Stein Håkon Låstad Lygre

Survival rates and causes of revision in cemented primary total knee replacement: A report from the Norwegian Arthroplasty Register 1994–2009

We evaluated the rates of survival and cause of revision of seven different brands of cemented primary total knee replacement (TKR) in the Norwegian Arthroplasty Register during the years 1994 to 2009. Revision for any cause, including resurfacing of the patella, was the primary endpoint. Specific causes of revision were secondary outcomes. Three posterior cruciate-retaining (PCR) fixed modular-bearing TKRs, two fixed non-modular bearing PCR TKRs and two mobile-bearing posterior cruciate-sacrificing TKRs were investigated in a total of 17 782 primary TKRs. The median follow-up for the implants ranged from 1.8 to 6.9 years. Kaplan-Meier 10-year survival ranged from 89.5% to 95.3%. Coxs relative risk (RR) was calculated relative to the fixed modular-bearing Profix knee (the most frequently used TKR in Norway), and ranged from 1.1 to 2.6. The risk of revision for aseptic tibial loosening was higher in the mobile-bearing LCS Classic (RR 6.8 (95% confidence interval (CI) 3.8 to 12.1)), the LCS Complete (RR 7.7 (95% CI 4.1 to 14.4)), the fixed modular-bearing Duracon (RR 4.5 (95% CI 1.8 to 11.1)) and the fixed non-modular bearing AGC Universal TKR (RR 2.5 (95% CI 1.3 to 5.1)), compared with the Profix. These implants (except AGC Universal) also had an increased risk of revision for femoral loosening (RR 2.3 (95% CI 1.1 to 4.8), RR 3.7 (95% CI 1.6 to 8.9), and RR 3.4 (95% CI 1.1 to 11.0), respectively). These results suggest that aseptic loosening is related to design in TKR.

Does patella resurfacing really matter? Pain and function in 972 patients after primary total knee arthroplasty An observational study from the Norwegian Arthroplasty Register

Background and purpose Resurfacing of the patella during primary total knee arthroplasty (TKA) is often recommended based on higher revision rates in non-resurfaced knees. As many of these revisions are insertions of a patella component due to pain, and since only patients with a non-resurfaced patella have the option of secondary resurfacing, we do not really know whether these patients have more pain and poorer function. The main purpose of the present paper was therefore to assess pain and function at least 2 years after surgery for unrevised primary non-resurfaced and resurfaced TKA, and secondary among prosthesis brands. Methods Information needed to calculate subscales from the knee injury and osteoarthritis outcome score (KOOS) was collected in a questionnaire given to 972 osteoarthritis patients with intact primary TKAs that had been reported to the Norwegian Arthroplasty Register. Pain and satisfaction on visual analog scales and improvement in EQ-5D index score ΔEQ-5D) were also used as outcomes. Outcomes were measured on a scale from 0 to 100 units (worst to best). To estimate differences in mean scores, we used multiple linear regression with adjustment for possible confounders. Results We did not observe any differences between resurfacing and non-resurfacing in any outcome, with estimated differences of ≤ 1.4 units and p-values of > 0.4. There was, however, a tendency of better results for the NexGen implant as compared to the reference brand AGC for symptoms (difference = 4.9, p = 0.05), pain (VAS) (difference = 8.3, p = 0.004), and satisfaction (VAS) (difference = 7.9, p = 0.02). However, none of these differences reached the stated level of minimal perceptible clinical difference. Interpretation Resurfacing of the patella has no clinical effect on pain and function after TKA. Differences between the brands investigated were small and they were assumed to be of minor importance.

