What Are the Mortality, Infection, and Nonunion Rates After Periprosthetic Femoral Fractures in the United States?

BACKGROUND: Periprosthetic femoral fractures are a serious complication that put a high burden on patients. However, comprehensive analyses of their incidence, mortality, and complication rates based on large-registry data are scarce. QUESTIONS/PURPOSES: In this large-database study, we asked: (1) What is the incidence of periprosthetic femoral fractures in patients 65 years and older in the United States? (2) What are the rates of mortality, infection, and nonunion, and what factors are associated with these outcomes? METHODS: In this retrospective, comparative, large-database study, periprosthetic femoral fractures occurring between January 1, 2010, and December 31, 2019, were identified from Medicare physician service records encompassing services rendered in medical offices, clinics, hospitals, emergency departments, skilled nursing facilities, and other healthcare institutions from approximately 2.5 million enrollees. These were grouped into proximal, distal, and shaft fractures after TKA and THA. We calculated the incidence of periprosthetic femur fractures by year. Incidence rate ratios (IRR) were calculated by dividing the incidence in 2019 by the incidence in 2010. The Kaplan-Meier method with Fine and Gray subdistribution adaptation was used to calculate the cumulative incidence rates of mortality, infection, and nonunion. Semiparametric Cox regression was applied with 23 measures as covariates to determine factors associated with these outcomes. RESULTS: From 2010 to 2019, the incidence of periprosthetic femoral fractures increased steeply (TKA for distal fractures: IRR 3.3 [95% CI 1 to 9]; p = 0.02; THA for proximal fractures: IRR 2.3 [95% CI 1 to 4]; p = 0.01). One-year mortality rates were 23% (95% CI 18% to 28%) for distal fractures treated with THA, 21% (95% CI 19% to 24%) for proximal fractures treated with THA, 22% (95% CI 19% to 26%) for shaft fractures treated with THA, 21% (95% CI 18% to 25%) for distal fractures treated with TKA , 22% (95% CI 17% to 28%) for proximal fractures treated with TKA, and 24% (95% CI 19% to 29%) for shaft fractures treated with TKA. The 5-year mortality rate was 63% (95% CI 54% to 70%) for distal fractures treated with THA, 57% (95% CI 54% to 62%) for proximal fractures treated with THA, 58% (95% CI 52% to 63%) for shaft fractures treated with THA, 57% (95% CI 52% to 62%) for distal fractures treated with TKA , 57% (95% CI 49% to 65%) for proximal fractures treated with TKA, and 57% (95% CI 49% to 64%) for shaft fractures treated with TKA. Age older than 75 years, male sex, chronic obstructive pulmonary disease (HR 1.48 [95% CI 1.32 to 1.67] after THA and HR 1.45 [95% CI 1.20 to 1.74] after TKA), cerebrovascular disease after THA, chronic kidney disease (HR 1.28 [95% CI 1.12 to 1.46] after THA and HR 1.50 [95% CI 1.24 to 1.82] after TKA), diabetes mellitus, morbid obesity, osteoporosis, and rheumatoid arthritis were clinical risk factors for an increased risk of mortality. Within the first 2 years, fracture-related infections occurred in 5% (95% CI 4% to 7%) of patients who had distal fractures treated with THA, 5% [95% CI 5% to 6%]) of patients who had proximal fractures treated with THA, 6% (95% CI 5% to 7%) of patients who had shaft fractures treated with THA, 6% (95% CI 5% to 7%) of patients who had distal fractures treated with TKA , 7% (95% CI 5% to 9%) of patients who had proximal fractures treated with TKA, and 6% (95% CI 4% to 8%) of patients who had shaft fractures treated with TKA. Nonunion or malunion occurred in 3% (95% CI 2% to 4%) of patients with distal fractures treated with THA, 1% (95% CI 1% to 2%) of patients who had proximal fractures treated with THA, 2% (95% CI 1% to 3%) of patients who had shaft fractures treated with THA, 4% (95% CI 3% to 5%) of those who had distal fractures treated with TKA, , 2% (95% CI 1% to 4%) of those who had proximal fractures treated with TKA, and 3% (95% CI 2% to 4%) of those who had shaft fractures treated with TKA. CONCLUSION: An increasing number of periprosthetic fractures were observed during the investigated period. At 1 and 5 years after periprosthetic femur fracture, there was a substantial death rate in patients with Medicare. Conditions including cerebrovascular illness, chronic kidney disease, diabetes mellitus, morbid obesity, osteoporosis, and rheumatoid arthritis are among the risk factors for increased mortality. After the surgical care of periprosthetic femur fractures, the rates of fracture-related infection and nonunion were high, resulting in a serious risk to affected patients. Patient well-being can be enhanced by an interdisciplinary team in geriatric traumatology and should be improved to lower the risk of postoperative death. Additionally, it is important to ensure that surgical measures to prevent fracture-related infections are followed diligently. Furthermore, there is a need to continue improving implants and surgical techniques to avoid often-fatal complications such as fracture-associated infections and nonunion, which should be addressed in further studies. LEVEL OF EVIDENCE: Level III, therapeutic study.

