<prompt> Aseptic loosening in cemented total hip replacement occurs as a result of hypersensitivity response to -Titanium debrisHigh density polythene debrisN.N - Dimethyltryptamine DMTFree radicals  <response>: Based on the type of fixation, THR is of two types:-i Cemented THR: Bone cement is used to fix the prosthesis with bone.ii Uncemented THR: Prosthesis is directly inserted into the bone without using cement. After sometime osteointegration over prosthesis takes place.In cemented THR, there may be loosening of the prosthesis. If it occurs without infection, it is called aseptic loosening or osteolysis.Particles 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. 