This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Pelvis and Hip injuries, Subject name: Orthopaedics
[{'content': "Mc Murray's osteotomy is done for \nSelect and explain. \nA. Malunited interochantric fracture of femur, B. Nonunion transcervical neck fracture of femur, C. Nonunion lateral condyle fracture of humerus, D. Malunited supracondylar fracture of humerus", 'role': 'user'}, {'content': 'Answer: B \nExplanation: Mc Murrary&;s osteotomy is an oblique osteotomy at the interochanteric region. The direction of osteotomy is medially upwards, beginning at the base of the greater trochanter & ending just above the lesser trochanter. Once osteotomy is made, the distal fragment is displaced medially & is abducted. The position is held by an external suppo( hip spica) or by internal fixation with plate& screws. The osteotomy conves the shearing stresses at the fracture site into compressive forces, thus enhancing fracture union. The line of weight bearing after osteotomy passes from the head to distal fragment. It, therefore, bypasses fracture site. By this osteotomy the head is suppoed by the distal fragment ( armchair effect) This helps the limb in taking weight on walking.T his operation is rarely done nowadays. Ref: Essential ohopaedics, Maheshwari, 9th edition, page no: 136', 'role': 'assistant'}]