Evaluation of Recurrent Instability.

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Figure 20

The physical examination (traumatic)

Signs and symptoms

If the diagnosis has been rigorously established from the history, for example by documented recurrent anterior dislocations, it is not necessary to risk redislocation on the physical examination. If such rigorous documentation is not available, however, the examiner must challenge the ligamentous stability of the shoulder in the suspected position of vulnerability being prepared to reduce the shoulder should a dislocation result.

The most common direction of recurrent traumatic instability is anteroinferior. Stability in this position is challenged by externally rotating and extending the arm elevated to various degrees in the coronal plane. It may be necessary to hold the arm in the challenging position for 1 to 2 minutes to fatigue the stabilizing musculature. When the muscle stabilizers tire, the capsuloligamentous mechanism is all that is holding the humeral head in the glenoid. At this moment the patient with traumatic anterior instability becomes apprehensive, recognizing that the shoulder is about to come out of joint. This recognition is strongly supportive of the diagnosis of traumatic anterior instability.

The magnitude of translation on the standard tests of glenohumeral laxity does not necessarily distinguish stable from unstable shoulders (see figure 13). However, the experienced examiner may detect a diminished resistance to anterior translation on the drawer test when the humeral head is compressed into the glenoid fossa, indicating loss of the anterior glenoid lip. This maneuver may also elicit grinding as the humeral head slides over the bony edge of the glenoid from which the labrum has been avulsed or catching as the head passes over a torn glenoid labrum.

Pain on abduction, external rotation and extension is not specific for instability. Such pain may relate to shoulder stiffness or alternatively to abutment of the glenoid against the cuff insertion to the head posteriorly. (Matsen, Lippitt, Sidles et al, 1994; Rossi, Ternamian, Cerciello et al, 1994; Walch, Liotard, Boileau et al, 1991; Walch, Liotard, Boileau et al, 1993) Relief of this pain by anterior pressure on the humeral head may result from diminished stretch on the anterior capsule or from relief of the abutment posteriorly (see figure 14).

In all patients with traumatic instability but particularly in those over age 35, the strength of the internal and external rotation must be examined to explore the possibility of cuff weakness or tear. Finally, a neurological examination is performed to determine the integrity of the axillary nerve and other branches of the brachial plexus.

Radiographs and other tests

Radiographs frequently help to provide confirmation of traumatic glenohumeral instability.

Humeral head changes

One of the most common findings is indentation or impaction in the posterior aspect of the humeral head from contact with the anteroinferior corner of the glenoid when the joint was dislocated (see figures 15 and 16). In their classic article (Hill and Sachs, 1940), Hill and Sachs evaluated the relationship of humeral head defects to shoulder instability. They concluded that more than two-thirds of anterior shoulder dislocations are complicated by a bony injury of the humerus or scapula. We quote:

"Compression fractures as a result of impingement of the weakest portion of the humeral head, that is, the posterior lateral aspect of the articular surface against the anterior rim of the glenoid fossa are found so frequently in cases of habitual dislocation that they have been described as a typical defect. These defects are sustained at the time of the original dislocation. A special sign is the sharp, vertical, dense medial border of the groove known as the line of condensation, the length of which is correlated with the size of the defect."

They reported the defect in only 27 per cent of 119 acute anterior dislocations and in 74 per cent of 15 recurrent anterior dislocations. However, they stated that the incidence of the groove defect was low, undoubtedly because it was only in the last 6 months of their 10-year study (1930 to 1940) that they used special radiographic views. The size of the defect varied in length (cephalocaudal) from 5 mm to 3 cm, in width from 3 mm to 2 cm, and in depth from 10 mm to 22 mm. (Hill and Sachs, 1940)

A number of special projections have been describe to enhance the view of the Hill Sachs defect. (Adams, 1950; Didiee, 1930; Hall et al, 1959; Hermodsson, 1934; Hill and Sachs, 1940; Moseley, 1961; Oppenheim et al, 1985; Pavlov, Warren, Weiss et al, 1985; Symeonides, 1972) Two of these views bear special mention.

The Stryker notch view

The patient is supine on the table with the cassette placed under the shoulder. (Hall, Isaac and Booth, 1959) The palm of the hand of the affected shoulder is placed on top of the head, with the fingers directed toward the back of the head. The elbow of the affected shoulder should point straight upward. The x-ray beam tilts 10 degrees toward the head, centered over the coracoid process (see figure 17). This technique was developed by William S. Stryker and reported by Hall and coworkers. (Hall, Isaac and Booth, 1959). They stated that they could demonstrate the humeral head defect in 90 per cent of 20 patients with a history of recurring anterior dislocation of the shoulder.

