Arthrography Techniques

Arthrography is the introduction of contrast material into a joint to improve the imaging of intra-articular structures. It is one of the most valuable diagnostic techniques for labral pathology, partial-thickness rotator cuff tears, cartilage lesions, loose bodies and capsular abnormalities.

The principle. Contrast fills the joint, outlining the intra-articular structures and separating them from one another. A tear that is invisible on non-contrast MRI becomes conspicuous once contrast insinuates into the defect and creates a high-contrast interface with the adjacent tissue.

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What distension adds. The distended capsule mechanically separates the labrum from the glenoid, the capsule from bone and one tendon layer from the next, and the contrast finds its way into partial-thickness tears (undersurface cuff tears, labral tears) that non-contrast MRI can miss. The distended capsule is itself informative: capsular redundancy in multidirectional instability, HAGL lesions, the capsular adhesions of adhesive capsulitis and loose bodies are all shown.

Direct and indirect. Direct arthrography is percutaneous injection of contrast into the joint under image guidance, fluoroscopy or ultrasound, which gives consistent, controlled distension and a high intra-articular contrast concentration. Indirect arthrography gives gadolinium intravenously and then has the patient exercise gently for 10-15 minutes so that contrast diffuses across the synovial membrane into the joint. It is non-invasive, but distension is less reliable and the intra-articular concentration lower, so direct arthrography is the technique of choice whenever arthrography is indicated.

MR and CT. MR arthrography uses dilute gadolinium, bright on T1, and its soft tissue contrast suits labral tears, partial cuff tears, cartilage defects and capsular pathology. CT arthrography uses dilute iodinated contrast and gives superior bony detail: quantification of glenoid bone loss, measurement of a Hill-Sachs lesion, and osteochondral defects. When each is chosen is set out under the joint-specific applications below.

Needle placement. A 22-gauge spinal needle is advanced into the joint under fluoroscopic or ultrasound guidance, and a small test injection of iodinated contrast confirms the intra-articular position on fluoroscopy before the diagnostic contrast goes in.

Why gadolinium is diluted. For MR arthrography the gadolinium is diluted to about 1:200 in saline, which is 2 mmol/L. Its effect on signal is biphasic, not paradoxical: gadolinium shortens both T1, which raises signal, and T2*, which lowers it, and above the peak concentration the T2* effect wins, so an undiluted agent goes dark. The test injection sets a trap here. Iodinated contrast mixed with gadolinium cuts T1 signal by about 26% at 2 mmol/L and shifts the peak to a lower gadolinium concentration, so a gadolinium-iodine mixture needs more dilution, not the standard recipe.

Volume. Enough is injected to distend the capsule and separate the intra-articular structures. The same volumes serve MR and CT arthrography:

• Shoulder: 10-20 mL
• Hip: 10-15 mL
• Elbow: 7-10 mL
• Ankle: 5-8 mL
• Wrist: 3-5 mL

Timing. Image within 30-60 minutes of the injection. The synovium absorbs contrast progressively, and diagnostic quality degrades with it.

Sequences. T1-weighted fat-suppressed images are the mainstay. Gadolinium is bright on T1, so a contrast-filled tear stands out against the dark background of fat-suppressed tendon and labrum. T2-weighted sequences complement them by showing effusion and oedema.

Arthrography is an invasive procedure, and the examiner expects you to be able to consent a patient for it and to recognise its complications and technical pitfalls.

Complications. Most are minor and self-limiting:

• Post-arthrography pain and transient chemical synovitis, common over the 24-48 hours after injection: a mild inflammatory response to contrast and distension, managed with rest, ice, simple analgesia or NSAIDs, and reassurance
• Vasovagal reaction during the injection: lie the patient flat, elevate the legs and observe
• Infection and septic arthritis: rare with strict aseptic technique, but the most feared complication. Suspect it with disproportionate pain, swelling, fever and erythema in the days after the procedure, and treat as septic arthritis: aspirate, culture, antibiotics
• Contrast reaction, allergic or physiological, to gadolinium or iodinated contrast, managed by the standard contrast-reaction protocols
• Bleeding and haematoma, especially in anticoagulated patients or after deep injections
• Needle injury to adjacent neurovascular structures, the concern at the hip, where the femoral bundle lies medial to the head-neck target

The interpretive skill that matters most in shoulder arthrography is telling a normal anterosuperior labral variant from a true tear. Mislabelling a sublabral foramen or a Buford complex as a Bankart lesion can lead to inappropriate surgery.

