Shoulder Joint Injection: Glenohumeral Injection Technique
Source
Surgeon:
Joonas Rautavaara
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Summary
Focus: Safe access to the glenohumeral joint for synovial fluid sampling, if needed, and local treatment.
Key elements: Patient positioning, posterior glenohumeral landmarks, injection trajectory toward the coracoid process, aspiration, synovial fluid analysis, aftercare, pitfalls, and complications.
Indications and Clinical Context
General
Medical expert: Joonas Rautavaara, rheumatologist
Name of procedure: Shoulder joint injection, shoulder joint puncture, glenohumeral joint injection, glenohumeral injection, shoulder injection
Goal of Operation
Safe access to the glenohumeral joint for synovial fluid sampling, if needed, and local treatment.
Problem
Unspecific shoulder joint effusion or the need for local treatment of an inflammatory joint condition, gout, or osteoarthritis.
Diagnosis
M13.9 Arthritis, unspecified
M05.8 Other rheumatoid arthritis with rheumatoid factor
M19.8 Other specified arthrosis
Short Pathophysiological Description
The glenohumeral joint, also known as the shoulder joint, is commonly inflamed in conditions such as rheumatoid arthritis, psoriatic arthritis, and reactive arthritis. Inflammatory conditions can lead to synovial hypertrophy and increased production of synovial fluid in the joint.
Glenohumeral injections are a common therapeutic approach for these conditions. They involve the direct injection of medicinal agents, usually corticosteroids and/or a local anesthetic, into the joint space. This helps to reduce inflammation, alleviate pain, and improve joint function.
Key Anatomy and Landmarks
Glenohumeral joint
Scapula
Glenoid
Acromial angle
Spine of scapula
Coracoid process
Humeral head
Synovial Fluid Analysis if a Sample Is TakenThe turbidity and color of the synovial fluid can be assessed visually. Fairly clear synovial fluid with visible scale is a sign of no pronounced infection. Cloudy synovial fluid is caused by a large number of white blood cells, making the scale marks invisible.
If the cause of joint effusion is unclear, synovial fluid should be obtained for diagnostic analysis.
Synovial fluid analysis:
Cell count with differential
Crystal analysis
Bacterial culture
If synovial fluid volume is limited, a bacterial swab may be obtained as an alternative for culture.
In cases of suspected septic arthritis with prior antibiotic exposure, bacterial PCR may be needed because cultures can be falsely negative after antibiotic treatment.
When Lyme arthritis is suspected, Borrelia PCR can help confirm the diagnosis.
Step-by-Step Technique
Preparations and Patient Positioning
The patient is seated with the arm relaxed at the side.
For example, a blue needle 23 G, 0.6 × 30 mm, or a green needle 21 G, 0.8 × 40 mm, can be used.
Landmarks and Injection Site
The posterior injection site for the glenohumeral joint is located by first palpating the spine of the scapula, which is usually quite prominent. This is followed laterally to the acromion.
The acromial angle, a prominent bony point at the junction of the lateral border of the acromion and the spine of the scapula, is easily palpated because it feels quite sharp and distinct.This point can be marked for reference.
Using the acromial angle as a landmark, the injection site is located by moving about 2 centimeters downward and about 1 centimeter medially.
To inject into the glenohumeral joint space, the needle is directed medially using the palpable coracoid process anteriorly as a landmark. Inserting perpendicular to the skin would hit the humeral head due to the angled orientation of the joint space.
Superior viewThe injection site can be marked with a blunt pen, for example.
Injection
The injection site is cleaned and allowed to dry before the injection is performed.
The coracoid process is palpated from the anterior side to establish the proper trajectory when inserting the needle.
The needle is inserted about 2 to 3 centimeters deep to reach the joint space.
Aspiration is performed to examine for synovial fluid and confirm proper needle placement. In osteoarthritis, synovial fluid may be minimal or absent.
The appropriate medicinal agent is injected according to the clinical situation. Resistance is typically minimal in the joint space.
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Piftalls and Complications
Wrong Injection Trajectory
If the injection is not angled towards the coracoid process, the tip of the needle can hit the humeral head and not enter the joint space. Before injecting, the coracoid process on the anterior side is palpated, and the needle is aimed towards it.
