Aseptic loosening in cemented total hip replacement occurs as a result of hypersensitivity response to -
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.
Titanium debris
High density polythene debris
N.N - Dimethyltryptamine (DMT)
Free radicals