The variants. Each is a normal finding that mimics a tear:

• Sublabral foramen: an opening between the anterosuperior labrum and the glenoid, present in about 12-18% of shoulders. A normal variant, not a Bankart lesion
• Sublabral recess: the superior labrum may have a normal recess beneath a meniscoid attachment, deepest at 11-1 o'clock, which can mimic a SLAP tear
• Buford complex: complete absence of the anterosuperior labrum with a thick, cord-like middle glenohumeral ligament. Not pathological and needs no treatment; never report the cord-like ligament as a displaced labral fragment

Labral morphology also varies normally, triangular, rounded, flat or cleaved, and variation alone does not indicate pathology. The normal synovial recesses, the axillary pouch and the subscapularis bursa, should likewise not be read as pathological collections.

Read an arthrogram structure by structure: the labrum, the rotator cuff, the biceps tendon, the capsule and ligaments, the articular cartilage, and then any filling defect within the contrast.

Arthrography is performed worldwide by radiologists or musculoskeletal subspecialty radiologists on referral from orthopaedic surgeons and sports physicians. Direct MR arthrography is the internationally accepted standard for glenohumeral labral assessment and acetabular labral evaluation. The injection is performed under fluoroscopic or ultrasound guidance; a gadolinium-based contrast agent (commonly gadopentetate dimeglumine or an equivalent macrocyclic agent) is diluted to approximately 2 mmol/L (about 1:200) in saline, and imaging is completed within 30–60 minutes before synovial absorption degrades joint distension.

Registry & outcome context. There is no dedicated arthrography registry; the downstream procedures that arthrography informs are tracked instead. Shoulder-instability and labral-repair outcomes feed into arthroplasty/soft-tissue datasets and instability cohorts, and glenoid bone-loss thresholds (the Sugaya en-face method and the glenoid track concept) drive the registry-relevant choice between Bankart repair and bony reconstruction (Latarjet/bone block). Accurate preoperative bone-loss quantification on CT (with or without intra-articular contrast) is therefore the key audited determinant of which instability procedure is performed.

High- vs limited-resource practice variation. In well-resourced settings, 3T MRI and dual fluoroscopic/US-guided injection allow routine direct MRA and 3D CT with en-face glenoid reconstruction for preoperative planning. Where MRI access is constrained, CT arthrography becomes the primary cross-sectional arthrogram because CT is faster, cheaper and more widely available, and still answers bony and many labral questions; conventional fluoroscopic arthrography remains a legitimate fallback for confirming intra-articular position or gross capsular leak. Where advanced imaging is unavailable, diagnostic arthroscopy assumes a larger role. This variation reflects equipment access and cost, not differing biology, and examiners expect candidates to justify the chosen modality by the clinical question and the local resource context.

Direct MRA against high-field non-contrast MRI. As 3T scanners and high-resolution sequences have improved, the incremental benefit of an invasive arthrogram over modern non-contrast 3T MRI for labral pathology is debated. Meta-analytic data still favour MRA for sensitivity, but some centres reserve arthrography for equivocal 3T studies, which reduces the number of injections. The optimal threshold for proceeding to MRA is not standardised.

Measuring bone loss. 3D CT with the Sugaya en-face view is the traditional reference for glenoid bone loss, but MRI-based and glenoid-track methods are increasingly used, to avoid radiation and to assess bipolar loss, glenoid plus Hill-Sachs, together. The percentage that mandates bony reconstruction is a continuum modified by the glenoid track concept rather than a single fixed cut-off.

Gadolinium in the joint. Intra-articular gadolinium is an off-label use of gadolinium-based contrast agents. Concern about tissue deposition has driven a shift towards macrocyclic agents, and some groups use saline-only arthrography or dilute iodinated CT arthrography to avoid intra-articular gadolinium altogether. Local consent and contrast-safety policy govern practice.

The place of indirect MRA. Its role is contested. Most experts limit it to patients in whom direct injection is refused or unavailable, and many musculoskeletal radiologists do not offer it at all.