Temporal trends in primary and revision total knee and hip replacement in Taiwan

The successful and safe conversion of joint arthroplasty to same-day surgery: A necessity after the COVID-19 pandemic

INTRODUCTION

A key strategy to address system pressures on hip and knee arthroplasty through the COVID-19 pandemic has been to shift procedures to the outpatient setting.

METHODS

This was a retrospective cohort and case-control study. Using the Discharge Abstract Database and the National Ambulatory Care Reporting System databases, we estimated the use of outpatient hip and knee arthroplasty in Ontario, Canada. After propensity-score matching, we estimated rates of 90-day readmission, 90-day emergency department (ED) visit, 1-year mortality, and 1-year infection or revision.

RESULTS

204,066 elective hip and 341,678 elective knee arthroplasties were performed from 2010-2022. Annual volumes of hip and knee arthroplasties increased steadily until 2020. Following the start of the COVID-19 pandemic (March 1, 2020) through December 31, 2022 there were 7,561 (95% CI 5,435 to 9,688) fewer hip and 20,777 (95% CI 17,382 to 24,172) fewer knee replacements performed than expected. Outpatient arthroplasties increased as a share of all surgeries from 1% pre-pandemic to 39% (hip) and 36% (knee) by 2022. Among inpatient arthroplasties, the tendency to discharge to home did not change since the start of the pandemic. During the COVID-19 era, patients receiving arthroplasty in the outpatient setting had a similar or lower risk of readmission than matched patients receiving inpatient arthroplasty [hip: RR 0.65 (0.56-0.76); knee: RR 0.86 (0.76-0.97)]; ED visits [hip: RR 0.78 (0.73-0.83); knee: RR 0.92 (0.88-0.96)]; and mortality, infection, or revision [hip: RR 0.65 (0.45-0.93); knee: 0.90 (0.64-1.26)].

CONCLUSION

Following the start of the COVID-19 pandemic in Ontario, the volume of outpatient hip and knee arthroplasties performed increased despite a reduction in overall arthroplasty volumes. This shift in surgical volumes from the inpatient to outpatient setting coincided with pressures on hospitals to retain inpatient bed capacity. Patients receiving arthroplasty in the outpatient setting had relatively similar outcomes to those receiving inpatient surgery after matching on known sociodemographic and clinical characteristics.

Predicting whether patients will achieve minimal clinically important differences following hip or knee arthroplasty

Aims

A substantial fraction of patients undergoing knee arthroplasty (KA) or hip arthroplasty (HA) do not achieve an improvement as high as the minimal clinically important difference (MCID), i.e. do not achieve a meaningful improvement. Using three patient-reported outcome measures (PROMs), our aim was: 1) to assess machine learning (ML), the simple pre-surgery PROM score, and logistic-regression (LR)-derived performance in their prediction of whether patients undergoing HA or KA achieve an improvement as high or higher than a calculated MCID; and 2) to test whether ML is able to outperform LR or pre-surgery PROM scores in predictive performance.

Methods

MCIDs were derived using the change difference method in a sample of 1,843 HA and 1,546 KA patients. An artificial neural network, a gradient boosting machine, least absolute shrinkage and selection operator (LASSO) regression, ridge regression, elastic net, random forest, LR, and pre-surgery PROM scores were applied to predict MCID for the following PROMs: EuroQol five-dimension, five-level questionnaire (EQ-5D-5L), EQ visual analogue scale (EQ-VAS), Hip disability and Osteoarthritis Outcome Score-Physical Function Short-form (HOOS-PS), and Knee injury and Osteoarthritis Outcome Score-Physical Function Short-form (KOOS-PS).

Results

Predictive performance of the best models per outcome ranged from 0.71 for HOOS-PS to 0.84 for EQ-VAS (HA sample). ML statistically significantly outperformed LR and pre-surgery PROM scores in two out of six cases.

Conclusion

MCIDs can be predicted with reasonable performance. ML was able to outperform traditional methods, although only in a minority of cases.

Pre- and Post-Operative Education and Health-Related Quality of Life for Patients with Hip/Knee Replacement and Hip Fracture

Arthroplasty for the hip/knee and surgeries for hip fractures are increasing worldwide. The aims of this study were to investigate changes in health-related quality of life (HRQOL) after surgery with an early mobility education program, and to explore their associations with pain and anxiety. Pain intensity and anxiety were assessed with the visual analogue scale (VAS) and Beck Anxiety Inventory (BAI), and HRQOL was assessed with the Short Form-36 (SF-36). The physical component summary (PCS) and mental component summary (MCS) and eight subscales of the SF-36 were calculated. At pre-operation, the patients suffered from moderate pain and mild anxiety, and their HRQOL scores were low (4.9, 7.8, 35.4, and 48.2 for the VAS, BAI, PCS, and MCS, respectively). The pain, anxiety, and HRQOL improved after surgery and had moderate to large effect sizes at 6-month follow-up (Glass's delta = 1.23, 0.88, 0.81, and 0.67 for VAS, BAI, PCS, and MCS, respectively). Pain and anxiety were strongly correlated to HRQOL at each stage, with the maximum correlation (r = -0.34 to -0.93) reached at 6-month follow-up. The surgery effectively improves HRQOL, as the reduced pain and anxiety lead to better physical and mental HRQOL.

Are joint replacement registries associated with burden of revision changes? A real-world panel data regression analysis

OBJECTIVES

The association of joint replacement registries with outcomes such as revision burden is uncertain. This study aimed to evaluate whether joint replacement registries are associated with the burden of revision changes while controlling for confounders that could affect the association.