Epidemiology and treatment of proximal femoral fractures in the elderly U.S. population.

Proximal femoral fractures are a serious complication, especially for elderly patients. Detailed epidemiological analyzes provide a valuable resource for stakeholders in the health care system in order to foresee future development possibly influenceable by adaption of therapeutic procedures and prevention strategies. This work aimed at answering the following research questions: (1) What are the incidence rates of proximal femoral fractures in the elderly U.S. population? (2) What is the preferred treatment procedure for these fractures? Proximal femoral fractures occurred between January 1, 2009 and December 31, 2019 in patients ≥ 65 years were identified from the Medicare Physician Service Records Data Base. The 5% sample of Medicare beneficiaries, equivalent to the records from approximately 2.5 million enrollees formed the basis of this study. Fractures were grouped into head/neck, intertrochanteric, and subtrochanteric fractures. The overall incidence rate, age and sex specific incidence rates as well as incidence rate ratios were calculated. Common Procedural Terminology (CPT) codes were used to identify procedures and operations. In 2019, a total number of 7982 femoral head/neck fractures was recorded. In comparison to 9588 cases in 2009, the incidence substantially decreased by 26.6% from 666.7/100,000 inhabitants to 489.3/100,000 inhabitants (z = - 5.197, p < 0.001). Also, in intertrochanteric fractures, a significant decline in the incidence by 17.3% was evident over the years from 367.7/100,000 inhabitants in 2009 to 304.0 cases per 100,000 inhabitants in 2019 (z = - 2.454, p = 0.014). A similar picture was observable for subtrochanteric fractures, which decreased by 29.6% (51.0 cases per 100,000 to 35.9 cases per 100,000) over the time period (z = - 1.612, p = 0.107). Head/neck fractures were mainly treated with an arthroplasty (n = 36,301, 40.0%). The majority of intertrochanteric fractures and subtrochanteric fractures received treatment with an intramedullary device (n = 34,630, 65.5% and n = 5870, 77.1%, respectively). The analysis indicated that the incidence of all types of proximal femoral neck fractures decreased for the population of elderly patients in the U.S. within the last decade. Treatment of head and neck fractures was mainly conducted through arthroplasty, while intertrochanteric and subtrochanteric fractures predominantly received an intramedullary nailing.

Femoral shaft fractures in eldery patients - An epidemiological risk analysis of incidence, mortality and complications.

