DEFINITION

Glenohumeral arthritis is characterized by loss of articular cartilage and varying degrees of soft tissue contracture, rotator cuff dysfunction, and bone erosion, depending on the underlying arthritic condition.

 

The results of surgical treatment are largely dependent on the integrity of the rotator cuff; therefore, glenohumeral arthritides are often subdivided on this basis.

 

Common arthritic and related conditions that generally involve an intact or reparable rotator cuff include osteoarthritis, posttraumatic arthritis, and avascular necrosis.

 

Although some patients with inflammatory arthritides such as rheumatoid arthritis have intact or reparable rotator cuffs, the rotator cuff is torn or dysfunctional in many patients. When reference is made to patients with inflammatory arthritis in this section, it pertains to the subset of patients in whom the cuff is intact or reparable.

 

ANATOMY

 

The pertinent surgical anatomy can be divided into bone, ligaments, muscles, and neurovascular structures.

 

Normal osseous relationships include humeral head center, thickness, and radius of curvature, humeral neckshaft angle, humeral head offset, glenohumeral offset, greater tuberosityto-acromion distance, greater tuberosity-to-humeral head distance, glenoid radius of curvature, glenoid size, glenoid version, and glenoid

offset (FIG 1).13,21

 

Humeral head radius and thickness are variable and correlate with patient size. Mean humeral head radius is about 24 mm, with a range of 19 to 28 mm. Mean humeral head thickness is about 19 mm, with a range of 15 to 24 mm.13,21

 

 

 

FIG 1 • The normal glenohumeral anatomic relationships. (Adapted from Iannotti JP, Gabriel JP, Schneck SL, et al. The normal glenohumeral relationships: an anatomical study of one hundred and forty shoulders. J Bone Joint Surg Am 1992;74A:491-500.)

 

 

The ratio of humeral head thickness to humeral head radius of curvature is remarkably constant at about 0.7 to 0.9, regardless of patient height or humeral shaft size.13,21

 

The center of the humeral head does not coincide with the projected center of the humeral shaft. The distance between the center of the humeral head and the central axis of the intramedullary canal is defined as the humeral head offset and is about 7 to 9 mm medial and 2 to 4 mm posterior (FIG 2).2,21

 

Humeral retroversion averages 20 to 30 degrees, with a wide range of about 20 to 55 degrees.2,13,21 The vertical distance between the highest point of the humeral articular surface and the highest point of the greater tuberosity (ie, head to greater tuberosity height) is about 8 mm and shows a relatively small range of

interspecimen variability.13

 

Humeral neck-shaft angle is defined as the angle subtended by the central intramedullary axis of the humeral shaft and the base of the articular segment and shows substantial individual variation. The average neck-shaft angle is 40 to 45 degrees (130 to 135 degrees), with a range of 30 to 55 degrees (120 to 145 degrees).2,13,21

 

Pertinent musculotendinous anatomy includes the deltoid, pectoralis major, conjoined tendon of the coracobrachialis and short head of the biceps, rotator cuff, and long head of the biceps.

 

Ligamentous structures that are potentially important in the surgical management of glenohumeral arthritis include the coracoacromial ligament and the glenohumeral capsular ligaments. In many cases of glenohumeral arthritis with an intact cuff, the anterior and inferior capsular ligaments are

 

P.3828

contracted, resulting in restriction of external rotation and posterior humeral head subluxation.

 

 

 

FIG 2 • The humeral head center, on average, lies 2 to 4 mm posterior and 7 to 9 mm medial to the projected center of the intramedullary canal. (Adapted from Boileau P, Walch G. The three-dimensional geometry of the proximal humerus: implications for surgical technique and prosthetic design. J Bone Joint Surg Br 1997;79B:857-865.)

 

 

Neurovascular structures are abundant and subject to potential injury during shoulder arthroplasty. The axillary artery and all of its branches, especially the anterior humeral circumflex, posterior humeral circumflex, and the subscapular arteries, are particularly vulnerable.

 

The entire brachial plexus traverses the anterior aspect of the shoulder and is subject to traction and other injuries. The two most pertinent nerves are the axillary nerve and the musculocutaneous nerve.

 

The axillary nerve is a terminal branch of the posterior cord of the brachial plexus and is composed primarily of motor fibers from the fifth and sixth cervical roots. It descends the anterior surface of the subscapularis to the inferior aspect of the joint capsule, where it courses through the quadrilateral space to enter the posterior aspect of the shoulder.

 

The musculocutaneous nerve is one of the terminal branches of the lateral cord of the brachial plexus that is anterior and lateral to the axillary nerve. It typically pierces the conjoined tendon of the coracobrachialis and short head of the biceps about 5 cm distal to the tip of the coracoid. However, this course is variable and the entry point into the conjoined tendon can be as proximal as 2 cm.

 

PATHOGENESIS

 

The biologic basis for glenohumeral arthritis is not known. However, the loss of articular cartilage associated

with primary osteoarthritis, posttraumatic arthritis, avascular necrosis, and other arthritides is, in some way, the result of imbalance in the normal cycle of cartilage damage and repair.

 

In some cases of posttraumatic arthritis, catastrophic cartilage damage associated with single event or repetitive trauma overwhelms the shoulder's cartilage repair mechanisms and arthritis ensues.

 

Primary osteoarthritis may be associated with mechanical factors such as glenoid hypoplasia and increased retroversion. However, in many cases, no cause is evident. The final common pathway involves a release of degradative enzymes, such as collagenase, gelatinase, and stromelysin, and a variety of inflammatory mediators, which further damage the cartilage, and eventually, the underlying bone.

 

A detailed discussion of the pathogenesis of avascular necrosis is beyond the scope of this chapter. However, the development of glenohumeral arthritis in this condition is likely the result of advanced cartilage damage following collapse of the humeral head. Involvement of glenoid articular cartilage does not occur until the later stages of the disease when the irregular humeral head has been articulating with the previously normal glenoid surface.

