Common Extensor Tendon

The lateral compartment of the elbow includes the extensor muscles of the wrist and hand that arise from the lateral epicondyle as the common extensor tendon , the brachioradialis, the extensor carpi radialis longus and the supinator muscles. 

The lateral aspect of the elbow is best examined with both elbows in extension, thumbs up, palms of the hands together (Barr and Babcock 1991). When examining the radial collateral ligament and the capsule, the elbow should be extended, keeping the hand pronated. Along the lateral elbow, high-resolution US can demonstrate the common extensor tendon, the lateral ulnar collateral ligament, the radial nerve with its superficial and deep (posterior interosseous nerve) branches, and the radio-capitellar joint. 

The common extensor tendon origin is best visualized in longitudinal planes as a beak-shaped hyperechoic structure located between the subcutaneous tissue and the lateral ulnar collateral ligament (Fig. 8.18). Deep to this tendon, the lateral epicon-dyle appears as a smooth down-sloping hyperechoic structure. The individual contributions from the extensor muscles to the common extensor tendon cannot be discriminated with US because they are... 

The most common disorder involving the lateral elbow is lateral epicondylitis, also known as tennis elbow , caused by repetitive traction on the osteoten-dinous attachment of the common extensor tendon (Regan et al. 1992). This condition can be the result of... 

In lateral epicondylitis, the lateral elbowligamentous complex, and especially the lateral ulnar collateral ligament, should be routinely assessed because this ligament is commonly injured in association with tears of the common extensor tendon as a result of the same forces or overuse mechanisms on adjacent structures (Bredella et al. 1999). An unsuspected tear of this ligament may be the cause of conservative therapy failure in patient with lateral epicon-... 

Fig. 8.41. Partial-thickness tear of the common extensor tendon. Long-axis 12-5 MHz US image in a manual laborer who presented with acute onset of lateral elbow pain reveals a linear hypoechoic split star) extending from the lateral epicondyle (LE) through the substance of the common extensor tendon origin. The torn deep libers arrowheads) are retracted just distal to the hypoechoic area. Note the integrity of the underlying lateral ulnar collateral ligament asterisks). RH, radial head...

Common extensor tendon from the lateral epicondyle of humerus. 

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