Early Infection Trends for Primary Total Knee Arthroplasty: A 5-Year Review.

The aim of this study was to track the annual rates and trends of overall, deep, and superficial surgical site infections (SSIs) following total knee arthroplasty using the most recent results from a large and nationwide database. A total of 197,192 cases were performed between 2012 and 2016 from a nationwide database stratified into years and based on superficial and/or deep SSIs. Cohorts were analyzed individually and then combined to evaluate overall SSI rates. The infection incidence for each year was calculated. After a 6-year correlation and trends analysis, univariate analyses were performed to compare the most recent year, 2016, with each of the preceding 4 years. Overall, there was a downward trend in overall SSI rates over the study period (2012-2016, with the lowest rate occurring in the most recent year, 2016 [0.11%]). Additionally, there was a decreasing trend for superficial SSI, with the lowest superficial SSI incidence occurring in 2016 (0.47%) and the greatest incidence occurring in 2012 (0.53%). An overall trend of decreasing SSI rates was observed nationwide over the 5-year period evaluated. A similar decreasing trend was also noted specifically for deep SSI rates, which can be potentially more complicated to manage, and result in decreased implant survivorship. The down trending SSI rates observed give potential credence to the value for newer and developing SSI preventative therapies as well as improved medical and surgical patient management. Nevertheless, there is still room for improvement, and continued efforts are needed to further lower SSIs after total knee arthroplasty.

Do patient-reported outcome measures improve after aseptic revision total hip arthroplasty?

BACKGROUND: The purpose of this study was to determine patient-reported outcome measures (PROMs) changes in: (1) pain, function and global health; and (2) predictors of PROMs in patients undergoing aseptic revision total hip arthroplasty (rTHA) using a multilevel model with patients nested within surgeon. METHODS: A prospective cohort of 216 patients with baseline and 1-year PROMs who underwent aseptic rTHA between January 2016 and December 2017 were analysed. The most common indication for rTHA was aseptic loosening, instability, and implant failure. The PROMs included in this study were HOOS Pain and HOOS Physical Function Short-form (PS), Veterans RAND-12 Physical Component Score (VR-12 PCS), and VR-12 Mental Component Score (MCS). Multivariable linear regression models were constructed for predicting 1-year PROMs. RESULTS: Mean 1-year PROMs improvement for aseptic revisions were 30.4 points for HOOS Pain and 22.1 points for HOOS PS. Predictors of better pain relief were patients with higher baseline pain scores. Predictors of better 1-year function were patients with higher baseline function and patients with a posterolateral hip surgical approach during revision. Although VR-12 PCS scores had an overall improvement, nearly 50% of patients saw no improvement or had worse physical component scores. Only 30.7% of patients reported improvements in VR-12 MCS. CONCLUSIONS: Overall, patients undergoing aseptic rTHA improved in pain and function PROMs at 1 year. Although global health assessment improved overall, nearly half of aseptic rTHA patients reported no change in physical/mental health status. The associations highlighted in this study can help guide the shared decision-making process by setting expectations before aseptic revision THA.

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

BACKGROUND: Psoriasis 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). METHODS: We 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. RESULTS: Psoriasis 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). CONCLUSION: Psoriasis 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.

Osseous Morphological Differences in Knee Osteoarthritis.

BACKGROUND: Improved understanding of the morphological characteristics of knees with osteoarthritis (OA) and various deformities can enable personalized implant positioning and balancing in total knee arthroplasty in an effort to continue improving clinical outcomes and optimizing procedural value. Therefore, the purpose of this study was to outline morphological differences in the medial and lateral distal femur and proximal tibia associated with varus and valgus deformities in knee OA. METHODS: A large computed tomography (CT) database was used to identify 1,158 knees, which were divided into normal and osteoarthritic groups; the latter was further divided on the basis of deformity into neutral, varus, and valgus subgroups. Morphological measurements included the non-weight-bearing hip-knee-ankle angle (nwHKA), mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), rotation of the posterior condylar axis (PCA) relative to the surgical transepicondylar axis (sTEA), ratio of medial to lateral posterior condylar offset, ratio of medial to lateral condylar radius, medial posterior slope (MPS), lateral posterior slope (LPS), medial coronal slope (MCS), and lateral coronal slope (LCS). RESULTS: Compared with the normal group, the OA group was in overall varus (nwHKA, -2.2° ± 5.0° compared with -0.2° ± 2.4°) and had a significantly smaller MPS (8.4° ± 4.0° compared with 9.2° ± 4.0°), larger LPS (9.2° ± 3.6° compared with 7.2° ± 3.3°), and smaller MCS (82.1° ± 4.3° compared with 83.9° ± 3.3°). Differences among the OA subgroups were also observed for the MCS and LCS. Compared with the normal group, the sTEA of the OA group was less externally rotated relative to the PCA (0.3° ± 1.5° compared with 1.2° ± 1.9°), and both the condylar offset ratio (1.01 ± 0.06 compared with 1.04 ± 0.07) and the condylar radius ratio (0.98 ± 0.07 compared with 1.03 ± 0.07) were smaller. Only the condylar radius ratio showed differences among the OA subgroups, with valgus deformity associated with a larger ratio. CONCLUSIONS: An analysis of CT scans of 965 healthy and 193 osteoarthritic knees revealed significant differences in PCA, condylar offset, and condylar radius as well as tibial slope in both the sagittal and coronal planes. CLINICAL RELEVANCE: There is a strong need to evolve toward a more personalized treatment for osteoarthritic knees that utilizes implants and technology to help tailor total knee arthroplasty on the basis of the patient's morphologic characteristics.