 

Rheumatoid arthritis is characterized by activation of the immune system that leads to an influx of lymphocytes into the joint and synovial tissue, with subsequent release of a variety of cytokines, destructive enzymes, and mediators of inflammation such as interleukins and tumor necrosis factor. This autoimmune response is

thought to be important in perpetuating joint destruction.25

 

NATURAL HISTORY

 

Glenohumeral arthritis of any type is characterized by progressive stiffness, pain, and loss of function.

 

Patients with primary osteoarthritis and many types of posttraumatic arthritis develop progressive loss of external rotation, posterior subluxation, and posterior glenoid bone loss. Large osteophyte formation, especially on the inferior humeral neck, is common. Full-thickness rotator cuff tears are distinctly uncommon and occur in 5% to 10% of patients.

 

Rheumatoid arthritis results in progressive regional osteopenia, central glenoid bone erosion, and rotator cuff tears. The prevalence of full-thickness rotator cuff tears in patients with rheumatoid arthritis of the shoulder is

25% to 40%.31 However, rotator cuff dysfunction and substantial partial tearing are extremely common.

 

PATIENT HISTORY AND PHYSICAL FINDINGS

 

Patients with glenohumeral arthritis will give a history of chronic (years) shoulder pain and restricted motion, often with a recent (months) exacerbation. Posttraumatic arthritis is typically associated with a history of prior injury, such as fracture or dislocation, or surgery.

 

Pain is often worse with activity and usually interferes with sleep. Neck pain, distal radiation below the elbow, and numbness and paresthesias in the fingers and hand are uncommon and should suggest other potential causes of shoulder pain, such as cervical stenosis or cervical radiculopathy.

 

Bilateral involvement is common in primary osteoarthritis. Contralateral symptoms are often present but to a lesser extent.

 

Physical findings in patients with glenohumeral arthritis and an intact rotator cuff include the following:

 

 

 

Posterior joint line tenderness, especially in osteoarthritis associated with posterior subluxation18 Generalized atrophy or flattening of the shoulder from long-term lack of function

 

Posterior prominence of the humeral head in cases of posterior subluxation

 

Symmetric loss of active and passive range of motion (FIG 3)

 

Disproportionate loss of external rotation in comparison to other motions, especially in osteoarthritis or after capsulorrhaphy arthropathy18

 

 

Increased pain with passive stretch of the capsule at the end range of motion, especially external rotation Intact neurologic function, except in rare patients with prior neurologic injury from trauma or surgery

IMAGING AND OTHER DIAGNOSTIC STUDIES

 

Glenohumeral arthritis is a radiographic diagnosis. Routine radiographs should include anteroposterior (AP) views in internal and external rotation and an axillary view.

 

Radiographic findings in primary osteoarthritis include subchondral sclerosis and cyst formation, osteophyte formation, and asymmetric posterior joint space narrowing (FIG 4A,B).18

 

In cases of posttraumatic arthritis, radiographs may reveal retained hardware.

 

 

Glenoid deformity in osteoarthritis has been classified by Walch et al33 according to the presence of posterior subluxation and posterior bone deformity:

 

 

Type A: centered

 

 

Type B: posteriorly subluxated (B1) and posteriorly subluxated with posterior erosion (B2) Type C: posteriorly subluxated with increased retroversion (hypoplasia)

 

 

 

FIG 3 • The hallmark of glenohumeral osteoarthritis is symmetric loss of both active and passive range of motion (A), especially external rotation (B).

 

 

 

FIG 4 • Radiographic findings in osteoarthritis include osteophyte formation, especially on the inferior humerus as seen on the AP view (A), and asymmetric posterior glenoid wear with posterior subluxation, as seen on the axillary view (B). C. CT scan reveals a large inferior humeral osteophyte and a type C glenoid, with increased glenoid retroversion. D. Coronal magnetic resonance (MR) image in a patient with rheumatoid arthritis reveals an intact but very thin rotator cuff with erosion of the humeral attachment site and evidence of rotator cuff dysfunction (ie, proximal humeral migration).

 

 

P.3830

 

Computed tomography (CT) scans are helpful in quantifying bone loss in patients with posterior subluxation (FIG 4C).

 

Magnetic resonance imaging (MRI) is useful in patients with rheumatoid arthritis to determine rotator cuff integrity (FIG 4D).

 

 

Electromyography may be used in patients suspected of having posttraumatic or postsurgical nerve injuries. Medical consultation is warranted in patients with substantial comorbidities.

DIFFERENTIAL DIAGNOSIS

 

Frozen shoulder

 

 

Posttraumatic or postsurgical infection Cervical stenosis

 

 

Cervical radiculopathy Neoplasm

NONOPERATIVE MANAGEMENT

 

 

Avoiding activities that are painful or place an undue strain on the shoulder, such as weightlifting, is important. Nonsteroidal anti-inflammatory medications may be helpful in reducing pain and inflammation.

 

In patients with rheumatoid arthritis, rheumatologic consultation for maximizing medical treatment is helpful.

 

Glucosamine chondroitin and other nutritional supplements may reduce the pain associated with arthritis, despite the relative lack of standardized data.

 

Intra-articular corticosteroid injections are almost always helpful, but the relief is often only temporary.

 

Hyaluronic acid derivatives are not yet approved by the U.S. Food and Drug Administration for use in the shoulder but may be of benefit in the future.

 

Therapeutic exercises should be used judiciously. Stretching to maintain flexibility may be helpful, but vigorous exercises may increase pain.

 

SURGICAL MANAGEMENT

 

Surgical options are considered when pain and dysfunction justify surgical intervention, nonoperative management has failed, medical comorbidities do not preclude surgery, and the patient is willing to accept the risks of surgery and the responsibility of postoperative rehabilitation and activity limitations.

 

Nonprosthetic options such as arthroscopic or open débridement are indicated in patients who are too young and active for any type of prosthetic replacement.

