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Indications & Patient Selection
Procedure Types
- Diagnostic: Arthrography (MR or CT) — inject contrast ± dilute gadolinium intra-articularly to distend the joint and outline labrum, cartilage, and ligaments
- Diagnostic: Aspiration — obtain synovial fluid for cell count, crystal analysis, Gram stain / culture
- Therapeutic steroid: Acute inflammatory flare, severe osteoarthritis, RA/gout, adhesive capsulitis
- Viscosupplementation (HA): Moderate OA (primarily knee); 1–3 weekly injections or single-injection formulations; effect 3–6 months; coverage varies by insurer
- PRP (emerging): Tendinopathy and OA; off-label; centrifuge 30–60 mL autologous blood → 3–5 mL PRP; see Pearl section
Common Joints & Indications
- Hip — most common IR referral; OA, AVN, post-surgical pain, pre-arthroplasty diagnostic injection, MR arthrography
- Shoulder — OA, adhesive capsulitis (frozen shoulder), rotator cuff tendinopathy, MR arthrography for labral tears
- Knee — OA, RA flare, effusion aspiration, viscosupplementation
- Ankle / Wrist / Elbow — inflammatory arthritis, post-traumatic pain, arthrography
Contraindications
- Absolute: Active joint infection (septic arthritis) — aspiration YES, steroid injection NO; overlying cellulitis or bacteremia
- Absolute: Allergy to injectate (contrast, corticosteroid, local anesthetic)
- Relative: Uncontrolled diabetes (steroid glucose spike); coagulopathy; prosthetic joint (higher infection risk — use strict sterile technique)
Pre-Procedure Workup
- X-ray of target joint — baseline; assess joint space, osteophytes, AVN, articular congruity
- Prior MRI/CT — identify labral tears, cartilage defects, effusion, synovitis
- Labs — WBC/ESR/CRP if infection concern; HbA1c in diabetics; coagulation if anticoagulated
- Confirm clinical indication — therapeutic vs. diagnostic vs. arthrogram; steroid vs. HA vs. PRP
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Pre-Procedure Checklist
Guidance modality. Fluoroscopy (hip, ankle, wrist, elbow — deep joints or bone-on-bone); Ultrasound (shoulder, knee, superficial ankle); CT (last resort for severely degenerated or inaccessible joints). US probe: linear 10–12 MHz for shoulder/knee/ankle; curvilinear 5–8 MHz for hip.
Needle selection. Hip: 20–22G, 3.5–5" spinal needle. Shoulder: 20–22G. Knee: 21–23G. Ankle/Wrist: 22–25G. For aspiration of thick fluid: 18G needle + 20–60 mL syringe. Always use 22G or finer for therapeutic injection to minimize cartilage injury.
Standard steroid injectate. Triamcinolone 40 mg (1 mL) + bupivacaine 0.5% (2–3 mL). Total volume scaled to joint size — hip/shoulder: 10–15 mL; knee: 5–10 mL; ankle/wrist: 3–6 mL / 1–3 mL.
Arthrogram contrast. Iohexol 180 or 300 (0.5 mL test dose to confirm intra-articular). For MR arthrography: dilute gadolinium (0.4 mL Gd + 10 mL iohexol 300, total 12–15 mL for hip). For CT arthrography: undiluted or 50:50 iohexol 300.
Aspiration setup. 18G needle, 20–60 mL syringe. Send fluid to lab: cell count + differential, LDH, glucose, Gram stain/culture, crystal analysis (polarized microscopy for gout/pseudogout). Label tubes immediately.
Sterile technique. Full sterile prep (ChloraPrep, sterile drape) for hip, shoulder, and arthrography. Clean but not strictly sterile acceptable for US-guided peripheral joints (knee, ankle) per many protocols — confirm institutional standard.
Consent. Post-injection flare (5–10%), infection (<0.001%), glucose elevation (diabetics), skin depigmentation if steroid tracks superficially, tendon rupture (avoid direct tendon injection), articular cartilage injury.
Diabetic patients. Warn of transient glucose elevation 24–48h post-steroid. Check recent HbA1c. Home glucose monitoring recommended.