Does Surgical Trainee Participation Affect Infection Outcomes in Primary Total Knee Arthroplasty?

OBJECTIVE: To evaluate whether the involvement of surgeons-in-training was associated with increased infection rates, including both prosthetic joint infection (PJI) and surgical site infection (SSI), following primary total knee arthroplasty (TKA). DESIGN: This was a retrospective review of outcomes following primary total knee arthroplasty. Surgeries were divided into two groups: (a) attending-only and (b) trainee-involved. Association with PJI and SSI were evaluated with univariate analysis and multivariate analysis to adjust for sex, age, body mass index (BMI), Charlson Comorbidity Index (CCI), year of surgery, operative time, and hospital/surgeon volume. SETTING: A single, large North-American integrated healthcare system between January 1, 2014 and December 31, 2017. PARTICIPANTS: A total of 12,664 primary TKAs with a minimum of one-year (mean of 2-years, range 1-4.5) follow-up were evaluated. RESULTS: Residents and fellows were more likely to participate in cases with longer operative times (p<0.001) than the attending-only group. A significant difference existed on univariate analysis between the trainee-involved group and attending-only group for PJI incidence (p=0.015) but not for SSI (p=0.840). After adjusting for patient- and procedure-related features, however, neither PJI nor SSI were independently associated with trainee involvement (PJI: p=0.089; SSI: p=0.998). CONCLUSIONS: Trainee participation did not directly correlate with increased infection risk, despite their association with longer-operative times and increased medical complexity. Further approaches to mitigating the risk of SSI and PJI for patients with increased comorbidities and in complex TKA cases, which demand longer operative times, are still required.

Nonunion and Reoperation Following Proximal Interphalangeal Joint Arthrodesis and Associated Patient Factors.

BACKGROUND: Proximal interphalangeal joint (PIPJ) arthrodesis can provide reliable pain relief and restore hand function in patients with PIPJ arthritis. However, there is a paucity of literature on patient-specific preoperative risk factors that are associated with adverse outcomes after PIPJ arthrodeses. Therefore, the primary purpose of this study was to assess preoperative predictors of nonunion and reoperation after PIPJ arthrodesis. METHODS: This study identified all patients who underwent PIPJ arthrodesis at a single community practice between 1987 and 2013. The final analysis included 415 PIPJs treated with arthrodesis. The mean follow-up was 1.3 years. Data on preoperative diagnosis, demographics, comorbidities, and operative techniques were recorded, as well as the occurrence of nonunions and reoperations. Logistic regression models were used to identify independent risk factors of nonunion and reoperation. RESULTS: There were 40 nonunions (10%) and 62 reoperations (15%). Of the reoperations, there were 39 incidences of isolated hardware removal, 9 irrigation and debridement, 8 amputations, 5 revision arthrodeses, and 1 corrective osteotomy. The highest number of nonunions occurred in the traumatic diagnosis group (37%), followed by the rheumatoid group (23%) and the scleroderma group (15%). The highest number of reoperations occurred within the traumatic joint disorder group (40%), followed by the rheumatoid group (24%) and the scleroderma group (11%). Multivariate analysis revealed that male sex (P < .01) and hepatic disease (P = .03) were significant risk factors of nonunion. Male sex was also significantly associated with increased reoperation risk (P < .01). CONCLUSION: Risks of nonunions and reoperations after PIPJ arthrodeses are low; however, these findings may guide clinicians and patients in the preoperative decision-making process and help with targeted postoperative surveillance to mitigate these risks.

Impact of Parkinson's Disease on Complications, Readmission Rates, and Costs of Care following Primary Total Knee Arthroplasty.