 

Prosthetic options include hemiarthroplasty, hemiarthroplasty plus biologic resurfacing, and total shoulder replacement.

 

Total shoulder replacement with a polyethylene glenoid component provides the most predictable pain relief but has the disadvantage of progressive polyethylene wear and eventual component loosening.29

 

The relative indications for hemiarthroplasty, hemiarthroplasty with biologic resurfacing, and total shoulder arthroplasty are controversial, vary among surgeons, and must be individualized according to patient age, activity level, and bone deformity, among other factors.

 

Similarly, the type of implant can be individualized according to patient factors and surgeon preference.

 

Concentricity of the joint, without subluxation, likely improves prosthetic performance in all circumstances. Therefore, fixed subluxation should be corrected when possible. Attempt should also be made to correct glenoid retroversion to the greatest degree possible, especially in the case of B2 glenoids, as component

retroversion has been associated with increased radiographic osteolysis.12 Options include contracture release and correction of bone deformity with some combination of asymmetric reaming, bone grafting, and specialized components.

 

General principles that summarize procedural and implant indications in patients with glenohumeral arthritis and an intact or reparable cuff include the following:

 

 

Total shoulder arthroplasty is preferred with adequate glenoid bone, age younger than 50 years, and sedentary or moderate activity levels.

 

Hemiarthroplasty is favored in patients with normal or minimally involved glenoids, inadequate glenoid bone, age of 50 years or younger, and activity levels that include weightlifting or other strenuous activity.

 

When substantial reaming or resurfacing of the glenoid is planned, the procedure is facilitated by removing the humeral head rather than resurfacing it. Currently, stemmed implants are most popular, but implants with metaphyseal fixation may be useful in patients with adequate bone quality.

 

These principles are merely guidelines and should be individualized.

 

The following sections will cover the technical aspects of total shoulder arthroplasty with and without bone

loss, including asymmetric reaming, augmented glenoid components, and glenoid bone grafting.

 

Preoperative Planning

 

Preoperative radiographs and CT scans should be reviewed to quantify humeral subluxation (especially posterior in osteoarthritis), version, and glenoid bone loss. This will identify the need for asymmetric glenoid reaming, augmented glenoid components, or a bone graft.

 

If the goals of asymmetric reaming are to correct glenoid deformity and to contain all fixation appendages of the glenoid component within the glenoid vault, the extent of reaming should be limited to about 5 mm or 15 degrees. If greater correction is desired, arrangements for glenoid bone grafting should be made. As little

subchondral bone as possible should be removed as this correlates with glenoid component subsidence.34

 

We typically use an augmented glenoid component (Global Steptech Anchor Peg Glenoid, DePuy, Warsaw, IN) when eccentric/posterior bone loss is between 3 mm and 11 mm. We asymmetrically ream 2 mm and use a 3-, 5-, 7-, or 9-mm augmented component to restore the native glenoid version.

 

If posterior bone loss is greater than 11 mm, a bone graft must be used behind the glenoid component to restore the anatomic version and to avoid medialization of the joint line.

 

Preoperative radiographs should be templated to gain an appreciation of the humeral head size, canal diameter, and neck-shaft angle. In patients with highly varus (115 to 120 degrees) or valgus (145 to 150 degrees) neck-shaft angles in whom cementless fixation of a stemmed implant is planned, alterations in the level of the humeral cut or the use of a prosthesis with neck-shaft angle variability will be required. Canal diameter should also be examined, especially if the patient is a small statured woman, as a standard humeral stem may not fit in this patient and a humeral resurfacing may need to be available.

 

 

P.3831

 

MRI scans should be read for substantial rotator cuff abnormalities in rheumatoid patients and others suspected of having rotator cuff tears.

 

All other relevant preoperative data should be reviewed, including consultations from medical colleagues. The presence of all surgical implants and instruments should be verified.

 

Passive range of motion should be measured intraoperatively, before positioning, to determine the need for contracture release. In particular, the degree of passive external rotation loss may dictate the method of subscapularis reflection and repair.

 

Subscapularis shortening is typically not a substantial factor in passive external rotation loss, unless the patient has had a prior subscapularis shortening or tightening procedure (eg, Putti-Platt or Magnuson-Stack) or the contracture is particularly severe (eg, external rotation of -30 degrees or more) and long-standing.

 

Methods of managing the subscapularis include intratendinous incision and anatomic repair, lesser tuberosity osteotomy and anatomic repair, lateral tendinous release with medial advancement, and Z-lengthening.

 

Recent evidence suggests that lesser tuberosity osteotomy is associated with better subscapularis function than soft tissue reflection and repair.7,22,27 However, randomized comparison data do not show an advantage to lesser tuberosity osteotomy versus a subscapularis peel.15,16 In addition, a recent study documents good postoperative subscapularis function with tenotomy and soft tissue repair.3

 

Our current preference for subscapularis management in primary shoulder arthroplasty is lesser tuberosity osteotomy and anatomic repair, with the following exceptions:

 

 

Rheumatoid arthritis with substantial erosion of the subscapularis attachment site on MRI

 

 

 

FIG 5 • A. Shoulder arthroplasty is carried out with the patient in the semirecumbent position; a special horseshoeshaped headrest may improve access to the superior aspect of the shoulder. B. Positioning should allow unrestricted adduction and extension to allow access to the humeral shaft. C. A mechanical arm-holding device may be used to help position the arm throughout the procedure.

 

 

History of a subscapularis shortening or tightening procedure (eg, Putti-Platt or Magnuson-Stack procedure)

 

Passive external rotation of less than -30 degrees

 

If lesser tuberosity osteotomy is not performed, lateral detachment with medial reattachment is most often adequate. Subscapularis Z-lengthening is rarely required.

