Which of the following holds TRUE of the Hill-Sachs lesion of the shoulder?

Correct Answer: C

Rationale: The correct answer is C because a Hill-Sachs lesion is indeed a compression fracture of the posterolateral aspect of the humeral head caused by abutment against the anterior rim of the glenoid fossa. This occurs during anterior shoulder dislocations. Option A is incorrect because a Hill-Sachs lesion is associated with anterior, not posterior, dislocations. Option B is incorrect because shoulder instability due to a Hill-Sachs lesion depends on the size and location of the defect, not a specific percentage of the articular surface. Option D is incorrect because Speed's test is used to assess biceps tendon pathology, not Hill-Sachs lesions.

Correct Answer: D

Rationale: The correct answer is D because a swan neck deformity is characterized by hyperextension of the metacarpophalangeal (MCP) and proximal interphalangeal (PIP) joints, along with flexion deformity at the distal interphalangeal (DIP) joint. This leads to a finger resembling a swan's neck shape. Choice A is incorrect because it describes hyperextension at the DIP joint, which is not typical of a swan neck deformity. Choice B is incorrect as it refers to synovitis and ligament disruption at the ulnar styloid, which is unrelated to a swan neck deformity. Choice C is incorrect as it describes hyperextension at the DIP joint instead of flexion deformity. In summary, the correct answer, D, accurately describes the key features of a swan neck deformity, making it the most appropriate choice among the options provided.

Correct Answer: B

Rationale: The correct answer is B: Melanocytes. Melanocytes are responsible for producing melanin, the pigment that gives skin its color. In burn patients, destruction of melanocytes leads to hypopigmentation as there is a reduced or absence of melanin production. Keratinocytes (A) are the most abundant cells in the epidermis, but they do not contribute to skin pigmentation. Basement membrane (C) provides structural support but does not play a direct role in skin pigmentation. Hair follicles (D) are primarily involved in hair growth and do not affect skin pigmentation directly.

Correct Answer: D

Rationale: The correct answer is D: Solid ankle cushioned heel (SACH). This term describes a common type of prosthetic foot design with a solid ankle and a cushioned heel. The solid ankle provides stability and support, while the cushioned heel helps absorb shock during walking. Choice A is incorrect because it does not accurately describe the components of a SACH foot. Choice B is incorrect as it refers to a different type of prosthetic foot design. Choice C is also incorrect as it does not represent the correct acronym for SACH.

Correct Answer: C

Rationale: The correct answer is C: Arterial insufficiency. Cold therapy constricts blood vessels, which can worsen arterial insufficiency by further reducing blood flow. Acute sprains, chronic muscle spasms, and spasticity benefit from cold therapy due to its ability to reduce inflammation, pain, and muscle spasm respectively. Cold therapy is contraindicated for arterial insufficiency as it can exacerbate the condition by further compromising blood flow.