Large-scale studies evaluating the effects of Parkinson's disease (PD) on primary total knee arthroplasty (TKA) are limited. The purpose of this study was to determine if PD patients undergoing primary TKA have increased: (1) medical complications; (2) implant-related complications; (3) readmission rates; and (4) costs. A query was performed using an administrative claims database. The study group consisted of all patients undergoing primary TKA who had a history of PD. Matched non-PD patients undergoing primary TKA served as a control group. The query yielded 72,326 patients (PD = 18,082; matching cohort = 54,244). Pearson's chi-square tests, logistic regression analyses, and Welch's t-tests were used to test for significance between the cohorts. Primary TKA patients who had PD were found to have greater incidences and odds of medical complications (4.21 vs. 1.24%; odds ratio [OR]: 3.50, 95% confidence interval [CI]: 3.15-3.89, p < 0.0001) and implant-related complications (5.09 vs. 3.15%; OR: 1.64, 95% CI: 1.51-1.79, p < 0.0001) compared with the matching cohort. Additionally, the rates and odds of 90-day readmission were higher (16.29 vs. 12.66%; OR:1.34, p < 0.0001) and episodes of care costs were significantly greater ($17,105.43 vs. $15,252.34, p < 0.0001) in patients who had PD. Results demonstrate that PD patients undergoing primary TKA had higher incidences of medical and implant-related complications. They also had increased 90-day readmission rates and costs compared with controls. The findings of this study should be used in risk stratification and should inform physician-patient discussion but should not be arbitrarily used to deny access to care.

Greater Prevalence of Mental Health Conditions in Septic Revision Total Knee Arthroplasty: A Call to Action.

The purpose of this study was to compare the prevalence of mental health conditions among patients undergoing (1) primary total knee arthroplasty (pTKA), (2) septic revision total knee arthroplasty (rTKA), and (3) aseptic revision total knee arthroplasty (TKA). The State Inpatient Databases were queried for all TKAs from 2005 to 2014 yielding 563,144 patients. Patients were separated into the following cohorts: primary, septic revision, and aseptic revision. Diagnoses of any mental health condition and the following specific conditions were compared between the three cohorts: schizophrenia/delusion, bipolar disorder, depression/mood disorder, personality disorder, anxiety/somatic/dissociative disorder, eating disorders, attention deficit hyperactivity disorder/conduct/impulse control, alcohol abuse, and drug abuse. Throughout the study period, an increase in the prevalence of mental health conditions was observed in septic and aseptic revision patients. Overall, there was a significantly higher prevalence of mental health conditions in the septic revision cohort (22.7%) compared with the primary (17.8%, p < 0.001) and aseptic revision (20.0%, p < 0.001) cohorts. Specifically, septic revision TKA patients had a higher prevalence of depression (p < 0.001), alcohol abuse (p < 0.001), drug abuse (p < 0.001), schizophrenia (p = 0.0007), and bipolar disorder (p < 0.001), compared with primary TKA patients. Additionally, there was a significantly higher prevalence of depression (p < 0.001), alcohol abuse (p < 0.001), and drug abuse (p < 0.001) among septic revision patients compared with aseptic revision patients. Mental health conditions were significantly higher among septic revision patients. Alcohol and drug abuse were approximately twice as prevalent in septic revision patients compared with primary and aseptic revision patients. These findings should serve as a call to action for mental health support for patients suffering from PJI.

Interim Spacer Exchange for Treatment of Periprosthetic Joint Infection: Almost Half the Patients Subsequently Fail.

BACKGROUND: Interim spacer exchange may be performed in patients undergoing 2-stage exchange for periprosthetic joint infection. Several studies have demonstrated that interim spacer exchange is associated with poor outcomes. This study investigated the survivorship and risk factors for failure in patients with an interim spacer exchange. METHODS: Two institutional databases identified 182 patients who underwent spacer exchange from 2000 to 2017. Primary outcomes included progression to reimplantation, treatment success, and mortality. Bivariate analysis was performed to evaluate risk factors associated with failure. Kaplan-Meier curves using host and local grades were generated to evaluate for primary outcomes and differences in survivorship. RESULTS: The overall failure rate was 49% in patients with a spacer exchange. Most patients (60%) failed before 2 years. Higher comorbidity scores, elevated erythrocyte sedimentation rate, and non-White race were more prevalent in patients who failed. Negative cultures at the time of exchange were more prevalent in patients who did not fail. Failure rate was higher in immunocompromised conditions, and those who had revision prior to exchange. After considering clinically relevant variables, advanced host grade C was the single factor associated with treatment failure. Although survivorship curves were not significantly different between extremity local grades, higher host grades were associated with treatment failure. CONCLUSION: Almost 1 out of 2 patients with spacer exchange were found to fail the intended 2-stage revision arthroplasty. Benefits of delivering additional antibiotic load with a new spacer should be balanced against poor outcomes in patients with the aforementioned risk factors.