 

Positioning

 

Shoulder arthroplasty is performed with the patient in the semirecumbent position (FIG 5A). The hips should be flexed about 30 degrees to prevent the patient from sliding down the table; the knees should be flexed about 30 degrees to relax tension on the sciatic nerves; the back should be elevated 35 to 40 degrees.

 

The entire shoulder should be lateral to the edge of the table to allow adduction and extension of the arm (FIG 5B). This is required for safe access to the humeral canal and can be accomplished by positioning the patient as far toward the operative side of the table as possible or by using a specialized table with removable cutouts behind the shoulders.

 

A specialized padded, horseshoe-shaped headrest may be helpful in facilitating access to the superior aspect of the shoulder.

 

An adjustable mechanical arm holder (McConnell Orthopedic Mfg. Co., Greenville, TX, or Tenet Medical Engineering, Inc., Calgary, Alberta, Canada) is helpful for positioning the arm. Alternatively, a padded Mayo stand can also be used (FIG 5C).

 

Intraoperative Nerve Monitoring

 

We typically use nerve monitoring when the patient has a history of open anterior stabilization and has less than -10 degrees of external rotation at the side.

 

 

P.3832

 

This may also be useful in cases of recovering nerve injury or when an axillary neurolysis is planned, for example, after a chronic dislocation.

 

The indications are still evolving and this technology has a high false-positive rate.

 

Approach

 

The most common approach for shoulder arthroplasty is the deltopectoral approach popularized by Neer.18 The advantages are preservation of the deltoid origin and insertion, extensibility, and excellent humeral exposure. The need for posterior deltoid retraction, especially in muscular men, can make posterior glenoid exposure difficult and can lead to injury of the cephalic vein, the deltoid itself, or the brachial plexus.

 

The superior or anterosuperior approach was popularized by MacKenzie17 and involves access to the shoulder by reflecting the anterior deltoid from the acromion. Advantages include excellent anterior and posterior glenoid exposure and a lower incidence of axillary nerve traction injuries than the traditional deltopectoral approach. Disadvantages include nonextensibility, difficult medial and inferior humeral exposure, and potential deltoid dehiscence.

 

Modifications of these exposures include the addition of a clavicular osteotomy and extensive takedown of the deltoid origin to aid in exposure for difficult cases.8,23

 

The deltopectoral approach is the most commonly used approach for primary arthroplasty with an intact or

reparable cuff and will be used in all subsequent sections of this chapter.

TECHNIQUES

• Total Shoulder Arthroplasty

Superficial Dissection

An 8- to 10-cm deltopectoral incision is made from the tip of the coracoid toward the deltoid insertion.

With the arm in neutral rotation, the distal end of the incision is centered over the humerus, roughly in the middle of the arm, in a medial to lateral dimension. In patients with significant obesity or patients who are muscular, the tissues lie primarily on the lateral side of the humerus. Because of this, there is a tendency to make the incision too lateral.

If the interval is not immediately apparent, the incision is generally too lateral. The tip of the coracoid process can also be used as a landmark for proximal dissection because it lies at the apex of a fatty triangle where the deltoid and pectoralis major tendons separate en route to the bare area of the clavicle.

The cephalic vein is taken laterally with the deltoid and the pectoralis major is taken medially.

The upper 1 cm of the pectoralis major may be released to improve visualization of the inferior aspect of

 

the joint, but this is not always needed.

Deep Dissection

 

The clavipectoral fascia is incised lateral to the conjoined tendon of the short head of the biceps and coracobrachialis and is carried superiorly to the coracoacromial ligament, which does not require excision or release to attain adequate exposure.

 

Digital palpation is used to verify the position of the axillary nerve, which is protected throughout the procedure. The musculocutaneous nerve is usually not easily palpable within the surgical field but can be palpated when its entrance is close to the tip of the coracoid. This should be noted so that excessive retraction of the conjoined tendon can be avoided.

 

With the conjoined tendon retracted medially and the deltoid laterally, the arm is placed in slight external rotation to expose the anterior humeral circumflex artery and veins “three sisters.” These are clamped and coagulated or ligated to avoid inadvertent injury and bleeding during the case.

 

The arm is placed in slight internal rotation and the long head of the biceps is exposed from the superior border of the pectoralis major to the supraglenoid tubercle by incising its investing soft tissue envelope and the rotator interval capsule sharply. The long head of the biceps is tenodesed to the upper border of the pectoralis major using two nonabsorbable sutures and is then released proximal to this tenodesis site and excised from the supraglenoid tubercle.

Lesser Tuberosity Osteotomy

 

A large (2 inch) curved osteotome is used to perform a lesser tuberosity osteotomy (TECH FIG 1A). The goal is to obtain a 0.5- to 1-cm thick, noncomminuted fragment with which to reflect the subscapularis.

 

This is most easily accomplished by placing the blade of the osteotome at the base of the bicipital groove with one hand, palpating the most anterior extent of the tuberosity with the index finger of the other hand, and allowing an assistant to strike the osteotome while the surgeon directs it.

 

Once the osteotomy is completed, a large straight osteotome is placed in the osteotomy and is rotated about its long axis to free the osteotomy fragment from any adjacent soft tissue attachments.

 

A large Cobb elevator is then placed in the osteotomy to lever the fragment anteriorly. This further frees the fragment from the underlying capsule and allows sectioning of the superior glenohumeral ligament attachment.

 

The fragment should now be freely mobile. Three 1-mm nonabsorbable sutures are passed around the lesser tuberosity fragment through the bone-subscapularis tendon junction for traction and later reattachment (TECH FIG 1B,C).

 

The arm is externally rotated to expose the most inferior portion of the subscapularis muscle. This may require a right-angle retractor for the pectoralis major. The muscle belly is incised superficially, in line with its fibers, about 1 cm superior to its most inferior border.

