Subacromial–Subdeltoid Bursa Injection

shouldersubacromialbursasubdeltoidimpingement

Treats

Contraindications

Active local skin infection or cellulitis at the entry site (absolute)
Suspected septic bursa (absolute — aspirate first, do not inject steroid)
Known allergy to local anesthetic, steroid, or antiseptic prep (absolute for that agent)
Therapeutic anticoagulation — review case-by-case
Uncontrolled diabetes (relative — steroid raises glucose for 3-5 days)

Pre-procedure checklist

Positioning

Modified Crass position: patient seated with palm of ipsilateral hand flat on the iliac crest, elbow directed posteriorly.
This internally rotates the humerus, bringing the supraspinatus footprint out from under the acromion.

Probe

Landmarking — find the view

Place the probe transversely just anterior to the lateral acromial edge.
Slide anterior-posterior to find the supraspinatus tendon passing under the acromion.
Center the lateral acromion at the screen edge while keeping the tendon in long-axis.
Identify the "Bursal Stripe": the thin hypoechoic plane between the deltoid and supraspinatus.

The correct ultrasound view

Needle corridor

Between deltoid (above) and supraspinatus tendon (below) — inject into the thin bursal stripe

Avoid

Cephalic vein near the anterior deltoid — relevant only if the entry drifts anterior; the standard lateral in-plane approach stays clear of it
Intratendinous rotator cuff injection
Axillary nerve (quadrilateral space ~5-7 cm inferoposterior to the acromial corner — do not direct needle inferiorly or posteriorly beyond the bursal plane)

Steps

1Use an in-plane lateral-to-medial approach along the probe long-axis (parallel to supraspinatus fibers), advancing from distal-lateral under the deltoid into the bursal plane under the acromion.
2Touch the bursal plane and inject a tiny test amount to confirm plane separation.
3Inject the planned volume slowly while watching for smooth medial spread beneath the acromion.
4STOP IMMEDIATELY if the patient reports electric, shooting, or paresthetic sensations — withdraw 1-2 mm and reposition before any further injection.

Tips

If you lose the needle, stop and realign before advancing.
Adhesions may require gentle needle-tip redirection.
Monitor injection pressure throughout — if resistance rises sharply before reaching target volume, stop. Overdistension can rupture the bursal wall into surrounding tissue.
Limit corticosteroid injection to ≤ 3 per joint/site per year.
If pre-scan or color Doppler shows an artery directly in the planned needle path, abandon and re-plan from a different angle.

Resident pearls

Think of the bursa as a "potential space" — like a balloon that has been stepped on. It only opens up once you start injecting.
Dissect the plane with local anesthetic first to confirm you are in the bursa before injecting steroid.
Check for a "bursogram" post-injection; if injectate is in the tendon, it suggests a rotator cuff tear.
The bursa extends beyond the supraspinatus footprint — use this to differentiate layers.
For DIAGNOSTIC SASD blocks, limit to ≤ 5 mL anesthetic to avoid anesthetizing the GH joint or AC joint and confounding the pain-generator localization.

Supplies

Post-procedure

Apply a clean dressing; remove after 24 hours.
Local anesthetic provides relief for 1-4 hours; pain may return before steroid takes effect.
Steroid effect typically begins 24-72 hours after injection.
Steroid 'flare' (transient worsening for 24-48 hours) occurs in 2–10% — manage with ice and acetaminophen.
Rest the shoulder for 24-48 hours; resume normal activity as tolerated thereafter.
Return immediately for: spreading redness, increasing swelling, fever, or pain disproportionate to expected (concern for infection).
Diabetics: expect a glucose rise of 50-100 mg/dL for 3-5 days.
Maximum frequency: typically no more than 3 injections per shoulder per year.