Total Knee Arthroplasty Population Research Articles

Same-Day Discharge Does Not Increase Resource Utilization Within One Year of Total Joint Arthroplasty

BackgroundWhile the safety of rapid recovery total joint arthroplasty is well established, less is known about its impact on postoperative care utilization patterns. We wished to examine whether same-day discharge—and its associated presumed reduction in hospital-based postoperative care and education—translates to the need for more postoperative support during the 1-year recovery period. MethodsA retrospective review of 1,237 total hip arthroplasty (THA) and 1,710 total knee arthroplasty (TKA) patients who had 0- or 1-day length of stay (LOS) from January 2020 to October 2023 was conducted. The primary outcome was the number of follow-up visits with total joint arthroplasty providers at our institution during the 1-year postoperative period. Secondary outcomes included 30-day emergency department returns, readmissions, 1-year physical therapy utilization, and improvement in Patient-Reported Outcomes Measurement Information System Physical Function scores at 6 to 12 months postoperatively. Bivariate and multivariable analyses were performed to compare outcomes between 0-day and 1-day LOS THA and TKA patients. ResultsIn both the THA and TKA populations, 0-day LOS patients were younger, had a lower average body mass index, were more likely to be White, men, and had an American Society of Anesthesiologists score < 3 than 1-day LOS patients. After controlling for differences between groups, no significant differences in the number of one-year follow-up visits, physical therapy visits, emergency department returns, or readmissions were seen between 0 and 1-day THA or TKA patients. In TKA patients, 1-day LOS was associated with lower improvements in Patient-Reported Outcomes Measurement Information System Physical Function scores. ConclusionsAfter risk adjustment, same-day discharge of THA and TKA patients did not result in increased resource utilization during the one-year postoperative period. In the setting of a coordinated joint arthroplasty program with nurse navigator support, same-day discharge can be safely performed without increasing the need for postoperative care in appropriately selected patients undergoing both THA and TKA.

The Impact of Cardiac Arrhythmias on Total Knee Arthroplasty Outcomes

BackgroundCardiac comorbidities are common in patients undergoing total knee arthroplasty (TKA). While there is an abundance of research showing an association between cardiac abnormalities and poor postoperative outcomes, relatively little is published on specific pathologies. The aim of this study was to assess the impact of cardiac arrhythmias on postoperative outcomes in the setting of TKA. MethodsThis retrospective cohort study included all patients undergoing TKA from a national database, from 2016 to 2019. Patients who had cardiac arrhythmias were identified via International Classification of Diseases, Tenth Revision, and Clinical Modification/Procedure Coding System codes and served as the cohort of interest. Multivariate regression was performed to compare postoperative outcomes. Gamma regression was performed to assess length of stay and total charges, while negative binomial regression was used to assess 30-day readmission and reoperation. Patient demographic variables and comorbidities, measured via the Elixhauser comorbidity index, were controlled in our regression analysis. Out of a total of 1,906,670 patients, 224,434 (11.76%) had a diagnosed arrhythmia and were included in our analyses. ResultsThose who had arrhythmias had greater odds of both medical (odds ratio [OR] 1.52; P < .001) and surgical complications (OR 2.27; P < .001). They also had greater readmission (OR 2.49; P < .001) and reoperation (OR 1.93; P < .001) within 30 days, longer hospital stays (OR 1.07; P < .001), and greater total charges (OR 1.02; P < .001). ConclusionsCardiac arrhythmia is a common comorbidity in the TKA population and is associated with worse postoperative outcomes. Patients who had arrhythmias had greater odds of both medical and surgical complications requiring readmission or reoperation. Study DesignLevel III; Retrospective Cohort Study.

RAPT and AM-PAC "6-Clicks": Do They Correlate on Predicting Discharge Destination After Total Joint Arthroplasty?