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Anatomy by Joint
Joint Access Summary
| Joint | Volume | Approach | Landmark |
|---|---|---|---|
| Hip | 10–20 mL (MR arthro: 12–15 mL) | Anterior or lateral; fluoroscopy preferred | Femoral head-neck junction (lateral) or anterior capsule (anterior approach) |
| Shoulder | 10–15 mL | Posterior, anterior, or lateral (US-guided) | Glenohumeral joint posterior: infraspinatus / teres minor interval; needle tip to posterior joint capsule at glenoid labrum |
| Knee | 5–10 mL | Lateral suprapatellar (US) or anteromedial approach | Lateral joint line (fluoroscopy); suprapatellar pouch (US) — visualize in real-time |
| Ankle | 3–6 mL | Anteromedial (fluoroscopy or US) | Between tibialis anterior tendon and medial malleolus; tibiotalar joint space |
| Wrist | 1–3 mL | Dorsal (radiocarpal or DRUJ) | Lister's tubercle as dorsal reference; radiocarpal joint just distal to radius on AP fluoroscopy |
| Elbow | 3–5 mL | Lateral (radiohumeral) | Triangle formed by lateral epicondyle, radial head, and capitellum — lateral approach with elbow flexed 90° |
Hip Anatomy Notes
- Deep joint — requires 3.5–5" spinal needle; superficial US probes (linear) cannot image hip joint in most adults
- Curvilinear 5–8 MHz probe for US-guided hip if BMI normal; fluoroscopy preferred in obese patients or severe OA
- Anterior approach: needle enters anterior capsule between femoral artery laterally and femoral nerve (both medial to needle — keep lateral to midline)
- Iliopectineal bursa communicates with hip joint in ~15% — contrast tracking superiorly into bursa is acceptable (intra-articular)
Shoulder Anatomy Notes
- Glenohumeral joint: posterior approach — probe placed over posterior shoulder; identify humeral head, glenoid, and posterior labrum on US
- Rotator cuff interval (anterior approach): between supraspinatus and subscapularis — used for anterior glenohumeral access
- Adhesive capsulitis: joint capacity severely reduced (<5 mL); injection with gentle hydraulic distension (hydrodilation) therapeutic
- Acromioclavicular (AC) joint: separate tiny joint (1–2 mL); access superiorly between acromion and clavicle
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Technique
Default RadCall approach · share your own below
Supplies
22G 3.5–5" spinal needle (hip)
22G needle (shoulder/knee)
18G needle + large syringe (aspiration)
C-arm fluoroscopy or US probe
Iohexol 180 or 300 (contrast)
Triamcinolone 40 mg
Bupivacaine 0.5%
1 mL + 3 mL + 10 mL syringes
Extension tubing (primed)
ChloraPrep
Sterile drape
Sterile dressing
Approach A — Hip Fluoroscopic Anterior Approach (Primary)
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Position + scout fluoroscopy
Supine positioning with hip in neutral rotation. AP fluoroscopy of hip. Identify femoral head-neck junction. Mark skin entry point over the femoral neck, lateral to the femoral vessels.
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Sterile prep + needle advance
Full sterile prep and drape. Skin and subcutaneous local anesthesia with 1% lidocaine. Advance 22G 3.5" spinal needle (5" for obese patients) toward lateral femoral neck under continuous fluoroscopy. Maintain lateral approach — stay lateral to avoid femoral vessels.
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Contact femoral neck periosteum
Advance needle until firm periosteal contact at the femoral neck. This is the definitive endpoint — "walking" the needle onto bone confirms depth and prevents over-advancement into joint proper.
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Contrast arthrogram — confirm intra-articular
Inject 0.5–1 mL iohexol under live fluoroscopy. Ring sign: contrast flows around the femoral head as a circumferential ring = confirmed intra-articular. Contrast pooling only at needle tip without joint fill = not yet intra-articular; redirect.
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Therapeutic injection (steroid)
Inject 1 mL triamcinolone 40 mg + 2 mL bupivacaine 0.5%. Flush with 1–2 mL saline. Remove needle, apply pressure, then sterile dressing.
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MR arthrography variant
After confirming intra-articular position with iohexol: inject dilute gadolinium solution (0.4 mL gadolinium contrast + 10 mL iohexol 300, total 12–15 mL). Patient proceeds immediately to MRI — do not delay >30 minutes.
Approach B — Shoulder US-Guided Posterior Approach
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Position + probe placement
Patient seated with arm in neutral or slight internal rotation. Place linear US probe (12 MHz) over posterior shoulder, transverse to identify humeral head and glenoid. Identify the infraspinatus tendon and posterior labrum.
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In-plane needle approach
In-plane technique: advance 22G needle from lateral aspect toward the posterior joint capsule at the infraspinatus/teres minor interval. Target: tip at posterior capsule just adjacent to glenoid labrum.
