This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Orthopaedics
[{'content': 'Aseptic loosening in cemented total hip replacement occurs as a result of hypersensitivity response to - \nSelect and explain. \nA. Titanium debris, B. High density polythene debris, C. N.N - Dimethyltryptamine (DMT), D. Free radicals', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Based on the type of fixation, THR is of two types:-\n\ni)\xa0Cemented THR: Bone cement is used to fix the prosthesis with bone.\nii) Uncemented THR: Prosthesis is directly inserted into the bone without using cement. After sometime osteointegration over prosthesis takes place.\n\nIn cemented THR, there may be loosening of the prosthesis. If it occurs without infection, it is called aseptic loosening (or osteolysis).\nParticles of metal (titanium, nickel, chromium etc), cement (PMMA) and polyethene all can produce periprosthetic osteolysis (aseptic loosening); but because they are most numerous polyethene particles appear to be the major culprit.', 'role': 'assistant'}]