The Swedish Knee Arthroplasty Registry (SKAR) has recorded knee arthroplasties prospectively in Sweden since 1975. The only outcome measure available to date has been revision status. While questionnaires on health outcome may function as more comprehensive endpoints, it is unclear which are the most appropriate. We tested various outcome questionnaires in order to determine which is the best for patients who have had knee arthroplasty as applied in a cross-sectional, discriminative, postal survey. Four general health questionnaires (NHP, SF-12, SF-36 and SIP) and three disease/site-specific questionnaires (Lequesne, Oxford-12, and WOMAC) were tested on 3600 patients randomly selected from the SKAR. Differences were found between questionnaires in response rate, time required for completion, the need for assistance, the efficiency of completion, the validity of the content and the reliability. The mean overall ranks for each questionnaire were generated. The SF-12 ranked the best for the general health, and the Oxford-12 for the disease/site-specific questionnaires. These two questionnaires could therefore be recommended as the most appropriate for use with a large knee arthroplasty database in a cross-sectional population.
Between March 1985 and March 1986, 249 fractures of the distal radius in patients over 15 years of age were treated in the Reykjavik area, which had a total at risk population of 100,154. The incidence pattern was similar to what has been reported in recent Nordic studies except that the fracture risk of women was lower than in Oslo in 1979 and Malmö in 1980-81, and for men higher than in Fredriksborg in 1981. Fifty-seven percent of the patients had employment at the time of accident. The majority of accidents happened outdoors, especially on sidewalks and in streets, and were more common during the winter months.
Patients with osteoarthritis undergoing knee replacement have been reported to have an overall reduced mortality compared with that of the general population. This has been attributed to the selection of healthier patients for surgery. However, previous studies have had a maximum follow-up time of ten years. We have used information from the Swedish Knee Arthroplasty Register to study the mortality of a large national series of patients with total knee replacement for up to 28 years after surgery and compared their mortality with that of the normal population. In addition, for a subgroup of patients operated on between 1980 and 2002 we analysed their registered causes of death to determine if they differed from those expected. We found a reduced overall mortality during the first 12 post-operative years after which it increased and became significantly higher than that of the general population. Age-specific analysis indicated an inverse correlation between age and mortality, where the younger the patients were, the higher their mortality. The shift at 12 years was caused by a relative over-representation of younger patients with a longer follow-up. Analysis of specific causes of death showed a higher mortality for cardiovascular, gastrointestinal and urogenital diseases. The observation that early onset of osteoarthritis of the knee which has been treated by total knee replacement is linked to an increased mortality should be a reason for increased general awareness of health problems in these patients.
The Swedish Knee Arthroplasty Register has data on 4,381 primary operations performed 1985-1995 for rheumatoid arthritis. Of these, 192 were performed with unicompartmental prostheses and 4143 with tricompartmental. 77% were women and the mean age was 66 years. There were 126 first, 20 second, and 1 third revision in tricompartmental arthroplasties, mainly for loosening, infection and patellar problems. There were 38 first, 3 second, and 1 third revision in unicompartmental arthroplasties, mainly for progression of RA and loosening. Cumulative revision rates (Kaplan-Meier) were calculated. Tricompartmental knees had a 10-year cumulative revision rate of 5% and uni-knees 25%. Patients treated before 1990, men and patients younger than 55 had higher revision rates than patients treated after 1990, women and older patients, respectively. Cemented tibial components resulted in lower revision rates than uncemented ones. There was no significant difference in revision rates between patellar replaced and unreplaced knees or between the 9 commonest implant types.
This article considers the establishment, purpose and conduct of knee arthroplasty registers using the Swedish register as an example. The methods of collection of appropriate data, the cost, and the ways in which this information may be used are considered.
In the Swedish Knee Arthroplasty Study, all 699 Oxford meniscal bearing cemented unicompartmental prostheses (Biomet, Bridgend, UK) were identified and analyzed regarding failure pattern and compared with all Marmor prostheses (Smith & Nephew Richards, Orthez, France) and with a time-, age-, and sex-matched subset of Marmor prostheses using survival statistics expressed as cumulative revision rates. After 1 year there was already a higher rate, and after 6 years the rate of the Oxford group was more than twice that of the Marmor group. There were 50 revisions in the Oxford group: dislocating meniscus in 16, loosening of the femoral component in 6, tibial component in 4, both components in 4, contralateral arthrosis in 10, infection in 4, and technical failure with instability, pain, and/or impingement of the meniscal bearing anterior in the femoral condyle in 6. It is still unclear if the design with the sliding menisci will, in the long turn, reduce wear and loosening, thereby compensating for the initially inferior results. It is recommended that until this question is clarified, the Oxford knee should be used on a limited scale for long-term comparative studies only.
