Cause-Specific Mortality Trends Following Total Hip and Knee Arthroplasty

Life Expectancy of Patients Undergoing Total Knee Arthroplasty: Comparison With General Population

BACKGROUND

This study aimed to analyze the life expectancy and cause of death in osteoarthritis (OA) patients who underwent total knee arthroplasty (TKA) and to identify risk factors that affect long-term mortality rate after TKA.

METHODS

Among 601 patients, who underwent primary TKA due to OA by a single surgeon from July 2005 to December 2011, we identified patients who died after the operation using data obtained from the National Statistical Office of Korea. We calculated 5-, 10-, and 15-year survival rates of the patients and age-specific standardized mortality ratios (SMRs) compared to general population of South Korea according to the causes of death. We also identified risk factors for death.

RESULTS

The 5-year, 10-year, and 15-year survival rates were 94%, 84%, and 75%, respectively. The overall age-specific SMR of the TKA cohort was lower than that of the general population (0.69; P < 0.001). Cause-specific SMRs for circulatory diseases, neoplasms, and digestive diseases after TKA were significantly lower than those of the general population (0.65, 0.58, and 0.16, respectively; all P < 0.05). Male gender, older age, lower body mass index (BMI), anemia, and higher Charlson comorbidity index (CCI) were significant factors associated with higher mortality after TKA.

CONCLUSION

TKA is a worthwhile surgery that can improve life expectancy, especially from diseases of the circulatory system, neoplasms, and digestive system, in patients with OA compared to the general population. However, careful follow-up is needed for patients with male gender, older age, lower BMI, anemia, and higher CCI, as these factors may increase long-term mortality risk after TKA.

LEVEL OF EVIDENCE

III.

Risk factors for postoperative medical morbidity and 3-month mortality in elderly patients with hip fracture following hip arthroplasty during COVID-19 pandemic

BACKGROUND

The purpose of the current study was to investigate the incidence of postoperative medical complications and 3-month mortality in patients  ≥ 70 years old with hip fracture following hip arthroplasty (HA) and independent risk factors associated with postoperative medical complications and 3-month mortality during the Coronavirus Disease 2019 (COVID-19) pandemic.

METHODS

A multicenter retrospective study was conducted, patients  ≥ 70 years old with HA for hip fracture under general anesthesia were included during COVID-19 and before COVID-19 pandemic. The outcome was defined as postoperative medical complications and 3-month mortality. The baseline characteristics and risk factors were collected, multivariable logistic regression was used to identify independent risk factors for postoperative medical complications and 3-month mortality.

RESULTS

A total of 1096 patients were included during COVID-19 pandemic and 1149 were included before COVID-19 pandemic in the study. Patients  ≥ 70 years with hip fracture for HA had longer fracture to operation duration (7.10 ± 3.52 vs. 5.31 ± 1.29, P < 0.001), and the incidence of postoperative medical complications (21.90% vs. 12.53%, P < 0.001) and 3-month mortality (5.20% vs. 3.22%, P = 0.025) was higher during COVID-2019 pandemic. Multivariate logistic regression analysis showed that dementia (OR 2.73; 95% CI 1.37-5.44; P = 0.004), chronic obstructive pulmonary disease (COPD) (OR 3.00; 95% CI 1.92-4.71; P < 0.001), longer fracture to operation duration (OR 1.24; 95% CI 1.19-1.30; P < 0.001) were associated with increased risk for postoperative medical complications. COPD (OR 2.10; 95% CI 1.05-4.17; P = 0.035), dementia (OR 3.00; 95% CI 1.11-7.94; P = 0.031), postoperative medical complications (OR 4.99; 95% CI 2.68-9.28; P < 0.001), longer fracture to operation duration (OR 1.11; 95% CI 1.04-1.19; P = 0.002) were associated with increased risk for 3-month mortality.

CONCLUSIONS

In conclusion, we found that postoperative medical morbidity and 3-month mortality in patients with hip fracture underwent HA were 21.90% and 5.20%, respectively, during the COVID-19. COPD, dementia and longer fracture to operation duration were associated with negative outcome in patients with hip fracture underwent HA during the COVID-19.

