Aim

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.

Background

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.

We cross-matched the Swedish Hip and Knee Arthroplasty Registers (SHAR and SKAR) to study the incidence of knee or hip arthroplasty in any of the remaining hip or knee joints.

177835 THR (55.8% females, mean age, SD: 68.5 10.1 years) and 128162 primary TKR (59.8% females, 69.4 9.0 years) procedures in patients with primary osteoarthritis, performed 1992–2014 were studied. Mean and maximum follow up were 7.7 and 23 years.

At the index operation more patients were operated on their right side for both locations (hip and knee). Patients who at the index operation had been operated with a TKR and especially on the left side most frequently (32.5%) received one or several additional TKR or THR. For patients who had a THR at their index operation and underwent a second operation of any of the remaining three joints the mean time to this second procedure was 4.0 years (SD: 3.9). In patients who were operated with a TKR this time period was shorter (3.1, 3.2, p<0.0005).

In patients who had undergone their first (index) operation of either hip the probability of not being subjected to further arthroplasty operations during the following 20 years amounted to 64.0±0.3%. The corresponding probability for patients who at the index operation had received a TKR was somewhat lower (58.4±0.4%). Decreasing age (HR: 1.029, 95% confidence interval: 1.028–1.0292), female gender (1.13 1.12–1.15), TKR at index operation (1.34 1.32–1.36) and left-sided index operation (1.12 1.10–1.13) were associated with higher probability for at least one additional primary joint replacement in the hip or the knee.

During our period of observation 25 to 33 percent of the patients who received their first total hip or knee replacement underwent at least one additional replacement of either the hip or the knee. Knee osteoarthritis more frequently results in staged bilateral joint replacement than in patients who primarily are suffering from osteoarthritis of the hip.

Aim

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.

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 identified a group of patients from the Swedish Arthroplasty Register who reported no relief of pain or worse pain one year after a total knee replacement (TKR). A total of two different patient-reported pain scores were used during this process. We then evaluated how the instruments used to measure pain affected the number of patients who reported no relief of pain or worse pain, and the relative effect of potential risk factors.

Between 2008 and 2010, 2883 TKRs were performed for osteoarthritis in two Swedish arthroplasty units. After applying exclusion criteria, 2123 primary TKRs (2123 patients) were included in the study. The Knee injury and Osteoarthritis Outcome Score (KOOS) and a Visual Analogue Scale (VAS) for knee pain were used to assess patients pre-operatively and one year post-operatively.

Only 50 of the 220 patients (23%) who reported no pain relief on either the KOOS pain subscale or the VAS for knee pain did so with both of these instruments. Patients who reported no pain relief on either measure tended to have less pain pre-operatively but a higher degree of anxiety. Charnley category C was a predictor for not gaining pain relief as measured on a VAS for knee pain.

The number of patients who are not relieved of pain after a TKR differs considerably depending on the instrument used to measure pain.

Cite this article: Bone Joint J 2014;96-B:1222–6.

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: Bone Joint Res 2014;3:217–22.

Satisfaction is increasingly employed as an outcome measure for a successful total knee replacement (TKR). Satisfaction as an outcome measure encompasses many different intrinsic and extrinsic factors related to a person’s experience before and after TKR. The Swedish Knee Arthroplasty Registry has previously demonstrated on a large population study that 17% of TKR recipients are not satisfied with their TKR outcome. This finding has been replicated in other countries. Similar significant factors emerged from these registry studies that are related to satisfaction. It would appear that satisfaction is better after more chronic diseases and whether the TKR results in pain relief or improved function. Importantly, unmet pre-operative expectations are a significant predictor for dissatisfaction following a TKR. It may be possible to improve rates by addressing the issues surrounding pain, function and expectation before embarking on surgery.

Cite this article: Bone Joint J 2013;95-B, Supple A:148–52.

Introduction

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.

Introduction: In recent years some countries have shown increasing interest and use of unicompartmental knee arthroplasty (UKA). Several studies have reported increasing use of UKA for osteoarthritis in younger patients with low revision rates. The aim of this study was to determine the outcome of UKA by combining two national databases containing prospectively collected data.

Method: Over 50 000 UKA procedures were analyzed to determine the cumulative percentage revision (CPR). Any reason for revision was used as the end point. The analysis was stratified according to age, gender and type of prosthesis to determine outcomes in patients younger than 65 years

Result: In this study both countries showed declining use of UKA in terms of the proportion of knee replacement procedures and of absolute numbers undertaken per year. The seven year CPR of UKA in patients younger than 65 years was 16.2%, and at 10 years was 17.5%. No significant difference was found between gender, however outcome did vary depending on the type of prosthesis used.

Conclusion: This study reports the outcomes from the two largest databases of UKA. Within 10 years of UKA a substantial number of revisions were seen in patients younger than 65 years, with varying results depending on the type of prosthesis used.

Background: The role of polyethylene (PE) wear in relation to synovitis and elevated hydrostatic pressure in the loosening process after THA has gained increased attention. The aim of our study was to investigate the correlation between prosthetic head size, PE wear and sonographic capsular distention, reflecting the degree of intracapsular synovitis/synovia/hydrostatic pressure.

Patients and methods: In 2005 we analyzed 60 randomly selected and unrevised OA patients 10 years after surgery with 32 or 28mm femoral heads. We evaluated radiographic signs of loosening, linear and volumetric PE wear. Sonographic examination was performed to measure the “capsular distance”, i.e. the capsular distension, defined as the distance between the metallic echo from the anterior surface of the prosthetic femoral neck, and the echo from the anterior surface of the anterior capsule.

