Arthrography Procedures: Shoulder & Knee Contrast Studies for Rad Techs

What Is Arthrography?

Arthrography is a fluoroscopic, CT, or MRI examination in which contrast material is placed inside a joint to evaluate structures that routine radiographs cannot show — the labrum, articular cartilage, joint capsule, and ligaments. In direct arthrography, a radiologist injects contrast directly into the joint space under fluoroscopic or ultrasound guidance. In indirect arthrography, iodinated or gadolinium contrast is injected intravenously and allowed to diffuse into the joint before imaging.

Direct arthrography is generally preferred because distending the joint separates its internal structures and improves evaluation of small abnormalities. It is often performed only if a non-arthrographic examination is felt to be inadequate in assessing a joint abnormality. As a radiologic technologist, you may assist with arthrography in the fluoroscopy suite, CT, or MRI setting — and arthrography concepts appear on the ARRT exam.

Indications for Arthrography

Arthrography is most often used to identify abnormalities within the shoulder, elbow, wrist, hip, knee, and ankle. Common indications include:

• Shoulder — rotator cuff evaluation. Conventional shoulder arthrography can demonstrate full-thickness rotator cuff tears as contrast passing from the glenohumeral joint into the subacromial-subdeltoid bursa. MR arthrography is now the standard for detailed rotator cuff and labral assessment.
• Shoulder — labral tears and instability. MR arthrography distends the joint and outlines the glenoid labrum, making labral tears (including SLAP lesions) and capsulolabral injuries more conspicuous, particularly after shoulder dislocation.
• Adhesive capsulitis (frozen shoulder). The joint capsule capacity is reduced — often to less than 7 mL — and injection may meet resistance.
• Knee — meniscal and ligament injuries, postoperative evaluation. CT or MR arthrography can assess meniscal re-tears after partial meniscectomy and evaluate cartilage defects. Routine MRI remains the primary knee examination.
• Hip — labral tears and femoroacetabular impingement (FAI). MR arthrography outlines the acetabular labrum and is commonly requested for young adults with hip pain.
• Wrist — TFCC and intrinsic ligament injuries. Wrist arthrography evaluates the triangular fibrocartilage complex and the scapholunate and lunotriquetral ligaments, sometimes using a three-compartment injection.
• Elbow and ankle — loose bodies, cartilage defects, and ligament injuries.
• Therapeutic injections. Local anesthetic and/or corticosteroids may be injected along with contrast for diagnostic-therapeutic effect; the response can help confirm the joint as a pain source.

Contraindications and Precautions

• Suspected septic arthritis — an absolute contraindication to injection. Aspiration is performed when infection is suspected.
• Overlying cellulitis or skin infection at the planned puncture site — avoid the infected field.
• Bleeding diathesis or anticoagulation — relative contraindication; physician assessment is required.
• Allergy to the planned contrast agent — allergic-like reactions are very rare with intra-articular injection because contrast is not given intravenously, but risk assessment is still required. For therapeutic injections in contrast-allergic patients, a small volume of air (3–5 mL) can be used to confirm intra-articular position.
• Pregnancy — for fluoroscopy- or CT-guided arthrography, exclude pregnancy per facility policy; MRI-guided studies avoid ionizing radiation but gadolinium administration requires the same screening.
• Severe kidney disease — may prevent administration of gadolinium-based (MRI) or iodinated (CT) contrast; the physician assesses renal function.

Patient Preparation

No special preparation is required before direct arthrography. Food and fluid intake do not need to be restricted unless sedation will be given. The technologist's preparation checklist typically includes:

• History and screening — document allergies (especially to iodinated or gadolinium-based contrast), kidney problems, medications, recent illness, and pregnancy status.
• Consent and time-out — the qualified practitioner explains the procedure, benefits, alternatives, and risks (infection, bleeding, allergic-like reaction, and rare joint or nerve injury) and obtains consent. Confirm patient, side, procedure, and contrast before starting.
• Prior imaging — recent radiographs may be used for reference; a scout radiograph of the joint may be obtained before injection.
• Clothing and metal screening — for MR arthrography, all metal and electronic items are removed; implant screening follows standard MRI safety policy.
• Positioning — the patient is positioned so the needle can be inserted directly along the direction of the X-ray beam without tube angulation (fluoroscopy), or comfortably for the operator (ultrasound).
• Sedation considerations — children under 13 may need sedation to hold still; claustrophobic patients may require anxiolysis for the MRI portion. Arrange a driver when sedation is used.

Contrast Media and Equipment

Contrast Agents by Modality

The contrast agent depends on the imaging method that follows the injection. Understanding the differences is important for the ARRT exam and for assisting the radiologist.

Equipment Setup

• Fluoroscopic unit — C-arm or fixed table with pulsed fluoroscopy, last-image-hold, and dose reporting.
• Ultrasound system (when US guidance is used) — linear high-frequency transducer; ultrasound is increasingly favored over fluoroscopy because it avoids ionizing radiation.
• Needles and syringes — joint-specific needle sizes (for example, 22-gauge for shoulder/knee/hip, 25-gauge for elbow/wrist/ankle/small joints); syringes for anesthetic, contrast, and aspiration.
• Sterile tray — antiseptic, sterile drapes, gauze, local anesthetic (lidocaine), and the ordered contrast agent.
• Air — for double-contrast technique and for confirming position in contrast-allergic patients.