Long-term Cognitive Trajectory After Total Joint Arthroplasty

IMPORTANCE

Individuals with total joint arthroplasty (TJA) have long-term exposure to metal-containing implants; however, whether long-term exposure to artificial implants is associated with cognitive function is unknown.

OBJECTIVE

To compare long-term cognitive trajectories in individuals with and without TJA.

DESIGN, SETTING, AND PARTICIPANTS

This population-based cohort study assessed serial cognitive evaluations of 5550 participants (≥50 years of age) from the Mayo Clinic Study of Aging between November 1, 2004, and December 31, 2020.

EXPOSURES

Total joint arthroplasty of the hip or the knee.

MAIN OUTCOMES AND MEASURES

Linear mixed-effects models were used to compare the annualized rate of change in global and domain-specific cognitive scores in participants with and without TJA, adjusting for age, sex, educational level, apolipoprotein E ε4 carrier status, and cognitive test practice effects.

RESULTS

A total of 5550 participants (mean [SD] age at baseline, 73.04 [10.02] years; 2830 [51.0%] male) were evaluated. A total of 952 participants had undergone at least 1 TJA of the hip (THA, n = 430) or the knee (TKA, n = 626) before or after entry into the cohort. Participants with TJA were older, more likely to be female, and had a higher body mass index than participants without TJA. No difference was observed in the rate of cognitive decline in participants with and without TJA until 80 years of age. A slightly faster cognitive decline at 80 years or older and more than 8 years from surgery was observed (b = -0.03; 95% CI, -0.04 to -0.02). In stratified analyses by surgery type, the faster decline was observed primarily among older participants with TKA (b = -0.04; 95% CI, -0.06 to -0.02).

CONCLUSIONS AND RELEVANCE

In this cohort study, long-term cognitive trajectories in individuals with and without TJA were largely similar except for a slightly faster decline among the oldest patients with TKA; however, the magnitude of difference was small and of unknown clinical significance.

No effect of fixation type on early and late mortality after total knee arthroplasty: a Dutch arthroplasty register study

PURPOSE

Postoperative mortality is commonly reported as outcome measurement after total knee arthroplasty (TKA). Mortality might be influenced by multiple factors including cementation of the prosthesis. Until now, the influence of cementation on early and late mortality after TKA is unknown. The aim of the present study was to determine the effect of fixation on early and late mortality after primary TKA.

METHODS

All patients in the Dutch Arthroplasty Register (LROI) with a primary TKA for osteoarthritis were eligible for inclusion. Data collected from 2007 to 2014 with follow-up until January 2020 were used. Survival analysis was performed by using Kaplan-Meier and Cox survival analysis to determine the mortality rate according to fixation. Adjustments were made for age at time of surgery, gender, American Society of Anaesthesiologists class, and year of surgery.

RESULTS

In total 108,687 TKA were included for analysis, which comprised 95,857 cemented, 6,140 cementless and 6,690 hybrid TKA. The early and late mortality rate in cemented TKA was statistically not different compared to cementless or hybrid TKA at 30 days, 31-90 days, 91 days-1 year and 1-5 years. The hazard ratio at 30 days was 1.05 (CI 0.49-2.25) for hybrid fixation, and 1.46 (CI 0.74-2.90) for cementless fixation compared to cemented fixation. The 1-5 years hazard ratio was 1.06 (CI 0.96-1.17) and 0.97 (CI 0.87-1.08), respectively.

CONCLUSION

Based on register data, method of fixation does not influence early mortality after primary TKA. This suggests that there is no preferred fixation technique for primary TKA based on the mortality rates.

LEVEL OF EVIDENCE

IV.

Contemporary Mortality Rate and Outcomes in Nonagenarians After Primary Total Knee Arthroplasty

BACKGROUND

Nonagenarians (90-99 years) have experienced the fastest percent growth in primary total knee arthroplasty (TKA) utilization recently. However, there are limited data on the results of the procedure in this population. The goals of this study are to determine the mortality rate, implant survivorship, clinical outcomes, and complications of primary TKAs in nonagenarians.

