Tennis, golfer's elbow and bursitis
The most common cause of elbow pain is lateral epicondylitis, or tennis elbow: a degenerative-inflammatory change at the insertion of the extensor tendons on the lateral epicondyle. Ultrasound shows thickening and heterogeneity of the tendon, microtears, calcifications and increased blood flow in the Doppler mode, and also makes it possible to distinguish this pathology from damage to the radial collateral ligament, which determines treatment tactics. The mirror condition on the inside is medial epicondylitis, golfer's elbow.
Olecranon bursitis appears as a noticeable swelling on the back of the elbow. Ultrasound distinguishes fluid accumulation from a dense formation, evaluates the nature of the contents, which is important when infection is suspected, and identifies gouty tophi and rheumatoid nodules inside the bursa. The puncture is performed under ultrasound guidance.
A separate task is the ulnar nerve in the cubital canal. Ultrasound measures its thickness during compression and - what is especially valuable - reveals subluxation of the nerve when bending the elbow: the nerve slips out of the groove, causing lumbago in the little finger. This mechanism is visible only when examined in motion, and no static photograph will show it.
What can be seen on an ultrasound of the joint
Ultrasound, better than any other method, shows the soft tissues surrounding the joint: tendons and their sheaths, ligaments, muscles, synovium, joint capsules and peripheral nerves. It reliably detects free fluid in the joint cavity and bursae, tendon ruptures and tears, cysts, bursitis and tendinitis.
There are also fundamental limitations. Ultrasound does not pass through the bone, so the internal structures - menisci along the entire length, cruciate ligaments, articular cartilage deep in the joint, bone marrow - remain inaccessible. They use magnetic resonance imaging, and X-rays are used to evaluate the bone itself.
The main advantage is exploration in motion
Unlike MRI, which takes a picture of a motionless joint, ultrasound allows you to look at the joint in dynamics. The doctor asks you to bend, straighten or rotate the limb straight during the scan and sees how the tendons and ligaments behave under load.
Many conditions manifest themselves only during movement: tendon subluxation from the groove, impingement, trigger finger, ligament instability. At rest, the picture looks normal, and without functional tests the diagnosis cannot be made.
When to start with ultrasound
Ultrasound is reasonable as the first method for pain and swelling of the joint without injury, for suspected bursitis, tendinitis and cysts, for monitoring the treatment of inflammatory diseases and, if necessary, to induce a puncture or blockade.
If there was a serious injury with a suspected fracture, you need to start with an x-ray. If a torn meniscus or cruciate ligament is suspected, MRI remains the method of choice.