In 1975, Sweden started registering primary knee replacement surgeries based on the personal identity number. Individual-based registrations of primary total hip replacements started in 1992 and for hemiarthroplasties the registration started in 2006. The completeness of these registrations is estimated at 98% during the last 10-year period. The long history and high completeness allow for accurate calculations of population-based prevalence of joint replacement and trends over time. We used all data on primary joint replacements available in the Swedish Arthroplasty Register. The prevalence was calculated using number of alive patients with 1) at least one joint replacement 2) at least one hip replacement 3) at least one knee replacement at the end of each year from 2010 – 2021. Publicly available population numbers were retrieved from Statistics Sweden. We calculated total prevalence and prevalence per age in years. By the end of 2021, 3.2% of the Swedish population had at least one hip or knee replacement. This was an increase from 2.5% in 2010. Among 80-year-old, the prevalence was 17.5% for any joint replacement. For both hip and knee replacement and all ages, the prevalence was higher for women. For knee replacement, the 2021 prevalence peaked at the age of 89 (9,4%) while the prevalence continuously increased with age for hip replacements. A considerable proportion of the Swedish elderly population is living with at least one hip or knee replacement. The prevalence has increased during the last 12-year period for both hips and knees. An increasing prevalence may also affect the incidence of fractures and infections. Knowledge about the prevalence is fundamental for planning future demand for primary and revision hip and knee replacement.
Increased collection of patient-reported outcome measures (PROM) in registries enables international comparison of patient-centered outcomes after knee and hip replacement. We aimed to investigate 1) variations in PROM improvement, 2) the possible confounding factor of BMI, and 3) differences in comorbidity distributions between registries. Registries affiliated with the International Society of Arthroplasty Registries (ISAR) or OECD membership countries were invited to report aggregate EQ-5D, OKS, OHS, HOOS-PS and KOOS-PS values. Eligible patients underwent primary total, unilateral knee or hip replacement for osteoarthritis within three years and had completed PROMs preoperatively and either 6 or 12 months postoperatively, excluding patients with subsequent revisions. For each PROM cohort, Chi-square tests were performed for BMI distributions across registries and 12 predefined PROM strata (male/female, age 20-64/65-74/>75, high or low preoperative PROM scores). Comorbidity distributions were reported for available comorbidity indexes. Thirteen registries from 9 countries contributed data, n~130000 knee (range 140 to 79848) and n~113000 hip (range 137 to 85281). Mean EQ-5D index values (10 registries) ranged from 0.53 to 0.71 (knee) and 0.50 to 0.70 (hips) preoperatively and 0.78 to 0.85 (knee) and 0.83 to 0.87 (hip) postoperatively. Mean OKS (6 registries) ranged from 19.3 to 23.6 preoperatively and 36.2 to 41.2 postoperatively. Mean OHS (7 registries) ranged from 18.0 to 23.2 preoperatively and 39.8 to 44.2 postoperatively. Four registries reported KOOS-PS and three reported HOOS-PS. Proportions of patients with BMI >30 ranged from 35 to 62% (10 knee registries) and 16 to 43% (11 hip registries). For both knee and hip registries, distributions of patients across six BMI categories differed significantly among registries (p30 were for patients in the youngest age groups (20 to 64 and 65 to 74 years) with the lowest baseline scores. Additionally, females with lowest preoperative PROM scores had highest BMI. These findings were echoed for the OHS and OKS cohorts. Proportions of patients with ASA scores ≥3 ranged from 7 to 42% (9 knee registries) and 6 to 35% (8 hip registries). PROM-score improvement varies between international registries, which may be partially explained by differences in age, sex and preoperative scores. BMI and comorbidity may be relevant to adjust for.
Periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) is a severe complication in terms of disability, morbidity, and cost. We performed a study to investigate whether early PJI (within 90 days of primary TKA) is associated with increased mortality. Secondary aims were to compare mortality rates over time and between surgical treatment methods. Patients with suspected PJI were identified by linkage of the Swedish Knee Arthroplasty Register (SKAR) and the Swedish Prescribed Drug Register (SPDR) in 2007–2008 and 2012–2013. Medical records of patients receiving more than 4 weeks of continuous antibiotic therapy were subsequently reviewed to verify the PJI diagnosis. Information on mortality was obtained through the SKAR which is updated daily from the tax agency and patients with PJI were compared to patients without PJI.Background
Methods
Strenuous efforts to minimize postoperative infection rates have been made, including the Swedish nation-wide initiative Prosthesis Related Infections Shall be Stopped (PRISS). The aim of this study was to calculate the incidence rate of periprosthetic joint infections (PJI) following primary total knee arthroplasty (TKA) before and after PRISS. All 45,438 primary TKAs registered in the Swedish knee arthroplasty register (SKAR) during 2007–2008 and 2012–2013 were included. Matched data on antibiotic prescriptions were obtained from the Swedish Prescribed Drug Register (SPDR). All patients with ≥28 days of continuous antibiotic treatment within 2 years of primary surgery had their medical charts reviewed to identify cases of PJI.Aim
Method
