Predicting Inpatient Status After Total Hip Arthroplasty in Medicare-Aged Patients

Background

The Centers for Medicare and Medicaid Services has solicited comments regarding the removal of total hip arthroplasty (THA) from its inpatient-only list. The goal of this study is to develop and internally validate a risk stratification nomogram to aid in the identification of optimal inpatient candidates in this patient population.

Increased Patient-Level Payment After Removal of Total Knee Arthroplasty From the Inpatient-Only List

BackgroundIn January 2018, the Centers for Medicare and Medicaid Services removed total knee arthroplasty (TKA) from the Inpatient Only (IPO) list. This study aimed to compare patient-level payments in TKA cases with a length of stay (LOS) <2 midnights before and after removal of TKA from IPO list.MethodsIn this retrospective cohort study, all Medicare patients who received a primary elective TKA from 2016-2019 with a LOS <2 midnights at an academic tertiary center were identified. Total and itemized charges and patient-level payments were compared between eligible TKA cases performed in 2016-2017 and those in 2018-2019. There were 351 eligible TKA cases identified: 151 in 2016-2017 and 200 in 2018-2019.ResultsThe percentage of patients making any out-of-pocket payment increased in 2018-2019 from 2016-2017 (51.0% versus 10.6%), as did median patient-level payment ($7.30 [range, $0.00-$3,389] versus $0.00 [range, $0.00-$1,248], P < .001 for both). A greater proportion of patients in 2018-2019 paid $1-$50 than in 2016-2017 (37.5% versus 1.3%, P < .001) with no change in the proportion of patients who made payments >$50. Total charges were less in 2018-2019 than in 2016-2017 (P = .001). Charges for drugs, laboratory tests, admissions/floor, and therapies decreased in 2018-2019, whereas charges for the operating room and radiology increased (P < .001 for all).ConclusionPatients receiving outpatient TKA in 2018-2019 were more likely to have out-of-pocket payments than patients with comparable hospital stay who were designated as inpatients, although most of these payments were less than $50.     

Outpatient Total Knee Arthroplasty Shows Decreasing Complication Burden From 2010 to 2020

BackgroundThe number of total knee arthroplasties (TKAs) performed on an outpatient basis continues to increase. The purpose of this study was to compare complication rates over the last decade to evaluate trends in the safety of outpatient TKA.MethodsPatients who underwent TKA from 2010 to 2020 from a large administrative claims database were retrospectively identified and stratified based on the year of surgery. Propensity-score matching was performed to match patients who were discharged within 24 hours of surgery to inpatients based on age, sex, comorbidity index, and year of surgery. Linear regression analyses were used to compare trends from 2010 to 2020. The 90-day adverse events in the early cohort (2010-2012) were compared to those in the late cohort (2018-2020) using multivariable regression analyses. Of the 547,137 patients in the sample, 28,951 outpatients (5.3%) were propensity matched to inpatients.ResultsThe incidence of outpatient TKA increased from 2010 to 2018 (1.9 versus 13.8%, P < .001). Despite a similar complication rate early (24.1 versus 22.6%, P = .164), outpatient TKA had fewer complications at the end of the study period (13.7 versus 16.7%, P < .001). Multivariate analyses demonstrated that the risk of any complication after outpatient TKA was lower than inpatient from 2018 to 2020 (odds ratio, 0.78; 95% confidence interval, 0.71-0.84).ConclusionsComplications in both cohorts declined dramatically suggesting improvements in quality of care over time, with the greatest decline in patients undergoing outpatient surgery. These results suggest that outpatient TKA today is not higher risk for the patient than inpatient TKA.Level of EvidenceLevel III.     

Discharge to Inpatient Rehab Does Not Result in Improved Functional Outcomes Following Primary Total Knee Arthroplasty

Background

Monitored rehabilitation has long been considered an essential part of the recovery process in total knee arthroplasty (TKA). However, the optimal setting for rehabilitation remains uncertain. We sought to determine whether inpatient rehabilitation settings result in improved functional and patient-reported outcomes after primary TKA.