Does Time Spent in the Post-Anesthesia Care Unit Affect Hospital Lengths of Stay following Primary Total Knee Arthroplasty?

Given the current healthcare economic environment, substantial efforts have been made to help streamline the in-hospital care for total knee arthroplasty (TKA) patients. While potential cost-reducing factors have been identified in the literature, analyses specifically considering post-anesthesia care unit (PACU) lengths of stay (LOS) are lacking. Therefore, the purpose of this study was to identify factors associated with (1) longer PACU LOS as well as (2) longer Hospital LOS. Prospectively collected TKA data from seven participating hospitals within a large health system were evaluated for patient demographics, body mass indices, Charlson Comorbidity Indices (CCI), surgeon volumes/training, admission types, anesthesia types, PACU LOS, and overall hospital LOS. Complete data was available for 1,690 patients (1,082 females, mean age: 67 years). Univariate and multivariate analytical models were constructed to identify which factors were predictive of longer PACU and overall hospital LOS. Same-day admissions, higher volume surgeons (≥ 100 cases per year), fellowship-trained arthroplasty surgeons, and longer operative times were associated with longer PACU LOS (p < 0.05). Multivariate analyses found age more than or equal to 65 years (ß= 0.124) and CCI more than or equal to 3 (ß= 0.088) to be associated with longer hospital LOS (p < 0.001). Operative times, PACU LOS, and procedure times (operative time plus PACU LOS) were not associated with longer hospital LOS (p > 0.05). These data identify associative factors for PACU LOS, as well as the influence of time spent in the PACU on overall hospital LOS. Interestingly, this analysis revealed that patients of arthroplasty fellowship-trained and higher-volume surgeons had longer PACU LOS; however, this could be explained by the observation that these particular surgeons tend to perform more complex deformity cases. Also of importance, increased PACU LOS, meaning the patient spent more time in a high-monitored setting immediately after surgery, did not necessarily confer a longer overall hospital LOS. Based on these data, it may be more beneficial to identify alternate sources than time spent in the operating room or PACU to potentially help reduce overall hospital LOS. LEVEL OF EVIDENCE: II, prospective cohort.

Diagnostic Utility of a Novel Point-of-Care Test of Calprotectin for Periprosthetic Joint Infection After Total Knee Arthroplasty: A Prospective Cohort Study.

BACKGROUND: Despite several synovial fluid biomarkers for the diagnosis of periprosthetic joint infection (PJI) having been investigated, point-of-care (POC) tests using these biomarkers are not widely available. Synovial calprotectin has recently been reported to effectively exclude the diagnosis of PJI. Thus, the objective of this study was to test the value of a calprotectin POC test for PJI diagnosis in patients undergoing total knee arthroplasty (TKA) using the 2013 Musculoskeletal Infection Society (MSIS) PJI diagnosis criteria as the gold standard. METHODS: Synovial fluid samples were prospectively collected from 123 patients who underwent revision TKA at 2 institutions within the same health-care system from October 2018 to January 2020. The study was conducted under institutional review board approval. Data collection comprised demographic, clinical, and laboratory data in compliance with the MSIS criteria. Synovial fluid samples were analyzed by calprotectin POC tests in accordance with the manufacturer's instructions. Revisions were categorized as septic or aseptic using MSIS criteria by 2 independent reviewers blinded to the calprotectin results. Calprotectin test performance characteristics with sensitivities, specificities, positive predictive values, negative predictive values, and areas under the receiver operating characteristic curve (AUC) were calculated for 2 different PJI diagnosis scenarios: (1) a threshold of ≥50 mg/L, and (2) a threshold of ≥14 mg/L. RESULTS: According to the MSIS criteria, 53 revision TKAs were septic and 70 revision TKAs were aseptic. In the ≥50-mg/mL threshold scenario, the calprotectin POC performance showed a sensitivity of 98.1%, a specificity of 95.7%, a positive predictive value of 94.5%, a negative predictive value of 98.5%, and an AUC of 0.969. In the ≥14-mg/mL threshold scenario, the sensitivity was 98.1%, the specificity was 87.1%, the positive predictive value was 85.2%, the negative predictive value was 98.4%, and the AUC was 0.926. CONCLUSIONS: The calprotectin POC test has excellent PJI diagnostic characteristics, including high sensitivity and specificity in patients undergoing revision TKA. This test could be effectively implemented as a rule-out test. However, further investigations with larger cohorts are necessary to validate these results. LEVEL OF EVIDENCE: Diagnostic Level I. See Instructions for Authors for a complete description of levels of evidence.

Cost Analysis of Medicare Patients with Varying Complexities Who Underwent Total Knee Arthroplasty.

