Of all the large joints in the body, the elbow is most suited to ultrasound examination. The open architecture of the elbow joint allows ultrasound access from many acoustic windows and the vast majority of important structures are readily accessible to ultrasound assessment.
This lecture will provide a comprehensive overview of elbow ultrasound beginning with techniques for assessment of elbow joint effusions and haemarthrosis.
The most common indication for elbow ultrasound is assessment of lateral epicondyle pain “tennis elbow”. Tendinosis of the common extensor origin (CEO) is often the result of repetitive work practices leading to time off work and the associated negative financial and social consequences. It is important to diagnose and manage CEO pathology in an accurate and expeditious manner, allowing a return to work and resumption of leisure activities.
The layered anatomy of the CEO will be described with particular emphasis on the enthesis footprints and collagen bundles of the individual components. The sonographic technique for differentiating individual components of the CEO in long axis and in short axis imaging will be discussed. In particular accurate localisation of the extensor carpi radialis brevis component of the CEO allowing accurate diagnosis of tendonopathy and placement of a variety of ultrasound guided therapeutic interventions.
Sonographic technique for assessment of the lateral collateral ligament structures will be discussed including diagnostic clues and provocative tests that assist the diagnosis of ligament failure.
The posterior interosseous nerve (PIN) will be explored as a cause of lateral elbow and dorsal forearm muscle pain or weakness. A technique is described for tracking the deep branch of the radial nerve from the upper arm through the Arcade of Frohse and into the supinator muscle. Common causes of entrapment and useful dynamic provocative tests are demonstrated.
The common flexor origin (CFO) will be discussed with an emphasis on patient positioning and targeted scanning of the enthesis and common tendon unit.
Assessment of the anterior band of the ulnar collateral ligament is an important extension to routine golfers elbow examinations.
The biceps brachii tendon insertion onto the radial tuberosity is an area that is traditionally difficult to assess with ultrasound. A variety of factors including anisotropy, deep location and poor quality acoustic window through muscle belly edges result in a technical challenge. A method of sonographic assessment using the pronator teres muscle belly as an acoustic window will be demonstrated allowing high-resolution assessment of the tendon insertions and the associated bicipito-radial bursa. This technique allows the examination to be extended beyond intact Vs ruptured differentiation to include more subtle findings such as tendinosis, partial tears and avulsions. The resulting images are of high resolution and diagnostic quality allowing visualization of the normal enthesis fibrocartilage at the tendon insertion. It is now possible to differentiate the individual long and short head tendons at their radial tuberosity insertions and “single head” injuries may now be diagnosed sonographically. A potential pitfall of accidental assessment of the brachialis insertion onto the ulna will be discussed and a simple dynamic maneuver will be demonstrated to avoid this pitfall. Two additional techniques will also be described for extended assessment of the biceps brachii apparatus. The first technique concentrates on high resolution assessment of the enthesis on the radial tuberosity. The second technique allows assessment of the musculotendinous junction and dynamic assessment of the biceps brachii apparatus.
Ulnar nerve assessment in the cubital tunnel will be explored in detail with an emphasis on assessment of the “roof and floor” of the tunnel as potential causes of ulnar neuropathy. A new technique for dynamic assessment of the ulnar nerve in the cubital tunnel will be discussed focusing on assessment of not only subluxation but extrinsic compression by the Osborne ligament. Extrinsic compression of the ulnar nerve during flexion results in the “pacman sign” which will be introduced as a new concept in ulnar nerve sonographic dynamic assessment. The concept of applying the median nerve wrist to forearm ratio concept to the ulnar nerve in the cubital tunnel will also be discussed as a potentially useful measurement parameter.
The posterior elbow will be briefly discussed with triceps, olecranon recess and posterior fat pad assessment techniques being explored.