OBJECTIVES: This work aimed at answering the following research questions: (1) What is the incidence of femoral shaft fractures in the geriatric population in the U.S.? (2) What is the rate of mortality, mechanical complications, nonunion and infection, and what are the associated risk factors? STUDY DESIGN AND SETTING: In this cross-sectional study, femoral shaft fractures occurred between January 1, 2009, and December 31, 2019, were identified from Medicare records. Rates of mortality, nonunion, infection, and mechanical complications were calculated with the Kaplan-Meier method with Fine and Gray sub-distribution adaptation. Semiparametric Cox regression was applied with twenty-three covariates to determine risk factors. RESULTS: Between 2009 through 2019 the incidence of femoral shaft fractures decreased by 12.07% to 40.8/100,000 inhabitants (p = 0.549). The 5-year mortality risk was 58.5%. Male sex, age over 75 years, chronic obstructive pulmonary disease, cerebrovascular disease, chronic kidney disease, congestive heart failure, diabetes mellitus, osteoporosis, tobacco dependence, and lower median household income were significant risk factors. The infection rate was 2.22% [95%CI: 1.90-2.58] and the union failure rate 2.52% [95%CI: 2.17-2.92] after 24 months. CONCLUSION: An early assessment of individual patient risk factors may be beneficial in the care and treatment of patients with these fractures.

State and Government Administrative Databases: Medicare, National Inpatient Sample (NIS), and State Inpatient Databases (SID) Programs.

The availability of large state and federally run administrative health-care databases provides potentially comprehensive population-wide information that can dramatically impact both medical and health-policy decision-making. Specific opportunities and important limitations exist with all administrative databases based on what information is collected and how reliably specific data elements are reported. Access to patient identifiable-level information can be critical for certain long-term outcome studies but can be difficult (although not impossible) due to patient privacy protections, while more easily available de-identified information can provide important insights that may be more than sufficient for some short-term operative or in-hospital outcome questions. The first section of this paper by Sarah K. Meier and Benjamin D. Pollock discusses Medicare and the different data files available to health-care researchers. They describe what is and is not generally available from even the most granular Medicare Standard Analytic Files, and provide an analysis of the strengths and weaknesses of Medicare administrative data as well as the resulting best and inappropriate uses of these data. In the second section, the Nationwide Inpatient Sample and complementary State Inpatient Database programs are reviewed by Steven M. Kurtz and Edmund Lau, with insights into the origins of these programs, the data elements that are recorded relating to the operative procedure and hospital stay, and examples of the types of studies that optimally utilize these data sources. They also detail the limitations of these databases and identify studies that they are not well-suited for, especially those involving linkage or longitudinal studies over time. Both sections provide useful guidance on the best uses and pitfalls related to these important large representative national administrative data sources.

Association Between Bio-Fermentation Derived Hyaluronic Acid and Healthcare Costs Following Knee Arthroplasty.

Background: Limiting access to intra-articular knee injections, including hyaluronic acid (HA), has been advocated as a cost-containment measure in the treatment of knee osteoarthritis. The association between presurgical injections and post-surgical complications such as early periprosthetic joint infection and revision remained to be investigated. This study evaluated pre- and post-surgical costs and rates of post-surgical complications in knee arthroplasty (KA) patients with or without prior HA use. Methods: Commercial and Medicare Supplemental Claims Data (IBM MarketScan Research Databases) from January 1, 2012 to December 31, 2018 were used to identify unilateral KA patients. Those who completed a course of bio-fermentation derived HA (Bio-HA) as the first-line HA therapy comprised of the test group (n = 4091), while the control group did not use HA prior to KA (n = 118,659). Using multivariable regression with propensity score (PS) weighting, overall healthcare costs, readmission rates, and revision rates were assessed at six months following KA. Results: Healthcare costs following KA were significantly lower for the Bio-HA group ($10,021 ± $22,796) than No HA group ($12,724 ± $32,966; PS p < 0.001). Bio-HA patients had lower readmission rates (8.9% vs 14.0%; PS p < 0.001) and inpatient costs per readmitted patient ($43,846 ± $50,648 vs $50,533 ± $66,150; PS p = 0.005). There were no differences in revision rate for any reason (Bio-HA: 0.78% vs No HA: 0.67%; PS p = 0.361) and with PJI (Bio-HA: 0.42% vs No HA: 0.33%; PS p = 0.192). Costs in the six months up to and including the KA were similar for both groups (Bio-HA: $49,759 ± $40,363 vs No HA: $50,532 ± $43,183; PS p = 0.293). Conclusion: Bio-HA use prior to knee arthroplasty did not appear to increase overall healthcare costs in the six months before and after surgery. Allowing access to HA injections provides a non-surgical therapeutic option without increasing cost or risk of post-surgical complications.

