Surg. 2015;24(2):179-185. ↵

25. Kim MS, Jeong HY, Kim JD, Ro KH, Rhee SM, Rhee YG. Difficulty in performing activities of daily living associated with internal rotation after reverse total shoulder arthroplasty. J Shoulder Elbow Surg. 2020;29(1):86-94. ↵

26. Mayne IP, Bell SN, Wright W, Coghlan JA. Acromial and scapular spine fractures after reverse total shoulder arthroplasty. Shoulder Elbow. 2016;8(2):90-100. ↵