METHODS

Our institutional total joint registry was used to identify 105 nonagenarians who underwent 119 primary cemented TKAs for osteoarthritis between 1997 and 2017. Mean age was 92 years, with 58% being female. Mortality, revision, and reoperation were assessed using cumulative incidence with death as a competing risk and Cox regression methods. Clinical outcomes were assessed using Knee Society Scores. A posterior-stabilized design was used in 88%. Mean follow-up was 4 years.

RESULTS

The mortality rates were 0%, 2%, 9%, and 47% at 90 days, 1 year, 2 years, and 5 years, respectively. The 5-year cumulative incidences of any revision and reoperation were 0% and 3%, respectively. The reoperations included 2 internal fixations for periprosthetic fracture and 1 hardware removal. The mean Knee Society Score improved significantly from 34 preoperatively to 80 at 5 years (P < .001). The 5-year cumulative incidence of any nonmortality complication was 66%. The most common complications were urinary tract infections and retention (8%) in the early postoperative period, and acquired idiopathic stiffness (10%) later.

CONCLUSION

Nonagenarians undergoing primary TKA had low mortality rates at 90 days (0%) and 1 year (2%) with substantial functional improvements. The cumulative incidences of revision and reoperation were low at 5 years.

LEVEL OF EVIDENCE

Level IV, retrospective cohort.

Risk of 30-day Readmission after Knee or Hip Replacement in Rheumatoid Arthritis and Osteoarthritis by non-Medicare and Medicare Payer Status

OBJECTIVE

To determine the indication and risk of 30-day rehospitalization after hip or knee replacement among rheumatoid arthritis (RA) and osteoarthritis (OA) by Medicare and non-Medicare status.

METHODS

Using the Nationwide Readmission Database (2010-2014), we defined an Index hospitalization as an elective hospitalization with a principal procedure of total hip or knee replacement among adults aged ≥18 years. Primary payer was categorized as Medicare or non- Medicare. Survey logistic regression provided the odds of 30-day rehospitalization in RA relative to OA. We calculated the rates for principal diagnoses leading to rehospitalization.

RESULTS

Overall, 3.53% of 2,190,745 index hospitalization had a 30-day rehospitalization. Patients with RA had a higher adjusted risk of rehospitalization after TKR (Odds Ratio [OR], 1.11; 95% Confidence Interval [CI], 1.02 to 1.21) and THR (OR, 1.39; 95% CI, 1.19 to 1.62). Persons with RA and OA did not differ with respect to rates of infections, cardiac events, or postoperative complications leading to the rehospitalization. After TKR, RA patients with Medicare had a lower VTE risk (OR, 0.58;95% CI, 0.58 to 0.88) while post-THR those with RA had a greater VTE risk (OR, 2.41;95% CI, 1.04 to 5.57).

CONCLUSION

RA patients had a higher 30-day rehospitalization than OA after TKR and THR regardless of payer type. While infections, postoperative complications, cardiac did not differ, there was a significant difference in venous thromboembolism as the rehospitalization's principal diagnosis.

Is It Worth Delaying Total Knee Replacement as Late as Possible? A Cost-Effectiveness Analysis Using a Markov Model in the Indian Setting

BACKGROUND

Total knee replacement (TKR) is often delayed in younger patients in an attempt to prolong the longevity of the prosthesis and avoid the risk of revision. But delaying a TKR might compromise the quality of life of young patients who are otherwise active and healthy.

METHODS

We built a Markov decision model to study the simulated clinical course of a 50-year-old patient with severe unilateral knee osteoarthritis who could be either treated with conservative therapies or with a TKR at some point in time. An Indian healthcare payer perspective model was used, and lifetime costs (in Indian rupees), quality-adjusted life-years (QALYs), and incremental cost-effectiveness ratio (ICER) were calculated.

