How the register works

The Swedish Arthroplasty Register collect data on patient’s demographics, information on the operation and patient reported outcome measure (PROM). An important outcome measure is the percentage of replacements having reoperations, another is the patients reported outcome. Several categories of health care professionals participate in the collection of data. The entry in the register's web form takes place at the units.

Results from the register are available in several ways. Every year, the SAR publishes an annual report. The data will also be reported online with filtering options on this web site under the heading Statistics. In addition, data is delivered on order to several stakeholders, for example implant suppliers and various healthcare providers. The implant companies also have the opportunity to access a special website that reports data on inserted implants. Data in the SAR is primarily used for quality work but also for research.

Hip replacement

A total hip prosthesis has a femoral neck, femoral head and cup. Around 20,000 patients in Sweden have a total hip replacement every year. The reason for replacement is usually osteoarthritis and the operation is planned. A hemi prosthesis only has the femoral neck and femoral head, but not the cup. About 4,000 patients receive hemi prostheses and mainly because of femoral fractures. These patients undergo acute surgery. In addition, approximately 2,400 revisions and reoperations after total and hemi prosthesis surgery are registered each year.

All units that operate hip prostheses in Sweden report to the SAR. A high percentage of the hip replacements are included in the register. The latest figure is from 2021 and shows that the coverage rate for total hips is 98.1% and for hemi prosthesis 97.9%. The completeness is calculated using the National Board of Health and Welfare’s patient register.

Knee replacement

A total knee prosthesis (TKA) with or without a patella component includes all three parts of the knee joint, femur, lower leg and patella. Approximately 15,000 TKAs are registered annually. The reason for surgery is usually osteoarthritis. A uni-compartmental prosthesis (UKA) includes the medial or lateral part of the knee joint. Medial UKA is most common and osteoarthritis is the most common reason for surgery. Just over 1,600 UKAs were registered in 2021. Knee replacement operations are mostly planned.

There are also other types of knee prostheses that include all or parts of the knee joint, but they are used to a lesser extent. In addition, roughly 1,000 revisions and reoperations are registered each year.

All units that operate knee prostheses in Sweden report to the SAR and most of the operations are included in the register. The latest figure is from 2021 and shows that the completeness for knee replacement surgery is just over 97%. The completeness is calculated using the National Board of Health and Welfare’s patient register.

Knee osteotomy

Knee osteotomy is a joint saving operation that can be performed with various techniques and methods. The operation is done to relieve the damaged joint surface in the knee joint or to correct an incorrect alignment. Knee osteotomy is usually used for younger and/or physically active patients with osteoarthritis of the medial or lateral part of the knee joint but also to correct congenital or acquired malalignment of the femur or lower leg, instability and local cartilage damage. Proximal tibia osteotomy (osteotomy just below the knee joint) was the standard treatment for unilateral osteoarthritis before modern knee replacements became more common. Distal femur osteotomy (osteotomy just above the knee joint) is relatively uncommon in Sweden and is mainly used for osteoarthritis on the lateral part of the knee joint or for more severe malalignment.

Knee osteotomies started to be registered in 2013 and approximately 200 knee osteotomies are registered per year. The completeness for knee osteotomies is more difficult to estimate than for knee and hip replacement surgeries, as the procedure codes are used for several other types of osteotomies on the lower leg and femur. However, the coverage rate in recent years has been estimated at 75-87%.