What are some of the potential uses of ultrasound in the evaluation of musculoskeletal conditions?
Ultrasound is well suited to detect abnormalities of superficial structures. High-frequency linear transducers offer high spatial resolution.
Potential indications include:
- • Tendon pathology: Tears and inflammation in tendons such as the posterior tibial tendon, Achilles tendon, shoulder, or finger tendons are well demonstrated. Fluid in the tendon sheath is also well visualized. Flexor tenosynovitis may be early predictor for persistent RA development.
- • Enthesitis: Can detect inflammatory enthesitis in peripheral areas.
- • Soft tissue masses: Non-radiopaque foreign bodies are often invisible on radiographs but are well demonstrated by ultrasound.
- • Joint and bursal inflammation: Synovitis and effusions of superficial joints are well shown. Can show “double contour” sign in gouty arthritis patients and hyperechoic chondral deposits in chondrocalcinosis. Can be used to predict evolution of RA and to follow disease activity and structural progression.
- • Guide articular and periarticular aspiration and/or injections.
- • Parotid and submandibular glands: Can detect changes compatible with Sjögren’s syndrome.
- • Nerve entrapment: Diagnose median nerve, ulnar nerve, and posterior tibial nerve entrapment.
Pitfalls of ultrasound imaging include:
- • Operator dependence: The accuracy of ultrasound is highly affected by the training level and experience of the user. Certain structures such as the metacarpal head may demonstrate a normal defect that simulates an erosion. Radiographs are needed for comparison and confirmation.
- • Deep central portions of joints are obscured: Cartilage and meniscal injuries are usually not visible.