The modern modular implants allow surgeons to combine different combinations of components within the same brand of which some may have completely different design. During 1999–2012 the same cemented femur component was used together with a cemented stemmed tibia baseplate and also against a cemented pegged tibia baseplate. We decided to compare the revision rate of total knee arthroplasties (TKAs) using these two tibia baseplates. This is a register study. During 1999–2012, 32,429 cemented, CR TKA's of a specific brand were reported to the Swedish Knee Arthroplasty Register (SKAR). The part numbers for the femur, tibia and insert (in modular implants) were available in 99.2% of cases. The most common combination used the cemented CR femur against a cemented stemmed baseplate in 50.3% of cases while the same CR femur was used against a cemented pegged baseplate in 8.3% of cases, mainly at two hospitals. In order to make the material more comparable, only patients having osteoarthritis (OA) were included and only TKAs using two types of regular constraint inserts and in which the patella had been left un-resurfaced. Chi-Square test was used to investigate gender distribution in the groups and t-test for the mean age at surgery. Kaplan Meier analysis and the log-rank test were used to evaluate the risk of revision until the end of 2016. A p-value <0.05 was considered statistically significant.Background
Methods
Patients reporting penicillin allergy do often receive clindamycin as systemic antibiotic prophylaxis. The effect of clindamycin has however not been compared to antibiotics with proven effect in joint arthroplasty surgery. The aim of the study was to reveal if there were differences in the rate of revision due to infection after total knee arthroplasty (TKA) depending on which antibiotic was used as systemic prophylaxis. Patients reported to the Swedish Knee Arthroplasty Register having a TKA performed due to osteoarthritis (OA) during the years 2009 – 2015 were included in the study. The type of prophylactic antibiotic is individually registered. For 80,018 operations survival statistics were used to calculate the rate of revision due to infection until the end of 2015, comparing the group of patients receiving the beta-lactam cloxacillin with those receiving clindamycin as systemic prophylaxis.Aim
Method
To reveal if patient reported knee-related pain, function, quality of life, general health and satisfaction at one year after primary total knee arthroplasty (TKA) is different between patients not being subject to revision surgery and those having had early treatment with open debridement and exchange of the tibial insert for postoperative PJI. The Swedish Knee Arthroplasty Register was used to identify 50 patients in the region of Skane that had a primary TKA during the years 2008 – 2012 and within 6 months were revised with open debridement and exchange of the tibial insert due to suspected or verified PJI. Only patients without further revisions were included. Patient reported outcome measurements (PROM) were obtained preoperatively and 1 year postoperatively and included knee related pain, function, quality of life using the Knee injury and Osteoarthritis Outcome Score (KOOS), general health using the EQ-VAS as well as satisfaction with the surgery. The scores were compared to those reported by 3,913 patients having a TKA during the same time but not revised during the first year. Welch's t-test and the Chi2-test were used in statistical analysis. Compared to the controls the infected patients were older (mean age 72 vs 69 years, p = 0.04) and were more morbid (ASA 3; 14/50 patients vs 14%, p = 0.02). The preoperative PROM data were similar. Complete 1 year PROM data was available for 31 of the patients. Those patients reported somewhat worse outcome one year postoperatively than the controls with statistically and clinically significant differences in general health (mean 61 vs 76, p=0.002), KOOS ADL (mean 65 vs 76, p=0.03) and knee related quality of life (mean 51 vs 63, p=0.02) with large variations on individual level. Just over half of the patients (17/29) treated for PJI were very satisfied or satisfied with the surgery compared to 79% of the controls. Patients treated with open debridement and exchange of the tibial insert due to early PJI after primary TKA reported less beneficial postoperative outcome than those without revision surgery during the first postoperative year but with large individual variations.
We are entering a new era with governmental bodies
taking an increasingly guiding role, gaining control of registries,
demanding direct access with release of open public information
for quality comparisons between hospitals. This review is written
by physicians and scientists who have worked with the Swedish Knee
Arthroplasty Register (SKAR) periodically since it began. It reviews
the history of the register and describes the methods used and lessons
learned. Cite this article:
In contrast to knee arthroplasty, there is no national register on high tibial osteotomy (HTO) in Sweden. The knowledge of the outcome of HTO as a treatment alternative for knee osteoarthritis (OA) is insufficient. The rate of revision to knee arthroplasty after HTO at 10 years has been reported to vary between 8 and 49%. The aim of the study was to evaluate the outcome of HTO performed in Sweden 1998–2007, expressed by rate of revision to knee arthroplasty. Patienter och Material: 3 196 HTO (69% men) 30 years or older operated on for knee OA in Sweden 1998–2007 were identified through the in- and out-patient care registers from the Swedish National Board of Health and Welfare. Side, left/right, that was operated, diagnosis and indication for surgery were verified through surgical records. Conversions of HTO to knee arthroplasty before 2010 were identified through the Swedish Knee Arthroplasty Register (SKAR). In about 10% of the cases it was unknown what side the HTO had been performed on and thus if the arthroplasty had been on the same knee. In these cases we assumed a worst case scenario of all having been on the same side as the HTO. A 10-year survival analysis was performed using revision to an arthroplasty as the end point. The mean age was 52 years (range 30- 80) with 97% of the patients younger than 65 years. The cumulative revision rate (CRR) at 10 year was 29.4% (95% CI 27.2–32.9) after adjusting for age and gender. The risk of revision increased by increasing age and the risk of revision after adjusting for age was significantly higher in women than men RR 1.30 (95% CI 1.11–4.54). Most of the HTO's were performed by open wedge osteotomy using external fixation. The risk of revision was higher for closed wedge osteotomies when comparing the closed and open wedge methods RR1.29 (95% CI 1.08–1.55).Introduction
Result