RESULTS

In the base case scenario, patients who did not receive a TKR had a total lifetime cost of ₹216 709 and accumulated 13.59 QALYS in their lifetime. Those who received a TKR without delay (at age 50) accumulated 16.71 QALYS in their lifetime with an ICER of ₹9789 per QALY. When TKR was delayed, the total QALYs decreased, and ICER increased with each year of delay. But the cumulative risk of revision decreased from 27.4% when TKR was performed at 50 years to 10.0% when TKR was done at 70 years.

CONCLUSION

Our analysis found that TKR is a cost-effective procedure when the healthcare payer is willing to pay at least ₹9789 ($132) per QALY. The results also suggested that an early TKR is preferred to a delayed TKR despite the higher incidence of revisions.

Contemporary Mortality Rate and Outcomes in Nonagenarians Undergoing Primary Total Hip Arthroplasty

BACKGROUND

Nonagenarians (90-99 years) have experienced the fastest percent growth in primary THA utilization recently. However, there are limited data on this population. This study aimed to determine the mortality rate, implant survivorship, clinical outcomes, and complications of primary THAs in nonagenarians.

METHODS

Our institutional total joint registry was used to identify 144 nonagenarians who underwent 149 primary THAs for osteoarthritis only between 1997 and 2017. The mean age was 92 years, with 63% being female. Mortality, revision, and reoperation were assessed using cumulative incidence with death as a competing risk and Cox regression methods. Clinical outcomes were assessed using Harris hip scores (HHSs). Cemented femoral components were used in 68%. The mean follow-up was 4 years.

RESULTS

The mortality rates were 6%, 8%, 14%, and 49% at 90 days, 1 year, 2 years, and 5 years, respectively. The 5-year cumulative incidences of any revision and reoperation were 1% and 4%, respectively. The mean HHS improved significantly from 48 preoperatively to 76 at 5 years (P < .001). The 5-year cumulative incidence of any complication was 69%, with the most common being periprosthetic femur fracture (7) intraoperatively, delirium (25) early postoperatively, and periprosthetic femur fracture (10) later postoperatively. Uncemented stem fixation was associated with a higher risk for intraoperative femur fracture (Hazard ratio 5, P = .04) but not with a higher 5-year periprosthetic postoperative femur fracture risk (P = .19).

CONCLUSION

Nonagenarians undergoing primary THA had substantial mortality rates at 90 days (6%) and 1 year (8%). While the cumulative incidence of any revision and reoperations were low at 5 years, the high complication rate is mostly due to periprosthetic fractures.

LEVEL OF EVIDENCE

Level IV, retrospective cohort.

Total knee arthroplasty reduces the risk of mortality in osteoarthritis patients up to 12 years: A Korean national cohort longitudinal follow-up study

INTRODUCTION

Mortality rates and causes of death after total knee arthroplasty (TKA) are of great interest to surgeons. However, there is a shortage of studies regarding those of the Asian population. The aim of this study was to compare the mortality rate and causes of death in patients after TKA to the general population.

METHODS

National sample cohort data from the Korean Health Insurance Review and Assessment Service were used. In this study, 1:4 matched patients after TKA (TKA group: 5072) and general participants (control group: 20,288) were selected as subjects. Their average follow-up duration was 57.2 months ranging from a year up to 12 years. The matches were processed for age, gender, income, region of residence, and past medical history. Mortality rates and causes of death were compared between groups. Regarding the mortality rates, we also performed subgroup analyses according to age.

RESULTS

Adjusted hazard ratio (HR) of the TKA group for mortality rate was less than 1 with significance (adjusted HR = 0.61 (95% confidence interval = 0.54-0.70, p < 0.001)). The ratios were less than 1 for both age groups (<70 and ≥70 years), respectively; however, for patients under 70, they were insignificant. Among the 11 major causes of death, the circulatory disease showed the most significantly reduced mortality rate for the TKA group compared to the control group. The neoplasm was the only other cause with a significantly reduced mortality rate for the TKA group.

CONCLUSION

The mortality rate in the TKA group was significantly lower than in the control group up to 12 years after the surgery in Korea. Among the major causes of death, circulatory disease and neoplasm showed a significant reduction in the mortality rate of the TKA group compared with the control group.