Background: The Risk Assessment and Prediction Tool (RAPT) and the Activity Measure for Post-Acute Care "6-Clicks" Mobility Score (AM-PAC) are validated discharge planning tools for patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA). Planning for discharge with these tools considers very different factors and it is important to determine if they relate. Purpose: We sought to determine whether the preoperative RAPT score would correlate with postoperative AM-PAC score for predicting discharge destination for THA and TKA populations. Secondarily, we sought to examine whether the AM-PAC and RAPT scores would remain statistically significant predictors of discharge destination despite covariates. Methods: A retrospective cohort study was performed for patients who underwent THA or TKA from January 2020 to December 2022 at a specialty orthopedic hospital. Primary variables included the RAPT score, the AM-PAC score, and discharge disposition. Correlation between AM-PAC and RAPT scores was tested using Pearson's correlation coefficient, and association between both scores and discharge destination was tested using chi-square tests and multivariable logistic regression. Results: Our comparison of AM-PAC scores and RAPT scores found a statistically significant, positive correlation in both THA and TKA patients. Regression analysis found that increased RAPT and AM-PAC scores resulted in higher odds of being discharged home for both populations, after adjusting for all other variables. In both cohorts, patients discharged to a facility were more likely to be female, be over the age of 70 years, have Medicare/Medicaid insurance, and have a higher number of preoperative social work visits or any incidence of an intraoperative or hospital complication. Conclusions: This retrospective study found that RAPT score correlated with AM-PAC score for predicting discharge destination for elective THA and TKA populations, suggesting that these scores may be predictors of home discharge destination even when accounting for covariates. Further study is recommended.

Assessing the Mortality Rate After Primary Total Knee Arthroplasty: An Observational Study to Inform Future Economic Analysis

BackgroundPrevious research has focused on the perioperative or short-term (<1 year) mortality rate of total knee arthroplasty (TKA), leaving the long-term (>1 year) mortality rate unresolved. In this study, we calculated the mortality rate up to 15 years after primary TKA. MethodsData from the New Zealand Joint Registry from April 1998 to December 2021 were analyzed. Patients aged 45 years or older who underwent TKA for osteoarthritis were included. Mortality data were linked with national records from births, deaths, and marriages. To determine the expected mortality rates in the general population, age-sex-specific life tables from statistics New Zealand were used. Mortality rate was presented as standardized mortality ratios (SMRs) – a comparison of relative mortality rate between the TKA and general populations. In total, 98,156 patients with a median follow-up of 7.25 years (range, 0.00 to 23.74) were included. ResultsOver the entire follow-up period, 22,938 patients (23.4%) had died. The overall SMR for the TKA cohort was 1.08 (95% confidence interval (CI): 1.06 to 1.09), suggesting that TKA patients have an 8% higher mortality rate compared to the general population. However, a reduction in short-term mortality rate was observed for TKA patients up to 5 years post TKA (SMR 5 years post TKA; 0.59 95% CI: 0.57 to 0.60]). On the contrary, a significantly increased long-term mortality rate was observed in TKA patients with greater than 11 years of follow-up, particularly in men over the age of 75 years (SMR 11 to 15 years post TKA for males ≥ 75 years; 3.13 [95% CI: 2.95 to 3.31]). ConclusionThe results suggest a reduction in short-term mortality rate for patients who undergo primary TKA. However, there is an increased long-term mortality rate particularly in men over the age of 75 years. Importantly, the mortality rates observed in this study cannot be causally attributed to TKA alone.

The Cost of Stiffness After Total Knee Arthroplasty

BackgroundStiffness after primary total knee arthroplasty (TKA) is debilitating and poorly understood. A heterogenous approach to the treatment is often utilized, including both nonoperative and operative treatment modalities. The purpose of this study was to examine the prevalence of treatments used between stiff and non-stiff TKA groups and their financial impact. MethodsAn observational cohort study was conducted using a large database. A total of 12,942 patients who underwent unilateral primary TKA from January 1, 2017, to December 31, 2017, were included. Stiffness after TKA was defined as manipulation under anesthesia and a diagnosis code of stiffness or ankylosis, and subsequent diagnosis and procedure codes were used to identify the prevalence and financial impact of multiple common treatment options. ResultsThe prevalence of stiffness after TKA was 6.1%. Stiff patients were more likely to undergo physical therapy, medication, bracing, alternative treatment, clinic visits, and reoperation. Revision surgery was the most common reoperation in the stiff TKA group (7.6%). The incidence of both arthroscopy and revision surgery were higher in the stiff TKA population. Dual component revisions were costlier for patients who had stiff TKAs ($65,771 versus $48,287; P < .05). On average, patients who had stiffness after TKA endured costs from 1.5 to 7.5 times higher than the cost of their non-stiff counterparts during the 2 years following index TKA. ConclusionPatients who have stiffness after primary TKA face significantly higher treatment costs for both operative and nonoperative treatments than patients who do not have stiffness.

