In a total hip replacement surgery (THR), an artificial implant is implanted to replace the diseased hip. Depending on the modality of fixation of the implant to the bone, there are 3 varieties of fixation/ types of replacements.
Types of Hip Replacements:
- Cemented hip replacement- both the socket and the stem are fixed into the bone using acrylic bone cement. This is advised for elderly patients above the age of 65 years with poor bone quality.
- Uncemented hip replacement- both the socket and the stem components are fitted into the bone without using acrylic bone cement. Fixation of this type of implant takes place by ongrowing bone from the host bone. This type of replacement is advised for younger patients.
- Hybrid hip replacement- either the socketor the stem is fixed into the bone using acrylic bone cement while other component is fitted without using the cement.
The total hip replacement implant is made up of 3 essential components: acetabular cup, femoral stem and femoral head.
- An acetabular cup is fixed into the socket of the hip joint. It is either a single piece made up of plastic (cemented THR) or two pieces made up of metallic shell and inside liner / insert made up of plastic, metal or ceramic (uncemented THR).
- A femoral stem is fits inside the cavity in the upper part of thigh bone (femur). It is always made up of a metal. Cemented stems have a polished surface and narrow tapered lower end. Uncemented stems have rough surface with or without special coating, to allow bone integration.
- A femoral head is fit over the top of femoral stem and articulates (moves) inside acetabular cup / liner. Its is made up of metal or ceramic.