The apical oblique view

Garth and coworkers (Garth, Allman and Armstrong, 1987; Garth et al, 1984) described the apical oblique projection of the shoulder (see figure 18). In this technique the patient sits with the scapula flat against the cassette (as for the anteroposterior view in the plane of the scapula). The arm may be in a sling. The x-ray beam is centered on the coracoid and directed perpendicular to the cassette (45 degrees to the coronal plane) except that it is angled 45 degrees caudally. The beam passes tangential to the articular surface of the glenohumeral joint and the posterolateral aspect of the humeral head. This view is likely to reveal both anterior glenoid lip defects and posterior lateral impression fractures of the humeral head.

The incidence of the Hill Sachs defect reported depends on both the radiographic technique and the patient population. Symeonides (Symeonides, 1972) reported the humeral head defect in 23 of 45 patients who had recurrent anterior dislocations of the shoulder. However, at the time of surgery he could confirm only 18 of 45.

Eyre-Brook (Eyre-Brook, 1971) reported an incidence of the Hill Sachs defect of 64 per cent in 17 recurrent anterior dislocations, and Brav (Brav, 1960) recorded a rate of 67 per cent in 69 recurrent dislocations. Rowe (Rowe et al, 1977) noted the defect in 38 per cent of 125 acute dislocations and in 57 per cent of 63 recurrent dislocations. Adams (Adams, 1948) noted that the defect was found at the time of surgery in 82 per cent of 68 patients. Palmer and Widen (Palmer and Widen, 1948) found the defect at surgery in all of 60 patients.

Calandra and coworkers (Calandra et al, 1989) prospectively studied the incidence of Hills-Sach lesions using diagnostic arthroscopy. In a young population of 32 patients with a mean age of 28 years, the frequency of this lesion was 47% for initial anterior shoulder dislocations.

Danzig, Greenway, and Resnick (Danzig et al, 1980) reported that in cadaveric and clinical studies no single view will always reveal the humeral head compression fracture. Pavlov and coworkers (Pavlov, Warren, Weiss et al, 1985) and Rozing and associates (Rozing et al, 1986) found that the Stryker notch view taken in internal rotation best revealed the posterolateral humeral head defect (see figure 14).

The demonstration of a posterior lateral humeral head defect strongly indicates that the shoulder has been subject to a traumatic anterior dislocation. When these factors are already known--for example, in a 17-year-old whose recurrent anterior dislocations began with a well-documented abduction-external rotation injury in football--it is not necessary to spend a great deal of effort demonstrating the humeral head defect because (1) it is very likely to be present even if not seen on the radiographs, and (2) the existence of such a lesion does not in itself alter our management of the patient.

Glenoid changes

Standard radiographs may reveal a periosteal reaction to the ligamentous avulsion at the glenoid lip or a fracture (see figure 19), erosion or new bone formation at the glenoid rim. Modifications of the axillary view may help the identification of glenoid rim changes. Rokous (Rokous et al, 1972) and colleagues described what has become known as the "West Point" axillary view. (Rockwood, 1984) In this technique the patient is placed prone on the x-ray table with the involved shoulder on a pad raised 7.5 cm from the top of the table. The head and neck are turned away from the involved side. With the cassette held against the superior aspect of the shoulder, the x-ray beam is centered at the axilla, 25 degrees downward from the horizontal and 25 degrees medial. The resulting x-ray is a tangential view of the anteroinferior rim of the glenoid (see figure 20). Using this view, Rokous and associates demonstrated bony abnormalities of the anterior glenoid rim in 53 of 63 patients whose histories indicated traumatic instability of the shoulder. Cyprien and coworkers (Cyprien, Vasey and Burdet, 1983) demonstrated lessening of the glenoid diameter and shortening of the anterior glenoid rim in shoulders with recurrent anterior dislocation. Blazina and Satzman (Blazina and Satzman, 1969) also reported anteroinferior glenoid rim fractures seen on the axillary view in nine of their cases.

Special radiographic techniques

Although pathology can be seen with additional radiographic views, (Green and Christensen, 1994; Minkoff and Cavaliere, 1993; Palmer and Caslowitz, 1995; Rafii et al, 1993) CT arthrography (Braunstein and O'Conner, 1982; Cramer et al, 1982; El-Khoury et al, 1986; Kelley, 1954; Kleinman et al., 1984; McGlynn et al, 1982; McMaster, 1986; Rafii et al, 1986; Rafii et al, 1987; Shively and Johnson, 1984), fluoroscopy (Norris, 1984) or MRI, these additional tests are rarely cost-effective in the clinical evaluation and management of shoulders with characteristic traumatic instability. (Engebretsen and Craig, 1993; Liu and Henry, 1996) While CT evidence of labral or capsular pathology is unlikely to change the management of the shoulder, contrast computerized tomography may help document the flattening of the anteroinferior glenoid concavity due to loss of articular cartilage. CT may also be useful in defining the magnitude of bone loss when sizable humeral head or glenoid defects are suggested on plain radiographs. (Gould et al, 1985; Seltzer and Weissman, 1985) When previous glenoid bone blocks have been carried out or hardware inserted, CT is useful for examining the possibility of their encroachment on the humeral head. (Cramer, 1882; Cramer, Von and Kramps, 1982; Danzig et al, 1982)