DESIGN

A longitudinal study involving a combination of cross-sectional and time series data from 1980 to 2018. The study was a panel regression analysis using the difference-in-difference method.

SETTING

Data from countries with joint replacement registries and countries without joint replacement registries were used. Registry data were obtained from joint replacement registries' annual reports, while non-registry data were obtained from each included country's pooled hospitals' annual revision burden reported in the literature.

OUTCOME MEASURES

Changes in revision burden from 1980 to 2018 was the outcome measure. The revision burden in the registry periods of registry countries was compared with the non-registry periods of registry and non-registry countries.

RESULTS

Data were obtained from 12 registry periods and 8 non-registry periods. The average difference in revision burden in the registry periods of registry countries relative to the non-registry periods of registry and non-registry countries was statistically significant for hip, -3.80 (95% CI (-2.50 to -5.10); p<0.001) percentage points and knee, -1.63 (95% CI (-1.00 to -2.30); p<0.001) percentage points. This translates to a 19.30%, and 21.85% reduction in revision burden for hip and knee registries, for the whole sampling period.

CONCLUSION

Joint replacement registries are associated with a significant reduction in the burden of revision. Although revision burden reduces over time even without the registries, the establishment of joint replacement registries is associated with an increased reduction. The establishment of joint replacement registries in non-registry countries would be a worthwhile decision as it will further improve the outcomes of arthroplasty surgeries.

Comparison of Clinical Outcomes for Patients Treated With Gradually Reducing Radius Versus Single-Radius Total Knee Arthroplasty Systems

The choice of implant used for primary total knee arthroplasty (TKA) may have an impact on clinical outcomes. Clinical outcomes after TKA with gradually reducing radius implants (group G) vs single-radius implants (group S) were evaluated among Asian patients. This study included 541 patients (754 knees) in group G and 187 patients (275 knees) in group S. Range of motion (ROM), flexion contracture, American Knee Society Knee and American Knee Society Function scores (KSKS and KSFS, respectively), and mechanical and anatomic tibiofemoral angles (MTFA and ATFA, respectively) were evaluated with electronic medical records. In univariate analysis, improvements in ROM, KSKS, and KSFS were significantly better in group G compared with group S at 1-year follow-up. Multivariable analyses showed greater ROM (4.52°, P=.002), decreased flexion contracture (-2.80°, P=.011), and improved KSKS (15.57, P<.001) at 1 year for group G vs group S. No significant differences in KSFS, MTFA, or ATFA were observed. Implant-related complications and radiologic loosening were not identified in either group at 2-year follow-up. The TKA implants with a gradually reducing radius showed greater 1-year improvements in ROM, flexion contracture, KSKS, and similar implant-related safety outcomes compared with a single-radius system. [Orthopedics. 2022;45(6):367-372.].

Increased Risk of Common Orthopedic Surgeries for Patients with Rheumatic Diseases in Taiwan

Background and Objectives: Rheumatic diseases, including rheumatoid arthritis, ankylosing spondylitis, psoriasis, and systemic lupus erythematosus (SLE), are characterized by chronic arthritis or spondyloarthritis, which can lead to joint and spine destruction. Our previous studies showed that the risk of common orthopedic surgeries, including total knee replacement (TKR), total hip replacement (THR), or spine surgery, was increased in patients with rheumatoid arthritis, ankylosing spondylitis, psoriasis, and SLE. The aim of this review was to summarize the risk of TKR, THR, cervical spine, and lumbar spine surgery on the basis of studies conducted using data from Taiwan’s National Health Insurance Research Database (NHIRD). Materials and Methods: The risk of TKR, THR, cervical spine surgery, and lumbar spine surgery in patients with rheumatoid arthritis, ankylosing spondylitis, psoriasis, and SLE was summarized from the results of our previous studies and unpublished findings based on NHIRD data. Results: Patients with rheumatoid arthritis and psoriasis and men with ankylosing spondylitis showed an increased risk of TKR. Patients with rheumatoid arthritis, ankylosing spondylitis, and women with SLE showed an increased risk of receiving THR. Only patients with ankylosing spondylitis had an increased risk of cervical spine surgery, and patients with rheumatoid arthritis or ankylosing spondylitis showed an increased risk of lumbar spine surgery. Although the risk of THR, TKR, or spine surgery in these patients has declined in the era of biologics use, direct evidence for the effects of biologics agents is not yet available. Conclusions: There was an increased risk of common orthopedic surgery in patients with rheumatoid arthritis, ankylosing spondylitis, psoriasis, and SLE. Clinicians should be vigilant to reduce the increased risk of TKR and THR in young and middle-aged patients with rheumatoid arthritis, THR in young patients with ankylosing spondylitis, and young female patients with SLE, as well as cervical spine surgery in young patients with ankylosing spondylitis.

Can minimal clinically important differences in patient reported outcome measures be predicted by machine learning in patients with total knee or hip arthroplasty? A systematic review

OBJECTIVES

To systematically review studies using machine learning (ML) algorithms to predict whether patients undergoing total knee or total hip arthroplasty achieve an improvement as high or higher than the minimal clinically important differences (MCID) in patient reported outcome measures (PROMs) (classification problem).

METHODS

Studies were eligible to be included in the review if they collected PROMs both pre- and postintervention, reported the method of MCID calculation and applied ML. ML was defined as a family of models which automatically learn from data when selecting features, identifying nonlinear relations or interactions. Predictive performance must have been assessed using common metrics. Studies were searched on MEDLINE, PubMed Central, Web of Science Core Collection, Google Scholar and Cochrane Library. Study selection and risk of bias assessment (ROB) was conducted by two independent researchers.

