History A 45-year-old right-handed man complains of pain and weakness in his right shoulder. He thinks he may have injured his shoulder while throwing a ball back and forth with his son, but admits he had some pain in his shoulder before the throwing injury, which occurred 1 week ago. The patient says that his shoulder is weak when he tries to lift it from his side. The patient is otherwise healthy, has no known medical problems, and takes no regular medications. He works in construction, where he does a lot of lifting and heavy manual labor. The patient does not drink alcohol or smoke tobacco. Family history is notable for hypertension. Physical Exam Vital signs are normal. Neurologic exam is normal, and reflexes are normal in all four extremities. When comparing the two sides, you notice considerable weakness in the first 15° of abduction in the right shoulder compared with the left. If you passively lift the right shoulder into 15° of abduction, the patient has normal strength and ability to move the shoulder into greater degrees of abduction, although this action causes the patient to have pain in his shoulder. The rest of the exam is unremarkable. Tests Hemoglobin: 15 g/dL (normal 12-16 g/dL) White blood cell count: 7800 μL (normal 4500-11,000/μL) Erythrocyte sedimentation rate: 8 mm/h (normal 0-20 mm/h)
Early developing Osteosarcoma, or Fibrous dysplasia of the bones at the area (humerus, scapula-extremitas acromialis, distal clavicula)
The patient in this case has a tear in the supraspinatus tendon, the most common cause of what is known as a "torn rotator cuff." The four muscles of the rotator cuff are the supraspinatus, infraspinatus, teres minor, and subscapularis. All arise from the scapula and insert into the humerus: the first three arise from the posterior aspect of the scapula and insert around the greater tuberosity; the subscapularis arises from the anterior aspect of the scapula and inserts around the lesser tuberosity. The tone of the rotator cuff muscles assists in holding the head of the humerus in the fairly shallow glenoid cavity of the scapula. This provides stability to the shoulder, the most commonly dislocated large joint in the body. The major weakness of the rotator cuff is inferiorly, where no muscles exist. Dislocated shoulders generally lie inferior and anterior to the glenoid cavity (an "anterior" dislocation, which accounts for 90% to 95% of shoulder dislocations). Although torn rotator cuffs are familiar to most professional baseball pitchers, they more commonly occur in older individuals secondary to chronic degeneration (i.e., "wear and tear"), often in people who perform repetitive shoulder movements (e.g., occupational). The supraspinatus is responsible for the first 15° of shoulder abduction, after which the deltoid muscle takes over and completes abduction to 90°. The infraspinatus and teres minor muscles help with lateral arm rotation, whereas the subscapularis helps rotate the arm medially.
