Lateral epicondylitis (tennis elbow), is a very familiar term used to describe pain on the outside (lateral aspect) of the elbow.
Usually affects middle aged patients with equal preponderance in males and females. Peak incidence is reported to be in early 50s.
Exact pathological process is still unclear, but is believed to be initiated as a microtear within the origin of the extensor carpi radialis brevis (ECRB). In later stage it can involve other tendons of the common extensor origin like extensor carpi radialis longus and the extensor digitorum communis.
Pain during activities that require repetitive supination and pronation of the forearm with the elbow in near full extension. Classically these movements are replicated when serving in Tennis, hence the name.
Pain typically gets worse when gripping small objects or when twisting the forearm as in turning handle of a door.
The pain may sometimes radiate into forearm or wrist, but not upwards into arm.
Tenderness, typically just distal and anterior to the lateral epicondyle.
Exacerbation of pain by resisted wrist dorsiflexion and forearm supination (Couzen’s test).,
Very rarely there may be swelling.
MRI: Tendon thickening with increased T1 and T2 signal intensity of the extensor carpi radialis brevis (ECRB) at the lateral epicondyle.
Plain X-ray: usually normal, but helps to exclude other conditions like calcific tendinitis or osteoarthritis of lateral compartment.
US: confirms inflammation or tears but is very operator dependant.
Microscopy: Histological examination may show immature inflammatory tissue.
Radial Plica: This is a synovial fold proximal to the annular ligament and blending into capsule superiorly. A thickened plica can mimic symptoms of tennis elbow. It can be difficult to diagnose on MRI, arthroscopy is diagnostic.
Osteochondritis dissecans of the capitellum: usually will present with locking due to loose body.
Lateral compartment arthritis: Other signs might include stiffness, intermittent swelling or synovitis.
Radial tunnel syndrome: It is a result of compression of the posterior interosseous nerve (PIN) in the radial tunnel. It is a diagnosis of exclusion, and the pain is usually located 3 to 4 cm distal to the lateral epicondyle.