Trends in the Prevalence and Postoperative Surgical Complications for Smokers Who Underwent a Total Knee Arthroplasty from 2011 to 2019: An Analysis of 406,553 Patients.

Smoking is a modifiable risk factor for complications following total knee arthroplasty (TKA). It is unclear if the declining prevalence of tobacco use in the U.S. population is reflected in patients undergoing elective TKA. This study aims to investigate (1) the incidence of 30-day complications following TKA in smokers and (2) trends in preoperative smoking status among TKA patients. In this study, patients undergoing primary elective TKA in the United States from 2011 to 2019 were identified in the American College of Surgeons' National Surgical Quality Improvement Program (ACS-NSQIP) database. Our cohort included 406,553 cases, 8.13% of which had smoked cigarettes within 1 year of undergoing TKA. Smokers were propensity score-matched to a group of nonsmokers, with each n = 32,533. The incidences of 30-day complications, readmission, and non-home discharge were compared between groups. The rate of preoperative smoking among elective primary TKA patients remained stagnant from 2011 to 2019. Smokers had higher rates of superficial surgical site infections (SSIs; 1.1 vs. 0.5%, p < 0.001), deep SSI (0.3 vs. 0.2%, p = 0.012), wound disruption (0.4 vs. 0.2%, p < 0.001), pneumonia (0.5 vs. 0.3%, p < 0.001), and 30-day readmission (3.6 vs. 2.7%, p < 0.001) compared with nonsmokers. No significant trends in 30-day complications were noted between 2011 and 2019. This study supports the success of national efforts to reduce the prevalence of smoking and reports a modest effect within the TKA population. However, almost 1 in 10 patients undergoing elective TKA continues to smoke and maintains a higher risk of postoperative complications.

Psoriasis and Post-Surgical Infections in Primary Total Knee Arthroplasty: An Analysis of 10,727 Patients

BackgroundPsoriasis is a dermatologic condition characterized by erythematous plaques that may increase wound complications and deep infections following total knee arthroplasty (TKA). There is a paucity of evidence concerning the association of this disease and complications after TKA. This study aimed to determine if patients who have psoriasis vs non-psoriatic patients have differences in demographics and various comorbidities as well as post-operative infections, specifically the following: (1) wound complications; (2) cellulitic episodes; and (3) deep surgical site infections (SSIs). MethodsWe identified 10,727 patients undergoing primary TKA utilizing an institutional database between January 1, 2017 and April 1, 2019. A total of 133 patients who had psoriasis (1.2%) were identified using International Classification of Diseases, Tenth Revision codes and compared to non-psoriatic patients. The rate of wound complications, cellulitic episodes, and deep SSIs were determined. After controlling for age and various comorbidities, multivariate analyses were performed to identify the associated risks for post-operative infections. ResultsPsoriasis patients showed an increased associated risk of deep SSIs (3.8%) compared to non-psoriasis patients (1.2%, P = .023). Multivariate analyses demonstrated a significant associated risk of deep SSIs (odds ratio 7.04, 95% confidence interval 2.38-20.9, P < .001) and wound complications (odds ratio 4.44, 95% confidence interval 1.02-19.2, P = .047). ConclusionPsoriasis is an inflammatory dermatologic condition that warrants increased pre-operative counseling, shared decision-making, and infectious precautions in the TKA population given the increased risk of wound complications and deep SSIs. Increased vigilance is required given the coexistence of certain comorbidities with this population, including depression, substance use disorder, smoking history, gastroesophageal reflux disease, and inflammatory bowel disease.

Time Trends in Patient Characteristics and In-Hospital Adverse Events for Primary Total Knee Arthroplasty in the United States: 2010-2017.

