Hip replacement

Hip replacement is indicated where conservative management has failed. Worldwide, more than 1 million hips are replaced annually.

With careful patient selection and meticulous surgical technique, good long term results occur in over 90% of cases.

• NICE state that prostheses for total hip replacement and resurfacing arthroplasty are recommended as treatment options for people with end-stage arthritis of the hip only if the prostheses have rates (or projected rates) of revision of 5% or less at 10 years (1)

In total hip replacement (THR) surgery

• the acetabulum (hip socket) is replaced with either a single-piece cup made from 1 material (polyethylene, ceramic or metal) or a 2-piece (modular) cup made from a metal outer shell and a polyethylene, ceramic or metal liner
• the head of the femur (thigh bone) is replaced with either a single-piece metal stem and head, or a modular component consisting of a metal stem (which may consist of more than 1 piece) with a metal, ceramic or ceramicised metal head
• THRs vary in what fixation method is used for each component of the prosthesis
  • in some THRs, all the components are fixed into position using cement (referred to as cemented THRs)
    • other types of THR are designed to be used without cement (referred to as cementless THRs); instead, they are inserted using press-fit fixation, and natural bone growth over time secures the prosthesis in place
    • some prostheses are hybrid, in which the femoral component is cemented into place while the cup is fixed without cement, or reverse hybrid, in which the femoral component is fixed without cement while the cup is cemented into place
• THRs may also vary by femoral head size, with a large head defined as being 36 mm or more in diameter
• consider a posterior or anterolateral approach for primary elective hip replacement (2)

Hip resurfacing arthroplasty

• involves removing and replacing the surface of the femoral head with a hollow metal hemisphere, which fits into a metal cup fixed into the acetabulum. All resurfacing arthroplasty prostheses currently on the market are metal-on-metal (MoM), and can be hybrid or cementless
• as with THR prostheses, resurfacing arthroplasty prostheses may also vary by femoral head size

Reference:

1. NICE (February 2014). Total hip replacement and resurfacing arthroplasty for endstage arthritis of the hip
2. NICE (June 2020). Joint replacement (primary): hip, knee and shoulder