|ESSR 2019 / P-0166|
|Radiographic evaluation of hip arthroplasty|
The hip joint is a ball and socket synovial joint formed by the articulation of the femoral head with the acetabulum.
Hip arthroplasty is one of the most common procedures performed for the treatment of advanced osteoarthritis and is also a required in approximately one-third of hip fracture patients.
Types of hip replacements
1. Hemiarthroplasty (Fig. 1)
Hemiarthroplasty is a surgery that replaces the femoral head, resulting in an articulation between a prosthetic femoral head and the native acetabular cartilage.
Hemiarthroplasty at the hip is generally performed for femoral head disease: osteonecrosis of the femoral head, femoral neck fractures or resection of a tumour.
2. Total hip arthroplasty (THA) (Fig. 2)
A THA is an operation that replaces both surfaces of the hip joint so the resulting articulation is between a prosthetic femoral head and a prosthetic acetabulum. In a resurfacing total hip arthroplasty, the femoral head and acetabulum are replaced, whereas the femoral neck is spared.
Bearing surfaces of the acetabulum may be made of polyethylene, metal, or ceramic. Femoral heads may be made of metal or ceramic.
The primary indication for total hip arthroplasty is severe pain and the limitation in activities of daily living that it causes, with joint diseases such as osteoarthritis accounting for 70% of cases. It is generally preferred that THA are performed on patients older than 60 years because the longevity of the prothesis.
Types of fixation techniques
1. Cemented fixation (Fig. 3)
Bone cement is commonly used as an adhesive or to fill spaces and contribute to a closer interference fit. Bone cement is radiopaque.
2. Cementless fixation (Fig. 2)
Prosthetic devices have also been developed that achieve fixation without cement either by “press-fit” or by biologic ingrowth methods.
Noncemented devices are most frequently used in young patients with high physical demands.
3. Hybrid fixation
Combination of a cemented femoral stem and a cementless acetabular cup are often used.
4. Reverse hybrid fixation
Combination of a cementless femoral stem and a cemented acetabular cup.