Hill – Sach’s lesion seen in:
**Core Concept**
Hill-Sachs lesions are a type of bony defect that occurs in the posterior aspect of the humeral head, typically resulting from an anterior shoulder dislocation. This occurs due to the head of the humerus impacting the anterior aspect of the glenoid, leading to a compression fracture of the humeral head.
**Why the Correct Answer is Right**
The mechanism of injury involves the humeral head being displaced anteriorly, causing it to compress against the anterior edge of the glenoid. This results in a fracture of the humeral head, forming a bony defect. The bone fragment that is typically displaced is a piece of the posterior-superior aspect of the humeral head, which is why Hill-Sachs lesions are often seen on MRI or CT scans as a bony defect in this region.
**Why Each Wrong Option is Incorrect**
* **Option A:** Not a valid option.
* **Option B:** Not related to Hill-Sachs lesions, which are a specific type of bony defect.
* **Option C:** Not a characteristic feature of Hill-Sachs lesions, which are typically seen in the posterior aspect of the humeral head.
**Clinical Pearl / High-Yield Fact**
A Hill-Sachs lesion is often associated with an anterior shoulder dislocation, and may be seen in conjunction with a Bankart lesion, which is a tear of the anterior glenoid labrum.
**Correct Answer:** A. Hill-Sachs lesions are seen in anterior shoulder dislocations.