Lateral epicondylitis, also known as tennis elbow, is an overuse syndrome of the common extensor tendon and predominantly affects the extensor carpi radialis brevis (ECRB) tendon.
Lateral epicondylitis occurs with a frequency seven to ten times that of medial epicondylitis. As with medial epicondylitis it typically occurs in the 4th to 5th decades of life. There is no recognised gender predilection.
Patients often present with lateral elbow pain, which is frequently exacerbated when they grasp objects during wrist extension with resistance. A history of tennis playing or similar racket sports is sometimes elicited, but the condition often results from other repetitive athletic or occupational activities, or without an identifiable cause.
It is thought that repetitive stress and overuse leads to tendinosis involving the origin of the extensor tendons at the lateral elbow, with microtrauma and partial tearing that may progress to a full-thickness tendon tear. Alternatively, it may also result from direct trauma.
MR imaging is the most widely used modality, although ultrasound may also be performed.
Up to 25% of patients with lateral epicondylitis may have calcification within the soft tissue around the lateral epicondyle.
Thickening of the common extensor tendon, associated with diffuse heterogeneity and areas of focal hypoechogenicity. There is often associated intra-tendon calcification and bony irregularity at the tendon insertion. The most common finding in a patient with lateral epicondylitis is focal areas of hypoechogenicity with a background of intrinsic tendinopathy.
The hallmarks of tendinosis and tearing of the common extensor tendon on MRI are abnormal morphology and signal intensity, as follows 7:
- the best diagnostic clue for diagnosis of lateral epicondylitis is abnormal thickening and increased signal intensity within the common extensor origin from the lateral epicondyle
- abnormal thickening and abnormal separation of the radial collateral ligaments and the extensor carpi radials brevis (ECRB) tendon with granulation tissue
- the imaging findings of tendinosis must be correlated with clinical data of lateral epicondylitis because if the patient is asymptomatic in presence of these findings, the case may be attributed to subclinical diagnosis or early tendon degeneration.
- partial or even full thickness tear of the ECRB tendon complicating tendinosis may be encountered in patient with lateral epicondylitis. It is manifested as fluid filled gap with or without loss of fibre continuity.
- peritendon oedema and associated focal bone marrow oedema at the site of tendon attachment to the humerus may simulate avulsion injury
- in chronic cases increased signal intensity of the nearby anconeus muscle may be seen
- associated radial nerve entrapment may occur in 5% of cases
- radial collateral ligament may also be disrupted
Treatment and prognosis
Autologous blood injection has been shown to more effective at long-term relief than corticosteroid injection, with 90% of patients in one study being pain-free at six months 5. Whole blood injection has been shown to be just as a effective as platelet-rich plasma injection and is also much less expensive 6.
Surgery is often performed if there is no clinical response after 3 to 6 months of conservative treatment.
History and etymology
It was initially described by Henry Morris as “lawn tennis arm” in 1882 9 and now most commonly termed as tennis elbow.
For a clinical differential diagnosis of lateral elbow pain, consider:
- occult fracture
- osteochondritis dissecans of the capitellum
- lateral osteoarthrosis
- lateral ulnar collateral ligament (LUCL) instability
- radial tunnel syndrome
- 1. Walz DM, Newman JS, Konin GP et-al. Epicondylitis: pathogenesis, imaging, and treatment. Radiographics. 2010;30 (1): 167-84. doi:10.1148/rg.301095078 - Pubmed citation
- 2. Connell D, Burke F, Coombes P et-al. Sonographic examination of lateral epicondylitis. AJR Am J Roentgenol. 2001;176 (3): 777-82. AJR Am J Roentgenol (full text) - Pubmed citation
- 3. Levin D, Nazarian LN, Miller TT et-al. Lateral epicondylitis of the elbow: US findings. Radiology. 2005;237 (1): 230-4. doi:10.1148/radiol.2371040784 - Pubmed citation
- 4. Potter HG, Hannafin JA, Morwessel RM et-al. Lateral epicondylitis: correlation of MR imaging, surgical, and histopathologic findings. Radiology. 1995;196 (1): 43-6. Radiology (abstract) - Pubmed citation
- 5. Dojode CM. A randomised control trial to evaluate the efficacy of autologous blood injection versus local corticosteroid injection for treatment of lateral epicondylitis. Bone Joint Res. 2012;1 (8): 192-7. doi:10.1302/2046-3758.18.2000095 - Free text at pubmed - Pubmed citation
- 6. Raeissadat SA, Rayegani SM, Hassanabadi H et-al. Is Platelet-rich plasma superior to whole blood in the management of chronic tennis elbow: one year randomized clinical trial. BMC Sports Sci Med Rehabil. 2014;6 (1): 12. doi:10.1186/2052-1847-6-12 - Free text at pubmed - Pubmed citation
- 7.Christine B. Chung, Lynne S. Steinbach. MRI of the Upper Extremity. ISBN: 9780781753135
- 8. Schuenke M, Schulte E, Schumacher U et-al. General Anatomy and Musculoskeletal System (THIEME Atlas of Anatomy). Thieme. ISBN:1604062924. Read it at Google Books - Find it at Amazon
- 9. Flatt AE. Tennis elbow. (2008) Proceedings (Baylor University. Medical Center). 21 (4): 400-2. Pubmed
- elbow anatomy
- elbow radiography
- MRI of the elbow - an approach
- supracondylar humeral fracture
- epicondyle fracture
- humeral condyle fracture
- transphyseal fracture
- radial head fracture
- radial neck fracture
- coronoid process fracture
- olecranon fracture
- Panner disease (osteochondrosis of the capitellum)