Gerald R. Williams
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.
FIG 1 • The normal glenohumeral anatomical 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.)
Normal osseous relationships include humeral head center, thickness, and radius of curvature, humeral neck–shaft 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).14,22
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.14,22
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.14,22
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).2,22
Humeral retroversion averages 20 to 30 degrees, with a wide range of about 20 to 55 degrees.2,14,22 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.14
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 (130–135) degrees, with a range of 30 to 55 (120–145) degrees.2,14,22
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.
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.)
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 contracted, resulting in restriction of external rotation and posterior humeral head subluxation.
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 shoulderƏs 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%.27
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:
Posterior joint line tenderness, especially in osteoarthritis associated with posterior subluxation20
Generalized atrophy or flattening of the shoulder from long-term lack of function
Posterior prominence of the humeral head in cases of posterior subluxation
Symmetrical 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 arthropathy20
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 asymmetrical posterior joint space narrowing (FIG 4A,B).20
In cases of posttraumatic arthritis, radiographs may reveal retained hardware.
FIG 3 • The hallmark of glenohumeral osteoarthritis is symmetrical 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 asymmetrical 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 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).
Glenoid deformity in osteoarthritis has been classified by Walch29 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)
Computed tomographic (CT) scans are helpful in quantifying bone loss in patients with posterior subluxation (FIG 4C).
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 weight lifting, 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.26
Hemiarthroplasty can be successful in providing pain relief, especially with minimal glenoid involvement or concentric glenoid wear. However, progressive glenoid erosion is likely and may require revision to total shoulder replacement.
Hemiarthroplasty with resurfacing of the glenoid with biologic materials such as meniscal allograft, capsular or fascia lata autograft, fascia lata allograft, dermal allograft, Achilles tendon allograft, or xenograft materials has been performed, particularly in patients too young or active for a polyethylene glenoid component.3,21,30
The additional benefit of biologic resurfacing of the glenoid over hemiarthroplasty alone has not been clearly demonstrated, nor has its durability been confirmed.10
Hemiarthroplasty may be accomplished by replacement or resurfacing of the humeral head.
Replacement of the humeral head is most commonly accomplished with a prosthetic head that is anchored to the shaft with a stem. However, more recently, humeral head replacements have been developed that are fixed to the metaphysis without violation of the diaphyseal canal.
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. 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 greater than 50, and sedentary or moderate activity levels.
Hemiarthroplasty is favored in patients with normal or minimally involved glenoids, inadequate glenoid bone, age of 50 or under, and activity levels that include weight lifting or other strenuous activity.
Biologic resurfacing of the glenoid may be added to hemiarthroplasty but may also fail in patients who participate in heavy weight lifting 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.
Humeral resurfacing is useful when hemiarthroplasty is indicated in the absence of substantial glenoid deformity. Resurfacing preserves humeral bone and obviates the need to address humeral head–humeral canal offset.
These principles are merely guidelines and should be individualized.
The following sections will cover the technical aspects of humeral resurfacing, humeral replacement, humeral replacement combined with biologic glenoid resurfacing with allograft lateral meniscus, and total shoulder arthroplasty. Glenoid bone grafting is beyond the scope of this chapter and will not be covered.
Preoperative Planning
Preoperative radiographs and CT scans should be reviewed to quantify humeral subluxation (especially posterior in osteoarthritis) and glenoid bone loss. This will identify the need for asymmetric glenoid reaming.
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.
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 (115–120 degrees) or valgus (145–150 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.
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 longstanding.
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.12,23 However, randomized comparison data are not currently available. In addition, a recent study documents good postoperative subscapularis function with tenotomy and soft tissue repair.4
My 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
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.
FIG 5 • A. Shoulder arthroplasty is carried out with the patient in the semirecumbent position; a special horseshoe-shaped 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 armholding device may be used to help position the arm throughout the procedure.
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, CA) is helpful for positioning the arm. Alternatively, a padded Mayo stand can also be used (FIG 5C).
Approach
The most common approach for shoulder arthroplasty is the deltopectoral approach popularized by Neer.20 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 MacKenzie19 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.13,24
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
HUMERAL RESURFACING
Superficial Dissection
A deltopectoral incision is made from the tip of the coracoid toward the deltoid insertion.
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. 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. 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 0.5to 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 blunt elevator is used to dissect the interval between the subscapularis and the underlying capsule. Once this interval is adequately developed, a scalpel is placed between the subscapularis and 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]: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 oƏclock 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). 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.
Humeral Preparation
Accurate placement of the central guide pin is the most important portion of the resurfacing procedure. This guide pin fixes the center and inclination of the articular surface in all planes. Once the guide pin is anatomically positioned, the remainder of the procedure is only a matter of choosing the appropriately sized head and placing it at the appropriate depth.
The pin should penetrate the head at its geometric center and should be advanced slightly through the lateral cortex at an angle that is perpendicular to the plane defined by the periphery of the native articular margin (ie, the anatomic neck).