BackgroundPerioperative care for total knee arthroplasty (TKA) has improved over time. We present an analysis of inpatient safety after TKA.Methods14,057 primary TKAs captured by the Medicare Patient Safety Monitoring System between 2010 and 2017 were retrospectively reviewed. We calculated changes in demographics, comorbidities, and adverse events (AEs) over time. Risk factors for AEs were also assessed.ResultsBetween 2010 and 2017, there was an increased prevalence of obesity (35.1% to 57.6%), tobacco smoking (12.5% to 17.8%), and renal disease (5.2% to 8.9%). There were reductions in coronary artery disease (17.3% to 13.4%) and chronic warfarin use (6.7% to 3.1%). Inpatient AEs decreased from 4.9% to 2.5%, (P < .01), primarily driven by reductions in anticoagulant-associated AEs, including major bleeding and hematomas (from 2.8% to 1.0%, P < .001), catheter-associated urinary tract infections (1.1% to 0.2%, P < .001), pressure ulcers (0.8% to 0.2%, P < .001), and venous thromboembolism (0.3% to 0.1%, P = .04). The adjusted annual decline in the risk of developing any in-hospital AE was 14% (95% confidence interval [CI] 10%-17%). Factors associated with developing an AE were advanced age (odds ratio [OR] = 1.01, 95% CI 1.00-1.01), male sex (OR = 1.21, 95% CI 1.02-1.44), coronary artery disease (OR = 1.35, 95% CI 1.07-1.70), heart failure (OR = 1.70, 95% CI 1.20-2.41), and renal disease (OR = 1.71, 95% CI 1.23-2.37).ConclusionsDespite increasing prevalence of obesity, tobacco smoking, and renal disease, inpatient AEs after primary TKA have decreased over the past several years. This improvement is despite the increasing complexity of the inpatient TKA population over time.

Effects of the Obesity Epidemic on Total Hip and Knee Arthroplasty Demographics

BackgroundHigher body mass index (BMI) is a well-known risk factor for the development of hip and knee osteoarthritis and predicts total hip arthroplasty (THA) and total knee arthroplasty (TKA) at an earlier age. The purpose of this study is to document the nationwide trends in age and obesity in primary THA and TKA throughout the obesity epidemic. MethodsA retrospective analysis of the National Inpatient Sample database was conducted on patients undergoing primary THA and TKA for primary OA between 2002 and 2017. Analysis of variance and chi-square tests were performed to examine changes in age and obesity percentage over time, respectively. Pearson correlations were used to assess the relationship between patient age, BMI, and year of surgery. ResultsA total of 688,371 THA and 1,556,651 TKA were identified over the sixteen-year period. Between 2002 and 2017, the proportion of obese patients increased for both THA (7.0% to 22.7%, P < .001) and TKA (10.7% to 30.4%, P < .001). Mean age significantly decreased for both THA (66.7 to 65.9 years, P < .001) and TKA (67.6 to 66.8 years; P < .001). Over time, BMI significantly increased (THA: r = 0.221 vs. TKA: r = 0.272) and patient age decreased (THA: r = -0.031 vs. TKA: r = -0.137) for both procedures (P < .001 for all). ConclusionTHA and TKA patients have become younger and increasingly more obese throughout the obesity epidemic, as obesity rates have tripled over this time period. The current investigation is the first to demonstrate significant trends in both age and obesity in the THA and TKA populations on a national level. Level of EvidenceIII.

Patient-reported outcome measures used in patients undergoing total knee arthroplasty.

Patient-reported outcome measures (PROMs) are being used increasingly in total knee arthroplasty (TKA). We conducted a systematic review aimed at identifying psychometrically sound PROMs by appraising their measurement properties. Studies concerning the development and/or evaluation of the measurement properties of PROMs used in a TKA population were systematically retrieved via PubMed, Web of Science, Embase, and Scopus. Ratings for methodological quality and measurement properties were conducted according to updated COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN) methodology. Of the 155 articles on 34 instruments included, nine PROMs met the minimum requirements for psychometric validation and can be recommended to use as measures of TKA outcome: Oxford Knee Score (OKS); OKS–Activity and Participation Questionnaire (OKS-APQ); 12-item short form Knee Injury and Osteoarthritis Outcome (KOOS-12); KOOS Physical function Short form (KOOS-PS); Western Ontario and McMaster Universities Arthritis Index-Total Knee Replacement function short form (WOMAC-TKR); Lower Extremity Functional Scale (LEFS); Forgotten Joint Score (FJS); Patient’s Knee Implant Performance (PKIP); and University of California Los Angeles (UCLA) activity score. The pain and function subscales in WOMAC, as well as the pain, function, and quality of life subscales in KOOS, were validated psychometrically as standalone subscales instead of as whole instruments. However, none of the included PROMs have been validated for all measurement properties. Thus, further studies are still warranted to evaluate those PROMs. Use of the other 25 scales and subscales should be tempered until further studies validate their measurement properties.Cite this article: Bone Joint Res 2021;10(3):203–217.

