A knee ultrasound visualizes soft-tissue structures: joint effusion, synovial thickening, bursitis, Baker’s cysts, tendon tears or tendinopathy (patellar, quadriceps), superficial ligament injuries, calcifications, and guides fluid aspiration or injections. Doppler detects increased blood flow from inflammation. It is limited for deep intra‑articular structures (e.g., menisci, cruciate ligaments) and bone marrow—MRI is better for those.

Therapeutic ultrasound can reduce knee osteoarthritis pain and stiffness short-term for some people, but evidence for long-term benefit or improved function is limited and mixed. Diagnostic ultrasound is useful for evaluating soft-tissue causes (tendons, bursae). It’s generally safe when applied by trained clinicians, but usually serves as an adjunct to exercise, weight management, and other treatments. Discuss suitability with your healthcare provider.

Position the patient supine or seated with the knee slightly flexed (about 20–30°) and a pillow for support. Use a high‑frequency linear transducer with ample gel. Scan longitudinal and transverse planes across the suprapatellar recess, patellar/quadriceps tendons, medial and lateral joint lines, and the popliteal fossa. Perform dynamic maneuvers, use color Doppler for hyperemia, compare the contralateral knee, and document images and measurements.

To prepare for a knee ultrasound, wear loose, easily removable clothing and avoid lotions or oils on the knee. Bring any prior imaging or reports and a list of medications. You may need to change into a gown and remove jewelry. Inform staff about implants, allergies, anticoagulant use, or pregnancy. No fasting is required; arrive a few minutes early and follow clinic instructions.

Knee ultrasound is very safe and uses no ionising radiation. Risks are minimal: mild discomfort from probe pressure or topical gel irritation, and rare allergic skin reactions. When used to guide injections or aspirations, additional risks include infection, bleeding, or nerve injury. Accuracy depends on operator skill and ultrasound may miss deep or bony pathology, so results can be limited.

MRI is generally the best scan for most knee problems because it visualizes ligaments, menisci, cartilage and bone marrow. X‑rays are first‑line for fractures and arthritis; CT is useful for complex bony injuries; ultrasound can assess effusions and superficial soft tissues. The ideal imaging depends on symptoms and clinical examination, so follow your doctor’s recommendation.