Challenges with Sample Aspiration
If sample aspiration is unsuccessful when acute gout is suspected, saline irrigation may be attempted. After 1 ml of fluid is injected, aspiration is repeated. This approach also provides a sample for bacterial analysis.
Storage of the Synovial Fluid Sample
A synovial fluid sample should be analysed promptly after taking the sample. Synovial fluid containing blood will rapidly coagulate. There may be cell degradation in the sample after just an hour. Crystals, on the other hand, are inorganic salts and are better preserved, so their analysis can be made the next day.
Injecting Too Frequently
In case of acute inflammation, intra-articular injections can be given at 1-month intervals for the first 3 months. Afterwards, if needed, 3 months apart.
There is no strong evidence of adverse effects of glucocorticoids on the joint, although frequent injections may cause unwanted systemic effects.
Complications
Infection
Intra-articular infection after a joint injection is very rare, the incidence being 1:2000-1:100 000, most commonly 1:10 000. Nevertheless, maintain aseptic technique while doing the procedure.
Joint Pain
Joint pain during 24 hours post-injection is an adverse effect occurring in up to 10% of cases, particularly with glucocorticoid injections. It may result from a local tissue injury caused by the needle alone but is usually due to an irritation reaction to the crystalline glucocorticoid or hyaluronate. The joint may be painful, perhaps even feel warm, for about 24 hours, but these symptoms ease spontaneously. The symptoms can be alleviated by analgesics or cold treatment.
Hemarthrosis
Intra-articular hemorrhage is a very rare complication of a joint injection. Antithrombotic treatment or anticoagulant medication is not a contraindication for intra-articular injection as the risk is very small, about 0-2%, even in patients using these medicines. In patients on anticoagulants, however, the smallest possible needle is recommended for joint injection.
Local Skin Atrophy or Hypopigmentation
Local skin atrophy occurs in about 1% of the patients after intra-articular injection of glucocorticoids. Typically, atrophy at the injection area develops at 1-4 months post-injection. In addition to atrophy, there may be hypopigmentation around the injection area. Atrophy and hypopigmentation are caused by subcutaneous glucocorticoid accumulation, potentially due to extracapsular injection or extracapsular seepage of the glucocorticoid via the puncture canal.
Tendon Tear
Tendon tears during intra-articular injections are very rare and are often due to unintentional injection of glucocorticoid into the adjacent tendon rather than the joint itself. To avoid tendon injuries, glucocorticoids should always be injected against low resistance.
Pericapsular Calcium Deposit
Pericapsular calcification, or calcium deposits around the joint capsule of the target joint, is very common, occurring after intra-articular injections in up to 10% of cases. Pericapsular calcium deposits are usually asymptomatic and harmless. In most cases, calcium is spontaneously absorbed from the synovial capsule, but in some patients X-ray images may show even permanent calcifications, particularly in small joints such as the PIP and the DIP joints of the fingers.
Compromise of Diabetes Management
Following intra-articular injections, some of the glucocorticoid dose will be absorbed into the systemic bloodstream and in diabetic patients, for example, blood sugar level might be elevated for a few days post-injection. The risk is highest for short-acting agents or when multiple injections are given together. Patients with diabetes should be advised to step up their blood sugar monitoring post-injection and, if necessary, to adjust their diabetes medication doses temporarily.
Aftercare
General Guidelines
The injection site is covered with an adhesive bandage and kept dry and clean for 24 hours to minimize infection risk.
For optimal therapeutic effect, stress on the injected joint is avoided for 24-48 hours, with heavy strain avoided for one week.
FAQ
What is the goal of shoulder joint injection?
The goal is safe access to the glenohumeral joint for synovial fluid sampling, if needed, and local treatment.
How is the posterior injection site located?
The posterior injection site is located by palpating the spine of the scapula, following it laterally to the acromion, identifying the acromial angle, and then moving about 2 centimeters downward and about 1 centimeter medially.
Why is the needle directed toward the coracoid process?
The needle is directed medially using the palpable coracoid process anteriorly as a landmark. Inserting perpendicular to the skin would hit the humeral head due to the angled orientation of the joint space.
What aftercare is recommended after the injection?
The injection site is covered with an adhesive bandage and kept dry and clean for 24 hours. Stress on the injected joint is avoided for 24-48 hours, with heavy strain avoided for one week.
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