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Make the Diagnosis: Shoulder Instability

Prior Probability

There are no adequate data for assessing the prevalence of these conditions among patients with shoulder discomfort because the existing data come only from patients undergoing surgery or arthroscopy. The incidence of shoulder discomfort is 0.9% to 2.5%. However, because shoulder pain can be chronic, the prevalence at a single point in time is 6.9% to 26%.

Population for Whom Shoulder Instability or Labral Tears Should Be Considered

Patients with shoulder pain should be screened for shoulder instability and labral tears. The annual incidence of shoulder dislocation in the general population may be as high as 1.7%. There are no data for the incidence or prevalence of labral tears.

Detecting the Likelihood of Shoulder Instability or a Labral Tear

The anterior release and relocation tests have the best measurement properties for shoulder instability (Table 44-7 and Figure 44-3). The assessment of apprehension will be more reliable than the assessment of pain for these maneuvers. The biceps load tests should be performed to assess for labral tears (Table 44-7 and Figure 44-3).

Table 44-7Likelihood Ratios for Tests of Shoulder Instability or a Labral Teara

Reference Standard Tests

Arthroscopy or surgery.

Original Article: Does This Patient Have an Instability of the Shoulder or a Labrum Lesion?

Clinical Scenario

A 24-year-old man with a history of shoulder complaints presents to his primary care physician. At age 16 years, his shoulder was injured during karate. He recovered and did not notice recurrence of symptoms. At age 21 years, while throwing a baseball, he developed sudden sharp left shoulder pain, with a popping noise. He sensed that the arm stretched out of range. He experienced a short period with shoulder discomfort, followed by recovery.

Recently, he has started playing tennis and experiences shoulder pain that requires cessation of play. On examination, the shoulder displays no swelling or atrophy. Internal and external rotation is somewhat painful but not limited. His neck moves normally, through the full range of motion, without pain. In considering the differential diagnosis, one might wonder whether the medical history suggests instability of the shoulder and ...

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