Intra-Articular Injection of the Glenohumeral Joint—Posterior Approach

Indications and Clinical Considerations

The posterior approach to intra-articular injection of the glenohumeral joint is useful in patients with conditions that would preclude an anterior approach (e.g., subclavian venous access ports and lines, pacemaker pulse generators, tumor, other anatomic abnormalities). Like the anterior approach, injection of the glenohumeral joint via the posterior approach can be done in the sitting position, facilitating patient comfort in the presence of fractures of the clavicle, humerus, and so forth. The posterior approach can be performed using anatomic landmarks as well as with the use of ultrasound and fluoroscopic guidance, which may simplify the procedure and improve the accuracy of needle placement.

The shoulder joint is susceptible to the development of arthritis from a variety of conditions that all have the ability to damage the joint cartilage. Osteoarthritis of the joint is the most common form of arthritis that results in shoulder joint pain; however, rheumatoid arthritis, posttraumatic arthritis, and rotator cuff tear arthropathy are also common causes of shoulder pain secondary to arthritis. Less common causes of arthritis-induced shoulder pain include the collagen vascular diseases, infection, villonodular synovitis, and Lyme disease. Acute infectious arthritis usually is accompanied by significant systemic symptoms, including fever and malaise, and should be easily recognized by the astute clinician and treated appropriately with culture and antibiotics rather than with injection therapy. The collagen vascular diseases generally manifest as a polyarthropathy rather than a monoarthropathy limited to the shoulder joint, although shoulder pain secondary to collagen vascular disease responds exceedingly well to the intra-articular injection technique described later.

In most patients with shoulder pain secondary to osteoarthritis, rotator cuff arthropathy, and posttraumatic arthritis pain, the pain is localized around the shoulder and upper arm. Activity makes the pain worse, and rest and heat provide some relief. The pain is constant and characterized as aching and may interfere with sleep. Some patients report a grating or popping sensation with use of the joint, and crepitus may be present on physical examination.

In addition to the previously described pain, patients with arthritis of the shoulder joint often experience a gradual decrease in functional ability with decreasing shoulder range of motion, making simple everyday tasks, such as hair combing, fastening a bra, or reaching overhead, difficult. With continued disuse, muscle wasting may occur, and a frozen shoulder may develop.

Plain radiographs are indicated for all patients with shoulder pain. On the basis of the patient’s clinical presentation, additional testing may be indicated, including complete blood cell count, sedimentation rate, and antinuclear antibody testing. Magnetic resonance imaging scan and ultrasound imaging of the shoulder are indicated if a rotator cuff tear is suspected as well as to clarify the etiology of the patient’s pain and functional disability.

Clinically Relevant Anatomy

The rounded head of the humerus articulates with the pear-shaped glenoid fossa of the scapula ( Fig. 29.1 ). The articular surface is covered with hyaline cartilage, which is susceptible to arthritis. The rim of the glenoid fossa is composed of a fibrocartilaginous layer called the glenoid labrum , which is susceptible to trauma should the humerus be subluxed or dislocated. The joint is surrounded by a relatively lax capsule that allows the wide range of motion of the shoulder joint at the expense of decreased joint stability. The joint capsule is lined with a synovial membrane that attaches to the articular cartilage. This membrane gives rise to synovial tendon sheaths and bursae that are subject to inflammation. The shoulder joint is innervated by the axillary and suprascapular nerves.

The major ligaments of the shoulder joint are the glenohumeral ligaments in front of the capsule, the transverse humeral ligament between the humeral tuberosities, and the coracohumeral ligament, which stretches from the coracoid process to the greater tuberosity of the humerus ( Fig. 29.2 ). Along with the accessory ligaments of the shoulder, these major ligaments provide strength to the shoulder joint. The strength of the shoulder joint also is dependent on short muscles that surround the joint: the subscapularis, the supraspinatus, the infraspinatus, and the teres minor. These muscles and their attaching tendons are susceptible to trauma and to wear and tear from overuse and misuse.