Prevalence of airway symptoms among hairdressers in Bergen, Norway

OBJECTIVE To assess respiratory symptoms among hairdressers in Norway. METHODS The study was based on a questionnaire sent to 100 hairdressers (91% responding) and 95 office workers (84% responding). The questionnaire sought information about allergy, respiratory symptoms in the past year, and symptoms after exposures to different types of pollutants, working conditions, and smoking habits. A population based control group was established because the hairdressers and office workers differed in age and smoking habits. RESULTS The prevalence of respiratory symptoms in the past year did not differ significantly between hairdressers and office workers after adjusting for age, atopy, and smoking. The hairdressers over 40 years of age reported significantly more symptoms—such as wheezing and breathlessness—in the past year than the office workers of the same age. Compared with the population based control group, both hairdressers younger than 30 and those over 40 reported more symptoms—such as breathlessness in the past year. The oldest hairdressers reported such symptoms as wheezing and breathlessness more often than did the younger hairdressers. These differences in breathlessness were significant after adjusting for smoking and wheezing. The same trend was not found among the office workers. The hairdressers reported significantly more wheezing, breathlessness, runny eyes, and blocked or runny nose from exposure to hair dyes, permanent oils, bleaching powder, and other chemicals used in a hairdressing salon, compared with the office workers. Prevalence of symptoms during exposure to other types of generel pollutants was similar in the two groups. CONCLUSIONS Hairdressers are exposed to low levels of various irritating chemicals every day. The prevalences of acute symptoms related to the exposure of hairdressers to hairdressing chemicals are very high. Hairdressers, especially the oldest hairdressers, have more asthma-like symptoms than the control groups.

Failure of total knee arthroplasty with or without patella resurfacing: A study from the Norwegian Arthroplasty Register with 0–15 years of follow-up

Background and purpose Patella resurfacing during primary total knee arthroplasty (TKA) is disputed and new prosthesis designs have been introduced without documentation of their survival. We assessed the impact on prosthesis survival of patella resurfacing and of prosthesis brand, based on data from the Norwegian Arthroplasty Register. Patients and methods 5 prosthesis brands in common use with and without patella resurfacing from 1994 through 2009 were included n = 11,887. The median follow-up times were 9 years for patella-resurfaced implants and 7 years for implants without patella resurfacing. For comparison of prosthesis brands, also brands in common use with only one of the two treatment options were included in the study population (n = 25,590). Cox regression analyses were performed with different reasons for revision as endpoints with adjustment for potential confounders. Results We observed a reduced overall risk of revision for patella resurfaced (PR) TKAs, but the statistical significance was borderline (RR = 0.84, p = 0.05). At 15 years, 92% of PR and 91% of patella non resurfaced (NR) prostheses were still unrevised. However, PR implants had a lower risk of revision due to pain alone (RR = 0.1, p < 0.001), but a higher risk of revision due to loosening of the tibial component (RR = 1.4, p = 0.03) and due to a defective polyethylene insert (RR = 3.2, p < 0.001). At 10 years, the survival for the reference NR brand AGC Universal was 93%. The NR brands Genesis I, Duracon, and Tricon (RR = 1.4–1.7) performed statistically significantly worse than NR AGC Universal, while the NR prostheses e.motion, Profix, and AGC Anatomic (RR = 0.1–0.7), and the PR prostheses NexGen and AGC Universal (RR = 0.4–0.5) performed statistically significantly better. LCS, NexGen, LCS Complete (all NR), and Tricon, Genesis I, LCS, and Kinemax (all PR) showed no differences in this respect from the reference brand. A lower risk of revision (crude) was found for TKAs performed after 2000 as compared to those performed earlier (RR = 0.8, p = 0.001). Interpretation Although revision risk was similar for PR and NR TKAs, we found important differences in reasons for revision. Our results also indicate that survivorship of TKAs has improved.

Good function after shoulder arthroplasty.

