Question

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R).
Assertion (A) : Excessive craniocaudal movement of the tibia relative to femur is called cranial drawer.
Reason (R) : Cranial drawer occurs due to rupture of cruciate ligament.
In light of the above statements, choose the correct answer from the options given below

• A. Both (A) and (R) are true and (R) is the correct explanation of (A).
• B. Both (A) and (R) are true and (R) is NOT the correct explanation of (A).
• C. (A) is true but (R) is false.
• D. (A) is false but (R) is true.

Hint:

- Cranial drawer sign = Rupture of the Cranial Cruciate Ligament (tibia moves cranially).
- Caudal drawer sign = Rupture of the Caudal Cruciate Ligament (tibia moves caudally).

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The stifle joint (femorotibial joint) is stabilized by several intra-articular and extra-articular ligaments. Rupture of these ligaments leads to joint instability, which can be diagnosed through specific manipulative physical tests.

Step 2: Detailed Explanation:
Let us analyze both statements and their relationship:
- Assertion (A):
In a normal stifle joint, the tibia is prevented from sliding forward or backward relative to the femur.
When the stifle is held and manipulated, any abnormal or excessive forward (cranial) or backward (caudal) translation of the tibia relative to the femur is referred to as the "drawer sign" or "drawer movement".
Therefore, Assertion (A) is correct.
- Reason (R):
The primary structures that prevent this translation are the intra-articular cranial and caudal cruciate ligaments.
The cranial cruciate ligament (CCL) specifically prevents the tibia from sliding cranially relative to the femur.
When the CCL is ruptured, this restraint is lost, allowing the tibia to be pushed forward during manipulation (the cranial drawer sign).
Therefore, Reason (R) is correct.
- Relationship between (A) and (R):
The cranial drawer sign (the excessive craniocaudal sliding of the tibia) occurs precisely because of the rupture of the cruciate ligament, which normally acts as the mechanical block to this movement.
Therefore, (R) is the direct, correct biological explanation of (A).

Step 3: Final Answer:
The correct option is (A).