Hip resurfacing arthroplasty
Hip resurfacing arthroplasties are a type of joint replacement which may be used in the treatment of active patients with end-stage pathology of the hip joint.
The major difference as compared to conventional hip arthroplasty is that resurfacing arthroplasties have femoral components with larger heads and smaller stems, allowing improved cup stability and preservation of more of the proximal femur.
In general terms, the steps of operative placement are as follows :
- the posterior surgical approach is most common, although lateral and anterior approaches are described
- once exposed, the acetabulum is reamed with a special tool so that it may receive the acetabular component at the proper location and angulation (partially abducted and anteverted)
- specially-designed acetabular components for dysplastic or deficient acetabula provide additional holes to reinforce with fixation screws
- acetabular component is installed, typically secured by "press fit", with the intent of allowing the acetabular bone to grow into the specially-designed porous outer surface of the cup
- the femoral head is reamed and shaped ("resurfaced") to receive the femoral component
- the femoral component is installed, usually at a neutral or valgus alignment
Use of bone cement is variable. Many acetabular implants are specifically designed with porous outer surfaces to encourage bony ingrowth and biological fixation. Use of cement is more common with the femoral component, applied at the large metal surface- transverse bone interface, although uncemented implants are also used .
Post-operative and follow up x-rays are routinely requested following total hip arthroplasty. The aim is to assess implant positioning, specifically the seating and angulation of both acetabular and femoral components.
In addition to implant positioning, imaging is important to evaluate for known complications, which include:
- femoral neck narrowing
- implant subsidence
- implant loosening
- periprosthetic fracture
- intercomponent impingement ('notching')
- iliopsoas tendinopathy
- particle disease