Background and purpose Different results after shoulder arthroplasty have been found for different diagnostic groups. We evaluated function, pain, and quality of life after shoulder arthroplasty in 4 diagnostic groups. Patients and methods Patients with shoulder arthroplasties registered in the Norwegian Arthroplasty Register from 1994 through 2008 were posted a questionnaire in 2010. 1,107 patients with rheumatoid arthritis (RA), osteoarthritis (OA), acute fracture (AF), or fracture sequela (FS) returned completed forms (65% response rate). The primary outcome measure was the Oxford shoulder score (OSS), which assesses symptoms and function experienced by the patient on a scale from 0 to 48. A secondary outcome measure was the EQ-5D, which assesses life quality. The patients completed a questionnaire concerning symptoms 1 month before surgery, and another concerning the month before they received the questionnaire. Results Patients with RA and OA had the best results with a mean improvement in OSS of 16 units, as opposed to 11 for FS patients. Both shoulder pain and function had improved substantially. The change in OSS for patients with AF was negative (–11), but similar end results were obtained for AF patients as for RA and OA patients. Quality of life had improved in patients with RA, OA, and FS. Interpretation Good results in terms of pain relief and improved level of function were obtained after shoulder arthroplasty for patients with RA, OA, and—to a lesser degree—FS. A shoulder arthropathy had a major effect on quality of life, and treatment with shoulder replacement substantially improved it.

Outcomes of Unicompartmental Knee Arthroplasty After Aseptic Revision to Total Knee Arthroplasty: A Comparative Study of 768 Tkas and 578 Ukas Revised to Tkas from the Norwegian Arthroplasty Register (1994 to 2011).

BACKGROUND The general recommendation for a failed primary unicompartmental knee arthroplasty (UKA) is revision to a total knee arthroplasty (TKA). The purpose of the present study was to compare the outcomes, intraoperative data, and mode of failure of primary UKAs and primary TKAs revised to TKAs. METHODS The study was based on 768 failed primary TKAs revised to TKAs (TKA→TKA) and 578 failed primary UKAs revised to TKAs (UKA→TKA) reported to the Norwegian Arthroplasty Register between 1994 and 2011. Patient-reported outcome measures (PROMs) including the EuroQol EQ-5D, the Knee Injury and Osteoarthritis Outcome Score (KOOS), and visual analog scales assessing satisfaction and pain were used. We performed Kaplan-Meier and Cox regression analyses adjusting for propensity score to assess the survival rate and the risk of re-revision and multiple linear regression analyses to estimate the differences between the two groups in mean PROM scores. RESULTS Overall, 12% in the UKA→TKA group and 13% in the TKA→TKA group underwent re-revision between 1994 and 2011. The ten-year survival percentage of UKA→TKA versus TKA→TKA was 82% versus 81%, respectively (p = 0.63). There was no difference in the overall risk of re-revision for UKA→TKA versus TKA→TKA (relative risk [RR] = 1.2; p = 0.19), or in the PROM scores. However, the risk of re-revision was two times higher for TKA→TKA patients who were greater than seventy years of age at the time of revision (RR = 2.1; p = 0.05). A loose tibial component (28% versus 17%), pain alone (22% versus 12%), instability (19% versus 19%), and deep infection (16% versus 31%) were major causes of re-revision for UKA→TKA versus TKA→TKA, respectively, but the observed differences were not significant, with the exception of deep infection, which was significantly greater in the TKA→TKA group (RR = 2.2; p = 0.03). The surgical procedure of TKA→TKA took a longer time (mean of 150 versus 114 minutes) and more of the procedures required stems (58% versus 19%) and stabilization (27% versus 9%) compared with UKA→TKA. CONCLUSIONS Despite TKA→TKA seeming to be a technically more difficult surgical procedure, with a higher percentage of re-revisions due to deep infection compared with UKA→TKA, the overall outcomes of UKA→TKA and TKA→TKA were similar.

