Which test is the most specific test to diagnose an ACL tear?

Correct Answer: A

Rationale: The correct answer is A: Pivot shift. This test is the most specific for diagnosing an ACL tear because it assesses the rotational instability of the knee joint, which is a key characteristic of an ACL injury. During the test, the examiner applies a valgus force and internal rotation to the knee while extending it, causing the tibia to subluxate anteriorly. If there is an ACL tear, the tibia will suddenly reduce back into place, producing a characteristic "pivot shift" movement. Summary of other choices: B: Lachman test - While also used to assess ACL integrity, it primarily evaluates anterior translation of the tibia and is not as specific for rotational instability. C: Anterior drawer sign - This test is primarily used to assess anterior translation of the tibia and is not specific to diagnosing an ACL tear. D: Ege's test - This test is not commonly used in clinical practice for diagnosing ACL tears.

Correct Answer: D

Rationale: The correct answer is D: Fast concentric. During fast concentric contractions, the muscle shortens quickly, generating the least force compared to other contractions. This is because the muscle fibers have less time to develop tension, resulting in lower force production. Slow eccentric contractions (choice A) generate more force as the muscle lengthens under tension. Fast eccentric contractions (choice B) produce more force than fast concentric contractions due to the muscle lengthening while under tension. Slow concentric contractions (choice C) generate more force than fast concentric contractions as the muscle shortens slowly, allowing for greater force development.

Correct Answer: D

Rationale: The correct answer is D: Fast concentric. Fast concentric contractions generate the least force because the muscle shortens quickly, leading to lower tension production compared to slow concentric contractions. In fast eccentric contractions (choice B), the muscle lengthens quickly, which can produce more force as it resists against gravity or an external load. Slow eccentric contractions (choice A) involve controlled lengthening of the muscle, resulting in higher force production compared to fast concentric contractions. Slow concentric contractions (choice C) involve controlled shortening of the muscle, leading to higher force production than fast concentric contractions.

Correct Answer: D

Rationale: The correct answer is D: Optic neuritis. Optic neuritis causes sudden, painful unilateral vision loss due to inflammation of the optic nerve. This condition often presents with reduced visual acuity, color vision changes, and afferent pupillary defect. Vitreous hemorrhage (A) typically causes painless vision loss, while central retinal artery occlusion (B) results in sudden painless vision loss. Macular degeneration (C) usually causes gradual central vision loss without pain.

Correct Answer: A

Rationale: The correct answer is A: Hepatitis A. Jaundice without risk factors for other types of hepatitis indicates an acute infection, which is most commonly caused by Hepatitis A virus. This virus is usually transmitted through contaminated food or water, making it more likely for a daycare worker to contract due to close contact with children. Hepatitis B is typically transmitted through blood or sexual contact, which the worker denies. Hepatitis C is also transmitted through blood, which is not reported. Hepatitis D requires Hepatitis B infection for replication, and since Hepatitis B is not indicated in this case, Hepatitis D is unlikely.