Step-by-Step Arthrography Procedure

The following is a representative sequence under fluoroscopic guidance. The examination is performed by or under the direction of a qualified physician; who may perform the injection depends on licensure, credentialing, and local policy.

Step 1: Scout Imaging and Positioning

Position the joint so the needle path aligns with the X-ray beam. A scout image confirms positioning and may identify abnormalities. For MR arthrography, the patient moves to the MRI suite after injection, so the injection itself is typically performed under fluoroscopy or ultrasound first.

Step 2: Sterile Preparation and Local Anesthesia

Cleanse the skin with antiseptic and apply a sterile drape. Inject local anesthetic through a small needle — the patient may feel a brief sting that usually subsides within 15–20 seconds.

Step 3: Joint Puncture

Advance the needle into the joint under fluoroscopic or ultrasound guidance. The ideal needle tip is superimposed over the hub on control images. Upon bone contact, withdraw the needle very slightly and test the injection with anesthetic; a decrease in resistance suggests intra-articular placement. With ultrasound, the needle is introduced tangentially to the transducer so it can be followed to the joint capsule.

Step 4: Confirmation of Intra-Articular Position

Inject a small amount of contrast gently and progressively. Flow of contrast away from the needle tip and opacification of the joint space confirm correct position. Do not inject against marked resistance. If fluid is aspirated, send it for laboratory analysis per protocol — aspiration is performed when infection is suspected.

Step 5: Contrast Administration and Imaging

Inject the ordered volume for the joint (typical diagnostic volumes: shoulder 8–15 mL; elbow about 5 mL; wrist about 2 mL; hip about 10 mL; knee 10–20 mL for diagnostic arthrography though capacity exceeds 40 mL; ankle about 5 mL). Ask the patient to move the joint to distribute the contrast. Obtain spot radiographs or proceed to CT/MRI per protocol. The radiologist may evaluate joint motion under fluoroscopy.

Step 6: Post-Injection Care

Remove the needle, apply pressure, and observe the patient. Provide aftercare instructions (below). A conventional arthrography examination is usually completed within 30 minutes; examinations involving MRI take longer.

Joint-Specific Approaches

The technique varies by joint; the following summarizes common approaches used in practice. Targeting the articular recess rather than the apparent joint space is a widely taught strategy that can make injection easier and safer.

Normal Findings vs. Pathologic Findings

Arthrography findings are interpreted by the radiologist, but the technologist benefits from recognizing the appearances:

• Rotator cuff tear (conventional arthrography) — contrast extends from the glenohumeral joint into the subacromial-subdeltoid bursa, indicating a full-thickness tear. Partial-thickness tears may not be detected with conventional arthrography — an important limitation.
• Labral tear (MR arthrography) — contrast tracks into the glenoid labrum; the distended joint improves detection of SLAP and Bankart-type lesions.
• Adhesive capsulitis — small capacity, resistance to injection, and reduced filling of the axillary recess.
• Meniscal re-tear (postoperative knee) — contrast extends into the meniscal remnant.
• Cartilage defects — contrast outlines chondral fissures and delamination; CT and MR arthrography are more sensitive than conventional radiography.
• Wrist ligament injuries — abnormal communication of contrast between compartments (for example, radiocarpal to midcarpal) suggests a scapholunate or lunotriquetral ligament tear.

Safety, Complications, and Aftercare

Complications

• Infection — the chance of infection requiring antibiotic treatment appears to be less than 1 in 1,000. Strict sterile technique is essential.
• Allergic-like contrast reaction — very rare with intra-articular injection because contrast is not given intravenously; mild nausea to severe cardiovascular reactions are possible in rare cases. The radiologist and staff follow the facility contrast-reaction protocol.
• Vessel or nerve injury — possible but minimal, particularly when the procedure is performed under ultrasound guidance.
• Bleeding or hemarthrosis — uncommon; physician assessment if significant.
• Post-procedure pain or swelling — expected to a mild degree; typically resolves within 48 hours.

Aftercare Instructions

• Apply ice to the joint for swelling; a mild over-the-counter analgesic may be taken for pain.
• Contact the provider if symptoms persist beyond two days.
• No vigorous exercise for at least 24 hours — there is a slight increased risk of dislocation after the procedure. Minimize activity using the injected joint for about 24 hours to allow elimination of the injected fluid.
• If steroids were injected, refrain from vigorous exercise of the joint for about two weeks; keep a log of joint discomfort if asked.
• Resume usual activities and normal diet immediately if no sedation was used.

Radiation Dose Considerations

Fluoroscopy- and CT-guided arthrography uses ionizing radiation; MR arthrography does not. Apply ALARA principles:

• Use pulsed fluoroscopy at the lowest acceptable frame rate and last-image-hold for documentation.
• Collimate tightly to the joint and limit beam-on time.
• Record fluoroscopy time and available dose indices per facility policy.
• For MR arthrography, gadolinium is used in very small intra-articular doses; nephrogenic systemic fibrosis is exceptionally rare with newer agents, and the physician assesses renal function before any contrast administration.

Arthrography vs. Alternative Imaging