RESULTS

517 studies were eligible for title and abstract screening. After screening title and abstract, 18 studies qualified for full-text screening. Finally, six studies were included. The most commonly applied ML algorithms were random forest and gradient boosting. Overall, eleven different ML algorithms have been applied in all papers. All studies reported at least fair predictive performance, with two reporting excellent performance. Sample size varied widely across studies, with 587 to 34,110 individuals observed. PROMs also varied widely across studies, with sixteen applied to TKA and six applied to THA. There was no single PROM utilized commonly in all studies. All studies calculated MCIDs for PROMs based on anchor-based or distribution-based methods or referred to literature which did so. Five studies reported variable importance for their models. Two studies were at high risk of bias.

DISCUSSION

No ML model was identified to perform best at the problem stated, nor can any PROM said to be best predictable. Reporting standards must be improved to reduce risk of bias and improve comparability to other studies.

Recovery patterns in patients undergoing revision surgery of the primary knee prosthesis

Purpose

Despite good survival rates of revised knee prostheses, little is known about recovery trajectories within the first 12 months after surgery. This retrospective observational study explored recovery trajectories in terms of pain, function and quality of life in patients after revision knee arthroplasty over 12 months.

Methods

Eighty-eight revision knee arthroplasty patients rated changes in daily physical functioning using the anchor question (0: very much worsened; 7: very much improved). Patient reported outcome measures (PROMs) of pain (range 0–10), function (Oxford Knee Score) and quality of life (EQ-5D-3L) were assessed preoperatively, at 3 and 12 months postoperatively. Four recovery trajectories were identified using the anchor question at 3 and 12 months postoperatively: no improvement, late improvement, early improvement, and prolonged improvement. Repeated measures ANOVA was conducted with recovery trajectories as dependent variable and PROM assessments as independent variables.

Results

Sixty percent reported improvement in daily physical functioning at 12 months postoperatively. Age and reason for revision differed between groups. Pain, function and EQ-5D-3L differed between groups over time. Late and prolonged improvement groups improved on all PROMs at 12 months. The early improvement group did not report improvement in daily physical functioning at 12 months, while improvements in function and pain during activity were observed.

Conclusions

Different recovery trajectories seem to exist and mostly match PROMs scores over time. Not all patients may experience beneficial outcome of revision knee arthroplasty. These findings are of importance to provide appropriate information on possible recovery trajectories after revision knee arthroplasty to patients.

Level of evidence

III

Supplementary Information

The online version contains supplementary material available at 10.1186/s40634-021-00436-w.

The reasons for and mortality of patients unable to receive reimplantation after resection arthroplasty for chronic hip periprosthetic infection

BACKGROUND

Two-stage exchange arthroplasty is a feasible treatment for chronic PJI (periprosthetic joint infection) of total hip arthroplasty (THA). However, there are large numbers of patients who are unable to ultimately receive reimplantation after resection arthroplasty owing to uncontrolled infection and multiple comorbidities. The purpose of the current study was to identify patient-related risk factors and reasons for being unable to undergo revision THA.

METHODS

Individuals undergoing resection arthroplasty for chronic PJI treatment from 2013 to 2020 at our institution were retrospectively reviewed. A variety of patient comorbidities, laboratory data, isolated pathogens, and follow-up status were collected for analysis.

RESULTS

A total of 84 patients (46 men and 38 women) with a 2.7 ± 2.1-year follow-up were analyzed. Thirty-eight (45.2%) patients eventually underwent revision THA, while the other 46 (54.8%) did not receive reimplantation during follow-up. The patients without receiving reimplantation had higher Charlson comorbidity index (CCI) score (3.1 ± 2.9 versus 1.2 ± 1.5; p = 0.001). Lower cumulative incidence of receiving reimplantation was observed in patients with chronic kidney disease (log-rank test, p = 0.019), anemia (p = 0.011), presence of initial fever (p = 0.030), and oxacillin-resistant strain infection (p = 0.030). The most common reasons for not receiving reimplantation were uncontrolled infection, unstable medical conditions, and death. The patients without reimplantation had a relatively higher mortality rate (log-rank test, p = 0.002).

CONCLUSION

Chronic hip PJI with poor medical conditions or oxacillin-resistant strain infection decreased the chance of undergoing revision surgery. These patients had unfavourable outcomes and a higher mortality rate after resection arthroplasty.

Burden and future projection of revision Total hip Arthroplasty in South Korea

Background

The annual number of hip arthroplasties is increasing combined with the aging population worldwide. In accordance with the increasing number of primary hip arthroplasties, the number of revision total hip arthroplasties (THAs) is expected to increase. The incidence and burden of revision THAs in the United States and have been reported by registry studies. To identify potential differences according to ethnics and regional practice, it is important to obtain data from East Asia. Nevertheless, there has been a lack of studies on the burden and future projection of revision THA based on a large-scale database in East Asia. The purpose of this study was to evaluate annual incidence and burden of revision THAs and to project the future burden in South Korea.

Methods

We identified primary THAs, primary hemiarthroplasties (HAs) and revision THAs, which were performed from 2010 to 2018, using database of Health Insurance and Review and Assessment (HIRA); nation-wide medical claim system of South Korea. The annual incidence rates (per 100,000) of primary THA, primary HA and revision THA, and the annual burden of revision THA; the number of revision THAs divided by the sum of primary hip arthroplasties and revision THAs, were calculated. The future burden of revision THAs were projected through 2030 using generalized linear model with Quasi-poisson regression.

