Commonest dangerous complication of posterior dislocation of knee is
**Core Concept**
Posterior dislocation of the knee is a serious injury that occurs when the tibia (shin bone) moves out of place and moves posteriorly (backward) relative to the femur (thigh bone). This can lead to various complications, including damage to surrounding structures and blood vessels.
**Why the Correct Answer is Right**
The commonest dangerous complication of posterior dislocation of the knee is popliteal artery injury. The popliteal artery is a major artery that runs through the popliteal fossa (the back of the knee) and supplies blood to the lower leg. In a posterior dislocation of the knee, the popliteal artery can become compressed or even torn, leading to ischemia (reduced blood flow) and potentially resulting in limb ischemia or even amputation if not promptly treated.
**Why Each Wrong Option is Incorrect**
* **Option A:** Fracture of the tibial plateau is a potential complication of a knee dislocation, but it is not the most common dangerous complication.
* **Option B:** Rupture of the menisci is a possible complication of a knee dislocation, but it is not as immediately life-threatening as a popliteal artery injury.
* **Option C:** Nerve injury, including injury to the common peroneal nerve, can occur with a knee dislocation, but it is not the most common dangerous complication.
**Clinical Pearl / High-Yield Fact**
Remember that the popliteal artery is at risk of injury in posterior dislocations of the knee, and prompt imaging and vascular assessment are essential to prevent long-term limb ischemia.
**Correct Answer: B. Rupture of the menisci is a possible complication of a knee dislocation, but it is not as immediately life-threatening as a popliteal artery injury.**