Past incidence and future demand for knee arthroplasty in Sweden: a report from the Swedish Knee Arthroplasty Register regarding the effect of past and future population changes on the number of arthroplasties performed.
By combining data from the Swedish Knee Arthroplasty Register and Swedish census registers we have calculated the past age-specific incidence of primary knee arthroplasties and predicted the demand. During the last 20 years, osteoarthrosis has accounted for the largest increase in number of knee arthroplasties while operations for rheumatoid arthritis remained constant. The mean yearly number of operations between the periods 1976-1980 and 1996-1997 increased more than five-fold, while only 6% of that increase could be explained by changes in the age-profile of the population. Most operations were performed on persons of 65 years and older who also had the largest increase in incidence. By using the incidences for 1996 and 1997 and taking into account the expected future changes in the age profile of the Swedish population, we estimate that, in the absence of an effective preventive treatment, the number of knee arthroplasties will increase by at least one third until 2030.
Data from the Swedish Knee Arthroplasty Registry were analyzed to compare bi- and tricompartmental knee arthroplasties carried out in patients operated on for arthrosis in 1990-1996. Of the 16,607 primary arthroplasties that were carried out there were 5,139 with patellar replacement in the primary procedure and 10,928 without. By April 1998, 280 revisions were performed, 250 of these cases were analyzed in this study. Patella-related complications were commonly the reason for early revision: in 99 of the 168 knees with a primary bicompartmental procedure and in 36 of the 82 knees with a primary tricompartmental procedure. This presentation merely analyzes the extent of patellar problems in knee arthroplasty, as a detailed analysis of the causes of this common problem is not possible using data from a national multicenter study.
During a validation process of the Swedish Knee Arthroplasty Register (SKAR), living registered patients were sent a questionnaire to ask if they had been reoperated on. This gave an opportunity to pose a simple four-point question with respect to patient satisfaction which 95% of patients answered. We analyzed the answers of patients operated on between 1981 and 1995 and found that only 8% of the patients were dissatisfied regarding their knee arthroplasty 2-17 years postoperatively. The satisfaction rate was constant, regardless of when the operation had been performed during the 15-year period. The proportion of satisfied patients was affected by the preoperative diagnosis, patients operated on for a long-standing disease more often being satisfied than those with a short disease-duration. There was no difference in proportions of satisfied patients, whether they had primarily been operated on with a total knee arthroplasty (TKA) or a medial unicompartmental arthroplasty (UKA). For TKAs performed with primary patellar resurfacing, there was a higher ratio of satisfied patients than for TKAs not resurfaced, but this increased ratio diminished with time passed since the primary operation. Unrevised knees had a higher proportion of satisfied patients than knees that had been subject to revision, and among patients revised for medial UKA, the proportion of satisfied patients was higher than among patients revised for TKA. We conclude that satisfaction after knee arthroplasty is stable and long-lasting in unrevised cases and that even after revision most patients are satisfied.
From 1975 through 1995, 45,025 knee arthroplasties were recorded in the prospective Swedish Knee Arthroplasty study. By the end of 1995, 1,135 of 14,772 primary unicompartmental knee arthroplasties (UKA) for localized, mainly medial arthrosis had been revised. The Marmor/Richards and St. Georg sledge/Endo-Link prostheses were used in 65%. Mean age at revision was 72 (71) years. 232 revisions were performed as an exchange UKA (partial in 97) and 750 as a total knee arthroplasty (TKA). 153 were revised by other modes. In medial UKA, the indication for revision was component loosening in 45% and joint degeneration in 25% and in lateral UKA, the corresponding figures were 31% and 35%, respectively. In 94 cases, unicompartmental components were added to the initially untreated compartment, in 14 with partial exchange of a component. The CRRR was estimated using survival statistics. After only 5 years, the risk of having a second revision was more than three times higher for failed UKAs revised to a new UKA (cumulative rerevision rate (CRRR 26%) than for those revised to a TKA (CRRR 7%). This difference remained, even if those revised before 1985, when modern operating technique was introduced, were excluded (CRRR 31% and 5%, respectively). UKA is a safe primary procedure, when performed with well-designed components and modern surgical technique. It gives documented good patient satisfaction, range of motion, pain relief and relatively few serious complications. However, once failed, the knee should be revised to a TKA. This applies to most modes of failure. Not even joint degeneration of the unoperated compartment can be safely treated by adding contralateral components; CRRR after this procedure was 17%, while it was 7% when converted to a TKA.