Results

During the 9-year period, the annual incidences of primary THA, primary HA and revision THA increased by 47, 29 and 3%, respectively, while the revision burden decreased from 0.13 to 0.10. Compared to 2018, the annual incidences of primary THA, HA, and revision THA were projected to increase by 7.2, 2.3 and 1.1% per year, respectively, whereas the burden of revision THA was projected to decrease to 0.07 in 2030.

Conclusion

Trends of revision THA in South Korea were similar with those of national registry studies from the United States. The annual incidence of revision THA has steadily increased, whereas its burden has decreased. Findings of our study could be used for epidemiological comparison between Western countries and East Asia as well as for the establishment of medical policies of revision THA in East Asian countries.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-021-04235-3.

Opposing Trends in Total Knee and Hip Arthroplasties for Patients With Rheumatoid Arthritis vs. the General Population-A 14-Year Retrospective Study in Taiwan

Objective: To determine the trend of incidence rate of total knee arthroplasty (TKA), total hip arthroplasty (THA), and TKA or THA (major joint arthroplasty, MJA) among rheumatoid arthritis (RA) population and compared them with general population (GP) in Taiwan.

Methods: Incidence rates and trends of TKA, THA, and MJA were determined over a 14-year period (2000–2013) among RA patients and compared them with GP. RA of patients was diagnosed based on the ACR 1987 criteria and extracted from GP. Subanalyses of incidences of TKA, THA, and MJA by year, 10-year age group, and gender were further conducted for demographic analysis. Patient profiles were extracted from the National Health Insurance Research Database (NHIRD) for interrupted time-series analysis and cohort studies.

Results: Patients enrolled were 168,457 receiving TKA, 64,543 receiving THA, and 228,191 receiving MJA surgery. Incidences of TKA, THA, and MJA in RA patients were significantly lower by 49.0, 41.5, and 41.0% compared with concomitantly rises in GP by 131.0, 25.1, and 90.0% among the GP during the study period. The dominant age population for TKA, THA, and MJA were those aged 70–79 years in both GP and RA groups.

Conclusions: We found an opposing trend in incidence of TKA, THA, and MJA between RA patients and the GP. The possible influence of pharmacological treatment is implicated for the lower incidence rates of TKA, THA, and MJA surgeries among RA patients.

Variation and trends in reasons for knee replacement revision: a multi-registry study of revision burden

Background and purpose - Studies describing time-related change in reasons for knee replacement revision have been limited to single regions or institutions, commonly analyze only 1st revisions, and may not reflect true caseloads or findings from other areas. We used revision procedure data from 3 arthroplasty registries to determine trends and differences in knee replacement revision diagnoses.Patients and methods - We obtained aggregated data for 78,151 revision knee replacement procedures recorded by the Swedish Knee Arthroplasty Register (SKAR), the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), and the Kaiser Permanente Joint Replacement Registry (KPJRR) for the period 2003-2017. Equivalent diagnosis groups were created. We calculated the annual proportions of the most common reasons for revision.Results - Infection, loosening, and instability were among the 5 most common reasons for revision but magnitude and ranking varied between registries. Over time there were increases in proportions of revisions for infection and decreases in revisions for wear. There were inconsistent proportions and trends for the other reasons for revision. The incidence of revision for infection showed a uniform increase.Interpretation - Despite some differences in terminology, comparison of registry-recorded revision diagnoses is possible, but defining a single reason for revision is not always clear-cut. There were common increases in revision for infection and decreases in revision for wear, but variable changes in other categories. This may reflect regional practice differences and therefore generalizability of studies regarding reasons for revision is unwise.

Current Trends and Projected Burden of Primary and Revision Total Knee Arthroplasty in Korea Between 2010 and 2030

BACKGROUND

This study aimed to (1) document the total knee arthroplasty (TKA) use in Korea from 2010 to 2018, (2) evaluate whether rapid increase in TKA use has been maintained, and (3) estimate the projected TKA burden to 2030 based on the current use.

METHODS

Using the Health Insurance Review and Assessment Korean database, procedural rate, growth rate, and revision burden of primary and revision TKAs in Korea between 2010 and 2018 were analyzed. TKA procedural numbers were also stratified by age and gender. Then, the projected TKA burden to 2030 including procedural number and medical costs were estimated using linear and quasi-Poisson regression models, respectively.

RESULTS

Between 2010 and 2018, procedural rate of primary and revision TKAs has increased by 35% and 68%, respectively. More than 85% of primary and revision TKAs were performed on female patients, and the subgroup of patients aged ≥80 years showed a marked increase in primary and revision TKA use. According to the projection model, the number of primary and revision TKAs is predicted to increase between 53% and 91%, and between 75% and 155%, respectively, by 2030.

CONCLUSION

Between 2010 and 2018, the procedural rates of primary and revision TKAs in Korea increased gradually by 35% and 68%, respectively, and previously observed striking growth rate has markedly slowed. Nevertheless, compared to 2018, the burdens of primary and revision TKAs are projected to increase up to 91% and 155%, respectively, by 2030.

LEVEL OF EVIDENCE

Therapeutic Level III.