Results: The linear wear was 0.2 mm per year and 0.1 mm per year in the 32 mm and 28 mm head size group respectively (p< 0.001), the volumetric wear was 139 mm3/year and 48 mm3/year (p< 0.001), and the capsular distention was 17 mm and 13 mm respectively (p< 0.001). There was also a significant positive correlation between PE volumetric wear and capsular distension (r=0.63, p< 0.001).

Interpretation: We conclude that 32 mm femoral heads were associated with almost three times higher volumetric wear as compared to 28 mm heads, and increased “capsular distension”, reflecting increased synovitis/synovia/hydrostatic pressure in prosthetic hip.

Introduction. Since the early days of total hip arthroplasty (THA) the choice of the proper diameter of the femoral head has been debated with respect to its effect on wear. The most widely accepted theory explaining aseptic loosening of THA is that of polyethylene particles induced osteolysis. In a previous study concerning 1,660 ScanHip THA’s that were followed for up to 12 years the cumulative revision rate was not found to be dependent on if a 22 mm or a 32 mm head size had been used1. We have reexamined these patients to see whether a longer follow-up time (9–21 years) would disclose an effect of head size on the revision rate.

Patients and Methods. We analyzed the CRR for 1,720 Scan Hip^® Classic I THA implanted in 1,550 patients, with 22 and 32mm heads, performed at Lund University Hospital during 1983 to 1995. Patients with the 3 most common diagnoses were included in the analysis, i.e. osteoarthritis, rheumatoid arthritis and femoral neck fracture. The end-point was defined as revision of any component for aseptic loosening before the end of 2004.

Results. Using the life table method analyzed cumulative revision rate for osteoarthritis, femoral neck fracture and rheumatoid arthritis patients and found that the 32 mm head had higher cumulative revision rate (p=0.04 (Wilcoxon)). Further analysis with Cox regression adjusting for age and sex showed that the 32 mm head had 2.8 times greater risk of revision (CI 1.7–4.6), p< 0.001. For each year increase in age the risk of revision was reduced 0.96 times (CI 0.95 – 0.97), p< 0.001, males had 1.5 times (CI 1.1 – 2.1), p=0.01 greater risk of revision than females.

Discussion. The reason that we did not find any significant difference in cumulative revision rates when followed up to 12 years, depending on head size in previous study (Kesteris et al. 1998) may be the time it takes for wear particles to induce the chain of events, eventually ending up in loosening. However extended follow-up up to 21 years after THA revealed significant differences in cumulative revision rates depending on head size.

Public disclosure of outcome-orientated ranking of hospitals is becoming increasingly popular and is routinely used by Swedish health-care authorities. Whereas uncertainty about an outcome is usually presented with 95% confidence intervals, ranking’s based on the same outcome are typically presented without any concern for bias or statistical precision. In order to study the effect of incomplete registration of re-operation on hospital ranking we performed a simulation study using published data on the two-year risk of re-operation after total hip replacement.

This showed that whereas minor registration incompleteness has little effect on the observed risk of revision, it can lead to major errors in the ranking of hospitals. We doubt whether a level of data entry sufficient to generate a correct ranking can be achieved, and recommend that when ranking hospitals, the uncertainties about data quality and random events should be clearly described as an integral part of the results.

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.

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.

Aims: Realizing the problems of choosing the optimal treatment at the time of rapid development of knee implants and surgery complicated with low individual volume and long follow-up time the orthopaedic profession initiated the Swedish Knee Arthroplasty Register in 1975. Methods: All centres performing knee arthroplasty in Sweden participate in the project and the unique ID number provided to all Swedish citizens allows for tracking of the vast majority of patients. Survival statistics using revision as an end-point have been used to estimate the cumulative revision rate (CRR) of different implants and methods and postal inquiries to gather information on patient satisfaction and health. Results: The register has proved beneficial in a number of ways: Research: It is a base of information that can provide data for direct analyses or be used to facilitate separate studies. Quality:Surgeons have been warned of inferior implants, technically demanding implants, diseases not to be treated with certain methods and specifics methods of treatment. Control and comparison helps decision-making and increases the probability for appropriate choices. Guidance: Surgeons can be guided regarding preferred techniques, implant- and patient-selection and patients can be guided regarding what to expect (risk evaluation), why specific methods are to be preferred and when to wait or proceed with surgery. Political/economical benefits:Purchasers of medical treatment, are more willing to provide financial means when; effects of previous financing can be shown, the results can be documented, improvement in quality can be demonstrated and future trends can be predicted. Conclusions: The register has helped improve quality, guide surgeons and patients and benefited the orthopaedic profession as well as the nation as a whole.

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.

A total of 10474 unicompartmental knee arthroplasties was performed for medial osteoarthritis in Sweden between 1986 and 1995. We sought to establish whether the number of operations performed in an orthopaedic unit affected the incidence of revision. Three different implants were analysed: one with a high revision rate, known to have unfavourable mechanical and design properties; a prosthesis which is technically demanding with a known increased rate of revision; and the most commonly used unicompartmental device.

Most of the units performed relatively few unicompartmental knee arthroplasties per year and there was an association between the mean number carried out and the risk of later revision. The effect of the mean number of operations per year on the risk of revision varied. The technically demanding implant was most affected, that most commonly used less so, and the outcome of the unfavourable design was not influenced by the number of operations performed.

For unicompartmental arthroplasty, the long-term results are related to the number performed by the unit, probably expressing the standards of management in selecting the patients and performing the operation.

We report a ten-year rate of survival of 96% for the cemented Freeman-Samuelson knee arthroplasty in patients from the Swedish Knee Registry and the Royal London Hospital with revision for aseptic loosening as the criterion for failure.