The Swedish Knee Arthroplasty Register

Otto Robertsson M.D., PhD.
The Swedish Knee Arthroplasty Register

The Swedish Knee Arthroplasty Register (SKAR) was started in 1975 and is thus the oldest national arthroplasty register. It was initiated by interested orthopaedic surgeons who realized a combined effort would be needed to assemble knowledge about this then relatively new procedure.

Initially the register was started with the help of research grants but later, the health authorities began to provide economic support. Presently, the Swedish Association of Local Authorities and Regions provides the main financing although additional funding still comes from research grants. Further, the offices are located at the University Hospital in Lund which indirectly funds the register by providing office space and taking on some indirect costs.

The government has no direct control of the register although the main part of the funding is provided by the authorities. The steering group is selected at the annual meeting of the Swedish Orthopaedic Federation and the register is managed by orthopaedic surgeons with the help of staff and consulting statisticians.

All hospitals performing knee arthroplasty in Sweden participate by providing data (presently 78 units). At every unit, a contact physician and a contact secretary have been appointed allowing for effective communication to and from the registry.

In the beginning, X-ray films were collected and clinical information was called for at one, three and ten year follow-ups. However, as the surgery gained popularity and the number of operations increased, the workload for the clinical follow-up was felt as being time-consuming. Thus, the compliance became inadequate and in 1990 the clinical follow-up was dropped in favour of reports on revisions performed. Intermittently, additional information on patient satisfaction and health status has been gathered by use of self-administrated health questionnaires. For the primary operation, the data collected is a minimal dataset which can be provided on one A4 page. It contains information regarding the identity of the patient and the operating hospital, the reason for the operation, date of operation, side operated, approach, implanted components (stickers with part numbers) and their fixation. For revisions, the reason for the revision has to be provided as well as information on what components have been extracted, added or replaced, a copy of the operative-report and the discharge letter. The information, which in 2006 concerned 11,000 arthroplasties, is input to a computer by the SKAR staff.

Once a year, after control of the logistics, a major analysis of the material is performed which results in an annual report being sent to all participants as well as published on the Web. Specific analyses and testing of hypotheses are performed on demand, as time permits. Hitherto, planning and performance of all research has been supervised by orthopaedic surgeons assisted by consulting statisticians.

Computerized information is reported back to each unit regarding their own cases. It includes additional information on revisions performed elsewhere which allows those interested to analyze their own results. Otherwise, all output from the register only shows aggregated results in which individual patients never can be identified.

Information is disseminated from the register by annual reports, at annual meetings (with contact persons and representatives from the industry), through participation in national and international meetings as well as by articles in peer-reviewed journals. In the recent years, the register has been required to disclose results for individual hospitals but not for individual surgeons (which is not possible as the identity of surgeons is not registered).

The registry has no specific guidelines with respect to early warning of inferior results. There may be several reasons for higher failure rate for certain implants or hospitals and, initially, it is difficult to say if this has been caused by differences in case-mix, underperforming surgeons or implants. Early deviating results would typically be discussed at our annual meetings and through our attendees (surgeons and representatives for the industry) - such information would quickly be disseminated to the Swedish orthopaedic community. We might also disclose such results in our annual report or try to have them published in peer-reviewed journals but in most cases, further monitoring and/or analyses of the failure pattern would be required. Hitherto, these measures have resolved most issues, either by surgeons quitting using specific implants/methods or by changes leading to improvement in results.

The information made available allows hospitals to compare their results to those of the State averages and they are thus stimulated to perform their best. Surgeons are helped to select proven methods and implants, and patients are also aided as they can be provided with information on what to expect and when it may be preferable to wait or proceed with surgery. Purchasers of medical care can be provided with information on the effects of previous financing and estimates of future needs. The monitoring of results is assuring and this benefits the orthopaedic profession in the hard competition for medical resources.

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