<prompt> Metal on Metal articulation should be avoided in -OsteonecrosisYoung femaleInflammatory arthritisRevision surgery  <response>: Based on the articulating surfaces of the prosthesis, THR may be of the following type:-Metal on poly: One surface is metallic femoral side and the other is of polyethene on the acetabular side.Metal on metal: Both articulating surfaces are of metal.Ceramic on ceramic: Both articulating surfaces are of ceramic.Contraindications to Metal on Metal Bearing surfacesMetal on Metal Total Hip Replacement or Metal on Metal Hip ResurfacingPatients with Renal Insufficiency Chronic Renal failure Kidney are chiefly responsible for eliminating metal ions from the bloodYoung females of childbearing age Women who may potentially still have children Elevated levels of metal ions have harmful effects on the fetusPatients with metal hypersensitivityContraindications to Metal on Metal Hip Resurfacing Not contraindications to Metal on metal articulationLoss of femoral head severe bone loss: poor bone stockLarge femoral neck cysts poor bone stock: found at surgeryThe small or bone deficient acetabulumConditions that require caution: Associated with increased risk of failureTall thin patientsFemale patientsPatients with femoral head cysts 1 cm on preoperative radiographsPatients with high body mass index 35Rheumatoid arthritis Inflammatory arthritis and Osteonecrosis AVIVRheumatoid arthritis Inflammatory arthritis and osteonecrosis of the hip perthes disease were earlier considered contraindications semi- contraindications for Resurfacing. These have now shown to have successful results. 