Outcomes of a First Total Knee Arthroplasty Are Associated With Outcomes of the Subsequent Contralateral Total Knee Arthroplasty

BackgroundTo determine if preoperative characteristics and postoperative outcomes of a first total knee arthroplasty (TKA) were predictive of characteristics and outcomes of the subsequent contralateral TKA in the same patient.MethodsRetrospective administrative claims data from (SPARCS) database were analyzed for patients who underwent sequential TKAs from September 2015 to September 2017 (n = 5,331). Hierarchical multivariable Poisson regression (length of stay [LOS]) and multivariable logistic regression (all other outcomes), controlling for sex, age, and Elixhauser comorbidity scores were performed.ResultsThe cohort comprised 65% women, with an average age of 66 years and an average duration of 7.3 months between surgeries (SD: 4.7 months). LOS was significantly shorter for the second TKA (2.6 days) than for the first TKA (2.8 days; P < .001). Patients discharged to a facility after their first TKA had a probability of 76% of discharge to facility after the second TKA and were significantly more likely to be discharged to a facility compared with those discharged home after the first TKA (odds ratio [OR]: 63.7; 95% confidence interval [CI]: 52.1-77.8). The probability of a readmission at 30 and 90 days for the second TKA if the patient was readmitted for the first TKA was 1.0% (OR: 3.70; 95% CI: 0.98-14.0) and 6.4% (OR: 9; 95% CI: 5.1-16.0), respectively. Patients with complications after their first TKA had a 27% probability of a complication after the second TKA compared with a 1.6% probability if there was no complication during the first TKA (OR: 14.6; 95% CI: 7.8.1-27.2).ConclusionThe LOS, discharge disposition, 90-day readmission rate, and complication rate for a second contralateral TKA are strongly associated with the patient’s first TKA experience. The second surgery was found to be associated with an overall shorter LOS, fewer readmissions, and higher likelihood of home discharge.Level of EvidenceLevel 3-retrospective cohort study.     

Inpatient Consults and Complications During Primary Total Joint Arthroplasty in a Bundled Care Model

Background

The Centers for Medicare and Medicaid Services (CMS) are implementing changes in hospital reimbursement models for total joint arthroplasty (TJA), moving to value-based bundled payments from the fee-for-service model. The purpose of this study is to identify consults and complications during the perioperative period that increase financial burden.

Risk Factors for Greater Than 24-Hour Length of Stay After Primary Total Knee Arthroplasty

BackgroundRecently, the Center for Medicare Services removed total knee arthroplasty (TKA) from the inpatient-only procedure list. The purpose of this study is to assess the role of demographics, medical comorbidities, and postsurgical complications in predicting safe discharge to home within 24 hours after TKA.MethodsPatients undergoing primary TKA between 2011 and 2016 were identified in the American College of Surgeons National Surgical Quality Improvement Program. Patients were grouped into those whose length of stay (LOS) was less than 24 hours after surgery vs those greater than 24 hours. Demographics, preoperative comorbidities, operative variables, and postoperative adverse events were studied as risk factors for LOS greater than 24 hours.ResultsA total of 210,075 patients undergoing primary TKA met the inclusion criteria, and of those, 18,134 (8.6%) patients were discharged within 24 hours postoperatively. In a risk-adjusted multivariate analysis, patients with increasing age, obesity, preoperative comorbidities of smoking, diabetes, dyspnea, chronic obstructive pulmonary disease, hypertension, bleeding disorder, corticosteroid use preoperatively, and dependent functional status conferred a greater risk for discharge greater than 24 hours. Male gender, spinal anesthesia, and monitored anesthesia care were protective against LOS greater than 24 hours.ConclusionThis study suggests that dependent functional status, preoperative comorbidities, and postoperative complications are all associated with a LOS greater than 24 hours after TKA. Surgeons and patients should be aware of the clinical and demographic variables associated with risk for LOS greater than 24 hours when considering outpatient status for patients undergoing TKA.     

Achieving Deep Flexion After Primary Total Knee Arthroplasty

Total knee arthroplasty patients often have difficulty performing activities involving flexion beyond 130°. The NexGen LPS Flex (Zimmer Inc, Warsaw, Ind) mobile bearing implant accommodates up to 155° of flexion. Two hundred eighteen total knee arthroplasties were performed using this implant on 125 patients over a 2-year period with a minimum of 5 years follow-up. All data were collected prospectively. Forty-four percent of preoperative cases had full flexion (ie, 140° active flexion and ability to kneel with thigh/calf contact for 1 minute). Five-year data showed an average flexion of 140° ± 11.5° and flexion greater than 140° in 103 knees (68%). There were no differences in patellofemoral pain levels, complications, or Knee Society scores despite our patients having, on average, an increase in flexion and function.     

