Fracture involving both the malleoli is
**Core Concept**
A bimalleolar fracture involves a break in both the medial (inner) and lateral (outer) malleoli of the ankle, which are part of the distal tibia and fibula bones. This type of fracture is often associated with significant trauma and ankle instability.
**Why the Correct Answer is Right**
A bimalleolar fracture typically occurs when the ankle is subjected to a severe twisting force, causing a break in both the medial and lateral malleoli. The medial malleolus is formed by the distal end of the tibia, while the lateral malleolus is formed by the distal end of the fibula. The break in both malleoli leads to instability and potential displacement of the ankle joint. The classification of bimalleolar fractures is based on the severity and location of the fracture, with types including medial and lateral malleolar fractures, as well as a trimalleolar fracture which involves the posterior malleolus.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify the involvement of both malleoli, which is a defining characteristic of a bimalleolar fracture.
**Option B:** This option is incorrect because it is a type of fracture that involves the posterior malleolus, but not both the medial and lateral malleoli.
**Option C:** This option is incorrect because it is a type of fracture that involves the medial malleolus, but not the lateral malleolus.
**Clinical Pearl / High-Yield Fact**
A bimalleolar fracture requires prompt and accurate diagnosis to prevent long-term ankle instability and potential arthritis. A thorough physical examination and imaging studies, such as X-rays, are essential for diagnosing this type of fracture.
**Correct Answer:** B.