Clinical history: 40 year old male carpenter with lateral elbow pain. Fat-suppressed T2-weighted coronal (1a) and axial (1b) images demonstrate the abnormality. What is your diagnosis?
1a
1b
Figure 1:
Fat-suppressed T2-weighted coronal (1a) and axial (1b) images demonstrate the abnormality.
Answer
2a
2b
Figure 2:
Coronal (2a) and axial (2b) fat-suppressed T2-weighted images demonstrate T2-hyperintensity compatible with an undersurface partial tear of the common extensor tendon origin (arrows). The radial collateral ligament (arrowhead) is mildly thickened but intact.
Diagnosis
Lateral epicondylitis
Discussion
The lateral elbow is a frequent site of work and sports-related overuse injury. Lateral epicondylitis is the most commonly encountered overuse syndrome in the elbow. This entity is seen in patients performing repetitive wrist extension, supination, heavy lifting, or excessive gripping. While lateral epicondylitis is overwhelmingly encountered in the workplace, it is popularly associated with tennis and is thus often referred to as “tennis elbow”.1
Lateral epicondylitis is a degenerative condition, which affects the extensor tendons of the hand and wrist at their origin. The extensor carpi radialis brevis tendon is almost always the primary site of tendon pathology with variable involvement of the other wrist extensors arising from the common extensor tendon.
3a
3b
3c
3d
Figure 3:
Normal anatomy: T2-weighted fat-suppressed coronal (3a), T1-weighted coronal (3b), and T2-weighted axial (3c and 3d) images demonstrate the common extensor tendon (arrows) as low signal intensity on T2 and T1-weighted images. The radial collateral ligament (arrowheads) is seen deep to the common extensor tendon.
The pathologic process in lateral epicondylitis is more appropriately termed a chronic tendinosis, since inflammatory cells are not a predominant histologic feature. The injury begins with angiofibrotic degeneration resulting in microscopic tears of the extensor tendons of the wrist and hand.2 With continued activity, the tendon may progress to macroscopic partial tearing at its undersurface and eventually to complete rupture.
Tendon degeneration is identified as intermediate to increased signal on T1 and T2-weighted images with associated alteration in tendon morphology. Partial thickness tears almost always occur as an undersurface partial avulsion of the common extensor origin from the lateral epicondyle. Both complete and partial tears typically demonstrate T2 hyperintensity, resulting from fluid filling the tendon defect. Coronal and axial T2-weighted fat-suppressed images are best for making this diagnosis.
Treatment options are controversial. Conservative management is often tried initially. In patients who are refractory to conservative regimens, MRI can establish the extent of tendon injury and assess for a coexisting radial collateral ligament injury (4a), which may hinder the patient’s response to conservative therapy. In addition, the lack of expected MRI changes in a patient with suspected lateral epicondylitis suggests radial nerve entrapment, which may mimic or coexist with lateral epicondylitis.3
4a
Figure 4:
(4a) Coronal T2-weighted fat-suppressed image demonstrates an undersurface partial thickness tear of the common extensor tendon (arrow) and an associated tear of the radial collateral ligament (arrowhead).
Conclusion
Lateral epicondylitis is among the most frequently diagnosed injuries at the elbow. In patients who fail to respond to conservative measures, MRI can accurately evaluate the common extensor tendon origin and detect coexisting conditions that may require surgical correction.
References
1 Frostick SP, Mohammad M, Ritchie DA. Sport injuries of the elbow. Br J Sports med 1999;33(5):301-11.
2 Nirschl RP. Elbow tendinosis/tennis elbow. Clin Sports Med 1992;11(4):851-70.
3 Lubahn JD, Cermak MB: Uncommon nerve compression syndromes of the upper extremity. J Am Acad Orthop Surg 1998 Nov-Dec; 6(6): 378-86.