 

A Freer elevator, then a small Cobb elevator, and then a large Cobb elevator are used to bluntly release the muscle tissue from the capsule. With the plane between the capsule and the subscapularis muscle defined medially and the osteotomy bed and osteotomy oriented laterally, a knife can be used to elevate the tendon free from the capsule. With the lesser tuberosity pulled anteriorly, the scalpel is passed laterally so that is exits inferior to the fragment. This is continued from inferior to superior to release the subscapularis and lesser tuberosity from the underlying anterior and inferior capsule.

 

 

 

TECH FIG 1 • A. A lesser tuberosity osteotomy is performed using a large curved osteotome placed in the base of the bicipital groove and driven medially to produce a lesser tuberosity fragment about 0.5 to 1.0 cm thick. B,C. A lesser tuberosity osteotomy has been performed in this right shoulder. B. After the fragment has been mobilized from the surrounding soft tissues, three heavy nonabsorbable sutures are placed around the fragment at the bone-tendon junction. C. The fragment is then reflected medially and the subscapularis and the accompanying lesser tuberosity are separated from the underlying capsule and retracted medially. (A: Adapted from Gerber C, Pennington SD, Yian EH, et al. Lesser tuberosity osteotomy for total shoulder arthroplasty: surgical technique. J Bone Joint Surg Am 2006;88A[suppl 1, pt 2]:170-177.)

Capsular Release and Osteophyte Excision

 

Once released, the subscapularis and attached lesser tuberosity are retracted medially to expose the anterior capsule. A blunt elevator is passed between the remaining inferior 1 cm of subscapularis and the inferior capsule to create a space for a blunt Hohmann retractor. This is used to retract and protect the axillary nerve during inferior capsular release and excision.

 

The anterior capsule is released from the anatomic neck of the humerus, starting superiorly and extending inferiorly, well past the 6 o'clock position. This is facilitated by gradually flexing and externally rotating the adducted humerus.

 

The humerus is then delivered into the wound with simultaneous adduction, extension, and external rotation (TECH FIG 2A). Resting of the patient's fist on the surgeon's hip allows the position to be maintained without an arm holder. All humeral osteophytes are removed using a combination of rongeurs and osteotomes (TECH FIG 2B). This allows identification of the anatomic neck and the peripheral extent of the native articular surface. We prefer to start at the anteroinferior part of the humeral head because the plane between the shaft and the osteophytes seems to be most readily apparent in this location. One can reproducibly find a thin fibrofatty layer between the osteophyte and the native bone. This is an

excellent reference point for the proper osteophyte resection plane. It is desirable to leave a ring of cortical bone between the lesser tuberosity and the humeral head osteotomy to maintain the structural integrity of the proximal humerus during retraction for glenoid exposure.

 

The rotator cuff can be evaluated and at this point, if a small tear exists, can be repaired.

Humeral Head Resection

 

The humeral head is removed with a saw at or near the anatomic neck (TECH FIG 3A). This can be accomplished freehand or with intramedullary or extramedullary guides.

 

 

 

TECH FIG 2 • A. The humerus is delivered into the wound with simultaneous adduction, extension, and external rotation in this right shoulder. Retractors include a Brown deltoid retractor superiorly, a large Darrach retractor medially, and a blunt Hohmann retractor anteroinferiorly on the calcar. B. All humeral osteophytes are removed at this stage to identify the anatomic neck.

 

 

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TECH FIG 3 • A. After removal of all osteophytes, the location of the anatomic neck is marked with an electrocautery. This can be done freehand or using an external guide. B. The humerus is cut in native retroversion, leaving 2 to 3 mm of bone medial to the supraspinatus insertion.

 

 

Retroversion of the cut in our practice is prescribed by the plane of the periphery of the native articular surface (ie, native retroversion). A small amount of bone (2 to 3 mm) can be left medial to the supraspinatus insertion (TECH FIG 3B).

 

The neck-shaft angle of the humeral cut is determined by the type of implant used.

 

With fixed neck-shaft angle devices, the cut should precisely fit the neck-shaft angle of the selected device.

 

With variable neck-shaft angle implants, there is more flexibility in osteotomy angle, especially if the variability of the implant neck-shaft angle is infinite within a range.

 

Preoperative templating should identify the patient with an extreme varus (<125 degrees) or valgus (>145 degrees) neckshaft angle.

 

In cases of extreme varus, use of a fixed-angle cementless stem will require a humeral cut that is more valgus than the native neck-shaft angle.

 

The cut exits superiorly 2 to 3 mm medial to the cuff reflection and inferiorly through the native head. This will leave a small portion of the native head in place, even after the inferior osteophyte is removed.

 

In cases of extreme valgus, use of a fixed-angle cementless stem will require a humeral cut that is more varus than the native neck-shaft angle.

 

The cut exits inferiorly at the native articular margin and superiorly through the native head. This will leave a small portion of the native head medial to the cuff reflection.

 

Alternatively, the cut can be made along the native neck-shaft angle and a variable neck-shaft angle device can be used to fit the native neck-shaft angle.

 

The size of the humeral head is estimated by placing trial humeral heads on the cut surface of the osteotomy. When checking the size of the humeral head, it is important to know that, in general, the anterior-posterior dimension of the head is smaller than its superior-inferior dimension. We generally prefer to fit the anterior-posterior dimension at the superior aspect of the head so as to reproduce a relatively anatomic greater tuberosity head height relationship. However, in extremely elliptical humeri, it is desirable to more closely fit the superior to inferior curvature so as to prevent the need to remove a portion of the calcar.

Glenoid Exposure, Capsular Excision, and Surface Preparation

 

With the humeral head resected, a Fukuda ring retractor is placed within the joint and the humerus is retracted posteriorly.

 

A reverse, double-pronged Bankart retractor is placed on the scapular neck anteriorly, between the anterior capsule and the subscapularis.

 

A blunt Hohmann retractor is placed along the anteroinferior portion of the scapular neck to retract and protect the axillary nerve, and the anterior and inferior capsule is excised.

 

The posterior capsule is released unless preoperative posterior humeral subluxation of greater than 25% was present, in which case, the posterior capsule is preserved.

