Glenohumeral joint injection (technique)

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Glenohumeral joint injections (often referred to as shoulder injections ) are performed as part of a number of therapeutic and imaging procedures using a variety of approaches and modalities. The underlying principles shared by all techniques are to avoid damage to the glenoid labrum, long head of biceps tendon, surrounding neurovascular structures and articular cartilage.

Indications

Injection into the glenohumeral joint may be necessary in the following settings:

Contraindications

Anticoagulation is a relative contraindication and should be assessed in the context of the risks of ceasing anticoagulation versus the risk of hemarthrosis. It some settings it will be best to avoid arthrography entirely or consider using indirect arthrography.

Procedure

A variety of approaches, both anterior and posterior, have been described to cannulate the glenohumeral joint using a variety of modalities, most commonly fluoroscopy or ultrasound. The procedure is carried out with sterile technique, without sedation and only requires local anesthetic to skin. A 21-gauge spinal needle is typically used .

A normal joint will usually have a capacity of 8-15 mL. This will be reduced in adhesive capsulitis .

Preprocedural evaluation

Routine patient interactions are carried out (the procedure is explained to the patient, informed consent obtained, allergy and comorbidity history obtained, time-out performed including ensuring the correct side is being investigated, etc).

The shoulder needs to be exposed and skin examined for active infection.

Equipment

sterile procedure pack, wash, gloves and gown
local anesthetic for skin (e.g. 1%/2% lignocaine) with needle (e.g. 23 or 25 G needle) and syringe
21 or 22-gauge spinal needle (length depends on the size of the patient)
syringe for injectable (this will depend on the indication - see above)
syringe for contrast if needed (depending on indication, modality and operator preference)
short connecting tube (optional)
dressing

Fluoroscopic technique

Regardless of technique meticulous sterile technique and generous antiseptic prep to the skin should be applied.

Anterior approach

The patient is placed supine with the arm somewhat externally rotated (palm facing upwards). Note, excessive external rotation not only may be painful, it will also tighten the anterior capsule reducing the space anteriorly .

Skin entry is marked over the upper medial quadrant of the humeral head . This is the rotator cuff interval, avoiding the tendons of supraspinatus, subscapularis and biceps tendon . Alternatively, a location somewhat lower down along the humeral head can be chosen, requiring passing through the subscapularis tendon . This notwithstanding, what is critical is that the needle is lateral to the medial humeral articular edge to avoid damaging the glenoid labrum.

The needle is then introduced vertically (needle tip overlying the hub) along the axis of the x-ray beam at the marked site until articular cartilage is encountered .

Intra-articular position is confirmed by the introduction of a small amount of contrast that should be seen to outline the joint space and the subcoracoid recess .

Posterior approach

The patient is placed prone with the shoulder to be injected elevated. Imaging is then oriented to see the joint line tangentially (i.e. joint space is visualized without overlap of glenoid and humeral head) .

Skin entry is marked over the inferomedial aspect of the articular surface, superomedial to the anatomical neck of the humerus (the site of capsular attachment) .

The needle is then introduced vertically along the axis of the x-ray beam at the marked site until articular cartilage is encountered .

Intra-articular position is confirmed by the introduction of a small amount of contrast .

Ultrasound technique

Both anterior and posterior approaches (see above) can also be performed under ultrasound guidance.

CT technique

Either an anterior or posterior technique can be taken with visualization of the glenohumeral joint allowing direct placement of needle-tip position. Injection of contrast is still required to ensure an intra-articular needle tip position.

Complications

Extracapsular injection is probably the most common complication. The most serious complication is septic arthritis. Hemarthrosis is also rarely encountered.