Psychometric properties of the 4-meter walk test after total knee arthroplasty

Objective To determine the reliability, responsiveness, and convergent validity of the Four-Meter Walk Test (4mWT) compared to the Six-Minute Walk Test (6MWT) surrounding total knee arthroplasty (TKA). Design Secondary analysis of a randomized controlled trial. Setting Research laboratory. Participants One hundred sixty-two patients (aged 63.5 ± 7.4 (mean ± sd) years; 89 females) undergoing TKA participated. Main outcome measures 4mWT (usual and fastest) and 6MWT were measured 1–2 weeks preoperatively, and 1, 2, 3, 6 and 12 months post-operatively. Results 4mWT demonstrated excellent test-retest reliability with Interclass Correlation Coefficients (ICC’s) ranging from 0.80 to 0.93 s. 4mWT also demonstrated small measurement error with Standard Error of Measurement (SEM) ranging from 0.15 to 0.35 s. 4mWT (fastest) demonstrated similar responsiveness to 6mWT in the first 2 months after surgery and better responsiveness from 2 to 3 months after surgery. Convergent validity between 6MWT and 4mWT (fastest) was high, with Pearson correlation coefficients ranging from 0.73 to 0.81. Conclusions The 4mWT (fastest) has excellent test-retest reliability, shows high responsiveness sufficient for clinical outcomes in the immediate postoperative time periods, and exhibits high convergent validity with 6MWT. Given space and time requirements to conduct each test, 4mWT may be preferred for routine clinical assessment. IMPLICATIONS FOR REHABILITATION Walking ability •Walking is an important functional ability for patients who undergo total knee arthroplasty (TKA). •While the Six-Minute Walk Test is a validated measure of walking ability in the TKA population, its clinical utility is limited by the space and time it takes to perform the test. •The Four-Meter Walk Test (fastest speed) is a valid, reliable, and responsive alternative to the 6MWT and is recommended for routine clinical use after TKA.

Impact of Postoperative Zolpidem Use on Primary Total Knee Arthroplasty: A Retrospective Matched-Controlled Analysis of a Private Insurance Database

IntroductionZolpidem has gained popularity as a pharmaceutical therapy for insomnia, being the most prescribed hypnotic in the United States today. However, it is associated with increased mortality and morbidity. Literature regarding zolpidem use in the total knee arthroplasty (TKA) population is limited. The aim of the study was to analyze postoperative zolpidem use in the TKA population regarding medical and implant complications, falls, and readmission. MethodsThe study group was queried according to zolpidem use. Controls consisted of patients who underwent primary TKA without a history of hypnotic drug use. Study group patients were matched to controls in a 1:5 ratio by demographics and comorbidities. Results yielded 99,178 study participants and 495,795 controls. Primary endpoints included 90-day medical and implant complications, fall risk, and readmission. Chi-squared test was used to compare categorical variables. Multivariate logistic regression was used to calculate odds (OR) for complications, fall risk, and readmission. A P value less than 0.05 was considered statistically significant. ResultsStudy group patients had increased odds of medical complications (OR: 1.76, 95% CI: 1.71-1.82, P < .0001) and implant complications (OR: 1.35, 95% CI: 1.23-1.47, P < .0001) compared to controls. Furthermore, patients in the study group were found to have an increased risk of 90- day falls (OR: 1.16, 95% CI: 1.11-1.21, P < .0001). Readmission was similar to controls (5.10% vs 4.84%, P = .12). ConclusionZolpidem use following primary TKA is associated with the risk of morbidity and falls. The findings are consistent with the literature regarding zolpidem. These findings may affect discussion between orthopedic surgeons and patients in the decision-making process prior to undergoing TKA.

Underestimation and undertreatment of osteoporosis in patients awaiting primary total knee arthroplasty.