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Confirm intra-articular position
Inject 1–2 mL saline or contrast under real-time US. Confirm: fluid tracks into glenohumeral joint with visible joint distension. If fluid tracks into muscle or tendon, reposition.
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Inject therapeutic
Inject triamcinolone 40 mg + 3 mL bupivacaine 0.5%. For adhesive capsulitis (hydrodilation): larger volume (10–15 mL) to distend contracted capsule. Withdraw and dress.
Approach C — Knee US-Guided Lateral Suprapatellar
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Position + probe
Supine, knee extended or slightly flexed (towel roll beneath popliteal fossa). Place linear US probe over lateral suprapatellar pouch in longitudinal orientation.
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Aspirate first if effusion
If effusion present: switch to 18G needle + 20–60 mL syringe. Aspirate all fluid before injecting steroid — reduces dilution and provides diagnostic specimen. For thick fluid: dilute with 5 mL normal saline to loosen.
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In-plane needle to suprapatellar pouch
Advance 22G from lateral through quadriceps fat pad into the suprapatellar pouch under real-time US visualization. Confirm: needle tip visible within the anechoic pouch space.
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Inject therapeutic or viscosupplement
Steroid: triamcinolone 40 mg + 3 mL bupivacaine 0.5%. HA (viscosupplementation): 1–3 mL Synvisc / Hyalgan / Monovisc. Visualize fluid spreading within pouch on US during injection.
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Fluoroscopic / US Landmarks
Hip — Fluoroscopy
- "Ring sign" — contrast circumferentially outlining the femoral head = confirmed intra-articular. This is the gold standard endpoint.
- Contrast tracking superiorly into iliopectineal bursa = intra-articular (bursa communicates with joint in ~15%) — still acceptable
- Contrast pooling only at needle tip = extracapsular — reposition
- Lateral fluoroscopy: confirm needle depth relative to femoral neck before injection
Shoulder — Ultrasound
- Posterior approach US: needle tip appears as hyperechoic point between humeral head (convex) and posterior glenoid labrum (triangular echogenic structure)
- On injection: anechoic fluid tracks anteriorly into glenohumeral joint — confirms intra-articular position in real-time
- Rotator cuff interval (anterior approach): needle passes through supraspinatus-subscapularis interval into anterior joint
Knee — Ultrasound
- Lateral suprapatellar pouch visible as anechoic space between quadriceps tendon and femur on longitudinal US
- Needle enters from lateral and tip visualized within the pouch in real-time — avoid the hyperechoic quadriceps tendon
- During injection: watch for fluid spread within the pouch — uniform filling confirms intra-articular position
- Effusion makes knee the most straightforward joint to access with US
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Troubleshooting
Problem
Bone contact only — no joint entry
Likely cause: Needle tip is on periosteum rather than within joint space; common with severe OA and reduced joint space.
Next step: Slightly withdraw the needle 2–3 mm and redirect with small angulation changes. Use small test injection of contrast to map location. Confirm intra-articular position with arthrogram before injecting steroid — never inject based on position alone.
Problem
Contrast extravasation outside joint
Likely cause: Needle tip in periarticular bursa, capsule tear, or periarticular soft tissue.
Next step: Reposition needle. Note: contrast tracking into an adjacent bursa (e.g., iliopsoas bursa for hip, subdeltoid bursa for shoulder) may still be therapeutic for concurrent bursitis. Document location and adjust clinical expectations accordingly.
Problem
Aspiration: thick fluid won't aspirate
Likely cause: Viscous effusion (inflammatory or post-hemorrhagic), or needle too small.
Next step: Upsize to 18G needle. Dilute with 5 mL normal saline injected into joint, then aspirate together — loosens viscous fluid. Apply steady suction rather than sharp pulls. If still no flow: rotate needle bevel, adjust depth slightly.
Problem
Joint not accessible — severe OA (bone-on-bone)
Likely cause: Advanced joint space narrowing with osteophyte bridging; particularly challenging at hip and ankle.
Next step: Fluoroscopy may succeed when US fails in bone-on-bone joints — use oblique views to find remnant joint space. CT-guided injection is the last resort and provides the greatest precision. A periarticular injection (into the capsule adjacent to the joint) may still provide clinical relief.
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Complications
Immediate / Periprocedural
- Post-injection flare (5–10%) — transient pain increase 24–48h after injection due to crystalline steroid; reassure patient; ice, NSAIDs; resolves spontaneously. Warn the patient before discharge.
- Vasovagal reaction — position supine; IV fluids; atropine if significant bradycardia. More common with anxious patients or prone positioning.
