This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thigh, Knee,Leg,Foot & Ankle injuries, Subject name: Orthopaedics
[{'content': 'Commonest dangerous complication of posterior dislocation of knee is- \nSelect and explain. \nA. Popliteal aery injury, B. Sciatic nerve injury, C. Ischaemia of lower leg compament, D. Femoral aery injury', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Dislocation of the knee- *This rare injury results from severe violence to the knee so that all of its suppoing ligaments are torn. *It is a major damage to the joint, and is often associated with injury to the popliteal aery. *Treatment is by reduction followed by immobilization in a cylinder cast. Clinical evaluation : (vascular exam) -Measure Ankle-Brachial Index (ABI) if ABI >0.9 >>>> then monitor with serial examination if ABI <0.9 >>>> -If pulses are absent or diminished confirm that the knee joint is reduced or perform immediate reduction and reassessment - Immediate surgical exploration if pulses are still absent following reduction &;schema time >8 hours has amputation rates - If pulses present after reduction then measure ABI then consider observation vs. angiography Clinical evaluation : (vascular exam) -Priority is to rule out vascular injury on exam both before and after reduction serial examinations are mandatory. - Palpate the dorsalis pedis and posterior tibial pulses if pulses are present and normal , >> it does not indicate absence of aerial injury. Ref: Maheshwari 9th ed p.142', 'role': 'assistant'}]