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.
TECH FIG 3 • A. The global Conservative Anatomic Prosthesis (Global CAP, Depuy, Warsaw, IN) shapes the humerus using triple reamers that are matched to the chosen size of the implant. Reaming proceeds over a centrally placed guidewire until the top of the humeral head is flattened completely. B. The excess bone is removed from the periphery to produce a flat shelf on which the component can be seated.
In some systems, there are guides that can assist in accurate pin placement. The guides usually are hemispherical and cannulated centrally so that the edge of the guide is positioned parallel to the articular margin in the visual center of the head.
Once the surgeon is satisfied with pin placement, shaping of the humeral head to fit the deep surface of the resurfacing implant can commence.
Reamers are selected based on the anticipated size of the prosthetic humeral head, which is, in turn, decided through a combination of preoperative templating and intraoperative measurements.
Proper selection of humeral head radius and thickness (ie, neck length) is critical and there is a tendency to choose a head that is too large.
The appropriate reamer is selected and the humerus is reamed until the reamer bottoms out on the humerus (TECH FIG 3). There is a tendency to underream. Reaming can continue to within 2 to 3 mm of the rotator cuff reflection superiorly.
Trial implants are placed over the guide pin onto the reamed humeral surface. Circumferential contact is verified.
The central punch is placed over the guide pin and driven into the humeral metaphysis to prepare it for the central peg of the prosthetic head.
Glenoid Inspection, Capsular Excision, and Release
The guide pin is removed and the glenoid is exposed by placing a humeral head retractor within the joint and retracting the humeral head posteriorly. Care should be taken not to damage the reamed surface of the humerus.
The axillary nerve is protected and the anteroinferior capsule is excised. If the labrum is present, it is left in place. The posterior capsule is released.
Substantial glenoid reaming should not be required, as these patients are treated with humeral head resection and a stemmed implant in my practice.
Humeral Component Placement and Lesser Tuberosity Repair
The humerus is redelivered into the wound and the appropriate humeral resurfacing implant is placed and impacted into position (TECH FIG 4). Care should be taken to ensure that the implant is completely seated. This requires removal of excess bone from around the periphery of the projected seating point of the implant.
Two small bone anchors are placed in the humerus medial to the osteotomy but lateral to the humeral prosthetic edge. The sutures on the anchors 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.
TECH FIG 4 • The final implant is impacted onto the prepared humeral surface and complete seating is verified by visualizing the periphery of the implant sitting flush against the peripheral shelf created on the humerus by the reaming process.
The clamps on these three sutures are pulled laterally to hold the lesser tuberosity in a reduced position. The rotator interval is then closed laterally with a 1-mm nonabsorbable suture.
After the rotator interval suture is tied, the three interfragmentary sutures are tied, followed by the sutures from the anchors. This provides a secure lesser tuberosity and subscapularis repair.
Passive motion achievable without undue tension on the subscapularis repair is noted for guidance of postoperative rehabilitation.
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.
HEMIARTHROPLASTY
Hemiarthroplasty with head resection is performed when concentric glenoid reaming is required.
The techniques of superficial and deep dissection, lesser tuberosity osteotomy, capsular release, and osteophyte excision are the same as described previously.
Humeral Head Resection
The humeral head is removed with a saw at or near the anatomic neck (TECH FIG 5A). This can be accomplished freehand or with intramedullary or extramedullary guides.
Retroversion of the cut in my 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 5B).
TECH FIG 5 • 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.
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 (less than 125) or valgus (greater than 145 degrees) neck–shaft 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.
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 centering drill hole for the glenoid reamer is drilled.
The orientation of this drill hole 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.
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 I 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, Warsaw, IN).
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 symmetrical 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 symmetrical 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 flush 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.
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 is the same as described for humeral resurfacing, except that the suture that was placed around the prosthetic neck before impaction into the humerus takes the place of the suture anchors that were placed in the anterior humerus between the osteotomy bed and the lateral extent of the resurfacing prosthesis (TECH FIG 6A).
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 6B)
The technique for wound closure is identical to that described for humeral resurfacing.
TECH FIG 6 • 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.
HEMIARTHROPLASTY WITH BIOLOGIC RESURFACING (LATERAL MENISCAL ALLOGRAFT)
All techniques are the same as described earlier for humeral resurfacing and hemiarthroplasty, except that placement of the allograft requires maximum glenoid exposure.
The allograft can be grossly sized using glenoid sizing disks. It is prepared by suturing the anterior and posterior horns together.
The glenoid surface should be concentric in order for biologic resurfacing with meniscal allograft to be successful. Therefore, reaming to correct glenoid bone deficiency (eg, posterior wear) should be performed before placing the allograft.
If the labrum can be preserved, it can be used to anchor the allograft to the glenoid.