Development and Validation of a Model for Predicting Rehabilitation Care Location Among Patients Discharged Home After Total Knee Arthroplasty

BackgroundDemand for joint replacement is increasing, with many patients receiving postsurgical physical therapy (PT) in non-inpatient settings. Clinicians need a reliable tool to guide decisions about the appropriate PT setting for patients discharged home after surgery. We developed and validated a model to predict PT location for patients in our health system discharged home after total knee arthroplasty.MethodsWe analyzed data for patients who completed a preoperative total knee risk assessment in 2017 (model development cohort) or during the first 6 months of 2018 (model validation cohort). The initial total knee risk assessment, to guide rehabilitation disposition, included 28 variables in mobility, social, and environment domains, and on patient demographics and comorbidities. Multivariable logistic regression was used to identify factors that best predict discharge to home health service (HHS) vs home with outpatient PT. Model performance was assessed by standard criteria.ResultsThe development cohort included 259 patients (19%) discharged to HHS and 1129 patients (81%) discharged to home with outpatient PT. The validation cohort included 609 patients, with 91 (15%) discharged to HHS. The final model included age, gender, motivation for outpatient PT, and reliable transportation. Patients without motivation for outpatient PT had the highest probability of discharge to HHS, followed by those without reliable transportation. Model performance was excellent in the development and validation cohort, with c-statistics of 0.91 and 0.86, respectively.ConclusionWe developed and validated a predictive model for total knee arthroplasty PT discharge location. This model includes 4 variables with accurate prediction to guide patient-clinician preoperative decision making.     

Causes of Instability After Total Knee Arthroplasty

The purpose of the present study was to characterize the underlying causes that lead to instability after total knee arthroplasty (TKA). We reviewed 83 revision TKAs (79 patients) performed for instability. After detailed analysis of patient's history, physical examination, operative report and radiographs, we identified six categories: flexion/extension gap mismatch, component malposition, isolated ligament insufficiency, extensor mechanism insufficiency, component loosening, and global instability. Twenty-five knees presented with multi-factorial instability. When these knees were classified according to the most fundamental category, each category above included 24, 12, 11, 10, 10 and 16 knees respectively. The unstable TKA may result from a variety of distinct etiologies which must be identified and treated at the time of revision. The revision TKA could be tailored to the specific causes.     

Stiffness After Revision Total Knee Arthroplasty

Stiffness after a revision total knee arthroplasty (TKA) is a disabling complication that has largely been overlooked in the literature. This study attempts to define the prevalence of stiffness after revision TKA and to determine the risk factors that may lead to its development. Thirty-two knees (4.0%) presented with stiffness that we defined as a range of motion less than 90°. Risk factors were found to be poor preoperative range of motion, stiffness as primary indication for revision, younger age, shorter interval between index primary and revision TKA, presence of well-fixed components at the time of revision, postoperative wound drainage, and lower Charlson index. Because of the challenges of treating stiffness, efforts should be invested in preventing this complication.     

Chronic Thrombocytopenia and In-Hospital Outcomes After Primary Total Hip and Knee Arthroplasty

BackgroundThere is a lack of data on the influence of chronic thrombocytopenia (cTCP) on clinical outcomes following primary total hip arthroplasty (THA) and total knee arthroplasty (TKA). Limited studies mainly focused on postoperative heparin-induced TCP from single centers with small sample sizes. This study aims to describe the characteristics, trend, and outcomes of cTCP in patients undergoing THA and TKA from a nationally reprehensive perspective.MethodsWe identified THA and TKA patients with and without cTCP from the 2005 to 2015 Nationwide Inpatient Sample. Annual percent changes were calculated to reflect cTCP trends. Multivariable regression and propensity score analyses were conducted to investigate the association of cTCP and mortality, preoperative complications, cost as well as length of stay.ResultsIn total, 578,278 and 1,237,331 patients underwent primary THA and TKA, respectively. Proportion of cTCP annually increased by 6.95% in THA and 6.66% in TKA. Patients with cTCP were associated with higher risk of medical (odds ratio [OR] 2.00, 95% confidence interval [CI] 1.89-2.11) and surgical complications (OR 2.72, 95% CI 2.55-2.90) in THA, and higher risk of mortality (OR 1.68, 95% CI 1.22-2.31), medical (OR 1.94, 95% CI 1.85-2.03) and surgical complications (OR 2.55, 95% CI 2.38-2.73) in TKA. Additionally, higher cost and longer length of stay were observed in patients with cTCP for both surgical procedures.ConclusionPatients with cTCP had higher risk of mortality for TKA, more perioperative complications for both TKA and THA. Further studies are warranted to improve the preoperative management and to prevent worse outcomes associated with cTCP.     

