An inability to extend the knee when the leg is flexed at 90° is known as:

Appeared in: DSSSB 12 August 2024

Explanation

The inability to straighten the leg (extend the knee) when the hip is flexed at a 90-degree angle is the classic definition of a positive Kernig's sign.
This sign indicates irritation of the meninges, the membranes that cover the brain and spinal cord.
It is a key physical assessment finding in patients with suspected meningitis or subarachnoid hemorrhage.
The pain and resistance are caused by the stretching of inflamed nerve roots (specifically the sciatic nerve) that pass through the inflamed meninges.

Option A: This tests for carpal tunnel syndrome, a condition affecting the median nerve in the wrist, not meningeal irritation.
Option B: This is a sign of hypocalcemia (low blood calcium) and is unrelated to the neurological assessment for meningitis.
Option D: Although this is also a sign of meningeal irritation, it is elicited by flexing the patient's neck, not by manipulating the leg.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Physical assessment for meningeal irritation as background academic context rather than a clinical decision trigger.
Recognizing Kernig's and Brudzinski's signs is a critical nursing skill for the early detection of life-threatening conditions like bacterial meningitis.
A positive finding is a red flag that requires immediate notification of the physician and preparation for urgent diagnostic procedures, such as a lumbar puncture to analyze cerebrospinal fluid (CSF).
Early diagnosis and initiation of antibiotic therapy are crucial to prevent severe neurological complications or death from meningitis.

How to Approach the Question

First, analyze the question stem to identify the specific clinical maneuver being described: 'inability to extend the knee when the leg is flexed at 90°'.
This is a factual recall question that tests your knowledge of specific diagnostic signs used in physical assessment.
Systematically review the definition of each sign provided in the options.
Recall that Phalen's sign is for carpal tunnel (wrist) and Trousseau's sign is for hypocalcemia (tetany). This eliminates options A and B.
Differentiate between the two signs for meningeal irritation: Kernig's sign involves the knee/leg, while Brudzinski's sign involves the neck.
Match the description in the stem to the correct definition. The maneuver described perfectly matches the procedure for eliciting Kernig's sign.

Concept Tested & Keywords

Concept Tested: Physical assessment for meningeal irritation
Stem keywords: inability to extend the knee, leg flexed at 90°, meningeal irritation
Lead-in keywords: known as
Negative lead-in flag: false

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Practise the full DSSSB 12 August 2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.