Clinical history and physical examination

CHAPTER 7 Clinical history and physical examination



Edward G. McFarland, MD, Juan Garzon-Muvdi, MD, Steve A. Petersen, MD



Key points



image The position of the patient’s arm at the time of an instability episode is critical for determining the direction of instability.

image The anterior apprehension test and relocation tests, when apprehension is used as the criterion for diagnosis, are very accurate.

image Any instability test (anterior or posterior) for which pain is the criterion for instability should not be taken as a diagnostic sign of instability.

image Shoulder laxity testing can help in the evaluation of shoulder instability if it reproduces symptoms of instability.

image What constitutes inferior glenohumeral instability has not been adequately established.


Introduction


The shoulder joint has been found by many providers to be difficult to examine, especially when it comes to making the diagnosis of instability. The good news is that most cases of traumatic anterior shoulder instability can be diagnosed with a good history and physical examination. However, posterior instability and patients with instability in more than one direction can create a diagnostic challenge. Similarly, a substantial number of patients can present with lesser degrees of shoulder instability in which they have a sense of looseness in the shoulder but cannot localize the direction of their symptoms. Such patients may or may not complain of symptoms only with certain shoulder motions. Because the shoulder has a wide range of normal laxities, whether such patients have a form of hyperlaxity or whether their condition should be called multidirectional instability is controversial; the challenge is to determine if the laxity is pathologic.


This chapter highlights the most reliable history and physical examination methods for evaluating patients with these various forms of instability, addresses the controversy over the role of instability in creating shoulder pain in the overhead athlete and how to interpret the examinations in such patients, and discusses the challenge of diagnosing multidirectional instability.



History


When evaluating patients with shoulder instability, patient history plays an important role in reliably determining the diagnosis. Patients should be asked about having any neurologic symptoms (such as paresthesias or weakness) because they are not typically caused by shoulder abnormalities and may indicate a neurologic cause of their symptoms. Patients also should be asked about coldness or swelling in the extremity because such symptoms may indicate a vascular cause, such as an exertional deep venous thrombosis or thoracic outlet syndrome.


Then questions should be directed to the mechanism of injury to the shoulder, the symptoms at the time of injury, the effect of the injury on the ability to perform activities of daily living, and if there is a history of any joint instability or connective tissue disorders in the individual or a family member. Patient demographic factors also play an important role in the choice of treatment plan.


The mechanism of injury refers to the activity the individual was performing at the time of the incident, the position of the arm at the time of the injury, and the direction of force on the arm. Traumatic anterior shoulder instability typically occurs when the arm is placed in an abducted and externally rotated position with the arm in extension, such as throwing a ball or reaching behind from the front to the back seat of a car. Posterior shoulder instability typically occurs when an axial load is applied to the arm when it is in front of the body, such as an offensive lineman in football blocking with his arms outstretched in front, but it can also occur when the leading arm comes across the body into abduction, such as in the follow-through of a golf swing or when a baseball player is batting. True inferior instability, or luxatio erecta, occurs when the arm is jerked with high force from an adducted position to an abducted position in the plane of the body, resulting in the arm being stuck at approximately 90 degrees of abduction. This arm position after a dislocation distinguishes it from anterior and posterior instability, in which the arm is typically closer to the side, at approximately 20 degrees to 30 degrees of elevation.


The symptoms at the time of injury are important because they can indicate the degree of the injury. Patients with traumatic shoulder instability typically have fairly severe pain until the shoulder is reduced. Patients with dislocations can usually tell the practitioner which way the humeral head was dislocated. Patients with traumatic subluxation may have severe pain but may not be able to distinguish the direction of instability. Usually patients with a dislocation or subluxation cannot continue with their sport or activity after the event, which is an indicator to the clinician of the severity of the injury.


Patients with recurrent shoulder instability experience dislocation or subluxation that affects their function and ability to participate in sports and may interfere with their activities of daily living. Therefore, determining the extent of disability is an important part of the decision-making process. The clinician also should elicit information about familial laxity and connective tissue disorders such as Ehlers-Danlos syndrome or Marfan syndrome because such patients are known to have dislocations of multiple joints and tend to have frequent recurrences.


Other demographic factors that may help determine treatment are patient age, whether the instability began with insidious onset or from a specific injury, whether the affected side is the dominant or nondominant extremity, whether the patient has concomitant injuries, and the patient’s sports of choice and aspirations for those sports.




Pearls



The mechanism and arm position at the time of injury are important clues to the direction of the shoulder instability.

The frequency of dislocations or subluxations is important information about the amount of disability the patient is experiencing.

Subluxations without trauma may suggest an underlying connective tissue disorder.


The basic examination


There are several basic portions of the physical examination that should be part of every examination. First, both shoulders of the patient should be exposed and examined for asymmetry that may indicate more severe injuries (e.g., subluxation versus dislocation; nerve injury versus no nerve injury) or subtle muscle atrophy. A neurologic examination of both upper extremities is also helpful to rule out nerve or vessel injury associated with shoulder instabilities. Although all dermatomes, myotomes, and peripheral nerves should be tested, particular attention should be paid to the function of the axillary nerve, which is the most common nerve injured in instability episodes. However, more extensive involvement of the brachial plexus or the peripheral nerves has been reported after shoulder instability, especially after inferior dislocations (i.e., luxatio erecta).


Strength testing should be performed, specifically of the rotator cuff muscles. The supraspinatus can be tested with the arm abducted 90 degrees; the infraspinatus, with resisted external rotation with the arm at the side; and the subscapularis, with the lift-off test or belly-press test. Lag signs, such as the external rotation lag sign and the lift-off lag sign, are also helpful for patients with suspected rotator cuff injury after a dislocation.1 Range of motion of the shoulder, including elevation, rotations at 90 degrees of elevation, external rotation with the arm at the side, and internal rotation with the arm up the back, should be assessed. Increased external rotation with the arm at the side may be helpful for diagnosing subscapularis tendon tears, but other tests more specific for testing the subscapularis tendon (e.g., the lift-off test or belly-press test) are typically more useful in making that diagnosis.