Why Do People Undergo THR and What Do They Expect to Gain-A Comparison of the Views of Patients and Health Care Professionals

Little concerted effort has been made to understand why individuals undergo total hip replacement (THR) surgery and their rehabilitation goals. Similarly, insight of views and perspective of health care professionals’ (HCPs) regarding surgery and what objective measures help them with decision-making is lacking. This patient and public involvement report aimed to explore both patients’ and HCPs’ perspectives of THR surgery. Twenty patients, 10 pre-THR, 10 post-THR, 9 physiotherapists, and 6 surgeons took part. Results suggest a consensus among patients and HCPs on pain reduction being the main reason for undergoing THR. The inability to carry out simple daily activities such as dog walking and sleep deprivation had a significant effect on patients’ mental and physical well-being. This article is the first to explore the views of THR patients and HCPs on reasons behind THR surgery amalgamated into a single report. As walking is important, wearable activity monitors are suggested as a possible motivator to enhance patient compliance to self-care rehabilitation and increase quality of life. A future research project on the use of such wearable activity monitors in enhancing mobility post-THR is therefore planned.

The Cost-Effectiveness of Platelet-Rich Plasma Injections for Knee Osteoarthritis: A Markov Decision Analysis

BACKGROUND

Use of platelet-rich-plasma (PRP) injections for treating knee osteoarthritis has increased over the past decade. We used cost-effectiveness analysis to evaluate the value of PRP in delaying the need for total knee arthroplasty (TKA).

METHODS

We developed a Markov model to analyze the baseline case: a 55-year-old patient with Kellgren-Lawrence grade-II or III knee osteoarthritis undergoing a series of 3 PRP injections with a 1-year delay to TKA versus a TKA from the outset. Both health-care payer and societal perspectives were included. Transition probabilities were derived from systematic review of 72 studies, quality-of-life (QOL) values from the Tufts University Cost-Effectiveness Analysis Registry, and individual costs from Medicare reimbursement schedules. Primary outcome measures were total costs and quality-adjusted life years (QALYs), organized into incremental cost-effectiveness ratios (ICERs) and evaluated against willingness-to-pay thresholds of $50,000 and $100,000. One and 2-way sensitivity analyses were performed as well as a probabilistic analysis varying PRP-injection cost, TKA delay intervals, and TKA outcomes over 10,000 different simulations.

RESULTS

From a health-care payer perspective, PRP resulted in 14.55 QALYs compared with 14.63 for TKA from the outset, with total health-care costs of $26,619 and $26,235, respectively. TKA from the outset produced a higher number of QALYs at a lower cost, so it dominated. From a societal perspective, PRP cost $49,090 versus $49,424 for TKA from the outset. The ICER for TKA from the outset was $4,175 per QALY, below the $50,000 willingness-to-pay threshold. Assuming the $728 published cost of a PRP injection, no delay time that was <10 years produced a cost-effective course. When the QOL value was increased from the published value of 0.788 to >0.89, PRP therapy was cost-effective with even a 1-year delay to TKA.

CONCLUSIONS

When considering direct and unpaid indirect costs, PRP injections are not cost-effective. The primary factor preventing PRP from being cost-effective is not the price per injection but rather a lack of established clinical efficacy in relieving pain and improving function and in delaying TKA. PRP may have value for higher-risk patients with high perioperative complication rates, higher TKA revision rates, or poorer postoperative outcomes.

LEVEL OF EVIDENCE

Economic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Increases in the rates of primary and revision knee replacement are reducing: a 15-year registry study across 3 continents

Background and purpose - Rates of knee replacement (KR) are increasing worldwide. Based on population and practice changes, there are forecasts of a further exponential increase in primary knee replacement through to 2030, and a corresponding increase in revision knee replacement. We used registry data to document changes in KR over the past 15 years, comparing practice changes across Sweden, Australia, and the United States. This may improve accuracy of future predictions.Patients and methods - Aggregated data from the Swedish Knee Arthroplasty Register (SKAR), the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), and the Kaiser Permanente Joint Replacement Registry (KPJRR) were used to compare surgical volume of primary and revision KR from 2003 to 2017. Incidence was calculated using population census statistics from Statistics Sweden and the Australian Bureau of Statistics, as well as the yearly active membership numbers from Kaiser Permanente. Further analysis of KR by age < 65 and ≥ 65 years was carried out.Results - All registries recorded an increase in primary and revision KR, with a greater increase seen in the KPJRR. The rate of increase slowed during the study period. In Sweden and Australia, there was a smaller increase in revision surgery compared with primary procedures. There was consistency in the mean age at surgery, with a steady small decrease in the proportion of women having primary KR. The incidence of KR in the younger age group remained low in all 3 registries, but the proportional increases were greater than those seen in the ≥ 65 years of age group.Interpretation - There has been a generalized deceleration in the rate of increase of primary and revision KR. While there are regional differences in KR incidence, and rates of change, the rate of increase does not seem to be as great as previously predicted.

Increased periprosthetic hip and knee infection projected from 2014 to 2035 in Taiwan

BACKGROUND

Periprosthetic joint infection (PJI) is a disastrous complication associated with hip and knee arthroplasty. The literature suggests that the economic consequences associated with treating PJI are substantial. Our study aimed to investigate the past trends of PJI rates, and to estimate the projected number of PJI cases, consequent bed-day requirements, and medical expenses in Taiwan up to year 2035.

METHODS

A nationwide epidemiological study was conducted using the inpatient database of the Bureau of National Health Insurance from 2004 through 2013. Patients with the International Classification of Disease-Clinical Modification, ninth revision (ICD9-CM) code 99,666 (PJI) who had received surgical treatment including debridement, removal of hip or knee prosthesis, or revision of total hip/knee arthroplasty (THA/TKA) were identified. Projections were performed with Poisson regression on historical incidence rates in combination with projections of arthroplasty numbers from 2014 to 2035.