Osteoporosis is generally regarded as a risk factor for periprosthetic fracture during or after primary total knee arthroplasty (TKA). Despite this, little is known about osteoporosis in patients undergoing elective primary TKA Therefore, we sought to investigate the prevalence of osteoporosis and rates of pharmacologic osteoporosis treatment prior to primary TKA. We hypothesized that preoperative osteoporosis is underestimated and undertreated in the primary TKA population. This retrospective study included consecutive 1972 patients scheduled for elective primary TKA at a single tertiary hospital (age, 50-89years). Charts were reviewed for patient demographics, prior pharmacologic osteoporosis treatment and Knee Society (KS) scoring system and WOMAC score. Dual energy X-ray absorptiometry (DEXA) measurement of the lumbar vertebrae and proximal femur was performed in all patients on the day before surgery. The associations of BMD with age, sex, body mass index (BMI), and clinical outcome were analyzed. The prevalence of osteoporosis was 50.0% (53.4% in women and 7.0% in men). Among patients with osteoporosis, only 15.1% (149/986) of patients (15.0% in women and 30.0% in men) had pharmacological osteoporosis treatment prior to primary TKA. Age, sex and WOMAC stiffness showed association with osteoporosis. Sex (odds ratio (OR): 20.83, p < 0.001) was the most significant factor associated with osteoporosis. Osteoporosis was highly prevalent in patients awaiting TKA, but the rates of diagnosis and pharmacologic osteoporosis treatment were low. Therefore, more attention needs to estimate and treat osteoporosis in patients awaiting primary TKA, especially in female patients.

Utilization of Debridement, Antibiotics, and Implant Retention for Infection After Total Joint Arthroplasty Over a Decade in the United States

BackgroundReported clinical outcomes have varied for debridement, antibiotics, and implant retention (DAIR) and little is known regarding trends in utilization. We sought to evaluate the rate of DAIR utilization for total knee arthroplasty (TKA) and total hip arthroplasty (THA) periprosthetic joint infection (PJI) over a decade and clinical factors associated with these trends. MethodsA retrospective study of primary TKAs and THAs was performed using Medicare data from 2005 to 2014 using the PearlDiver database platform. Current Procedural Technology and International Classification of Diseases Ninth Edition codes identified patients who underwent a surgical revision for PJI, whether revision was a DAIR, as well as associated clinical factors including timing from index arthroplasty. ResultsThe proportion of revision TKAs and THAs performed using DAIR was 27% and 12% across all years, respectively. This proportion varied by year for TKAs and THAs with a linear trend toward increasing relative use of DAIR estimated at 1.4% and 0.9% per year (P < .001; P < .001). DAIR for TKA and THA performed within 90 days increased at a faster rate, 3.4% and 2.1% per year (P < .001; P < .001). Trends over time in TKA DAIRs showed an association with Elixhauser Comorbidity Index (ECI), 0-5 group increasing at 2.0% per year (P = .03) and patients >85 years (P = .04). ConclusionThe proportion of revision arthroplasty cases for PJI managed with DAIR has been increasing over time in the United States, with the most substantial increase seen <90 days from index arthroplasty. Age, gender, and ECI had a minimal association with this trend, except in the TKA population >85 years and in those with a very low ECI score.

The Association of Race/Ethnicity and Total Knee Arthroplasty Outcomes in a Universally Insured Population

BackgroundPrior studies have documented racial/ethnic disparities in the United States for total knee arthroplasty (TKA) outcomes. One factor cited as a potential mediator is unequal access to care. We sought to assess whether racial/ethnic disparities persist in a universally insured TKA population. MethodsA US integrated health system’s total joint replacement registry was used to identify elective primary TKA (2000-2016). Racial/ethnic differences in revision and 90-day postoperative events (readmission, emergency department [ED] visit, infection, venous thromboembolism, and mortality) were analyzed using Cox proportional hazard and logistic regression with adjustment for confounders. ResultsOf 129,402 TKA, 68.8% were white, 16.2% were Hispanic, 8.4% were black, and 6.6% were Asian. Compared to white patients, Hispanic patients had lower risks of septic revision (hazard ratio [HR] = 0.69, 95% confidence interval [CI] = 0.57-0.83) and infection (odds ratio [OR] = 0.42, 95% CI = 0.30-0.59), but a higher likelihood of ED visit (OR = 1.28, 95% CI = 1.22-1.34). Black patients had higher risks of aseptic revision (HR = 1.61, 95% CI = 1.42-1.83), readmission (OR = 1.13, 95% CI = 1.02-1.24), and ED visit (OR = 1.31, 95% CI = 1.23-1.39). Asian patients had lower risks of aseptic revision (HR = 0.67, 95% CI = 0.54-0.83), septic revision (HR = 0.78, 95% CI = 0.60-0.99), readmission (OR = 0.89, 95% CI = 0.79-1.00), and venous thromboembolism (OR = 0.59, 95% CI = 0.45-0.78). ConclusionWe observed differences in TKA outcome, even within a universally insured population. While lower risks in some outcomes were observed for Asian and Hispanic patients, the higher risks of aseptic revision and readmission for black patients and ED visit for black and Hispanic patients warrant further research to determine reasons for these findings to mitigate disparities. Level of EvidenceLevel III.

