CLINICAL HISTORY AND EXAMINATION

Although description of a detailed shoulder history and examination are beyond the scope of this textbook, certain aspects of the history and physical examination are important in preoperative planning for unconstrained shoulder arthroplasty. The shoulder-specific complaints of the patient are reviewed, such as the type of symptoms (pain, stiffness, weakness), duration of symptoms (weeks, months, years), and previous treatment (activity modification, nonsteroidal anti-inflammatory medications, corticosteroid injections, viscosupplementary injections, previous surgery). These shoulder-specific complaints help the surgeon decide which patients are candidates for shoulder replacement surgery. A patient with complaints of only mild pain, mild weakness, or mild stiffness (or any combination of these complaints) may initially best be treated with nonoperative (or nonarthroplasty) modalities, even if radiographs demonstrate end-stage glenohumeral arthritis. Similarly, a patient with a sudden onset of symptoms of a short duration to date may be experiencing a transient acute rotator cuff tendinitis concomitantly with chronic glenohumeral arthritis that has been well tolerated. In this situation, a period of nonoperative treatment would certainly be indicated. Special attention is given to factors that could make the operative procedure more difficult. Chronic use of nonsteroidal anti-inflammatory medications can result in excessive operative blood loss, so such drugs should be discontinued the week before surgery.

Any previous surgery merits special consideration. The type of surgery should be noted. Although previous arthroscopic procedures are usually inconsequential to the performance of shoulder arthroplasty, previous open procedures may introduce difficulties. Specifically, previous instability surgery may have resulted in severe stiffness, especially in external rotation, and may have caused excessive scar tissue that will make the surgical approach more difficult. The type of surgical procedure should be elucidated whenever possible. Procedures that alter normal anatomic relationships, such as tendon transfers (subscapularis transfers, i.e., the Magnusson-Stack procedure) and coracoid transfers, are especially important when considering the surgical approach. Previous rotator cuff surgery may focus attention on determining preoperative rotator cuff integrity.

Any symptoms of infection, especially in patients who have previously undergone surgery or injections, should be investigated further. If patients have a history of infection after shoulder surgery or have had symptoms suggestive of infection (systemic fever; shoulder warmth, redness), a preoperative infection workup, including hematologic evaluation with a complete blood cell count and differential, a sedimentation rate, and C-reactive protein, is indicated. Additionally, a fluoroscopically guided shoulder aspirate is obtained and the specimen submitted for aerobic, anaerobic, fungal, and mycobacterial culture. If the findings are suggestive or diagnostic of infection, shoulder arthroplasty is postponed or canceled until infectious disease consultation is obtained and the infection is appropriately treated (Table 7-1).

Table 7-1 WORKUP FOR INFECTION BEFORE UNCONSTRAINED SHOULDER ARTHROPLASTY

Any medical history of systemic illness (diabetes mellitus, cardiac problems) should be considered in the preoperative planning. Although these factors may not affect the actual surgical procedure, they may necessitate special considerations in the patient’s postoperative care. Appropriate medical consultations should be obtained well in advance of the surgery date. The availability of appropriate care, including consultants for these systemic illnesses, should be confirmed before surgery.

All our patients undergo a thorough shoulder examination. Motion and rotator cuff strength are of critical importance. Both active and passive mobility is recorded. Mobility parameters recorded are elevation in the plane of the scapula (Fig. 7-1), abduction (Fig. 7-2), external rotation with the arm at the side (Fig. 7-3), external rotation with the arm abducted 90 degrees (when possible) (Fig. 7-4), and internal rotation as determined by the vertebral level reached with an outstretched thumb (Fig. 7-5). Any incongruity of the glenohumeral joint as indicated by the presence of glenohumeral crepitus with motion is noted, as is any discrepancy in active and passive mobility.

Figure 7-1 A and B, Elevation in the plane of the scapula.

Figure 7-2 A and B, Abduction. The arm is kept in the coronal plane.

Figure 7-3 A and B, External rotation with the arm at the side.

Figure 7-4 External rotation with the arm abducted 90 degrees. Measurement of this mobility parameter is not possible in all patients because of limited mobility in severe cases.

Figure 7-5 Internal rotation as measured by the vertebral level reached with an outstretched thumb.

Rotator cuff examination consists of testing each tendon of the rotator cuff by isolating it as much as possible. Jobe’s test is used to test supraspinatus integrity (Fig. 7-6).¹ The external rotation lag sign and evaluation of external rotation strength with the arm at the side are used to test the infraspinatus (Figs. 7-7 and 7-8).² The teres minor is tested via the horn blower’s sign (Fig. 7-9).³ The subscapularis is tested with the belly press test and, when mobility allows, the lift-off test (Figs. 7-10 and 7-11).⁴

Figure 7-6 A and B, Jobe’s test for supraspinatus integrity. The patient elevates the pronated arm in the plane of the scapula and resists the downward force of the examiner.