 

The labrum is excised circumferentially to expose the entire periphery of the glenoid. If greater than 25% posterior humeral subluxation was present preoperatively, care is taken to preserve the posterior capsular attachment to the glenoid.

 

The glenoid is sized with a sizing disk. The previously estimated humeral head size may give some idea of the glenoid size.

 

The center of the glenoid is marked and a guide pin for the glenoid reamer is placed.

 

The orientation of this guide pin should be perpendicular to the estimated reamed surface. This can be estimated using preoperative CT measurements of the amount of posterior glenoid bone loss.

 

The glenoid is reamed until a concentric surface is obtained.

 

Concentric glenoid reaming is an important step in glenoid resurfacing that improves initial seating and stability. This is accomplished by reaming over the centrally placed guide pin (TECH FIG 4A). Special glenoid reamers are used to ream concentrically around the center pin (TECH FIG 4B). A standard glenoid component, without posterior augmentation, is used in cases of 3 mm or less of glenoid bone loss after asymmetric reaming over the guide pin.

 

After the surface of the glenoid has been reamed concentrically, the anchoring holes for the glenoid component are created. Both pegged and keeled components are available. The technique described is for an off-axis pegged system (Anchor Peg Glenoid).

 

The center hole for the larger fluted central peg is drilled with a cannulated drill over the central guide pin. The peripheral drill guide is then placed and the holes for the three peripheral pegs are drilled (TECH FIG 4C). Penetration of any of the peripheral holes is uncommon but should be noted so that a bone plug from the humeral head can be placed before filling the hole with cement.

 

 

A trial glenoid component is placed and complete seating and stability are verified. The holes are irrigated and dried.

 

Bone cement is placed into the three peripheral holes using a syringe to pressurize the cement column. Any holes that required bone grafting from drill perforation should receive cement with minimal pressurization.

 

The glenoid component is impacted into position and can be held with digital pressure until the cement hardens (TECH FIG 4D).

 

P.3835

 

 

 

TECH FIG 4 • A center pilot hole is drilled in the glenoid surface (A) and a spherical reamer is used to create a concentric surface (B). C. The centering hole is enlarged and the three peripheral anchoring holes are drilled in the glenoid surface. D. A polyethylene glenoid component is then cemented into place.

Technique for Augmented Glenoid

 

If there is between 3 and 11 mm of posterior glenoid bone loss, then a posteriorly augmented, all-polyethylene implant is used.

 

The guidewire for glenoid preparation is placed using the anterior/anatomic glenoid surface to correspond to the native version. An augmented guide can also be used to judge the amount of version correction prior to placing the pin.

 

The anterior portion of the glenoid is reamed in standard fashion to accomplish approximately 2 cm of asymmetric reaming.

 

The amount of augmentation is determined, the central hole for the component is drilled, and the steptech guide is placed onto the anterior portion of the glenoid and secured with two pins (TECH FIG 5A).

 

A burr is used to remove the first 1 to 2 mm of sclerotic bone on the posterior half of the glenoid. The corresponding vibratory rasp is then used to prepare the posterior glenoid, typically only removing a small amount of subchondral bone from the central portion of the posterior glenoid.

 

The guide is removed and a burr may be needed to clean the periphery of the glenoid to ensure proper seating of the augmented implant (TECH FIG 5B). A corresponding sizer disc with the appropriate-sized step is placed to confirm the chosen augment size.

 

 

 

TECH FIG 5 • Posteriorly augmented component: When using this particular augmented component (DePuy), a prep guide for the posterior half of the component is placed on the prepared anterior half of the native glenoid (A). Final preparation results in a stepped configuration of the glenoid surface with drill holes for anchoring the component (B).

 

 

The peripheral drill guide is placed and the peripheral holes are now drilled, with extra attention paid to cortical breach of any of the holes.

 

A trial implant is placed to ensure complete seating. There should be no rocking of the implant and the entire backside should sit flush with the bone.

 

The augmented glenoid component is then placed in similar fashion to the standard implant.

Technique for Glenoid Bone Grafting

 

If greater than 11 mm of posterior bone loss is present (typically type B2 or C glenoids) with posterior subluxation of the joint, then a bone graft will be used.

 

The humeral head is removed in standard fashion, with care taken to preserve the orientation of the head.

 

Depending on preoperative measurements, a portion of the head corresponding to the posterior defect is cut with a saw to restore an anatomic version.

 

This graft is then placed back into the defect on the glenoid after preparing the posterior glenoid using a curette to remove any soft tissue or cartilage that may remain. No perforations are made through the subchondral bone.

 

The graft is then held in place using 1.6-mm K-wires.

 

 

P.3836

 

 

 

TECH FIG 6 • Intraoperative photo (A) demonstrating posterior glenoid bone grafting using humeral head autograft. The screw heads should be countersunk below the level of the graft. Postoperative axillary radiograph (B) reveals good position of the graft with the humeral head component centered on the face of the glenoid.

 

 

Two 3.5-mm screws are then placed into the graft, perpendicular to the native glenoid face. The holes are drilled through the graft and through the native glenoid, the length is measured from the subchondral bone of the head to the native cortex, neglecting the soft, cancellous bone within the head graft. The screws are implanted, securing the subchondral bone of the graft to the native glenoid surface (TECH FIG 6A).

 

The glenoid implant is then placed in the standard fashion including reaming, which must be done slowly and carefully (TECH FIG 6B).

Humeral Preparation and Component Placement

 

The humerus is redelivered into the wound and the humeral canal is reamed with sequentially larger reamers until light purchase is obtained within the intramedullary canal.

 

A box osteotome that corresponds to the final reamer size is passed into the humerus to cut the footprint of the humeral implant.

 

A broach that corresponds to the size of the box osteotome and final canal reamer is placed to the appropriate depth.