Cobalt and Chromium Ion Release in Metal-on-Polyethylene and Ceramic-on-Polyethylene THA: A Simulator Study With Cellular and Microbiological Correlations

BACKGROUND

The aims of this study were to determine the levels of cobalt (Co) and chromium (Cr) ions generated in simulators from metal-on-polyethylene (MoP) and ceramic-on-polyethylene (CoP) constructs. Furthermore, we aimed to investigate the cytotoxic effect of these ion levels on native tissues and their potential to modify periprosthetic joint infection risk.

METHODS

We used in vitro culture of human adipose-derived mesenchymal stem cells (AMSCs) and Staphylococcus epidermidis cultures, respectively. Ten hip simulator constructs (5 MoP and 5 CoP) were assembled and run for 1,000,000 cycles in bovine serum and evaluated for CoCr concentration. Cytotoxicity and growth impact on AMSCs and S. epidermidis was compared between CoCr and inert silicon dioxide.

RESULTS

After 1,000,000 cycles, mean MoP and CoP Co concentration was 2264 and 0.6 ng/mL, respectively (P < .001). Mean MoP and CoP Cr concentration was 217 and 4.3 ng/mL, respectively (P < .001). Mean MoP Co:Cr ratio was 10:1. Co ions were significantly more toxic to human AMSCs than control silicon dioxide in a dose-response manner (P < .001). S. epidermidis growth was not significantly impacted by Co concentrations observed in the simulators.

CONCLUSION

MoP constructs built in ideal conditions generated substantial CoCr debris, highlighting a baseline risk with these implants that may be exacerbated by host factors or imperfect surgical technique. Evaluation of impact on AMSCs suggests that debris levels produced under simulator conditions can be cytotoxic. In addition, these concentrations did not potentiate or inhibit S. epidermidis growth, suggesting that elevated periprosthetic joint infection rates with adverse local tissue reaction are related to other factors potentially associated with tissue necrosis.

Intra-Articular Steroid Injection for Patients with Hip Osteoarthritis: A Systematic Review and Meta-Analysis

Purpose

The aim of this current review was to confirm the efficacy of intra-articular steroid therapy (IAST) for patients with hip osteoarthritis (OA) and discuss the duration and influential factors of IAST.

Methods

Online databases (Medline, EMBASE, and Web of Science) were searched from inception to May 2019. Both randomized controlled trials (RCTs) and noncontrolled trials assessing the efficacy of hip IAST on pain were included. Common demographics data were extracted using a standardized form. Quality was assessed on the basis of Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence.

Results

12 trials met the inclusion criteria. According to data from individual trials, IAST had significant efficacy on hip OA in both immediate and delay pain reduction, which persisted up to 12 weeks after IAST. The influences of the baseline severity of hip OA or synovitis and injection dose or volume on the clinical outcome of IAST were still controversial. The IAST appeared to be well tolerant by most of the participants.

Conclusion

IAST was proved to be an efficacious therapy in both immediate and delay pain reduction for hip OA patients within 12 weeks. The longer follow-up data of efficacy and safety and potentially influential factors are still unclear and needed further confirmation.

Does Bariatric Surgery Normalize Risks After Total Knee Arthroplasty? Administrative Medicare Data

Patients with morbid obesity, defined as body mass index of greater than 40 kg/m², are being referred for weight loss and bariatric surgery before being accepted for a total knee arthroplasty (TKA). Previous studies have identified the risks associated with doing a TKA in an individual with an increased body mass index. We now present data identifying the same risks in individuals who have undergone bariatric surgery before submitting to TKA.

Change in the cause of inpatient mortality after arthroplasty: a retrospective study

Background

Although arthroplasty has been proved to be a safe and effective procedure, data regarding inpatient mortality rates associated with arthroplasty in China is unclear. We aimed to investigate the inpatient mortality rate after arthroplasty and the determinants of mortality at our center to ensure improved perioperative management.