Changes in prescription pain medication and intra-articular corticosteroid utilization after intra-articular bio-fermentation derived hyaluronic acid use in patients undergoing multimodal pain management.

BACKGROUND: Multiple interventions may be used to treat symptomatic knee osteoarthritis (OA), but concerns have been raised about the safety and efficacy of some therapies. Clinical trials have shown that hyaluronic acid (HA) can provide pain relief up to 6 months and possibly to 12 months, while real-world data has shown that pain medication and intra-articular corticosteroid (CS) injection utilization are reduced within 6 months after HA. OBJECTIVE: To examine changes in prescription pain medication and CS utilization during 1 year after multimodal therapy that included high molecular weight, bio-fermentation derived HA (Bio-HA) use for knee OA. METHODS: Commercial and Medicare Supplemental claims data (IBM MarketScan Research Databases) (1 January 2012, through 31 December 2018) was used to identify unilateral Bio-HA patients using multimodal therapy (any combination of CS injection, opioids, and non-opioid pain medication). Monthly therapy utilization was compared in the 12 months after Bio-HA therapy initiation to the 4-month intra-multimodal period. RESULTS: A total of 13,999 patients underwent Bio-HA therapy with concurrent multimodal therapy. The number of filled opioid prescriptions decreased from 2,913.0/month to 2,861.5/month after Bio-HA, with a reduction in mean monthly prescriptions from 0.60 to 0.43 per user (p < 0.001). A number of opioid days supplied also decreased from 48,914/month to 39,730/month, with a decrease from 10.1/month to 6.0/month per user (p < 0.001). Bio-HA patients had prescription pain medication-free days for 71% of the time post-multimodal period compared to 53% during the intra-multimodal period (p < 0.001). The proportion of patients with CS injections after Bio-HA decreased from 53.8% to 29.6% (p < 0.001). Total monthly CS injections decreased from 2,292 to 663. CONCLUSIONS: Our data suggest that high molecular weight Bio-HA, as part of multimodal therapy, may be effective in providing longer-term pain relief with the reduction in pain therapy (CS injections and opioids) and increase in prescription pain medication-free days.

Intra-Articular Corticosteroid or Hyaluronic Acid Injections Are Not Associated with Periprosthetic Joint Infection Risk following Total Knee Arthroplasty.

This study evaluated whether the preoperative use and timing of the use of hyaluronic acid (HA) and/or corticosteroid (CS) injections were associated with an increased risk of periprosthetic joint infections (PJIs) following primary total knee arthroplasty (TKA). We tested the hypothesis that preoperative injection of HA or CS within 3 months prior to primary TKA was associated with an increased risk of PJI by specifically evaluating the association between PJI risk and (1) injection type; (2) timing; (3) patient demographic factors; and (4) surgery-related factors, such as surgeon injection volume, knee arthroscopy (pre- and postoperative), and hospital length of stay. The 5% Medicare part B claims database was queried for patients who received CS and/or HA injections. Cox proportional hazards regressions evaluated the risk of PJIs after TKA, adjusting for patient and clinical factors, as well as propensity scores. The unadjusted incidence of PJI at 2-year post-TKA was 0.75% for the CS group, 0.89% for the HA group, 0.96% for both CS and HA group, and 0.75% for those who did not use HA or CS in the 12 months before TKA. For patients who used HA and/or CS within 3 months prior to TKA, the unadjusted incidence of PJI at 2-year post-TKA was 0.75% for the CS group, 1.07% for the HA group, and 1.00% for both CS and HA group, compared with 0.77% for those who did not use HA or CS. The number of injections performed per year was inconsistently associated with PJI risk. Overall, we found that intra-articular injections given within the 4-month period prior to TKA were not associated with elevated PJI risk (evaluated at 1, 3, 12, and 24 months after the index TKA) within the elderly Medicare patient population.