 

The system we use allows either a fixed 135-degree neck-shaft angle or an infinitely variable neck-shaft angle within 120 to 150 degrees (Global AP, DePuy).

 

Therefore, a collar is screwed into the broach that creates a 135-degree neck-shaft angle. A calcar reamer is placed over the collar and, if the reamer is nearly parallel to the osteotomy surface, it is used to plane the surface to 135 degrees so that an implant with a fixed neck-shaft angle of 135 degrees can be used.

 

A trial humeral head is placed over the collar; it is rotated into the offset position that provides the most symmetric coverage of the humeral metaphysis, and the collar is locked to the broach.

 

If the planes of the calcar reamer and the osteotomy surface are not nearly parallel, a variable neck-shaft angle implant will be used. The 135-degree collar is removed and a trial ball taper fitted with a humeral head trial is inserted into the broach. The trial head and ball taper are placed into the position that provides symmetric coverage of the humeral metaphysis, and the taper is locked to the broach.

 

With the trial humeral head locked into position, the remaining humeral osteophytes are removed so that the humeral bone is flushed with the humerus around the entire periphery.

 

Assuming the humerus has been reduced and adequate soft tissue tension and stability have been verified, the trial broach is removed and the real implant is assembled with either a fixed 135-degree taper or a variable ball taper in the same position as the trial.

 

The humeral implant should translate posteriorly 50% and spontaneously reduce from a posterior subluxed position. If there is excessive posterior instability, a posterior capsular plication can be performed using percutaneous suture anchors into the posterior glenoid. One must be careful not to overtighten the posterior capsule and create anterior subluxation or reduced internal rotation.

 

A nonabsorbable suture is passed around the neck of the prosthesis and the prosthesis is impacted into the humerus with the two ends of the suture protruding anteriorly.

 

The humerus is then reduced.

Lesser Tuberosity Repair

 

The technique for lesser tuberosity repair involves a mattress suture made from the suture that was placed around the prosthetic neck before impaction into the humerus and the three previously placed sutures around the lesser tuberosity.

 

The suture ends from around the prosthesis are passed in a mattress configuration through the subscapularis tendon from deep to superficial at the bone-tendon junction. The sutures are clamped but not tied yet.

 

With the humerus reduced and the arm in neutral rotation, the deep limbs of the three sutures previously passed around the lesser tuberosity are passed through the cancellous bone of the osteotomy bed as far laterally as possible, deep to the bicipital groove and out the lateral cortex of the humerus using a large, cutting free needle. A new needle is used for each pass and the sutures are clamped but not tied.

Occasionally, a tamp and mallet are needed on the free needle to complete this step. The limbs of the mattress sutures are passed with the upper and lower sutures around the lesser tuberosity.

 

The clamps on these three sutures are pulled laterally to hold the lesser tuberosity in a reduced position. Additionally, a large, toothed pickup is used to hold the lesser tuberosity in position.

 

The mattress suture is tied first to hold the lesser tuberosity in alignment and prevent rotation or malreduction. In patients with soft bone, the sutures can be tied over a small plate or plastic sleeve or button. The three interfragmentary sutures are then tied starting in the middle. This provides a secure lesser tuberosity and subscapularis repair. The rotator interval is then closed laterally with a 1-mm nonabsorbable suture.

 

Passive motion achievable without undue tension on the subscapularis repair is noted for guidance of postoperative rehabilitation (TECH FIG 7A).

 

P.3837

 

 

 

TECH FIG 7 • A. The final implant is seated and any remaining bone prominences are removed. The three interfragmentary sutures around the lesser tuberosity are visible posterior to the prosthesis. The strands from the suture that was placed around the neck of the prosthesis can be seen exiting the space between the prosthetic humeral head and the anterior humeral metaphysis. B. The lesser tuberosity has been repaired with a superior side-to-side suture in the lateral rotator interval, the three interfragmentary sutures tied over the bicipital groove, and the medial suture passed from the prosthetic neck through the bone-tendon junction.

 

Therefore, the osteotomy is stabilized with three suture groups:

 

 

The three interfragmentary sutures from the lesser tuberosity to the osteotomy bed The rotator interval closure suture at the superior aspect of the osteotomy

 

The suture from the prosthetic through the bone-tendon junction (TECH FIG 7B)

 

 

 

TECH FIG 8 • The subscapularis tendon is released with maximum length from the lesser tuberosity and dissected off the anterior capsule (A). The anterior capsule is released from the glenoid (B) and dissected all the way out to its humeral attachment to provide maximum length (C).

 

 

The technique for wound closure is identical to that described for humeral resurfacing.

Z-Plasty of Subscapularis

 

Anticipation of a Z-plasty of the subscapularis must occur prior to performing a lesser tuberosity osteotomy and anterior capsular release.

 

With the shoulder exposed to the level of the intact subscapularis tendon, the interval between the muscular subscapularis and the anterior capsule is created in the same fashion as for the lesser tuberosity osteotomy, with a longitudinal incision made in the line with the muscle fibers of the inferior subscapularis and then defining the plane using first a Freer, then a small Cobb and then a large Cobb elevator to completely separate the subscapularis.

 

The subscapularis insertion is then detached sharply, with care taken not to disrupt the insertion of the anterior capsule on the humeral side, and three 1-mm Dacron sutures are placed in a locking fashion in the subscapularis tendon (TECH FIG 8A).

 

A blunt elevator is passed between the remaining inferior 1 cm of subscapularis and the inferior capsule to create a space for a blunt Hohmann retractor. This is used to retract and protect the axillary nerve during inferior capsular release.

 

The anterior capsule is released off of the glenoid side and also split lateral to medial at the level of the inferior subscapularis tendon, creating a stout sleeve of tissue attached to the anterior humerus (TECH FIG 8B,C).

 

At the end of the procedure, the sutures in the end of the subscapularis tendon are passed through the laterally based capsular flap and tied at a point that allows approximately 40 degrees of external rotation with the arm at the side.