RESULTS

A total of 4935 hip (1871) and knee (3064) PJIs were identified between 2004 and 2013. The rates of PJI were 2.46% for hip arthroplasty and 1.63% for knee arthroplasty. The number of PJIs was expected to increase markedly with time from 728 in 2013 to 3542 in 2035 (a 4.87-fold increase). The bed-day requirements for treating PJI was 17,205 in 2013 and is expected to be 82,509 bed-days in 2035 (a 4.79-fold increase). The total hospitalization cost will increase 4.86-fold by 2035.

CONCLUSIONS

The number of PJI cases is increasing rapidly due to the increasing numbers of arthroplasty surgery and the cumulative number of latent infection. This may place a large economic burden on the health care system.

Predictors for Unfavorable Early Outcomes in Elective Total Hip Arthroplasty: Does Extreme Body Mass Index Matter?

Background

Studies of previous cohorts have demonstrated a controversial association between extreme body mass index (BMI) and complication rates following total hip arthroplasty (THA). The purpose of this study was to compare 30-day perioperative complications in underweight (BMI <18.50 kg/m²), normal-weight (BMI 18.50–24.99 kg/m²), overweight (BMI 25.00–29.99 kg/m²), class I obesity (BMI 30.00–34.99 kg/m²), and morbidly obese (BMI ≥35.00 kg/m²) groups.

Methods

We performed a cohort study including patients who underwent unilateral primary THA by a single surgeon between January 2010 and December 2015 at our institution. We assessed 30-day complications, operation time, operative blood loss, and length of hospital stay.

Results

We identified 1565 primary THAs that were performed in patients with varying BMI levels. Compared with the normal-weight patients, the morbidly obese group had a higher 30-day complication rate (8.9% vs. 2.4%), longer operative time (79 minutes vs. 70 minutes), and more blood loss (376 mL vs. 302 mL). Underweight patients did not present any 30-day complications, and there were no differences among underweight and normal-weight patients regarding complication rates, operative time, or blood loss. The mean length of hospital stay was comparable among the different BMI groups. In the multivariate regression model, higher BMI was not associated with a higher risk of 30-day complications. Independent risk factors for 30-day complications were advanced age, prolonged operative time, and cardiovascular comorbidities.

Conclusion

Although increased operative time, blood loss, and perioperative complications were seen in the morbidly obese patients, BMI alone was not an independent risk factor for a higher 30-day complication rate. Therefore, our data suggest clinicians should make elderly patients aware of increased 30-day complications before the procedure, particularly those with cardiovascular comorbidities. Withholding THA solely on the basis of BMI is not justified.

Pre-operative pressure pain thresholds do not meaningfully explain satisfaction or improvement in pain after knee replacement: a cohort study

OBJECTIVES

Pain sensitization could be a risk factor for poor outcomes after knee replacement surgery (KR) for knee osteoarthritis (KOA). We aimed to evaluate the association between pre-operative central and peripheral pain sensitization measured using a digital pressure algometer and KR outcomes.

METHODS

Consecutive patients with severe KOA listed for KR were recruited. Sociodemographic and symptoms data were collected prior to surgery. Pre-operative pressure pain thresholds (PPTs) were measured using a digital pressure algometer at the index knee and forearm. Patient satisfaction at 6 and 12 months after KR was assessed using a 4-point Likert scale, and dichotomized to satisfied and dissatisfied to KR. Western Ontario and McMaster Universities Index (WOMAC) Pain and function was assessed. The associations between pre-operative PPTs with KR outcomes at 6 and 12 months were evaluated.

RESULTS

Of the 243 patients recruited, response rate at 6 and 12 months were 95.5% and 96.7%. The dissatisfaction rates were 8.2% and 5.1% at 6 and 12 months. There was no statistically significant association between pre-operative index knee or forearm PPTs and patient satisfaction. PPTs measured at the knee, but not the forearm, were weakly associated with change in the WOMAC pain score at 12 months, after adjustment for confounding factors.

CONCLUSION

Pre-operative central sensitization, measured by handheld digital algometry, was not statistically significantly associated with satisfaction or change in pain after KR. Pre-operative peripheral sensitization was associated with change in pain symptoms after KR; however, this association was weak and unlikely to be a meaningful predictor of KR outcome in clinical practice.

Biological Activation of Bioinert Medical High-Performance Oxide Ceramics by Hydrolytically Stable Immobilization of c(RGDyK) and BMP-2

High-performance oxide ceramics (HPOC), such as alumina, zirconia, and dispersion ceramics thereof are successfully used as articulating components in joint arthroplasty. HPOC exhibit excellent wear resistance, high strength, and cytocompatible behavior; however, they lack sufficient tissue bonding capability. Thus, they are primarily deployed as low-wear-bearing articulating components in arthroplasty without direct tissue contact, although proper cellular stimulation would hold significant advantages. Here, we describe a surface modification approach for HPOC, enabling hydrolytically stable interfacial binding of c(RGDyK) peptides and BMP-2 proteins to significantly improve the adhesion and osteogenic differentiation of human mesenchymal stem cells (hMSCs) without altering the mechanical properties of the underlying ceramic substrates. Analyses of cellular attachment of murine fibroblasts (L929), human alveolar basal epithelial cells (A549), hMSCs on c(RGDyK), and osteogenic differentiation of hMSCs on BMP-2-coated interfaces demonstrate significant improvements of cell adhesion and an enhanced osteogenic differentiation potential in vitro. The presented approach provides a strategy for the development of a novel class of bioactive HPOC with osseointegration potential that could lead to novel therapeutic solutions for biomedical applications. Furthermore, the developed surface modification is designed in a way to be readily translated to other medically employed bioinert materials in the future.