The effort to reduce overall healthcare costs may affect more complex patients, as their pre- and postoperative care can be substantially involved. Therefore, the purpose of this study was to use a large nationwide insurance database to compare (1) costs, (2) reimbursements, and (3) net losses of 90-day episodes of care (EOC) for total knee arthroplasty (TKA) patients according to Elixhauser's Comorbidity Index (ECI) scores. All TKAs performed between 2005 and 2014 in the Medicare Standard Analytic Files were extracted from the database and stratified based on ECI scores, ranging from 1 to 5. ECI 1 patients served as the control cohort, while ECI 2, 3, 4, and 5 patients were considered study cohorts. Each study cohort and control cohort were matched based on age and sex, resulting in a total of 715,398 patients included for analysis. Total EOC costs, reimbursements, and total net losses (defined as total EOC costs minus total EOC reimbursements) were compared between the cohorts. Overall, total EOC costs increased with ECI. For example, compared with the matched ECI 1 cohorts, the total EOC costs for ECI 5 patients ($56,589.19 vs. $51,747.54) were significantly greater (p < 0.01). Although reimbursements increased with increasing ECI, so did net losses. The net losses for ECI 5 patients were greater than that for ECI 1 patients ($42,309.39 vs. $40,007.82). The bundled payments for care improvement (BPCI) and comprehensive care for joint replacement (CJR) are alternative payment models that might de-incentivize treatment of more complex patients. Our study found that despite increasing reimbursements, overall costs, and therefore net losses, were greater for more complex patients with higher ECI scores.

Annual Nationwide Infection Trends for Revision Total Knee Arthroplasty.

Several recent intraoperative and wound management techniques have been developed and implemented in the United States over the past decade; however, it is unclear what the effects of these newer modalities have on reducing surgical site infection (SSI) rates. Therefore, the purpose of this study was to track the annual rate and trends of (1) overall, (2) deep, and (3) superficial SSIs following revision total knee arthroplasty (TKA). The National Surgical Quality Improvement Program database was queried for all revision TKA cases performed between 2011 and 2016, which yielded 9,887 cases. Cases with superficial and/or deep SSIs were analyzed separately and then combined to evaluate overall SSI rates. After an overall 6-year correlation and trends analysis, univariate analysis was performed to compare the most recent year, 2016, with the preceding 5 years. Correlation coefficients and chi-square tests were used to determine correlation and statistical significance. No significant correlations between combined, deep, and/or superficial SSI rates and year were noted (p > 0.05). The lowest overall SSI incidence was in 2012 (1.16%), while the greatest incidence was in 2014 (1.76%). The deep SSI incidence over the 6 years was 0.67% (66 out of 9,887 cases). Deep SSI rate decreased by 10% in 2016 compared with 2011 (0.50 vs. 0.56%, p > 0.05). In this 6-year period, 94 cases out of 9,887 were complicated by a superficial SSI, an incidence of 0.95%. The lowest superficial SSI incidence occurred in 2015 (n = 17, 0.77%). Overall, the incidence of SSIs in revision TKA has remained fairly low with some annual variance, indicating room for improvement. These variations likely as revision surgeries can be more complex and have several associated confounding factors influencing outcomes, when compared with primary cases. Further research is needed to identify revision-specific strategies to reduce the risk of surgical site infections.

Does Increasing Patient Complexity Have an Effect on Medical Outcomes and Lengths-of-Stay after Total Knee Arthroplasty?

A greater number of medically complex patients with multiple comorbidities are now more readily considered for total knee arthroplasty (TKA). Therefore, the purpose of this study was to determine whether comorbidity burden, measured with the Elixhauser Comorbidity Index (ECI), correlated with 90-day medical complications and longer in-hospital lengths-of-stay (LOS) in TKA patients. The PearlDiver supercomputer was queried for all primary TKA patients in the Medicare Standard Analytic Files from 2005 to 2014 using International Classification of Disease, 9th edition codes. Patients were included based on ECI scores, ranging from 1 to 5. ECI 1 patients served as the control cohort, while ECI 2, 3, 4, and 5 patients were considered study cohorts. Each study cohort was matched based on age and gender to the control cohort, resulting in a total of 715,398 patients included for analysis (ECI 1, n = 144,072; ECI 2, n = 144,072; ECI 3, n = 144,072; ECI 4, n = 144,072; ECI 5, n = 139,110). Logistic regression analyses were performed to compare 90-day medical complications and Welch's t-tests were performed to compare LOS between the cohorts. Patients with higher ECI scores were more likely to develop medical complications and have longer LOS compared with matched patients in the control cohort. Compared with matched ECI 1 patients, patients with ECI scores of 2 (odds ratio [OR]: 1.19, 95% confidence interval [CI]: 1.14-1.24), 3 (OR: 1.27, 95% CI: 1.21-1.32), 4 (OR: 1.32, 95% CI: 1.27-1.38), and 5 (OR: 1.33, 95% CI: 1.27-1.39) were significantly more likely to develop 90-day medical complications. Additionally, the mean LOS of patients in the ECI 2 (2.59 ± 1.49 vs. 2.73 ± 1.52 days), ECI 3 (2.59 ± 1.49 vs. 2.88 ± 1.51 days; p < 0.001), ECI 4 (2.59 ± 1.49 vs. 3.01 ± 1.56 days; p < 0.001), and ECI 5 (2.61 ± 1.49 vs. 3.14 ± 1.61 days; p < 0.001) groups were significantly longer than the mean LOS in the control ECI 1 group. In an increasingly complex patient population, associations between comorbidities and outcomes after TKA procedures can guide providers on how to modify their pre- and postoperative care. These results demonstrate that higher ECI scores are associated with a greater likelihood of 90-day medical complications and longer in-hospital LOS.