Wound Closure

A drain is placed deep to the deltoid and is brought out through a separate stab wound distal to the axillary nerve.

The wound is closed in layers with interrupted absorbable sutures in the subcutaneous tissues and a running subcuticular monofilament suture.

 

 

PEARLS AND PITFALLS

Imaging

• Radiographic evaluation must include a quantification of glenoid version,

asymmetric wear, and available bone stock. This requires either a perfect axillary lateral or cross-sectional study, preferably a CT scan.

Patient

selection

• Glenoid components should be used cautiously if at all in young (ie, younger

than age 50 years) or active patients.

Patient

positioning

• Safe access to the humerus during humeral preparation and component

placement requires maximum humeral adduction. Therefore, patient positioning must prevent interference from the edge of the operating table.

Glenoid

exposure

• Adequate glenoid exposure requires accurate humeral resection, humeral

osteophyte excision, and adequate capsular excision and releases.

Humeral

preparation

• Do not overexternally rotate or overream. This may lead to periprosthetic

fracture.

Nerve ▪ Know the position of the axillary nerve and protect it throughout the procedure.

management Avoid excessive traction on the conjoined tendon, especially if the musculocutaneous nerve is close to the tip of the coracoid. Take the arm out of extreme positions whenever possible.

 

 

POSTOPERATIVE CARE

 

Early rehabilitation (6 weeks)

 

 

The goals of rehabilitation during the first 6 weeks after surgery are to maximize passive range of motion and to allow healing of the subscapularis or lesser tuberosity.

 

The safe range of glenohumeral motion that prevents excessive tension on the subscapularis is identified intraoperatively.

 

This range of passive motion is performed starting the first postoperative day.

 

In general, uncomplicated shoulder arthroplasty will allow passive elevation to 140 degrees and passive external rotation to 40 degrees. If there is concern for the subscapularis repair, elevation and external rotation can be dropped to 130 and 30 degrees, respectively. If the tissue is poor quality, one may even

drop the limits to 90 degrees of elevation and 0 degrees of external rotation.

 

These exercises are performed for 6 weeks postoperatively, in combination with pendulum exercises.

 

The sling may be discontinued at home after the first week or 10 days, when the hand can be used as a helping hand for daily activities.

 

Active elevation above 90 degrees is delayed until 6 weeks postoperatively.

 

Midterm rehabilitation (6 to 12 weeks)

 

 

During midterm rehabilitation, active range of motion is encouraged, passive stretching is instituted, and strengthening exercises for the rotator cuff, deltoid, and scapular stabilizers are pursued.

 

Active assisted range of motion within the limits of pain is accomplished with an overhead pulley and 3-foot stick.

 

 

This is progressed to active range of motion as tolerated. End-range stretching in all planes is begun and progressed.

 

Strengthening exercises with the Theraband commence when active range of motion is maximized.

 

Late rehabilitation (12 to 24 weeks)

 

 

Strengthening exercises for the rotator cuff, deltoid, and scapular stabilizers continue throughout the late stage of rehabilitation.

 

 

Patients will be functional with most daily activities, except at the extremes of motion. Total arm strengthening and gradual return to activities are encouraged.

 

Although improvement in function will continue for about 1 year, the vast majority of improvement from formal rehabilitation will be seen in the first 24 weeks (6 months).

 

OUTCOMES

 

Total shoulder arthroplasty

 

 

Many studies document consistent improvement in pain and function with total shoulder arthroplasty.

 

Several studies document better pain relief and, in some cases, better function with total shoulder arthroplasty in comparison to hemiarthroplasty. Survivorship of total shoulder arthroplasty in patients with an intact or reparable cuff is 84% to 88% at 15 years and 81% at 20 years.9,28,29

 

Glenoid design

 

 

Keeled versus pegged—pegged glenoid design likely leads to less radiographic and clinical component loosening.32

 

Promise has also been shown with a partially cemented, pegged, bone ingrowth components over the short to midterm.35

 

Total shoulder arthroplasty with retroversion

 

 

Eccentric reaming—this is the commonly employed technique and typically can be performed when less than 15 degrees of version correction is needed.5,9,20

 

Gerber et al6 and Habermeyer et al10 showed very promising results with no posterior subluxation in any

patient at short-term follow-up.

 

However, failure to adequately correct the version to within 15 degrees of neutral has biomechanical

disadvantages and has been reported to result in increased osteolysis,12 although no clinical differences have been reported.

 

Bone grafting

 

 

Bone grafting is rarely needed in total shoulder arthroplasty, and therefore, limited clinical data is available. Small series have been reported: 10 of 12 fully incorporated grafts with a stepcut graft (2

reoperations) at short-term follow-up by Sabesan et al,26 high rates of radiolucency (54%) with mixed clinical results (5 unsatisfactory, 10 satisfactory results of 28 patients) by Steinmann and Cofield,30 16 of 19 satisfactory results with no reoperations by Neer and Morrison,19 and mixed results by Hill and Norris11 with only 53% of patients stable after bone grafting.

 

P.3839

 

Augmented glenoid

 

 

The stepped type augment is relatively new and clinical outcomes have not been reported. However, biomechanical testing has shown that a stepped design for an augmented glenoid has superior fixation

and less anterior liftoff in the presence of eccentric loading compared to a wedge design.14

 

A small series reported 7 of 12 persistent posterior subluxation and mixed clinical results using a wedge design that corrected version by only 4 degrees. This product's use was subsequently discontinued by

the authors.24

 

COMPLICATIONS

 

The reported complication rate after shoulder arthroplasty is 12% to 14.7%.1,4,36 One series reports a decrease in the complication rate with time, which may be explained by glenoid and humeral component

 

loosening in only one shoulder.4 Complications include the following:

 

 

Instability Rotator cuff tear

 

Ectopic ossification

 

 

Glenoid component loosening Intraoperative fracture

 

 

Nerve injury Infection

 

Humeral component loosening

 

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