Hospital Costs for Unsuccessful Two-Stage Revisions for Periprosthetic Joint Infection.

BACKGROUND: Although 2-stage exchange arthroplasty is the preferred surgical treatment for periprosthetic joint infection (PJI) in the United States, little is known about the risk of complications between stages, mortality, and the economic burden of unsuccessful 2-stage procedures. METHODS: The 2015-2019 Medicare 100% inpatient sample was used to identify 2-stage PJI revisions in total hip and knee arthroplasty patients using procedural codes. We used the Fine and Gray sub-distribution adaptation of the conventional Kaplan-Meier method to estimate the probability of completing the second stage of the 2-stage PJI infection treatment, accounting for death as a competing risk. Hospital costs were estimated from the hospital charges using "cost-to-charge" ratios from Centers for Medicare and Medicaid Services. RESULTS: A total of 5094 total hip arthroplasty and 13,062 total knee arthroplasty patients had an index revision for PJI during the study period. In the first 12 months following the first-stage explantation, the likelihood of completing a second-stage PJI revision was 43.1% (95% confidence interval [CI] 41.7-44.5) for hips and 47.9% (95% CI 47.0-48.8) for knees. Following explantation, 1-year patient survival rates for hip and knee patients were 87.4% (95% CI 85.8-88.9) and 91.4% (95% CI 90.6-92.2), respectively. The median additional cost for hospitalizations between stages was $23,582 and $20,965 per patient for hips and knees, respectively. Hospital volume, Northeast or Midwest region, and younger age were associated with reduced PJI costs (P < .05). CONCLUSION: Although viewed as the most preferred, the 2-stage revision strategy for PJI had less than a 50% chance of successful completion within the first year, and was associated with high mortality rates and substantial costs for treatment failure.

Knee Osteoarthritis Treatment Costs in the Medicare Patient Population.

BACKGROUND: Several nonoperative options have been recommended for the treatment of knee osteoarthritis (OA), with varying degrees of evidence. Adhering to the American Academy of Orthopaedic Surgeons clinical practice guidelines has been suggested to decrease direct treatment costs by 45% in the year before knee arthroplasty, but this does not consider the cost of the entire episode of care, including the cost of surgery and postsurgery care. OBJECTIVES: To analyze the total treatment costs after a diagnosis of knee OA, as well as the proportion of arthroplasty interventions as part of the total knee OA-related costs, and whether the total costs differed for patients who received intra-articular hyaluronic acid and/or had knee arthroplasty. METHODS: We identified patients newly diagnosed with knee OA using the 5% Medicare data sample from January 2010 to December 2015. Patients were excluded if they were aged <65 years, had incomplete claim history, did not reside in any of the 50 states, had claim history <12 months before knee OA diagnosis, or did not enroll in Medicare Part A and Part B. The study analyzed knee OA-related costs from a payer perspective in terms of reimbursements provided by Medicare, as well as the time from the diagnosis of knee OA to knee arthroplasty for patients who had knee arthroplasty, and the time from the first hyaluronic acid injection to knee arthroplasty for those who received the injection. We compared patients who received hyaluronic acid and those who did not receive hyaluronic acid injections. Patients who received hyaluronic acid injection who subsequently had knee arthroplasty were also compared with those who did not have subsequent knee arthroplasty. RESULTS: Of the 275,256 patients with knee OA, 45,801 (16.6%) received a hyaluronic acid injection and 35,465 (12.9%) had knee arthroplasty during the study period. The median time to knee arthroplasty was 16.4 months for patients who received hyaluronic acid versus 5.7 months for those who did not receive hyaluronic acid. Non-arthroplasty-related therapies and knee arthroplasty accounted for similar proportions of knee OA-related costs, with hyaluronic acid injection comprising 5.6% of the total knee OA-related costs. For patients who received hyaluronic acid injections and subsequently had knee arthroplasty, hyaluronic acid injection contributed 1.8% of the knee OA-related costs versus 76.6% of the cost from knee arthroplasty. Patients who received hyaluronic acid injections and did not have knee arthroplasty incurred less than 10% of the knee OA-related costs that patients who had surgery incurred. CONCLUSION: Although limiting hyaluronic acid use may reduce the knee OA-related costs, in this study hyaluronic acid injection only comprised a small fraction of the overall costs related to knee OA. Among patients who had knee arthroplasty, those who received treatment with hyaluronic acid had surgery delayed by a median of 10.7 months and associated costs for a significant period. The ability to delay or avoid knee arthroplasty altogether can have a substantial impact on healthcare costs.

