What is the purpose of Phalen's sign in a clinical setting?

Phalen's sign is a physical examination maneuver specifically designed to assess for carpal tunnel syndrome, which is a condition caused by the compression of the median nerve as it travels through the wrist. The test involves having the patient flex their wrists at a 90-degree angle and hold that position for about 60 seconds. If the patient experiences pain, tingling, or numbness in the fingers innervated by the median nerve (typically the thumb, index, middle, and part of the ring finger), this is indicative of carpal tunnel syndrome.

The other options involve different assessments entirely. Evaluating knee joint stability typically utilizes different tests such as the Lachman test or the McMurray test. Thyroid function is assessed through blood tests measuring hormone levels and not through a physical maneuver like Phalen's sign. Diagnosing a navicular fracture would require imaging studies, such as an X-ray, rather than a physical examination test associated with nerve function. Thus, the correct purpose of Phalen's sign is directly related to the diagnosis of carpal tunnel syndrome.