Total Shoulder Arthroplasty for Osteoarthritis

Stephanie H. Hsu, MD

Louis U. Bigliani, MD

Dr. Bigliani or an immediate family member has received royalties from Zimmer. Neither Dr. Hsu nor any immediate family member has received anything of value from or has stock or stock options held in a commercial company or institution related directly or indirectly to the subject of this chapter.

PATIENT SELECTION

Total shoulder arthroplasty (TSA) is becoming more common, especially with an active aging population. A successful outcome is dependent on several factors, including patient selection, preoperative planning, surgical technique, and postoperative rehabilitation.

The most common etiologies leading to TSA are primary and secondary osteoarthritis, which account for more than 60% of all cases. The pathology of osteoarthritis usually includes osteophyte formation, joint space narrowing with subchondral sclerosis and cyst formation, and posterior glenoid wear in severe cases. Rheumatoid and inflammatory arthritis, as well as osteonecrosis, are also indications for TSA.¹^,²

Contraindications include rotator cuff tear arthropathy, active infection, brachial plexopathy, excessive glenoid bone loss, and Charcot arthropathy. Studies have demonstrated full-thickness rotator cuff tears in only 5% to 10% of patients with osteoarthritis.³^,⁴ Fortunately, most patients with osteoarthritis have good rotator cuff tissue. A functioning rotator cuff is essential for a successful TSA.

FIGURE 1 Images obtained before total shoulder arthroplasty for osteoarthritis. A, AP radiograph of a right shoulder demonstrates loss of glenohumeral joint space, marginal osteophyte formation, sclerosis, subchondral cysts, and maintenance of acromiohumeral distance, suggesting an intact rotator cuff. B, Axillary lateral radiograph demonstrates marginal osteophytes and posterior glenoid wear. C, Axial CT cut illustrates posterior wear of the glenoid, with good glenoid vault bone stock and glenoid version.

PREOPERATIVE IMAGING

The preoperative workup includes routine blood tests and medical clearance as indicated. We obtain a series of plain radiographs (Figure 1, A and B), including a true AP (Grashey) view in neutral, external rotation, and internal rotation; an axillary view; and a scapular Y view. A CT scan is often obtained, especially for evaluation of the axial cuts (Figure 1, C). These help to determine retroversion of the glenoid, depth of the glenoid vault, and wear pattern.¹^,⁵ If there is any history or clinical concern for the rotator cuff integrity, we order an MRI to evaluate for a rotator cuff tear, as well as for atrophy of the muscle bellies.

VIDEO 31.1 Total Shoulder Arthroplasty. Louis U. Bigliani, MD; Stephanie H. Hsu, MD; Howard Y. Park, BA (6 min)

View Quicktime Video

Video 31.1

PROCEDURE

Room Setup/Patient Positioning

For anesthesia, we prefer an indwelling regional interscalene catheter block for its safety, effectiveness, and pain control postoperatively. This can be used in conjunction with monitored anesthesia care or a laryngeal mask airway as per anesthesia. General anesthesia may also be considered, especially for a muscular patient who may require paralysis for exposure.

Antibiotics are given within 1 hour of incision and are continued for 24 to 48 hours postoperatively. We prefer cefazolin or clindamycin if a penicillin allergy is of concern.

We use a beach-chair position, with the head of the bed raised approximately 30° to 40°. A padded head positioner is placed to protect the cervical spine from extension or overrotation. The head is secured gently to the head positioner with a folded towel and tape. A towel “collar” is also placed to protect the interscalene catheter and keep it out of the surgical field. The patient is positioned toward the edge of the table on the surgical side, with the shoulder over the edge laterally, to allow the arm to extend and rotate beyond the bed. Two folded towels are placed under the patient’s scapula. A small, short side arm board is placed at the level of the distal humerus, with the ability to slide distally to free the arm for extension and rotation for exposure and humeral work (Figure 2, A).

After setup, the range of motion of the surgical side is checked under anesthesia. The surgical shoulder is then prepared and draped in the standard fashion. We prefer not to shave the axilla.

The hand is placed in a stockinette, with self-adherent wrap over the elbow. A small bump is placed under the arm on the short arm board (Figure 2, B). Relevant anatomy— usually only the coracoid landmark—and previous incisions are marked. Two full Ioban sheets (3M) are used to create a “sandwich,” fully covering the surgical site underneath and above.

FIGURE 2 Photographs show patient positioning and setup for total shoulder arthroplasty. A, A short arm board is used to support the surgical extremity, and a headrest is used to stabilize the patient’s head. B, The extremity is draped, and a small towel bump is placed beneath the upper arm for support.

Special Instruments/Equipment/Implants

The TSA system of the surgeon’s choice is prepared. Additional instruments often used during the case are listed in Table 1.

Surgical Technique

Approach

A deltopectoral approach is preferred. An incision starting approximately 2 cm inferior to the clavicle and just lateral to the coracoid continues toward the deltoid insertion, approximately 10 to 12 cm as needed for exposure (Figure 3, A). As the deltopectoral fascia is exposed, two large Gelpi retractors are placed at the proximal and distal thirds of the incision for exposure. A needle-tip Bovie is used to raise full-thickness skin flaps medially and laterally, with meticulous hemostasis. Dissection is continued proximally to the level of the clavicle and inferiorly to the midpectoralis level.

The cephalic vein is identified adjacent to a strip of fat in the deltopectoral interval. It is mobilized and usually taken laterally with the deltoid because there are fewer communicating branches from the pectoralis medially. Loop retractors, Richardson retractors, a straight Adson, and a needle-tip Bovie are used to accomplish this. The Richardson retractors can also act as blunt dissectors to expose and clear the clavipectoral fascia.

The clavipectoral fascia is incised with cautery lateral to the conjoined tendon, and blunt dissection is performed underneath so that the strap muscles may be retracted medially with a Richardson retractor. The axillary nerve is palpated under the inferior border of the subscapularis to localize its position. When the arm is externally rotated, the axillary nerve will stay medial and out of the surgical field.

To improve visualization and exposure in the subacromial space, the anterior leading edge of the coracoacromial ligament is excised, along with any “veil” of bursal
tissue that may obscure the view superiorly (Figure 3, B). Placing the arm in maximal internal rotation, any remaining subacromial bursal tissue is excised. It is important to define subacromial and contiguous subdeltoid space. An elevator is used if there are any adhesions, especially in patients with a history of previous surgery.

TABLE 1 Instruments Used in Total Shoulder Arthroplasty