What is a goniometer used for?

A goniometer is specifically designed to measure angles, particularly the range of motion in joints. This instrument allows healthcare professionals, such as physical therapists, to quantify how much a joint can move in various directions. By measuring these angles, practitioners can assess a patient's mobility, track changes in joint function over time, and evaluate the effectiveness of treatment or rehabilitation programs.

Measuring muscle strength, assessing joint stability, or diagnosing injuries involves different tools and methods. Muscle strength is typically evaluated using handheld dynamometers or functional tests. Joint stability can be assessed through specific physical examination techniques and tests that check for ligament integrity. Diagnosing injuries may require imaging tools like X-rays or MRI, along with clinical assessments, rather than just measuring angles. Thus, the unique function of the goniometer as an angle-measuring device makes it the correct answer to the question.