Methods

This retrospective study included all patients who underwent arthroplasty at our center. Clinical data of mortality patients were collected. The incidence and the causes of inpatient mortality after arthroplasty were analyzed.

Results

A total of 4176 total knee arthroplasties, 2164 total hip arthroplasties, and 1031 femoral head replacements were performed. A rapid growth in surgery volume was observed, and more than 50% of the surgeries were performed in the last 5 years. The overall inpatient mortality rate is 0.3%; however, the mortality rate even decreased in the last 5 years. The cause of death changed over time. Pneumonia has become the leading cause of death in the past 5 years instead of cardiovascular complications.

Conclusions

Arthroplasty is a safe and effective procedure associated with a relatively low inpatient mortality in China. And inpatient mortality does not increase as the growing surgery volume due to improvement of perioperative management. However, patients presenting with risk factors and those undergoing non-elective procedures demonstrated a relatively high incidence of postoperative complications, particularly pneumonia.

Long-Term Mortality Trends After Revision Total Knee Arthroplasty

BACKGROUND

Long-term mortality following primary total knee arthroplasty (TKA) is lower than the general population. However, it is unknown whether this is true in the setting of revision TKA. We examined long-term mortality trends following revision TKA.

METHODS

This retrospective study included 4907 patients who underwent 1 or more revision TKA between 1985 and 2015. Patients were grouped by surgical indications and followed until death or October 2017. The observed number of deaths was compared to the expected number of deaths using standardized mortality ratios (SMR) and Poisson regression models.

RESULTS

Compared to the general population, patients who underwent revision TKA for infection (SMR, 1.45; 95% confidence interval [CI], 1.33-1.57; P < .0001) and fracture (SMR, 1.16; 95% CI, 1.00-1.34; P = .04) experienced a significantly higher mortality risk. Patients who underwent revision TKA for infection and fracture experienced excess mortality soon after surgery which became more pronounced over time. In contrast, the mortality risk among patients who underwent revision TKA for loosening and/or bearing wear was similar to the general population (SMR, 0.95; 95% CI, 0.89-1.02; P = .16). Aseptic loosening and/or wear and instability patients had improved mortality initially; however, there was a shift to excess mortality beyond 5 years among instability patients, and beyond 10 years among aseptic loosening and/or wear patients.

CONCLUSION

Mortality is elevated soon after revision TKA for infection and fracture. Mortality is lower than the general population after revision TKA for loosening and/or bearing wear but gets worse than the general population beyond the first postoperative decade.

Do Patients Live Longer After THA and Is the Relative Survival Diagnosis-specific?

BACKGROUND

Hip replacements are successful in restoring mobility, reducing pain, and improving quality of life. However, the association between THA and the potential for increased life expectancy (as expressed by mortality rate) is less clear, and any such association could well be influenced by diagnosis and patient-related, socioeconomic, and surgical factors, which have not been well studied.

QUESTIONS/PURPOSES

(1) After controlling for birth year and sex, are Swedish patients who underwent THA likely to survive longer than individuals in the general population? (2) After controlling for relevant patient-related, socioeconomic/demographic factors and surgical factors, does relative survival differ across the various diagnoses for which THAs were performed in Sweden?

METHODS

Data from the Swedish Hip Arthroplasty Register, linked to administrative health databases, were used for this study. We identified 131,808 patients who underwent THA between January 1, 1999, and December 31, 2012. Of these, 21,755 had died by the end of followup. Patient- and surgery-specific data in combination with socioeconomic data were available for analysis. We compared patient survival (relative survival) with age- and sex-matched survival data in the entire Swedish population according to Statistics Sweden. We used multivariable modeling proceeded with a Cox proportional hazards model in transformed time.

