Total hip replacement

Total hip replacement

A total hip replacement (arthroplasty) is an artificial joint designed to replace the arthritic hip

The procedure is done by making an incision on the outside of the hip. The joint capsule is entered and the femoral neck is cut to remove the worn out femoral head (ball).

The acetabulum (socket) is shaped with a reamer to re-create the hip socket and a titanium cup is placed with a plastic liner. This plastic liner is your “new cartilage”

For further information please visit: https://hipknee.aahks.org/total-hip-replacement/

Anterior versus posterior approach

There are many approaches to hip arthroplasty and there are benefits and drawbacks to each. From a patient perspective, what will make a difference in the long-term is a capable surgeon who is able to execute the procedure with minimal tissue damage, in a reasonable amount of operative time, and will place the components in the correct position

This does not necessarily mean the smallest incision or any particular approach.

I will use posterior and anterior approaches depending on what is right for the patient. The majority of primary hip replacements can be done with an anterior approach

Dislocation is a major complication of hip arthroplasty, and results when the head of the prosthetic hip is forced out of the acetabular cup component. This requires procedures and possibly revision surgery to correct.

Anterior approach hip replacement may have the benefit of a lower dislocation rate. In my practice I do not require activity restrictions or precautions post-operatively.

Hip Replacement Materials

Almost all acetabular and femoral components are press fit (cementless). Press fit surfaces are designed to allow the bone to grow into the implant. Press fit implants are typically made out of titanium alloys.

Titanium is an excellent material for implantation in bone because titanium is more flexible than most other metals like cobalt chrome. Titanium is easy to machine and apply surface coating to. Titanium can not be used as a bearing surface because it can be easily scratched which could lead to wearing of the articular surface.

Cemented femoral implants are used less frequently. Patients with fragile bones are good candidates for a cemented femoral component. The cement works as a grout, filling in the cracks in the bone and holding the implant in the femoral canal. There is a slightly lower risk of intra-operative fracture with cemented implants

Ceramic on polyethylene (COP) is the most common bearing surface. The ceramic femoral head provides a hydrophobic surface that pulls lubrication into the hip joint and creates a fluid film layer between the ceramic head and the highly crossed linked polyethylene liner.

This COP bearing surface wears at about 0.1mm/yr, which means it may take 60-70 years to wear through the 6-7 mm thick polyethylene liner.