Knee OA cost comparison for hyaluronic acid and knee arthroplasty.

BACKGROUND: Limiting treatment to those recommended by the American Academy of Orthopaedic Surgeon Clinical Practice Guidelines has been suggested to decrease costs by 45% in the year prior to total knee arthroplasty, but this only focuses on expenditures leading up to, but not including, the surgery and not the entire episode of care. We evaluated the treatment costs following knee osteoarthritis (OA) diagnosis and determined whether these are different for patients who use intra-articular hyaluronic acid (HA) and/or knee arthroplasty. METHODS: Claims data from a large commercial database containing de-identified data of more than 100 million patients with continuous coverage from 2012 to 2016 was used to evaluate the cumulative cost of care for over 2 million de-identified members with knee OA over a 4.5-year period between 2011 and 2015. Median cumulative costs were then stratified for patients with or without HA and/or knee arthroplasty. RESULTS: Knee OA treatment costs for 1,567,024 patients over the 4.5-year period was $6.60 billion (mean $4210/patient) as calculated by the authors. HA and knee arthroplasty accounted for 3.0 and 61.5% of the overall costs, respectively. For patients who underwent knee arthroplasty, a spike in median costs occurred sooner for patients without HA use (around the 5- to 6-month time point) compared to patients treated with HA (around the 16- to 17-month time point). CONCLUSIONS: Non-arthroplasty therapies, as calculated by the authors, accounted for about one third of the costs in treating knee OA in our cohort. Although some have theorized that limiting the use of HA may reduce the costs of OA treatment, HA only comprised a small fraction (3%) of the overall costs. Among patients who underwent knee arthroplasty, those treated with HA experienced elevated costs from the surgery later than those without HA, which reflects their longer time to undergoing knee arthroplasty. The ability to delay or avoid knee arthroplasty altogether can have a substantial impact on the cost to the healthcare system.

Projections of Primary TKA and THA in Germany From 2016 Through 2040.