RESULTS

Patients undergoing elective THA had a slightly improved survival rate compared with the general population for approximately 10 years after surgery. At 1 year after surgery, the survival in patients undergoing THA was 1% better than the expected survival (r = 1.01; 95% confidence interval [CI], 1.01-1.02; p < 0.001); at 5 years, this increased to 3% (r = 1.03; 95% CI, 1.03-1.03; p < 0.001); at 10 years, the difference was 2% (r = 1.02; 95% CI, 1.02-1.03; p < 0.001); and by 12 years, there was no difference between patients undergoing THA and the general population (r = 1.01; 95% CI, 0.99-1.02; p = 0.13). Using the diagnosis of primary osteoarthritis as a reference, hip arthroplasties performed for sequelae of childhood hip diseases had a similar survival rate (hazard ratio [HR], 1.02; 95% CI, 0.88-1.18; p = 0.77). Patients undergoing surgery for osteonecrosis of the femoral head (HR, 1.69; 95% CI, 1.60-1.79; p < 0.001), inflammatory arthritis (HR, 1.49; 95% CI, 1.38-1.61; p < 0.001), and secondary osteoarthritis (HR, 2.46; 95% CI, 2.03-2.99; p < 0.001) all had poorer relative survival. Comorbidities and the Elixhauser comorbidity index had a negative association with relative survival. Level of achieved education (middle level of education: HR, 0.90, 95% CI, 0.87-0.93, p < 0.001; high level: 0.76, 95% CI, 0.73-0.80, p < 0.001) and marital status (single status: HR, 1.33; 95% CI, 1.28-1.38; p < 0.001) were also negatively associated with survival.

CONCLUSIONS

Whereas it has been known that in most patients, THA improves quality of life, this study demonstrates that it also is associated with a slightly increased life expectancy that lasts for approximately 10 years after surgery, especially among patients whose diagnosis was primary osteoarthritis. This adds further proof of a health-economic value for this surgical intervention. The reasons for the increase in relative survival are unknown but are probably multifactorial.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Thirty-day mortality following total knee arthroplasty over 7 years at a tertiary referral centre of orthopaedic excellence

Total Knee Arthroplasty (TKA) is one of the most successful orthopaedic procedures. Around 100,000 TKAs are performed yearly in the United Kingdom. The aim of this study was to report the mortality rate within 30 days after a TKA in an Orthopaedic Centre of Excellence. We reviewed prospectively collected data of 7067 TKAs performed between April 2009-November 2016. All mortalities within 30 days of a TKA were recorded. Data such as age, sex, ASA, comorbidities and cause of death was recorded. There were 14 (0.198%) deaths within 30 days of TKA. There were eight male patients and six female patients who died. No statistical difference was demonstrated between gender. (p = 0.37). The mean age was 77.9 years (66-94 years). Means days to death from post-op were 9.6 days (2-30 days). One patient was ASA 1, six patients were ASA 2, six patients were ASA 3 and one patient did not have an ASA recorded. There was no statistical difference between the difference ASA groups. (p = 0.27). Cause of death documented was as follow: acute left ventricular failure-3; myocardial infarction-2; pneumonia-2; pulmonary oedema-1; gastrointestinal bleed-1 and multiorgan failure-1. Four patients did not have their cause of death recorded. The 30-day mortality rate after TKA in our institute is low and is comparable to other institutes. This emphasizes that primary TKA is a safe procedure. The predominant cause of perioperative mortality is cardiopulmonary disease.

Comorbidity does not predict long-term mortality after total hip arthroplasty

Background and purpose - In-hospital death following total hip arthroplasty (THA) is related to comorbidity. The long-term effect of comorbidity on all-cause mortality is, however, unknown for this group of patients and it was investigated in this study. Patients and methods - We used data from the Swedish Hip Arthroplasty Register, linked to the National Patient Register from the National Board of Health and Welfare, for patients operated on with THA in 1999-2012. We identified 120,836 THAs that could be included in the study. We evaluated the predictive power of the Charlson and Elixhauser comorbidity indices on mortality, using concordance indices calculated after 5, 8, and 14 years after THA. Results - All comorbidity indices performed poorly as predictors, in fact worse than a base model with age and sex only. Elixhauser was, however, the least bad choice and it predicted mortality with concordance indices 0.59, 0.58, and 0.56 for 5, 8, and 14 years after THA. Interpretation - Comorbidity indices are poor predictors of long-term mortality after THA.