Unrecognized Osteoporosis Is Common in Patients With a Well-Functioning Total Knee Arthroplasty

BackgroundPeri-prosthetic fractures after total knee arthroplasty (TKA) are associated with poorer outcomes and high costs. We hypothesize that osteoporosis is under-recognized in the TKA population. The purpose of this study is to report osteoporosis prevalence in a healthy cohort of patients with well-functioning TKA and to compare prevalence between males and females. MethodsThis study is a cross-sectional study of 30 adults (15 males/15 females) aged 59-80 years without known bone health issues who volunteered to undergo routine dual-energy X-ray absorptiometry 2-5 years (average 3.2 ± 0.8) after primary unilateral TKA. These data plus clinical risk factors were used to estimate fracture risk via the Fracture Risk Assessment Tool and skeletal status (normal, osteopenic, osteoporotic) was determined based on the World Health Organization definition. The National Osteoporosis Foundation criteria for treatment were applied to all patients. ResultsSix of 30 (20%) patients had T-score ≤ −2.5. Eighteen of 30 (60%) patients had T-score between −1 and −2.5 and 6 (20%) patients had T-score ≥ −1. Five patients with normal or osteopenic bone mineral density (BMD) had occult vertebral fractures. Eleven of 30 (36.7%) patients met National Osteoporosis Foundation criteria for pharmacologic treatment. ConclusionThe prevalence of occult osteoporosis meeting treatment guidelines after TKA is substantial in this sample (36.7%). BMD and osteoporosis prevalence are similar between men and women. This underappreciated prevalence of osteoporosis may contribute to peri-prosthetic fracture risk. Arthroplasty surgeons and bone health specialists must be aware of post-operative changes in bone density. These data support the further study of post-operative osteoporosis and consideration of routine BMD screening after TKA. Level of EvidenceIII.

Mid-flexion laxity in the asymptomatic native knee is predominantly present on the lateral side.

During total knee arthroplasty (TKA), an orthopaedic surgeon is focused on soft-tissue balance in extension (0°) and in flexion (90°). Patients with instability problems of the knee often report a feeling of instability during daily life activities, at around 30° knee flexion. There are no reference values available for knee laxity of healthy subjects in mid-flexion (30°) and flexion (90°) for comparison with the TKA population. Therefore, the aim was to quantify varus and valgus knee laxity in extension, mid-flexion and flexion in the asymptomatic native knee. In 40 healthy volunteers matched for age, gender and BMI with the TKA-population, varus and valgus knee laxity in extension (0°), mid-flexion (30°) and flexion (90°) was measured on low-dose radiographs. For each subject, one randomly selected knee was stressed in extension, mid-flexion and flexion (with 15Nm) using a stress device. Varus laxity in mid-flexion was higher than in extension and flexion (p < 0.01). Valgus laxity tended to be highest in mid-flexion laxity; however, no differences in knee laxity between flexion angles were seen (n.s.). Varus knee laxity in extension was higher in females than in males (p < 0.05). Mid-flexion laxity in the native knee is more prominent on the lateral side of the knee, while the medial side is more stable and constrained. Varus knee laxity in extension was shown to be higher in females than in males. Prognostic Level II.