Effects of pay for performance on risk incidence of infection and of revision after total knee arthroplasty in type 2 diabetic patients: A nationwide matched cohort study

As the world's population ages, the number of people receiving total knee arthroplasty (TKA) has been on the rise. Although patients with diabetes mellitus are known to face greater risks of TKA postoperative infection and revision TKA owing to diabetic complications, studies on whether such patients' participation in pay for performance (P4P) programs influences the incidence rates of TKA postoperative infection or revision TKA are still lacking. This study examined the 2002-2012 data of Taiwan's National Health Insurance Research Database to conduct a retrospective cohort analysis of diabetic patients over 50 years old who have received TKA. To reduce any selection bias between patients joining and not joining the P4P program, propensity score matching was applied. The Cox proportional hazards model was used to examine the influence of the P4P program on TKA postoperative infection and revision TKA, and the results indicate that joining P4P lowered the risk of postoperative infection (HR = 0.91, 95% CI: 0.77-1.08), however, which was not statistically significant, and significantly lowered the risk of revision TKA (HR = 0.53, 95% CI: 0.39-0.72). Being younger and male, having multiple comorbid conditions or greater diabetic severity, receiving care at regional or public hospitals, and not having a diagnosis of degenerative or rheumatoid arthritis were identified as factors for higher risk of TKA postoperative infection for patients with diabetes. As for the risk of revision TKA, postoperative infection and being younger were identified as factors for a significantly higher risk (p < 0.05).

Effects of nurse-led lower extremity strength training on knee function recovery in patients who underwent total knee replacement

AIMS AND OBJECTIVES

To examine the effects of lower extremity muscle strength training on knee function recovery and quality of life in patients who underwent total knee replacement.

BACKGROUND

Patients with knee osteoarthritis after surgery experience decreased knee function that impacts their quality of life. However, patients typically lack a long-term, home-based and continuous leg exercise training method and rarely have studies explored the effects of exercise training on knee function recovery and quality of life.

DESIGN

A experimental and longitudinal study design.

METHODS

The simple randomised sampling (based on patients' admission priority order) was used to collect participant data. Outcome measurements included the Knee Injury and Osteoarthritis Outcome Score. Participants were randomised to receive and starting lower extremity muscle strength training before surgery (training group, n = 100) or to receive usual care (nontraining group, n = 100). Data were collected and followed up with the patients before surgery (T1) and at 2 weeks (T2), 1 month (T3), 2 months (T4) and 3 months (T5) after discharge.

RESULTS

The Knee Injury and Osteoarthritis Outcome Score subscale scores showed that both groups of patients experienced knee function and quality of life decreases 2 weeks after total knee replacement, but all subscale scores gradually increased from the first month to the third month after total knee replacement. Both groups and times were significantly different, but the training group's knee function and quality of life recovered earlier and better than the nontraining group does.

CONCLUSIONS

This study confirmed that lower extremity muscle strength training helps to improve quality of life and knee function in patients who undergo total knee replacement. Healthcare staff should include this training in presurgical nursing care and in patients' discharge plans as a continuous, daily rehabilitation activity at home.

RELEVANCE TO CLINICAL PRACTICE

When patients are diagnosed with knee osteoarthritis and undergo surgery, a presurgical exercise education and discussion of knee function rehabilitation should be part of standard care.

The incidence rate, trend and microbiological aetiology of prosthetic joint infection after total knee arthroplasty: A 13 years' experience from a tertiary medical center in Taiwan

BACKGROUND/PURPOSE

Total knee arthroplasty (TKA) improves the patient's quality of life by relieving pain, correcting the deformity, and helping the patient resume normal activities. However, post-TKA prosthetic joint infection leads to implant failure, is difficult to treat, and causes a significant burden both economically and health-wise. Therefore, an understanding of the current trends in this infection and microbiology data is essential for preventing and treating it.

METHODS

A retrospective study was conducted on 10,768 patients who underwent primary TKA at Taipei Veterans General Hospital, Taiwan, from 2002 to 2014. The incidence of post-TKA prosthetic joint infection in different time periods was investigated, and microbiological results in early- (<3 months post-TKA) and delay-onset prosthetic joint infection were analyzed.

RESULTS

The 2 years incidence of post-TKA prosthetic joint infection was 1.93% (2002-2006), 1.05% (2007-2010), and 0.76% (2011-2014). The incidence of post-TKA prosthetic joint infection decreased significantly from 2002 to 2014. Although Staphylococcus species was most commonly isolated, a significantly higher proportion of gram-negative bacteria were isolated from early-onset compared with delay-onset post-TKA prosthetic joint infection patients: 9/29 (31.0%) versus 13/100 (13%); p = 0.023.

CONCLUSIONS

The results showed that the risk of post-TKA prosthetic joint infection is decreasing. Microbiology results showed that early-onset post-TKA prosthetic joint infection is associated with a higher risk of gram-negative bacterial infection. Physicians should be aware of this risk in order to correctly select empirical agents.

The Role of One-Stage Exchange for Prosthetic Joint Infection

PURPOSE OF REVIEW

In an era of increasing numbers of hip and knee replacements, strategies to manage prosthetic joint infection (PJI) that are effective at infection control with good patient-reported outcomes and cost containment for health systems are needed. Interest in single-stage exchange for PJI is rising and we assess evidence from the last 5 years related to this treatment strategy.

