Diagnostic Injections About the Shoulder

Edward McFarland, MD; Johnathan Bernard, MD, MPH; Eric Dein, MD; Alex Johnson, MD

Disclosures

J Am Acad Orthop Surg. 2017;25(12):799-807. 

In This Article

The Glenohumeral Joint

Presentation and Evaluation

Indications for glenohumeral joint infection vary from treating known abnormalities to determining whether an abnormality inside the joint is contributing to the patient's shoulder pain and dysfunction. When injections into the glenohumeral joint are used for diagnostic purposes, the possibility that more than one condition is contributing to the pain can complicate interpretation of the results. Disorders that may present with similar pain patterns and produce similar results during physical examination tests include abnormalities involving the long head of the biceps tendon, superior labrum anterior to posterior lesions, partial rotator cuff tears, chondral lesions, shoulder stiffness, and internal impingement.

Interpreting the result of an intra-articular shoulder injection can be particularly challenging when the patient has a concomitant stiff shoulder. Determining the cause of shoulder stiffness with an intra-articular injection alone also can be difficult. For example, although a diagnostic injection of the glenohumeral joint may relieve pain, it cannot help the clinician to distinguish between a frozen shoulder and glenohumeral arthritis. Therefore, radiography is recommended to rule out arthritis or other conditions before intra-articular injection of the glenohumeral joint.

Technique Summary

The two main approaches for injecting the glenohumeral joint are anterior and posterior (Figure 5). When the patient has a massive rotator cuff tear, a lateral approach can be used to inject the glenohumeral space. Studies of the accuracy of unguided anterior and posterior approaches to glenohumeral joint injection are summarized in Table 3.[5,30–38]

Figure 5.

Illustration of an anterior view of the shoulder showing an injection of the glenohumeral joint. (Copyright Louis Okafor, MD, Baltimore, MD.)

Generally, when a blind injection technique is used without imaging, the anterior approach provides a more predictable result than the posterior approach (65% versus 46% accurate).[38] In a study of 80 cadaver specimens, Patel et al[39] found that, when using a posterior approach, the accuracy of ultrasonography-guided glenohumeral injections versus landmark-guided injections was 92.5% versus 72.5%, respectively (P = 0.02).

During glenohumeral joint injection, the patient should be seated. For anterior injection, the coracoid can usually be palpated by the examiner (Figure 6). With rotation of the arm internally and externally, the joint line can be appreciated just lateral to the coracoid. The soft spot just lateral and slightly superior to the coracoid is the rotator cuff interval, which is the ideal location for placing the needle. When the needle is inserted, it is helpful to have someone support the patient's arm by the elbow, with the elbow at the side, and to gently rotate the arm into internal and external rotation (Figure 7).

Figure 6.

Photograph of the anterior view of a shoulder showing the location of the injection site just lateral and slightly superior to the coracoid for injecting the glenohumeral joint.

Figure 7.

Photograph showing the rotation of the humerus (blue arrow) during glenohumeral joint injection to facilitate entering the glenohumeral space accurately.

Often, the needle can be inserted directly into the joint with mild resistance. When the needle hits bone and the bone is not moving, the needle is too medial and is on the glenoid rim or other portion of the scapula. The needle can then be moved gradually laterally until the joint is encountered and the joint can be entered by the needle. When the humeral head is felt to be moving upon insertion of the needle, the needle can be moved more medially into the joint space.

Patients should be encouraged to relax their muscles during the procedure because muscle tension closes the joint and makes the injection more difficult. When the needle is in the joint, the assistant should stop rotating the arm to prevent the needle from breaking or damaging the cartilage.

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