Figure 7-7 A and B, External rotation lag sign for infraspinatus integrity. The examiner maximally externally rotates the arm at the side and asks the patient to maintain this position. If the patient is unable to maintain this position, the test is considered positive for infraspinatus insufficiency.

Figure 7-8 A and B, Evaluation of external rotation strength with the arm at the side. The patient resists the examiner’s internally directed force. Weakness in this position may indicate infraspinatus insufficiency.

Figure 7-9 A and B, The horn blower’s sign for evaluation of the teres minor. The patient is asked to actively externally rotate the 90-degree abducted arm. Inability to perform this maneuver may indicate teres minor insufficiency.

Figure 7-10 Belly press test for subscapularis insufficiency. The test is considered positive if the patient must flex the wrist and extend the arm to press on the abdomen. A, Positive test. B, Negative test.

Figure 7-11 The lift-off test for subscapularis insufficiency. The test is considered positive if the patient is unable to lift the hand off the back. A, Positive test. B, Negative test.

The results of the clinical history and physical examination are documented in the patient’s chart and are reviewed well in advance of surgery as part of preoperative planning.

RADIOGRAPHY

Radiographs are obtained in all patients who are candidates for shoulder arthroplasty. We prefer an anteroposterior view of the glenohumeral joint with the arm in neutral rotation (Fig. 7-12), an axillary view (Fig. 7-13), and a scapular outlet view (Fig. 7-14). The anteroposterior radiograph is used to evaluate the glenohumeral joint space, the presence of humeral and glenoid osteophytes, the size of the humeral canal (Fig. 7-15), the presence of any loose bodies (Fig. 7-16), and the presence of any deformity of the humeral shaft (Fig. 7-17) because these factors may all have an impact on the planned procedure. The axillary radiograph is used to evaluate the glenohumeral joint space, the presence of anterior or posterior humeral head subluxation, and the presence of osseous glenoid wear and dysplasia (Fig. 7-18). The scapular outlet radiograph is used to evaluate the presence of anterior or posterior humeral head subluxation (Fig. 7-19), the presence of loose bodies in the subscapularis recess, and any deformity of the humeral shaft. Findings on these radiographs assist the surgeon in predicting the need for custom implants (proximal humeral deformity), predicting the need to remove large loose bodies in the subscapularis recess that may not be visible at the time of surgery, and predicting cases in which the glenoid portion of the procedure may be exceptionally difficult.

Figure 7-12 Anteroposterior radiograph of the glenohumeral joint with the arm in neutral rotation.

Figure 7-13 Axillary radiograph.

Figure 7-14 Scapular outlet radiograph.

Figure 7-15 Anterior posterior radiograph of a patient with juvenile rheumatoid arthritis and an exceptionally small humeral intramedullary canal. A standard humeral component is too large for this patient, so a custom-manufactured stem is required.

Figure 7-16 Large loose body (arrows) in the subscapularis recess identified on an anteroposterior radiograph. It should be removed at the time of arthroplasty.

Figure 7-17 Proximal humeral diaphyseal malunion in a patient with glenohumeral arthritis. A standard uncemented humeral stem should not be used in this patient.

Figure 7-18 Posterior glenoid wear with posterior humeral head subluxation identified on an axillary radiograph.

Figure 7-19 Anterior humeral head subluxation with coracohumeral impingement identified on a scapular outlet radiograph.

Ideally, these radiographs are taken with magnification under fluoroscopic control to allow accurate assessment of the glenohumeral joint space and an accurate measure of the acromiohumeral interval, an important predictor of static humeral subluxation resulting from rotator cuff insufficiency. Some patients arrive at our clinic with radiographs taken by a referring physician. If these radiographs are judged to be of sufficient quality and less than 6 months old and no unusual circumstances (excessively small humeral intramedullary canal) exist, radiographs are not repeated. In all other cases, radiographs are repeated with magnification and fluoroscopically controlled techniques.

Most shoulder arthroplasty prosthetic systems have radiographic templates available for preoperative planning (Fig. 7-20). Use of an adaptable, anatomic prosthetic system minimizes the need for radiographic templates in most cases because humeral stem size, humeral head size and position, and glenoid size will be determined intraoperatively. In select cases, such as patients with substantial deformity of the proximal humerus (Fig. 7-21) or an excessively small humeral canal, use of radiographic templates preoperatively is mandatory. We use these templates to determine whether existing prefabricated implants are sufficient or a custom-manufactured implant is required.

Figure 7-20 Radiographic templates for preoperative planning for unconstrained shoulder arthroplasty.