Functional Disabilities and Satisfaction After Total Knee Arthroplasty in Female Asian Patients

This study was conducted to investigate functional disabilities and patient satisfaction in Korean patients after total knee arthroplasty (TKA). Of 372 female patients who had undergone TKA with a follow-up longer than 12 months, 261 patients (70.2%) completed a questionnaire designed to evaluate functional disabilities, perceived importance, and patient satisfaction. The top 5 severe functional disabilities were difficulties in kneeling, squatting, sitting with legs crossed, sexual activity, and recreational activities. The top 5 in order of perceived importance were difficulties in walking, using a bathtub, working, recreation activities, and climbing stairs. Severities of functional disabilities were not found to be correlated with perceived importance. The 23 patients (8.8%) dissatisfied with their replaced knees had more severe functional disabilities than the patients satisfied for most activities. The dissatisfied patients tended to perceive functional disabilities in high-flexion activities to be more important than the satisfied.     

Predicting Functional Outcomes After Above Knee Amputation for Infected Total Knee Arthroplasty

Background

Above knee amputation (AKA) is a rare, but serious, complication of total knee arthroplasty with relatively poor functional outcomes. The purpose of this study was to identify the factors predicting ambulatory status after AKA for periprosthetic joint infection of the knee and to elucidate the effects of this procedure on general health outcomes.

Development of Machine Learning Algorithms to Predict Patient Dissatisfaction After Primary Total Knee Arthroplasty

BackgroundPostoperative dissatisfaction after primary total knee arthroplasty (TKA) that requires additional care or readmission may impose a significant financial burden to healthcare systems. The purpose of the current study is to develop machine learning algorithms to predict dissatisfaction after TKA.MethodsA retrospective review of consecutive TKA patients between 2014 and 2016 from 1 large academic and 2 community hospitals was performed. Preoperative variables considered for prediction included demographics, medical history, flexion contracture, knee flexion, and outcome scores (patient-reported health state, Knee Society Score [KSS], and KSS-Function [KSS-F]). Recursive feature elimination was used to select features that optimized algorithm performance. Five supervised machine learning algorithms were developed by training with 10-fold cross-validation 3 times. These algorithms were subsequently applied to an independent testing set of patients and assessed by discrimination, calibration, Brier score, and decision curve analysis.ResultsOf 430 patients, a total of 40 (9.0%) were dissatisfied with their outcome after primary TKA at a minimum of 2 years postoperatively. The random forest algorithm achieved the best performance in the independent testing set not used for algorithm development (c-statistic: 0.77, calibration intercept: 0.087, calibration slope: 0.74, Brier score: 0.082). The most important factors for predicting dissatisfaction were age, number of medical comorbidities, presence of one or more drug allergies, preoperative patient-reported health state score, and preoperative KSS.ConclusionThe current study developed machine learning algorithms based on partially modifiable risk factors for predicting dissatisfaction after TKA. This model demonstrates good discriminative capacity for identifying those at greatest risk for dissatisfaction and may allow for preoperative health optimization.     

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.     

Most Patients Can Kneel After Total Knee Arthroplasty

Background

Patients commonly report difficulty kneeling after total knee arthroplasty (TKA). The purpose of this study was to retrospectively assess patients’ ability to kneel after TKA and to prospectively determine whether patients with reported difficulty can be taught to kneel.

Relative Contribution of Outpatient Arthroplasty Risk Assessment Score Medical Comorbidities to Same-Day Discharge After Primary Total Joint Arthroplasty

BackgroundSelection of patients who can safely undergo outpatient total joint arthroplasty (TJA) is an increasing priority given the growth of ambulatory TJA. This study quantified the relative contribution and weight of 52 medical comorbidities comprising the Outpatient Arthroplasty Risk Assessment (OARA) score as predictors of safe same-day discharge (SDD).MethodsThe medical records of 2748 primary TJAs consecutively performed between 2014 and 2020 were reviewed to record the presence or absence of medical comorbidities in the OARA score. After controlling for patients not offered SDD due to OARA scores and patients who were offered but declined SDD, the final analysis sample consisted of 631 cases, 92.1% of whom achieved SDD and 7.9% of whom did not achieve SDD. Odds ratios were calculated to quantify the extent to which each comorbidity is associated with achieving SDD.ResultsDemographic characteristics of analysis cases were consistent with a high-volume TJA practice in a US metropolitan area. Among testable OARA comorbidities, 53% significantly decreased the likelihood of SDD by 2.3 (body mass index [BMI] ≥40 kg/m²) to 12 (history of post-operative confusion and pacemaker dependence) times. BMI between 30 and 39 kg/m² did not affect the likelihood of SDD (P = .960), and BMI ≥40 kg/m² had the smallest odds ratio in our study (2.28, 95% confidence interval 1.11-4.67, P = .025).ConclusionStudy findings contribute to the refinement of the OARA score as a successful predictor of safe SDD following primary TJA while maintaining low 90-day readmission rates.