Although many articles have been written regarding the use of MRI in imaging the unstable shoulder (e.g. Chandnani et al, 1993; Gross et al, 1990; Iannotti et al, 1991; Kiett et al, 1988; Meyer and Dalinka, 1990; Neumann et al, 1991; Palmer and Widen, 1948; Richards et al, 1994; Runkel et al, 1993; Vellet et al, 1991) the clinical usefulness of this examination awaits definition. Iannotti et al (Iannotti, Zlatkin, Esterhai et al, 1991), reported the sensitivity and specificity of MRI in the diagnosis of lateral tears associated with glenohumeral instability were 88 and 93%, respectively. However, in a blinded study, Garneau et al (Garneau et al, 1991) found that it was insensitive and nonspecific for labral pathology. Even if MRI reliably yielded this information, it is unclear how it would be cost-effective in the management of the patient: patients with refractory instability would be considered for surgery with or without such data.

Rotator cuff imaging

In a patient whose onset of traumatic instability occurred after age 35 there may be evidence on history and physical examination of rotator cuff pathology. Particular concern arises if weakness of external rotation or elevation persist longer than a week or so. In these situations, preoperative imaging of cuff integrity may play an important role in surgical planning: the approach for rotator cuff repair is quite different than the approach for the repair of an anterior inferior capsular lesion. Arthrography, ultrasound or MRI may be useful in this situation.

Electromyography

Electromyography may be helpful in the evaluation of the patient with recurrent traumatic instability if the history and physical examination suggest residual brachial plexus lesions.

Arthroscopy

Diagnostic arthroscopy is not a necessary prelude to open surgical repair of documented recurrent traumatic instability. While it uncommonly changes the surgical approach, shoulder arthroscopy has helped define some of the pathology associated with recurrent instability. Such lesions include labral tears, capsular rents, humeral head defects, and rotator cuff defects. (Andrews et al, 1983; Carew-McColl, 1980; Frizziero, 1981; Garth, Allman and Armstrong, 1987; Ha'eri and Maitland, 1981; Hintermann and Gachter, 1994; Johnson, 1980; Lilleby, 1982; McMaster, 1986; Mital, 1980; Older, 1976; Parisien, 1983; Wiley and Austwick, 1982; Wiley and Older, 1980; Zizzi et al, 1981)

A classification of anterior labral "Bankart" lesions was proposed by Green and Christensen. (Green and Christensen, 1995) In 37 cases, they described the arthroscopic appearance common to five separate groups. Type I is the normal intact labrum. Type II is a simple detachment of the labrum from the glenoid. Type III is an intrasubstance tear of the glenoid labrum. Type IV is a detachment of the labrum with significant fraying or degeneration and Type V is a complete degeneration of absence of the glenoid labrum.

Neviaser found that occasionally the anterior labroligamentous periosteal sleeve is avulsed from the supporting anterior inferior ligamentous and labral structure. (Neviaser, 1993)

Habermeyer and Gleyze found that shoulders with more than five recurrent dislocations were found to have anterior articular cartilage erosion. (Gleyze and Habermeyer, 1996) Harryman noted labral damage in all cases treated for recurrent anterior traumatic instability and significant articular erosion to subchondral bone in 20%. (Harryman, 1996)

Other lesions may be associated with Bankart lesions. Snyder et al (SnyderBanasKarzel, 1995) and Warner (Warner et al, 1994) found the association of superior labral detachment and Bankart lesions.

Wolf reported that 6 of 64 patients with anterior instability had avulsion of glenohumeral ligaments from the humerus while 47 had true Bankart lesions (73.5%). (Wolf et al, 1995)

Arthroscopy also reveals defects in the articular cartilage of the posterior lateral humeral head, which would not be detected on radiographs.

Disclaimer

This resource has been provided by the University of Washington Department of Orthopaedics and Sports Medicine as general information only. This information may not apply to a specific patient. Additional information may be found at http://www.orthop.washington.edu or by contacting the UW Department of Orthopaedics and Sports Medicine.

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