Ultrasonography in Orthopaedic Practice
DNB Orthopaedics • June 2014 • Paper I • 10 Marks
Introduction
Ultrasonography (USG) is a non-invasive imaging modality that uses high-frequency sound waves to generate real-time images of tissues. In orthopaedics, it is particularly useful for assessment of superficial soft tissues, tendons, muscles, ligaments, bursae, peripheral nerves, joints and collections.
Unlike plain radiography and CT, ultrasound does not use ionising radiation, and unlike MRI, it permits dynamic examination during movement and can be used for real-time image-guided procedures.
Key concept
Orthopaedic ultrasound is especially valuable where the pathology is superficial, dynamic or requires image-guided intervention.
Definition
Ultrasonography is an imaging technique in which high-frequency mechanical sound waves are transmitted into tissues and the returning echoes are detected and converted into an image according to their amplitude, timing and frequency characteristics.
Principles of Ultrasonography
1. Ultrasound Waves
Ultrasound consists of sound waves with frequencies above the audible range of the human ear. Diagnostic musculoskeletal ultrasound generally uses frequencies in the megahertz range.
| Probe frequency | Characteristics | Typical use |
|---|---|---|
| High frequency | Better spatial resolution but poorer tissue penetration | Tendons, ligaments, nerves, superficial muscles and small joints |
| Lower frequency | Greater penetration but lower resolution | Deeper structures such… |