RECENT FINDINGS

Only five series for total knee replacement and ten series for total hip replacement have been reported in the last five years. More review articles and opinion pieces have been written. Reinfection rates in these recent studies range from 0 to 65%, but a meta-analysis and systematic review of all studies showed a reinfection rate of 7.6% (95% CI 3.4-13.1) and 8.8% (95% CI 7.2-10.6) for single-stage and two-stage revisions respectively. There is emerging evidence to support single-stage revision in the setting of significant bony deficiency and atypical PJIs such as fungal infections. Prospective randomised studies are recruiting and are necessary to guide the direction of single-stage revision selection criteria. The onus of surgical excellence in mechanical removal of implants, necrotic tissue, and biofilms lies with the arthroplasty surgeon and must remain the cornerstone of treatment. Single-stage revision may be considered the first-line treatment for all PJIs unless the organism is unknown, the patient is systemically septic, or there is a poor tissue envelope.

The increase in total knee replacement surgery in Taiwan: A 15-year retrospective study

Total knee replacement (TKR) is considered as one of the most success among clinical interventions for patients with who suffering from knee osteoarthritis (OA). We sought to estimate the incidence of TKR using demographics, incidence rates, lengths of hospital stay, and costs from 1996 to 2010 by analyzing Taiwan's National Health Insurance Research Database. A total of 154,553 patients obtained primary TKR surgery between 1996 and 2010. The diagnosis code for knee OA and the procedure code for TKR were selected from the records. To compare the rate of TKR between covariables, we calculated the TKR risk ratios and 95% confidence interval (CI) of these variables (gender, age, age group, and primary diagnoses). A 2-tailed P-value of .05 was considered statistically significant. The statistical package SPSS version 20.0 (SPSS, Chicago, IL) was used to conduct all the statistical analyzes. We analyzed 154,553 TKRs performed by surgeons in Taiwan from 1996 to 2010. The overall crude incidence increased from 26.4 to 74.55 TKR per 100,000 inhabitants from 1996 to 2010. TKR incidence for the 70 to 79 years age group increased from 227 to 505 per 100,000 people from 1996 to 2010. The age-standardized rate ratios for TKR of women to men ranged from 2.5 to 3.0. The mean average length of stay in hospital was 15 days in 1996 and decreased to 8 days in 2010. During the study period, the adjusted mean cost per patient decreased from US$7485 to US$4827. Health expenditures for TKR were 5% of total National Health Insurance expenditure every year. Over the 15-year period, Taiwan's TKR incidence tripled, which is consistent with population ageing. Arthritis will be a major public health issue in the ageing population in the future.

Does a Program Based on Cognitive Behavioral Therapy Affect Kinesiophobia in Patients Following Total Knee Arthroplasty? A Randomized, Controlled Trial With a 6-Month Follow-Up

BACKGROUND

To evaluate the effects of a cognitive behavioral therapy (CBT) program on kinesiophobia, knee function, pain and pain catastrophizing in patients following total knee arthroplasty (TKA).

METHODS

This was a parallel-group, randomized, controlled pilot study in which 100 patients who exhibited kinesiophobia after TKA were randomly assigned to participate in a CBT (experimental group) or standard care (control group) program. Each group included 50 patients. Before intervention (preintervention), 4 weeks after intervention (postintervention), and 6 months after the end of intervention (follow-up), patients were assessed via the Tampa Scale for Kinesiophobia, the Pain Catastrophizing Scale, a numerical rating scale, and the Hospital for Special Surgery knee rating scale. Repeated-measures analysis of variance was used to test the significance of each outcome measure.

RESULTS

The CBT program had significant group (P < .001), time (P < .001), and group-by-time interaction (P < .001) effects on kinesiophobia, pain catastrophizing, and knee function, and these effects lasted for at least 6 months after the end of the intervention. Pain was reduced in both groups after the intervention, but there were significant time and group effects (P = .003) in favor of the experimental group.

CONCLUSION

The CBT program was superior to standard care in reducing kinesiophobia, pain catastrophizing, and knee pain and in enhancing knee function in patients who have a high level of kinesiophobia following TKA. The treatment effect was clinically significant and lasted for at least 6 months after the end of the intervention.

Prevalence of knee arthroplasty in the state of São Paulo between 2003 and 2010

CONTEXT AND OBJECTIVE:

The volume of knee arthroplasty procedures has increased over the last decade. The aim of this study was to estimate the frequency of these procedures performed within the public healthcare system of the state of São Paulo between 2003 and 2010.

DESIGN AND SETTING:

Cross-sectional study conducted in the state of São Paulo by researchers at Hospital do Servidor Público do Estado de São Paulo.

METHODS:

A sample of 10,952 patients (7,891 females and 3,061 males) who underwent primary total knee arthroplasty (TKA) and revision of total knee arthroplasty (RTKA) in the state of São Paulo between 2003 and 2010 was evaluated. The patients were cataloged using the public healthcare service's TABNET software. All of the patients presented primary osteoarthritis of the knee. The variables of gender, number of primary TKA procedures and number of RTKA procedures were evaluated.

RESULTS:

A total of 10,952 TKA procedures were performed (annual average of 1369), of which 9,271 (85%) were TKA and 1,681 (15%), RTKA. Of the TKA procedures, 72% were carried out on females (P < 0.0001), while 70% of the RTKA procedures were on females (P < 0.0001). The average ratio of TKA to RTKA was 5.5:1 (P < 0.0001); the ratios in 2003 and 2010 were 9.0:1 and 4.4:1 (P < 0.0001), respectively.

CONCLUSION:

The number and frequency of TKA and RTKA procedures increased in the state of São Paulo between 2003 and 2010. This increase was relatively greater in RTKA than in TKA and was predominantly in female patients.