Failure of aseptic revision total knee arthroplasties

Background and purpose — In Norway, the proportion of revision knee arthroplasties increased from 6.9% in 1994 to 8.5% in 2011. However, there is limited information on the epidemiology and causes of subsequent failure of revision knee arthroplasty. We therefore studied survival rate and determined the modes of failure of aseptic revision total knee arthroplasties. Method — This study was based on 1,016 aseptic revision total knee arthroplasties reported to the Norwegian Arthroplasty Register between 1994 and 2011. Revisions done for infections were not included. Kaplan-Meier and Cox regression analyses were used to assess the survival rate and the relative risk of re-revision with all causes of re-revision as endpoint. Results — 145 knees failed after revision total knee arthroplasty. Deep infection was the most frequent cause of re-revision (28%), followed by instability (26%), loose tibial component (17%), and pain (10%). The cumulative survival rate for revision total knee arthroplasties was 85% at 5 years, 78% at 10 years, and 71% at 15 years. Revision total knee arthroplasties with exchange of the femoral or tibial component exclusively had a higher risk of re-revision (RR = 1.7) than those with exchange of the whole prosthesis. The risk of re-revision was higher for men (RR = 2.0) and for patients aged less than 60 years (RR = 1.6). Interpretation — In terms of implant survival, revision of the whole implant was better than revision of 1 component only. Young age and male sex were risk factors for re-revision. Deep infection was the most frequent cause of failure of revision of aseptic total knee arthroplasties.

Have the Causes of Revision for Total and Unicompartmental Knee Arthroplasties Changed During the Past Two Decades

BackgroundRevisions after knee arthroplasty are expected to increase, and the epidemiology of failure mechanisms is changing as new implants, technology, and surgical techniques evolve.Questions/purposes(1) Was there improvement in survival for TKA and unicompartmental knee arthroplasty (UKA) when comparing two consecutive 11-year periods with similar followups in a national registry? (2) Were there changes in the causes of revision during the two times? (3) Could the changes in revision causes be attributed to patient or implant characteristics?MethodsA total of 60,623 TKAs (2426 revisions) and 7648 UKAs (725 revisions) were selected from the Norwegian Arthroplasty Register and analyzed based on year of primary surgery: 1994 to 2004 (Period 1) and 2005 to 2015 (Period 2). TKAs had median followup of 3.5 years in Period 1 and 4.2 years in Period 2. Median followup for UKAs was 2.7 years in Period 1 and 4.6 years in Period 2. Of the patients included in the registry, 99.6% were accounted for at the time of analysis, whereas 0.4% had moved abroad. We used Kaplan-Meier analyses and log-rank test to investigate changes in survival. Relative risk of revision in Period 2 relative to Period 1 was calculated for each registered revision cause in a Cox regression model adjusted for age, sex, diagnosis, fixation, and patella resurfacing.ResultsFor TKAs, the 10-year Kaplan-Meier survival free from revision improved from Period 1 to Period 2 from 91% (95% CI, 90%–92%) to 94% (95% CI, 94%–95%; p < 0.001). Revisions resulting from aseptic loosening of the femoral component, polyethylene wear/breakage, patellar dislocation, and unexplained pain decreased, whereas revisions resulting from early infection increased. Patients in Period 2 were younger and more often men compared with patients in Period 1. A higher risk of revision was found for male sex (relative risk [RR], 1.1; 95% CI, 1.0–1.2; p = 0.048) and age younger than 65 years (RR, 1.7; 95% CI, 1.6–1.9; p < 0.001). With UKAs, the 10-year survival free from revision was 80% (95% CI, 76%–84%) in Period 1 and 81% (95% CI, 79%–83%; p = 0.261) in Period 2. Revisions resulting from tibial aseptic loosening, polyethylene wear/breakage, and periprosthetic fractures decreased, but there were more revisions resulting from progression of osteoarthritis. In Period 2, there were more men and the average age was younger than for patients in Period 1. For UKAs, age younger than 65 years had a higher risk of revision (RR, 1.7; 95% CI, 1.5–2.0; p < 0.001), whereas sex did not affect the risk of revision.ConclusionsWe found an improvement in survival free from revision for TKA in the last period, but no similar improvement for UKA, and the survivorship for UKAs remains rather dramatically lower than that observed for TKAs. The decision to perform a UKA should be made with the explicit awareness that its survivorship is substantially inferior to that of TKA; any perceived advantages of UKA should be balanced against this issue of its decreased durability.Level of EvidenceLevel III, therapeutic study.