- Tendon rupture — avoid direct tendon injection; inject around tendon, not into it; use real-time US to confirm needle position relative to tendon.
- Articular cartilage injury — use fine needle (22G or smaller); avoid multiple punctures in the same session; confirm intra-articular before injecting.
Delayed
- Septic arthritis (<0.001%) — fever, severe worsening joint pain, elevated WBC/ESR/CRP within days to weeks; aspiration mandatory; broad-spectrum antibiotics; orthopaedic or IR drainage if abscess; sterile technique is paramount.
- Steroid-related glucose elevation — inform diabetic patients; monitor home glucose 24–48h; usually resolves within 48–72h.
- Skin depigmentation / subcutaneous atrophy — occurs if steroid tracks to dermis; confirm intra-articular injection; use minimum volume; do not inject while withdrawing needle.
- Steroid arthropathy — degenerative joint changes with repeated injections; limit to 3–4 per joint per year; document each injection.
- Contrast allergy (for arthrography) — use low-osmolar water-soluble contrast; gadolinium for MR arthrography in iodine-allergic patients; pre-medicate if prior mild reaction.
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Provide patient with a pain diary to track daily pain scores before their follow-up visit — helps calibrate treatment response and guides repeat intervention decisions.
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Critical Pearls
✶
Always confirm intra-articular position before injecting steroid. Blind injections miss the joint 30–40% of the time. Always confirm with contrast arthrogram (fluoroscopy) or real-time US visualization. The ring sign for hip arthrograms and real-time fluid tracking for US-guided injections are non-negotiable confirmation steps.
✶
Hip requires specialized imaging — fluoroscopy or curvilinear US. Superficial linear probes (12 MHz) cannot image the hip joint in most adult patients. Deep anatomy requires a 3.5–5" spinal needle. For obese patients or severe OA, fluoroscopy is more reliable than US for hip access. Never attempt hip injection with standard short needles.
✶
Maximum steroid frequency: 3–4 injections per joint per year. Repeated corticosteroid injection beyond this limit causes steroid arthropathy (cartilage thinning, subchondral bone loss). Document every injection with date and drug. If a patient reports frequent prior injections elsewhere, check records before proceeding.
✶
Aspirate first if there is effusion. Aspiration before injection serves two purposes: (1) reduces steroid dilution, improving efficacy; (2) provides diagnostic synovial fluid for analysis. This is especially important when infection or crystal arthropathy is on the differential. Never inject steroid into a joint you suspect may be septic.
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PRP preparation and emerging indications. Centrifuge 30–60 mL autologous whole blood at 1500–3000 rpm for 8–10 minutes to yield 3–5 mL platelet-rich plasma (buffy coat / platelet-rich layer). Knee OA: multiple RCTs show PRP superior to hyaluronic acid for pain at 6–12 months. Shoulder rotator cuff tendinopathy: emerging data favorable. Off-label; insurance coverage variable; document informed consent.
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Viscosupplementation (hyaluronic acid) — knee OA protocol. Synvisc (3 × weekly), Hyalgan (3–5 × weekly), or Monovisc / Synvisc-One (single injection). Total HA volume: 1–3 mL. Inject intra-articularly — confirm with US or fluoroscopy. Effect lasts 3–6 months. Not covered by all insurance plans; confirm coverage before scheduling. Avoid in active effusion — aspirate first.
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References & Community Cards
Citations
- Prologo JD, Ray CE Jr., eds. Advanced Pain Management in Interventional Radiology: A Case-Based Approach. Thieme; 2024. Ch. 39–40 (Filippiadis D, Kelekis A; Wadhwa V, Thakur U, Pezeshk P, Chhabra A).
- Guo JJ, Mu W, Niu X, et al. Accuracy of ultrasound- versus fluoroscopy-guided hip injection. Clin Rheumatol. 2015;34(1):35–40.
- Filippiadis DK, Kelekis A. A review of current trends in spinal and musculoskeletal interventional procedures for pain management. Quant Imaging Med Surg. 2017;7(6):651–659.
- Bannuru RR, et al. OARSI guidelines for the non-surgical management of knee, hip, and polyarticular osteoarthritis. Osteoarthritis Cartilage. 2019;27(11):1578–1589.
- Doria C, et al. Intra-articular injection with platelet-rich plasma versus hyaluronic acid in knee OA: a systematic review. Int Orthop. 2017;41(12):2403–2412.
- SIR Standards of Practice Committee. Consensus Guidelines for Periprocedural Management of Coagulation Status. J Vasc Interv Radiol. 2012;23(6):727–736.