Benedict’s hand is due to injury to
**Core Concept**
Benedict's hand, also known as Bennett's fracture, is a type of intra-articular fracture of the thumb's basal joint, specifically involving the first metacarpal bone. This injury is often caused by a forceful abduction and rotation of the thumb, resulting in a fracture of the metacarpal neck with or without dislocation of the carpometacarpal joint.
**Why the Correct Answer is Right**
The mechanism of injury involves a combination of axial loading and rotational force, leading to a fracture of the metacarpal neck. The fracture often occurs at a right angle to the joint surface, resulting in a displaced and potentially unstable fracture. The carpometacarpal joint, which is a saddle joint, is highly dependent on the integrity of the metacarpal bone for its stability and function.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the correct bone involved in Benedict's hand. The fracture is not primarily associated with the phalanges or the metacarpal shaft.
**Option B:** This option is incorrect because it does not accurately describe the joint involved in Benedict's hand. The carpometacarpal joint, specifically the first carpometacarpal joint, is the joint affected by the fracture.
**Option C:** This option is incorrect because it does not specify the correct mechanism of injury. While Bennett's fracture can occur due to a fall onto an outstretched hand, the primary mechanism involves a forceful abduction and rotation of the thumb.
**Clinical Pearl / High-Yield Fact**
Benedict's hand is a classic example of an intra-articular fracture that requires precise reduction and immobilization to restore joint stability and function. Failure to properly manage this fracture can result in chronic pain, reduced dexterity, and joint degeneration.
**Correct Answer: B. Carpometacarpal joint.**