Better survival of hybrid total knee arthroplasty compared to cemented arthroplasty.

Background and purpose — There have been few comparative studies on total knee replacement (TKR) with cemented tibia and uncemented femur (hybrid TKR). Previous studies have not shown any difference in revision rate between cemented and hybrid fixation, but these studies had few hybrid prostheses. We have evaluated the outcome of hybrid TKR based on data from the Norwegian Arthroplasty Register (NAR). Patients and methods — We compared 4,585 hybrid TKRs to 20,095 cemented TKRs with risk of revision for any cause as the primary endpoint. We included primary TKRs without patella resurfacing that were reported to the NAR during the years 1999–2012. To minimize the possible confounding effect of prosthesis brands, only brands that were used both as hybrids and cemented in more than 200 cases were included. Kaplan-Meier survival analysis and Cox regression analysis were done with adjustment for age, sex, and preoperative diagnosis. To include death as a competing risk, cumulative incidence function estimates were calculated. Results — Estimated survival at 11 years was 94.3% (95% CI: 93.9–94.7) in the cemented TKR group and 96.3% (CI: 95.3–97.3) in the hybrid TKR group. The adjusted Cox regression analysis showed a lower risk of revision in the hybrid group (relative risk = 0.58, CI: 0.48–0.72, p < 0.001). The hybrid group included 3 brands of prostheses: LCS classic, LCS complete, and Profix. Profix hybrid TKR had lower risk of revision than cemented TKR, but the LCS classic and LCS complete did not. Kaplan-Meier estimated survival at 11 years was 96.8% (CI: 95.6–98.0) in the hybrid Profix group and 95.2% (CI: 94.6–95.8) in the cemented Profix group. Mean operating time was 17 min longer in the cemented group. Interpretation — Survivorship of the hybrid TKR at 11 years was better than that for cemented TKR, or the same, depending on the brand of prosthesis. Hybrid fixation appears to be a safe and time-efficient alternative to cemented fixation in total knee replacement surgery.

Cleaning at Home and at Work in Relation to Lung Function Decline and Airway Obstruction

Rationale: Cleaning tasks may imply exposure to chemical agents with potential harmful effects to the respiratory system, and increased risk of asthma and respiratory symptoms among professional cleaners and in persons cleaning at home has been reported. Long‐term consequences of cleaning agents on respiratory health are, however, not well described. Objectives: This study aimed to investigate long‐term effects of occupational cleaning and cleaning at home on lung function decline and airway obstruction. Methods: The European Community Respiratory Health Survey (ECRHS) investigated a multicenter population‐based cohort at three time points over 20 years. A total of 6,235 participants with at least one lung function measurement from 22 study centers, who in ECRHS II responded to questionnaire modules concerning cleaning activities between ECRHS I and ECRHS II, were included. The data were analyzed with mixed linear models adjusting for potential confounders. Measurements and Main Results: As compared with women not engaged in cleaning (&Dgr;FEV1 = −18.5 ml/yr), FEV1 declined more rapidly in women responsible for cleaning at home (−22.1; P = 0.01) and occupational cleaners (−22.4; P = 0.03). The same was found for decline in FVC (&Dgr;FVC = −8.8 ml/yr; −13.1, P = 0.02; and −15.9, P = 0.002; respectively). Both cleaning sprays and other cleaning agents were associated with accelerated FEV1 decline (−22.0, P = 0.04; and −22.9, P = 0.004; respectively). Cleaning was not significantly associated with lung function decline in men or with FEV1/FVC decline or airway obstruction. Conclusions: Women cleaning at home or working as occupational cleaners had accelerated decline in lung function, suggesting that exposures related to cleaning activities may constitute a risk to long‐term respiratory health.