Ultrasound of the elbow allows high-resolution imaging of elbow anatomy while simultaneously allowing dynamic evaluation of the joint, tendons, and ligaments.
Approach
There are multiple possible approaches to imaging the elbow with ultrasound. A typical protocol is as follows 1:
Anterior elbow
Elbow is in an extended and supinated position:
- transverse sweep from 5 cm proximal to the elbow joint to 5 cm distal to the elbow joint. Evaluate biceps and brachialis muscles, brachial artery, median nerve.
- evaluate the distal biceps tendon (long axis). Follow the tendon to its insertion on the radial tuberosity (watch out for anisotropy).
- evaluate the anterior joint recess (a small amount of fluid in the coronoid fossa is normal).
- evaluate the radial and posterior interosseous nerves along their course (short axis).
Lateral elbow
Often examined with the elbow in 90° flexion:
- evaluate the common extensor tendon (long and short axis).
- evaluate the radiocapitellar joint. Check with pronation and supination.
- evaluate the annular ligament (fluid in the annular recess is abnormal).
Medial elbow
Often examined with the forearm in external rotation with the elbow extended or slightly flexed:
- evaluate the common flexor tendon and medial collateral ligament (long and short axis). Dynamic scanning with gentle valgus stress on the elbow can help evaluate the patency of the medial collateral ligament if warranted.
Posterior elbow
Often examined with elbow flexed while the palm is flat on the table (the "crab" position):
- evaluate the triceps tendon to its insertion (long and short axis).
- evaluate the olecranon fossa (examining at 45° flexion may increase the amount of fluid in the fossa, if any).
- evaluate the cubital tunnel and ulnar nerve (short axis)
- evaluate for ulnar nerve translation with a short axis view of the nerve at the level of the medial epicondyle. Watch the region while the patient flexes his or her arm and look for translation of the nerve over the medial epicondyle.
Pathology
A number of elbow joint abnormalities can be identified on ultrasound, including:
- elbow joint effusion (inflammatory/traumatic/septic)
- biceps tendinosis or tear
- triceps tendinosis or tear
- common extensor tendinosis (lateral epicondylitis)
- common flexor tendinosis (medial epicondylitis)
- ulnar collateral ligament tear
- radial collateral ligament tear
- bicipitoradial bursitis
- olecranon bursitis
- triceps tendon insertion enthesopathy
- radial head subluxation
- snapping triceps syndrome
- cubital tunnel syndrome
- supinator syndrome
- median nerve entrapment
- epitrochlear lymph nodes