Painful elbow is not always tennis elbow

Even the medical term for tennis elbow is difficult to find; many synonyms are used, but by definition most of them are not fully accurate.

By means of histological studies, it could be shown that there is no inflammatory (tendinitis) but rather a degenerative (tendinosis) disease of the tendon.
Thus, the term "epicondylitis humeri radialis" (inflammation of the outer epicondyle of the humerus) as a synonym for tennis elbow is misleading.

"Epicondylopathia humeri radialis" (painful disease of the epicondyle of the humerus) is another common but not fully accurate term, as it is not a disease of the epicondyle.
Therefore, when tennis elbow is reported, it is usually still referred to under the diagnostic collective terms "epicondylitis" or "epicondylagia" (lateral elbow pain).

Keypoints

I. Tennis elbow is not an inflammation, but a degenerative disease (angiofibroblastic hyperplasia) of the tendons of the extensors (especially the extensor carpi radialis brevis muscle).1

II. the most important differential diagnoses of a painful lateral elbow2:

• Tennis elbow
•  Elbow instability (posterolateral rotational instability)
• Pinching fold of the joint mucosa (plica radialis)
• Aseptic necrosis of the bone below the articular cartilage (osteochondrosis dissecans/pathology of the radiocapitellar cartilage).
• Nerve compression (radial nerve)
• Irritation or damage to a nerve root of the cervical spine (radiculopathy)

¹ Schneider, M. M. et al., 2018. Tennis elbow - the value of manual and surgical therapy. Manual Medicine, 2(56), pp. 133-146.
² Vavken, P., 2018. evidence-based treatment of lateral elbow pain. Orthopaedics & Rheumatology, Issue 3, pp. 62-65.