Defining growth potential and barriers to same day discharge total knee arthroplasty

Outpatient arthroplasty programs are becoming well established. Adverse event rates have been demonstrated to be no worse than inpatient arthroplasty in the literature for selected patients. The purpose of this study was to determine our rate of outpatient total knee arthroplasty (TKA), examine justification for exclusions, and estimate the proportion of TKAs that can occur safely on an outpatient basis. Retrospective case series of 400 consecutive TKAs from Oct 2014 to Mar 2017. Patient demographics, allocation to outpatient surgery vs standard admission, and reason for exclusion from outpatient surgery were recorded. Ninety-day Emergency department (ED) visits, readmission rates, and length of stay (LOS) were compared between groups using independent sample t test and Chi-squared test. Outpatients were younger (p = 0.001), had lower BMI (p < 0.001), and ASA scores (p < 0.001) than inpatients. One hundred twenty-five (31%) TKAs were assigned to outpatient surgery and 123 achieved discharge on the same day. There was no difference in 90-day ED visits (p = 0.889) or readmission rates (p = 0.338) between groups. Reasons for exclusion from outpatient surgery included medical (absolute 43% and relative 31%), distance > one hour from hospital (18%), no help (7%), and other/unclear (10%). LOS was significantly longer for medical than non-medical exclusions (p < 0.001) and for the absolute compared to relative medical exclusions (p = 0.004). Outpatient TKA is safe in selected patients, and inclusion can likely be broadened by addressing modifiable exclusions and narrowing medical exclusions. We found that 55% of our TKA population could be appropriate for outpatient surgery.

Predictors and Cost of Readmission in Total Knee Arthroplasty

BackgroundThe Comprehensive Care for Joint Replacement bundle was created to decrease total knee arthroplasty (TKA) cost. To help accomplish this, there is a focus on reducing TKA readmissions. However, there is a lack of national representative sample of all-payer hospital admissions to direct strategy, identify risk factors for readmission, and understand actual readmission cost. MethodsWe used the Nationwide Readmission Database to examine national readmission rates, predictors of readmission, and associated readmission costs for elective TKA procedures. We fit a multivariable logistic regression model to examine factors associated with readmission. Then, we determined mean readmission costs and calculated the readmission cost when distributed across the entire TKA population. ResultsWe identified 224,465 patients having TKA across all states participating in the Nationwide Readmission Database. The mean unadjusted 30-day TKA readmission rate was 4%. The greatest predictors of readmission were congestive heart failure (odds ratio [OR] 2.51, 95% confidence interval [CI] 2.62-2.80), renal disease (OR 2.19, 95% CI 2.03-2.37), and length of stay greater than 4 days (OR 2.4, 95% CI 2.25-2.61). The overall median cost for each readmission was $6753 ± 175. Extrapolating the readmission cost for the entire TKA population resulted in the readmission cost being 2% of the overall 30-day procedure cost. ConclusionsA major focus of the Comprehensive Care for Joint Replacement bundle is improving cost and quality by limiting readmission rates. TKA readmissions are low and comprise a small percentage of total TKA cost, suggesting that they may not be the optimal measure of quality care or a significant driver of overall cost.

Preoperative characteristics of working-age patients undergoing total knee arthroplasty.

ObjectiveTotal Knee Arthroplasty (TKA) is performed more in working-age (<65 years) patients. Until now, research in this patient population has been conducted mainly among retired (≥65 years) patients. Aim of this study was therefore to describe demographic, physical, psychological and social characteristics of working TKA patients and to subsequently compare these characteristics with retired TKA patients and the general population.MethodsA cross-sectional analysis. Preoperative data of 152 working TKA patients was used. These data were compared with existing data of retired TKA patients in hospital registers and with normative values from literature on the general population. Demographic, physical, psychological and social (including work) characteristics were analyzed.ResultsThe majority (83.8%) of working TKA patients was overweight (42.6%) or obese (41.2%), a majority (72.4%) was dealing with two or more comorbidities, and most (90%) had few depressive symptoms. Mean physical activity level was 2950 minutes per week. Compared to the retired TKA population, working TKA patients perceived significantly more stiffness and better physical functioning and vitality, were more physically active, and perceived better mental health. Compared to the general population working TKA patients perceived worse physical functioning, worse physical health and better mental health, and worked fewer hours.ConclusionThis study shows that a majority of working TKA patients are overweight/obese, have multiple comorbidities, but are highly active in light-intensity activities and have few depressive symptoms. Working patients scored overall better on preoperative characteristics than retired patients, and except for physical activity scored overall worse than the general population.