Ultrasound examination of the elbow allows a low-cost, non-invasive, and dynamic evaluation of the periarticular tendons and nerves as well as several joint ligaments. The commonest indication for elbow ultrasound is for pain around either the lateral or medial aspect of the joint (“tennis” and “golfers” elbow). However, ultrasound may also aid clinicians in the assessment of a wide variety of other disorders, including trauma (partial and complete tendon ruptures, ligament tears, and fractures), overuse problems (lateral and medial epicondylosis, triceps tendon enthesopathy), inflammatory diseases (osteoarthritis, rheumatoid arthritis, and bursitis), and neuropathies (ulnar or radial nerve entrapment neuropathies and nerve instability). Ultrasound is also capable of detecting very small joint effusions not identified clinically, synovial hypertrophy, and associated marginal joint erosions.
A high-frequency (7-15 MHz) linear probe with a relatively large footprint should be used for diagnostic imaging to allow sufficient anatomical resolution. The examination should include dynamic assessment where appropriate
4.1 Diagnostic Imaging of the Elbow: Introduction
The elbow may be considered as consisting of four quadrants, anterior, medial, lateral, and posterior. Ultrasound would normally be focused on only one or two of these quadrants depending on the clinical diagnosis.
Imaging includes the following:
Anterior
Brachialis muscle.
Brachial artery and vein.
Median nerve.
Anterior radiocapitellar joint.
Radial fossa.
Anterior humeroulnar joint.
Coronoid fossa.
Distal biceps tendon.
Lateral
Lateral epicondyle and common extensor tendon.
Radial collateral ligament including dynamic varus stress as indicated.
Radiocapitellar joint.
Medial
Medial epicondyle and common flexor tendon.
Ulnar collateral ligament including dynamic valgus stress as indicated.
Humeroulnar joint.
Ulnar nerve including dynamic scan for subluxation as indicated.
Posterior
Triceps tendon.
Olecranon process and olecranon bursa.
Olecranon fossa and posterior joint.
4.1.1 Anterior
Transverse Scan
The patient is seated opposite the clinician with the arm resting on a table. The elbow should be placed in extension and full supination. A few degrees of flexion may be of use if an effusion is suspected as full extension will tend to force any fluid from the anterior aspect of the elbow resulting in a false-negative result. The probe is placed in the anatomical transverse plane over the anterior aspect of the elbow (Fig. 4‑1 , Fig. 4‑2 , Fig. 4‑3 ).
As the elbow consists of two distinct articulations, two separate longitudinal views are required: one of the lateral radiocapitellar joint the other of the medial humeroulnar joint.
Radiocapitellar Joint
The elbow should be in extension and full supination. The probe is placed in the sagittal plane over the lateral half of the anterior aspect of the antecubital fossa.
Humeroulnar Joint
The elbow is maintained in extension and full supination. The probe remains in the sagittal plane and is moved medially over the medial half of the anterior aspect of the antecubital fossa (Fig. 4‑4 , Fig. 4‑5 ,Fig. 4‑6 ,Fig. 4‑7 , Fig. 4‑8 ).
The distal biceps tendon is best examined longitudinally. Transverse imaging is of little practical value due to anisotropy.
The forearm should be placed in full extension and supination to bring the radial tuberosity into an anterior position. The probe is aligned in an oblique orientation and aimed laterally a few degrees toward the radius. In addition, the probe may be “toed-in” distally to allow better visualization of the biceps tendon. Even so the tendon is difficult to image particularly in patients with muscular forearms or who have pathology involving the tendon and are reluctant to allow optimal positioning due to pain inhibition (Fig. 4‑9, Fig. 4‑10 , Fig. 4‑11 ).
Fig. 4.12 Longitudinal image of the distal biceps tendon (yellow arrows). The proximal tendon to the left of the image appears of normal fibrillar pattern. Distally toward the right and bottom of the image some tendon fibers can be seen. However, there is a 24-mm gap within the tendon indicating a complete rupture. RT, radial tuberosity.Fig. 4.13 (a) Longitudinal image of the distal biceps tendon. The tendon appears intact; however, there is evidence of a low echo collection deep to the tendon (white arrowheads). (b) Transverse image of the same tendon (yellow arrow) with evidence of a low echo swelling around the tendon (white arrowhead). The patient was a 32-year-old climber with insidious-onset elbow pain felt deep in the joint and aggravated with end range pronation. Findings are indicative of an effused bicipitoradial bursa in keeping with a diagnosis of a “climber’s elbow.” RH, radial head; RT, radial tuberosity; yellow arrow, distal biceps tendon; white arrowhead, fluid and thickening around the distal biceps tendon.
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