Estimated glomerular filtration rate is a prognosticator of adverse outcomes after primary total knee arthroplasty among patients with chronic kidney disease and glomerular hyperfiltration.

BACKGROUND: The goals of this study were: (1) to test whether patients with an Estimated glomerular filtration rate (eGFR) that is higher or lower than population-based standards have an increased risk of 30-day mortality, return to the operating room, readmission, non-home discharge, any complication, major complications, and minor complications after primary total knee arthroplasty (TKA); and (2) to find out whether there is a significant non-linear relationship between eGFR and those same variables. METHODS: A total of 168,919 primary TKAs were identified using The National Surgical Quality Improvement Program (NSQIP) database between 1 January 2008 and 31 December 2016. The following outcomes were assessed at 30 days: mortality, return to the operating room, readmission, non-home discharge, any complication, major complications, and minor complications. RESULTS: Multivariate binomial logistical regression found that patients with hyperfiltration had higher rates of readmission (P < 0.03), non-home discharge (P < 0.01), any complication (P < 0.01), major complications (P = 0.03), and minor complications (P < 0.01) compared to reference patients with eGFR in the normal range. Patients with an eGFR less than 60 (stage 3 chronic kidney disease or higher) had increased odds of mortality (P < 0.05), readmission (P < 0.05), any complication (P < 0.01), major complications (P < 0.01), and minor complications (P < 0.01). Spline regression found statistically significant non-linear relationships between eGFR and mortality (P < 0.001), return to the operating room (P = 0.0029), and readmission as well as non-home discharge (P < 0.001). CONCLUSION: Low eGFR and hyperfiltration may be associated with elevated risk of 30-day adverse events. GFR can be used as a risk stratification tool to counseling patients with particular attention paid to those with a GFR < 30 ml/min/1.73 m2.

The Potential Effects of Imposing a Body Mass Index Threshold on Patient-Reported Outcomes After Total Knee Arthroplasty.

BACKGROUND: Operative eligibility thresholds based on body mass index (BMI) alone may risk restricting access to improved pain control, function, and quality of life. This study evaluated the use of BMI-cutoffs to offering TKA in avoiding: 1) 90-day readmission, 2) one-year mortality, and 3) failure to achieve clinically important one-year PROMS improvement (MCID). METHODS: A total of 4126 primary elective unilateral TKA patients from 2015 to 2018 were prospectively collected. For specific BMI(kg/m2) cutoffs: 30, 35, 40, 45, and 50, the positive predictive value (PPV) for 90-day readmission, one-year mortality, and failure to achieve one-year MCID were calculated. The number of patients denied complication-free postoperative courses per averted adverse outcome/failed improvement was estimated. RESULTS: Rates of 90-day readmission and one-year mortality were similar across BMI categories (P > .05, each). PPVs for preventing 90-day readmission and one-year mortality were low across all models of BMI cutoffs. The highest PPV for 90-day readmission and one-year mortality was detected at cutoffs of 45 (6.4%) and 40 (0.87%), respectively. BMI cutoff of 40 would deny 18 patients 90-day readmission-free, and 194 patients one-year mortality-free postoperative courses for each averted 90-day readmission/one-year mortality. Such cutoff would also deny 11 patients an MCID per avoided failure. Implementing BMI thresholds alone did not influence the rate of improvements in KOOS-PS, KRQOL, or VR-12. CONCLUSION: Utilizing BMI cutoffs as the sole determinants of TKA ineligibility may deny patients complication-free postoperative courses and clinically important improvements. Shared decision-making supported by predictive tools may aid in balancing the potential benefit TKA offers to obese patients with the potentially increased complication risk and cost of care provision.