Lastly, it is often helpful to ask patients if they can reproduce their instability episodes, especially if they have indicated they could subluxate the shoulder from an early age. The ability to subluxate the shoulder over the glenoid rim intentionally with muscle activity or by positioning the arm has been called “voluntary,” “habitual,” “involuntary,” and “demonstrable” instability. Because such patients typically can reduce the shoulder subluxation themselves, measuring generalized joint hyperlaxity may be helpful to rule out such disorders as Marfan or Ehlers-Danlos syndromes.



Types of shoulder instability



Anterior shoulder instability


Anterior shoulder instability can result from traumatic or atraumatic causes. In patients who are experiencing true instability where the shoulder dislocates or subluxates, the physical examination findings are fortunately fairly accurate and can reliably make the diagnosis. However, it is important to note that these physical examination tests are most accurate when the criterion for a positive test is “apprehension” with the test and not pain alone.


For anterior shoulder instability, the time-proven examination test is the anterior apprehension test.2 In this test, the arm is abducted, externally rotated, and extended until the patient reports apprehension that the shoulder will subluxate or dislocate (Fig. 7-1). Lo et al3 found that the position of apprehension averaged 90 degrees abduction and 83.44 degrees of external rotation. Some studies have found that the anterior apprehension test has excellent specificity (95.7% to 100%) and sensitivity (50% to 55.6%) (Table 7-1).3,4 If a patient has a positive test for apprehension then the likelihood ratio has been reported to be as high as 20.4 However, if the patient has only pain with this maneuver, then the sensitivity and specificity are significantly lower4; pain alone with this maneuver should not be interpreted as a sign of anterior instability (see Table 7-1).


image

FIGURE 7-1 The anterior apprehension test.



Table 7-1 Diagnostic Value of Physical Examination Tests for Anterior Shoulder Instability

image

A variation of the anterior apprehension test is the relocation maneuver.5 This test is performed essentially like a supine apprehension test: the patient is positioned supine, and the arm is placed in abduction, external rotation, and extension until the patient reports apprehension that the shoulder may subluxate or dislocate. When the patient reports apprehension, the examiner places a posterior force on the humeral head from the front, thereby stabilizing the humeral head (Fig. 7-2). If the patient reports that this maneuver relieves the apprehension, then the test is positive and strongly supports the diagnosis of anterior instability (likelihood ratio = 10, sensitivity = 81%, specificity = 92%).4 However, if pain is used as the criterion for a positive test instead of apprehension, Farber et al4 found that the sensitivity and specificity are much lower, and the likelihood ratio is only 31.13; they also found that the likelihood ratio of the relocation test is 3.4


image

FIGURE 7-2 The relocation test.


(From McFarland EG: Shoulder range of motion. In Kim TK, Park HB, El Rassi G, Gill H, Keyurapan E, editors: Examination of the shoulder: The complete guide, New York, 2006, Thieme, pp 15–87.)


A third test reported to be equally sensitive and specific for anterior instability is the surprise test.3 This test is performed exactly like a relocation test as described above except that after the humeral head has been stabilized by the examiner, the examiner then suddenly releases the stabilizing posterior force on the humeral head. This should “surprise” the patient as it recreates suddenly the forces that produce symptoms of instability. Lo et al3 reported that this test had a sensitivity of 63.89% and a specificity of 98.91%. However, they admitted that this test should be performed with caution because the patient may be caught unaware and the shoulder might subluxate or dislocate. Therefore, we do not include this test in our examination of patients with anterior instability.


The last test for making the diagnosis of anterior shoulder instability is the use of shoulder laxity testing. Laxity of the shoulder is the measure of translation of the humeral head on the glenoid surface. A certain degree of shoulder laxity is normal because it allows the shoulder to have such a wide range of motion. However, when the laxity becomes excessive and leads to symptomatic subluxations, it is considered abnormal and is called instability.


There are basically two ways to test shoulder laxity on examination. One is by performing the anterior and posterior drawer tests (Figs. 7-3 and 7-4) as described by Gerber et al.6 These tests are performed by elevating the arm to 70 to 80 degrees and then stabilizing the scapula by creating an axial force up the humerus into the glenoid. The hands are then used to subluxate the shoulder anteriorly and posteriorly to see if the humeral head can be subluxated over the glenoid rim (see Fig. 7-2). The second way to measure shoulder laxity is with the load-and-shift test,7 which is typically performed with the patient sitting. This test is performed by stabilizing the scapula and shoulder by placing one hand on the top of the shoulder and placing the second hand on the arm. The arm is held in a position of 20 degrees of abduction, 20 degrees of flexion, and in neutral, and the clinician exerts an anterior and posterior force to translate the humeral head over the glenoid rim.


image

FIGURE 7-3 Laxity testing using the anterior (A, B) and posterior (C, D) drawer signs.


(Parts A and C from McFarland EG: Instability and laxity. In Kim TK, Park HB, El Rassi G, Gill H, Keyurapan E, editors: Examination of the shoulder: The complete guide, New York, 2006, Thieme, pp 162–212.)


image

FIGURE 7-4 Laxity in the shoulder can be graded using a modified Hawkins scale.


(From McFarland EG, et al: Posterior shoulder laxity in asymptomatic athletes. Am J Sports Med 24(4): 468-471, 1996.)

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Jan 21, 2017 | Posted by in ORTHOPEDIC | Comments Off on Clinical history and physical examination

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