Elbow Ultrasound

Reference: Musculoskeletal Ultrasound: Anatomy and Technique, Springer 2008.

Setup

• High-frequency linear probe.
• Patient seated facing you, arm extended on a table or couch.
• Scan in four parts: anterior, lateral, medial, posterior.
• Compare with the other elbow for subtle changes.

Scan sequence

1. Anterior (Distal biceps tendon)

Distal biceps tendon: elbow in full extension, forearm in full supination, probe long axis with slight oblique. The tendon dives deep and oblique to the radial tuberosity, so anisotropy is the main problem. Start at the musculotendinous junction and follow it down. The last few cm are hard to see.

2. Lateral (Common extensor tendon)

Elbow flexed about 90 degree.

Palpate the lateral epicondyle.

Probe long axis over the lateral epicondyle.

The first view should have lateral epicondyle and radiocapitellar joint.

The common extensor tendon is a bright triangle crossing the joint. Check the bone surface for spurs or irregularity.

Radial collateral ligament: thin fibrillar band deep to the common extensor tendon, running from the epicondyle to the radius.

3. Medial (Common flexor tendon)

Elbow extended, forearm fully supinated.

Palpate the medial epicondyle.

Probe long axis over the medial epicondyle.

The common flexor tendon is broader than the lateral tendon.

Ulnar collateral ligament (anterior band): lies deep to the flexor tendon and runs obliquely from the epicondyle to the ulna. Tilt the probe slightly off the tendon plane to follow it.

4. Posterior

Patient palm down on the table with the elbow flexed 90 degrees, or hand on the hip.

Triceps tendon inserting onto the olecranon, long and short axis. Flex and extend to scan dynamically.

Olecranon fossa: normally filled with a bright fat pad. Joint effusion is best seen here with the elbow flexed.

Olecranon bursa: no pressure, or you squash it away.

Ulnar nerve: bridge the probe between the medial epicondyle and olecranon. Oval, dark nerve beside the epicondyle. Flex and extend the elbow with light pressure to check for subluxation or snapping.

Pitfalls

• Do not mistake joint fluid and cartilage for each other. Gentle compression and Doppler help.
• Anisotropy at the distal biceps and the common tendons.
• Heavy probe pressure hides bursa fluid and stops the ulnar nerve from subluxing.

Checklist

• Patient seated, arm supported, both elbows available for comparison
• Distal biceps tendon followed to the radial tuberosity
• Lateral epicondyle, common extensor tendon, radial collateral ligament
• Medial epicondyle, common flexor tendon, ulnar collateral ligament
• Triceps tendon and olecranon, dynamic flexion and extension
• Posterior fat pad and olecranon fossa for effusion
• Olecranon bursa scanned with a light touch
• Ulnar nerve scanned, including dynamic check for subluxation