Developing a personalized outcome prediction tool for knee arthroplasty.

AIMS: The purpose of this study was to develop a personalized outcome prediction tool, to be used with knee arthroplasty patients, that predicts outcomes (lengths of stay (LOS), 90 day readmission, and one-year patient-reported outcome measures (PROMs) on an individual basis and allows for dynamic modifiable risk factors. METHODS: Data were prospectively collected on all patients who underwent total or unicompartmental knee arthroplasty at a between July 2015 and June 2018. Cohort 1 (n = 5,958) was utilized to develop models for LOS and 90 day readmission. Cohort 2 (n = 2,391, surgery date 2015 to 2017) was utilized to develop models for one-year improvements in Knee Injury and Osteoarthritis Outcome Score (KOOS) pain score, KOOS function score, and KOOS quality of life (QOL) score. Model accuracies within the imputed data set were assessed through cross-validation with root mean square errors (RMSEs) and mean absolute errors (MAEs) for the LOS and PROMs models, and the index of prediction accuracy (IPA), and area under the curve (AUC) for the readmission models. Model accuracies in new patient data sets were assessed with AUC. RESULTS: Within the imputed datasets, the LOS (RMSE 1.161) and PROMs models (RMSE 15.775, 11.056, 21.680 for KOOS pain, function, and QOL, respectively) demonstrated good accuracy. For all models, the accuracy of predicting outcomes in a new set of patients were consistent with the cross-validation accuracy overall. Upon validation with a new patient dataset, the LOS and readmission models demonstrated high accuracy (71.5% and 65.0%, respectively). Similarly, the one-year PROMs improvement models demonstrated high accuracy in predicting ten-point improvements in KOOS pain (72.1%), function (72.9%), and QOL (70.8%) scores. CONCLUSION: The data-driven models developed in this study offer scalable predictive tools that can accurately estimate the likelihood of improved pain, function, and quality of life one year after knee arthroplasty as well as LOS and 90 day readmission. Cite this article: Bone Joint J 2020;102-B(9):1183-1193.

Opioid Use Disorder Is Associated with an Increased Risk of Infection after Total Joint Arthroplasty: A Large Database Study.

BACKGROUND: Recent studies have shown that patients with opioid use disorder have impaired immunity. However, few studies with large patient populations have evaluated the risks of surgical site infection (SSI) and prosthetic joint infection (PJI) with opioid use disorder after total joint arthroplasty (TJA), and there is a lack of evidence for revision TJA in particular. QUESTIONS/PURPOSES: Are patients with opioid use disorder who undergo (1) primary THA, (2) primary TKA, (3) revision THA, or (4) revision TKA at a higher risk of experiencing SSIs 90 days after surgery or PJIs 2 years after surgery than those who do not have opioid use disorder? METHODS: All primary and revision TJAs performed between 2005 and 2014 were identified from the Medicare Analytical Files of the PearlDiver Supercomputer using ICD-9 codes. This database is one of the largest nationwide databases; it comprehensively and longitudinally tracks patients based on all insurance claims rather than particular hospital visits, and has a low error rate (estimated at 1.3%). Boolean command operators were used to form a study group of patients with a history of opioid use disorder before surgery. ICD-9 diagnosis codes 304.00 to 304.02 and 305.50 to 305.52 were used to identify patients with opioid use disorder. Study group patients were matched 1:1 to control participants without opioid use disorder undergoing TJA, according to age, sex, and comorbidity burden (Elixhauser comorbidity index [ECI]). The ECI is comprised of 31 different comorbidities and can be used for large administrative databases. The query yielded a study population of 54,332 patients: 14,944 undergoing primary THA (opioid use disorder: n = 7472), 23,680 undergoing primary TKA (opioid use disorder: n = 11,840), 8116 undergoing revision THA (opioid use disorder: n = 4058), and 7592 undergoing revision TKA (opioid use disorder: n = 3796). The primary outcomes analyzed were SSI at 90 days and PJI at 2 years postoperatively, which were identified with ICD-9 codes. Logistic regression analyses were performed to calculate the risk that an infection would develop in a patient with opioid use disorder compared with the matched control patients without opioid use disorder. RESULTS: Patients with opioid use disorder undergoing primary THA had an increased risk of SSI at 90 days (OR 1.85 [95% CI 1.51 to 2.25]; p < 0.001) and PJI at 2 years (OR 1.66 [95% CI 1.42 to 1.93]; p < 0.001). Compared with matched controls, opioid use disorder patients undergoing primary TKA had an increased risk of SSI at 90 days (OR 1.72 [95% CI 1.46 to 2.02]; p < 0.001) and PJI at 2 years (OR 1.31 [95% CI 1.16 to 1.47]; p < 0.001). Similarly, for revision THAs, there was an increase in 90-day SSIs (OR 1.89 [95% CI 1.53 to 2.32]; p < 0.001) and 2-year PJIs (OR 4.24 [95% CI 3.67 to 4.89]; p < 0.001). The same held for revision TKAs for 90-day SSIs (OR 1.88 [95% CI 1.53 to 2.29]; p < 0.001) and 2-year PJIs (OR 4.94 [95% CI 4.24 to 5.76]; p < 0.001). CONCLUSIONS: After accounting for age, sex, and comorbidity burden, these results revealed that patients with opioid use disorder undergoing TJA were at increased risk of having SSIs and PJIs. Based on these findings, healthcare systems and/or administrators should recognize the increased associated PJI and SSI risks in patients with opioid use disorder and enact clinical policies that reflect these associated risks. Additionally, these findings should encourage surgeons to pursue multidisciplinary approaches to help patients reduce their opioid consumption before their arthroplasty procedure. LEVEL OF EVIDENCE: Level III, therapeutic study.