Often, the labrum is absent or too degenerative to dependably hold sutures. Under these circumstances, absorbable suture anchors are used to attach the allograft around the periphery of the glenoid. Four to six anchoring points should be used, depending on the size of the glenoid (TECH FIG 7A).
The sutures are passed into the periphery of the ringshaped allograft above the wound at appropriate positions (TECH FIG 7B). The allograft is then shuttled down the sutures onto the glenoid surface and the sutures are tied (TECH FIG 7C).30
If there is no bleeding bone exposed from reaming, drilling a few holes through the subchondral surface into the glenoid cavity may assist in decompressing the glenoid vault and providing progenitor cells that can assist in healing.
TECH FIG 7 • A. The glenoid in this right shoulder is exposed with a Fukuda retractor posteriorly, a large Darrach retractor anteriorly on the neck of the scapula, and a single-prong Bankart retractor posterosuperiorly. Anchors have been placed in the four quadrants of this small glenoid. B. The meniscal allograft has been sutured into a ring and sutures from the previously placed anchors are passed through the meniscal allograft above the joint. C. The allograft is then transported down the sutures onto the glenoid surface and the sutures are tied. (From Williams G. Hemiarthroplasty and biological resurfacing of the glenoid. In: Zuckerman JD, ed. Advanced Reconstruction: Shoulder. Rosemont, IL: AAOS, 2007:545–556.)
TOTAL SHOULDER ARTHROPLASTY
All techniques are the same as described earlier for humeral resurfacing and hemiarthroplasty except for placement of the glenoid component.
Concentric glenoid reaming is an important step in glenoid resurfacing that improves initial seating and stability. This is accomplished by drilling a pilot hole in the center of the glenoid (TECH FIG 8A). Special glenoid reamers are used to ream concentrically around the center pilot hole (TECH FIG 8B).
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, Depuy, Warsaw, IN).
The center hole for the larger fluted central peg is drilled, followed by the holes for the three peripheralpegs (TECH FIG 8C). 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 not receive pressurized cement.
The glenoid component is impacted into position and can be held with digital pressure until the cement hardens (TECH FIG 8D).
TECH FIG 8 • 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.
PEARLS AND PITFALLS
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
Resurfacin.
Reports of resurfacing arthroplasty are relatively sparse. Most data come out of a single institution.
In general, the results parallel the results of hemiarthroplasty. In one series of 103 patients with 5 to 10 years of follow-up, constant scores for patients with osteoarthritis undergoing total shoulder arthroplasty and hemiarthroplasty were 93.7% and 73.5% respectively. Lucency around the humeral component was 30.7%, and 1.9% required revision.17
In another series of patients with osteoarthritis undergoing resurfacing, hemiarthroplasty was found to be similar to total shoulder replacement.16
Hemiarthroplast.
NeerƏs original article on replacement for osteoarthritis in 1974 included primarily hemiarthroplasties. Over 90% of patients had good or excellent results.20
The addition of concentric glenoid reaming to encourage the formation of a biologic membrane to resurface the glenoid has been reported by Matsen et al.8,18 The authors note that similar pain relief and function are possible with this procedure but that patients may take longer than total shoulder replacement patients to reach maximum improvement. In addition, in one of their series, 3 of 37 patients were no better or worse after the surgery.18
Additional studies have stressed the importance of concentricity of the glenoid in attaining a successful result as well as the relative difficulty in converting a painful hemiarthroplasty to total shoulder replacement.5
In addition, progressive, painful glenoid erosion can be associated with hemiarthroplasty.
Survivorship of hemiarthroplasty in one series decreased substantially with increasing follow-up, with 92%, 83%, and 73% survival at 5, 10, and 15 years, respectively.26
Hemiarthroplasty with biologic resurfacin.
Although descriptions of this procedure exist before 1993, Burkhead popularized the concept of combining hemiarthroplasty with biologic glenoid resurfacing.3
A more recent report from Krishnan et al15 with longterm follow-up revealed only 5 of 39 patients with unsatisfactory results. Moreover, the patient population was relatively young and active.
Elhassan et al10 reported poor results in 13 patients undergoing hemiarthroplasty with biologic glenoid resurfacing. Ten of 13 patients required revision to total shoulder arthroplasty at a mean of 14 months after hemiarthroplasty.
Two additional studies,21,30 one with a minimum 2-year follow-up,30 confirm good early pain relief and return of function in young active patients undergoing hemiarthroplasty and glenoid resurfacing with lateral meniscal allograft. Both emphasize the importance of articular concentricity and offer data that may be interpreted to question the durability of the allograft.
Total shoulder arthroplast.
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.9,26
COMPLICATIONS
The reported complication rate after shoulder arthroplasty is 12% to 14.7%.1,6,31 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.6
Complications include.
Instability
Rotator cuff tear
Ectopic ossification
Glenoid component loosening
Intraoperative fracture
Nerve injury
Infection
Humeral component loosening
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