Figure 7-21 A, Preoperative radiographic templating in a patient with a proximal humeral diaphyseal malunion. B, In this case, a small prefabricated cemented humeral stem was selected and successfully implanted.

SECONDARY IMAGING

A secondary imaging study is obtained in all patients before unconstrained shoulder arthroplasty to evaluate the rotator cuff and, more importantly, glenoid morphology. Our preferred secondary imaging modality is computed tomographic arthrography. We find that it provides the greatest osseous detail and allows concomitant evaluation of the rotator cuff tendons and musculature. Some patients come to our clinic with a magnetic resonance imaging scan. If the scan allows sufficient evaluation of the osseous structures and rotator cuff and is less than 6 months old, we will not order additional secondary imaging.

Glenoid morphology is classified by computed tomography (or magnetic resonance imaging) according to the system of Walch and colleagues (Fig. 7-22).⁵ In type A, or concentric glenoid morphology, the humeral head is centered, and loads are equally distributed on the glenoid. Glenoid osseous erosion may be minor, type A1, or major, type A2. Type B, or nonconcentric glenoid morphology, is characterized by a posteriorly subluxated humeral head and asymmetric loads across the glenoid. Type B1 shows narrowing of the posterior joint space, subchondral sclerosis, and osteophytes, and type B2 demonstrates a biconcave glenoid resulting from posterior osseous erosion. The final glenoid morphology, type C or dysplastic, is defined by glenoid retroversion greater than 25 degrees and a centered or only slightly subluxated humeral head. Classification of glenoid morphology is critical in two scenarios when performing unconstrained shoulder arthroplasty. First, in a patient with severe glenoid erosion (A2 and B2) or severe dysplasia (C), insufficient glenoid bone stock may prohibit implantation of a standard glenoid component (Fig. 7-23). In this case the surgeon must opt for hemiarthroplasty or choose to alter the glenoid component (i.e., shorten the keel or pegs). Second, in cases of posterior humeral head subluxation and a biconcave glenoid (B2), posterior capsulorrhaphy may be required at the time of shoulder arthroplasty. When these cases are identified by preoperative secondary imaging, an additional step of testing glenohumeral stability with the trial components is included as part of the surgical technique (Chapter 13).

Figure 7-22 Schematic of glenoid morphology as described by Walch and colleagues. A, Type A1 glenoid with concentric loading. B, Type A2 glenoid with concentric loading and excessive central wear. C, Type B1 glenoid with eccentric loading causing posterior subluxation of the humeral head. D, Type B2 glenoid with eccentric loading, posterior subluxation of the humeral head, and excessive posterior glenoid wear (biconcave glenoid). E, Type C glenoid representing glenoid dysplasia.

Figure 7-23 Measurement of the depth of the glenoid vault with a computed tomogram preoperatively to determine whether a standard glenoid implant may be used in this case.

The rotator cuff is next evaluated with secondary imaging modalities, including assessment of tendon integrity and evaluation of muscle quality (fatty infiltration). In addition, the condition of the long head of the biceps tendon is noted, particularly its position (centered, subluxated, dislocated, ruptured) to assist in identifying it at the time of surgery. Although full-thickness rotator cuff tears limited to the supraspinatus tendon may not change the operative plan, tears of the supraspinatus combined with either posterior (infraspinatus) or anterior (subscapularis) rotator cuff tears are contraindications to glenoid resurfacing and may best be treated with a reverse-design prosthesis (Fig. 7-24).⁶ The degree of fatty infiltration of the supraspinatus and infraspinatus musculature has been shown to influence the results of unconstrained shoulder arthroplasty in patients with primary osteoarthritis.⁶ Although we do not necessarily change our operative plan based on fatty infiltration, we routinely classify the degree of fatty infiltration of these muscles by using a three-tiered modification of the Goutallier classification to assist in determining the patient’s postoperative prognosis.⁷ The soft tissue axial sections of a computed tomogram or the T1-weighted axial sections of magnetic resonance imaging are used to classify fatty infiltration (Fig. 7-25).

Figure 7-24 Computed tomographic arthrography demonstrating a large tear of the rotator cuff involving the supraspinatus and infraspinatus, for which unconstrained total shoulder arthroplasty is contraindicated. In this case either a semiconstrained reverse-design prosthesis (preferable) or hemiarthroplasty should be used.

Figure 7-25 Fatty infiltration of the infraspinatus on computed tomography using a three-tiered modification of the Goutallier classification.⁷ In this system, mild fatty infiltration (Goutallier stage 0 and stage 1) is defined by essentially normal muscle without any or with minimal fatty streaks (A). Moderate fatty infiltration (Goutallier stage 2) is characterized by marked fatty infiltration, but there is more muscle than fat (B). In severe fatty infiltration (Goutallier stage 3 and stage 4), there is at least as much fat as muscle (C). The same classification system is used for the subscapularis.