What Are Risk Factors for Infection after Primary or Revision Total Joint Arthroplasty in Patients Older Than 80 Years?

BACKGROUND: Patients older than 80 years of age form an increasing proportion of the patient population undergoing total joint arthroplasty (TJA). With increasing life expectancy and the success of TJA, orthopaedic surgeons are more likely to operate on patients older than 80 years than ever before. Given that most other studies focus on younger populations, only evaluate primary TJA, or limit patient populations to institutional or regional data, we felt a large-database, nationwide analysis of this demographic cohort was warranted, and we wished to consider both primary and revision TJA. QUESTIONS/PURPOSES: In this study, we sought to investigate the risk factors for surgical site infections (SSIs) at 90 days and periprosthetic joint infections (PJIs) at 2 years after surgery in patients aged 80 years and older undergoing (1) primary and (2) revision lower extremity TJA. METHODS: All patients aged 80 years or older who underwent primary or revision TJA between 2005 and 2014 were identified using the Medicare Analytical Files of the PearlDiver Supercomputer using ICD-9 codes. This database is unique in that it is one of the largest nationwide databases, and so it provides a large enough sample size of patients 80 years or older. Additionally, this database provides comprehensive and longitudinal patient data tracking, and a low error rate. Our final cohort consisted of 503,241 patients (TKA: n = 275,717; THA: n = 162,489; revision TKA: n = 28,779; revision THA: n = 36,256). Multivariate logistic regression models were constructed to evaluate the association of risk factors on the incidences of 90-day SSI and 2-year PJI. Variables such as sex, diabetes, BMI, and congestive heart failure, were included in the multivariate regression models. Several high-risk comorbidities as identified by the Charlson and Elixhauser comorbidity indices were selected to construct the models. We performed a Bonferroni-adjusted correction to account for the fact that multiple statistical comparisons were made, with a p value < 0.002 being considered statistically significant. RESULTS: For primary TKA patients, an increased risk of 90-day SSIs was associated with male sex (OR 1.28 [95% CI 1.25 to 1.52]; p < 0.001), BMI greater than 25 k/m (p < 0.001), and other comorbidities. For primary THA patients, an increased risk of 90-day SSIs was associated with patients with obesity (BMI 30-39 kg/m; OR 1.91 [95% CI 1.60 to 2.26]; p < 0.001) and those with morbid obesity (BMI 40-70 kg/m; OR 2.58 [95% CI 1.95 to 3.36]; p < 0.001). For revision TKA patients, an increased risk of SSI was associated with iron-deficiency anemia (OR 1.82 [95% CI 1.37 to 2.28]; p < 0.001). For revision THA patients, electrolyte imbalance (OR 1.48 [95% CI 1.23 to 1.79]; p < 0.001) and iron-deficiency anemia (OR 1.63 [95% CI 1.35 to 1.99]; p < 0.001) were associated with an increased risk of 90-day SSI. Similar associations were noted for PJI in each cohort. CONCLUSIONS: These findings show that in this population, male sex, obesity, hypertension, iron-deficiency anemia, among other high-risk comorbidities are associated with a higher risk of SSIs and PJIs. Based on these findings, orthopaedic surgeons should actively engage in comanagement strategies with internists and other specialists to address modifiable risk factors through practices such as weight management programs, blood pressure reduction, and electrolyte balancing. Furthermore, this data should encourage healthcare systems and policy makers to recognize that this patient demographic is at increased risks for PJI or SSI, and these risks must be considered when negotiating payment bundles. LEVEL OF EVIDENCE: Level III, therapeutic study.