BACKGROUND: Future projections for both TKA and THA in the United States and other countries forecast a further increase of already high numbers of joint replacements. The consensus is that in industrialized countries, this increase is driven by demographic changes with more elderly people being less willing to accept activity limitations. Unlike the United States, Germany and many other countries face a population decline driven by low fertility rates, longer life expectancy, and immigration rates that cannot compensate for population aging. Many developing countries are likely to follow that example in the short or medium term amid global aging. Due to growing healthcare expenditures in a declining and aging population with a smaller available work force, reliable predictions of procedure volume by age groups are requisite for health and fiscal policy makers to maintain high standards in arthroplasty for the future population.Questions/purposes (1) By how much is the usage of primary TKA and THA in Germany expected to increase from 2016 through 2040? (2) How is arthroplasty usage in Germany expected to vary as a function of patient age during this time span? METHODS: The annual number of primary TKAs and THAs were calculated based on population projections and estimates of future healthcare expenditures as a percent of the gross domestic product (GDP) in Germany. For this purpose, a Poisson regression analysis using age, gender, state, healthcare expenditure, and calendar year as covariates was performed. The dependent variable was the historical number of primary TKAs and THAs performed as compiled by the German federal office of statistics for the years 2005 through 2016. RESULTS: Through 2040, the incidence rate for both TKA and THA will continue to increase annually. For TKA, the incidence rate is expected to increase from 245 TKAs per 100,000 inhabitants to 379 (297-484) (55%, 95% CI 21 to 98). The incidence rate of THAs is anticipated to increase from 338 to 437 (357-535) per 100,000 inhabitants (29% [95% CI 6 to 58]) between 2016 and 2040. The total number of TKAs is expected to increase by 45% (95% CI 14 to 8), from 168,772 procedures in 2016 to 244,714 (95% CI 191,920 to 312,551) in 2040. During the same period, the number of primary THAs is expected to increase by 23% (95% CI 0 to 50), from 229,726 to 282,034 (95% CI 230,473 to 345,228). Through 2040, the greatest increase in TKAs is predicted to occur in patients aged 40 to 69 years (40- to 49-year-old patients: 269% (95% CI 179 to 390); 50- to 59-year-old patients: 94% (95% CI 48 to 141); 60- to 69-year-old patients: 43% (95% CI 13 to 82). The largest increase in THAs is expected in the elderly (80- to 89-year-old patients (71% [95% CI 40 to 110]). CONCLUSIONS: Although the total number of TKAs and THAs is projected to increase in Germany between now and 2040, the increase will be smaller than that previously forecast for the United States, due in large part to the German population decreasing over that time, while the American population increases. Much of the projected increase in Germany will be from the use of TKA in younger patients and from the use of THA in elderly patients. Knowledge of these trends may help planning by surgeons, hospitals, stakeholders, and policy makers in countries similar to Germany, where high incidence rates of arthroplasty, aging populations, and overall decreasing populations are present. LEVEL OF EVIDENCE: Level III, economic and decision analysis.

Unicondylar Knee Arthroplasty Has Fewer Complications but Higher Revision Rates Than Total Knee Arthroplasty in a Study of Large United States Databases.

BACKGROUND: Unicondylar knee arthroplasty (UKA) has superior functional outcomes compared to total knee arthroplasty (TKA) with good mid-term and long-term survival data from high-volume institutions. We sought to quantify the risk of complications, re-operation/revision, hospital re-admission for any reason, and mortality of knee arthroplasty patients in the US patient population using 2 large databases. METHODS: UKA and TKA patients who were identified in the 2002-2011, 5% sample of Medicare data and 2004-2012 (June) MarketScan Commercial and Medicare Supplemental Databases were followed to evaluate the risk of complications, hospital re-admission for any reason, and mortality within 90 days of surgery. Survival probability defined by re-operation was calculated using the Kaplan-Meier method at 0.5, 2, 5, 7, and up to 10 years post-operatively. RESULTS: Compared to UKA, complication rates for TKA patients were significantly higher, including wound complication, pulmonary embolism, stiffness, peri-prosthetic joint infection, myocardial infarction, re-admission, and death. Age was found to be a significant risk factor (P < .05) for all complications in the Medicare cohort, except stiffness (P = .839), and all complications in the MarketScan cohort, except re-admission (P = .418), whereas gender had a variable effect on complications based on age. Survivorship of UKA was lower than TKA at all time points. Additionally, younger age adversely affected implant survival. By 7 years post-surgery, UKA survivorship in the Medicare and MarketScan cohorts was 80.9% and 74.4%, respectively. In contrast, TKA survivorship for the same cohorts was 95.7% and 91.9% by the same time point. CONCLUSION: Patients undergoing UKA have fewer post-operative complications and re-admissions than those undergoing TKA. However, patients undergoing UKA have a higher rate of re-operation and revision at up to 10 years of follow-up. It appears that age, as well as surgeon and hospital volume significantly impacts implant survivorship while gender does not have a relation. LEVEL OF EVIDENCE: Level III.

What Are the Migration Patterns for U.S. Primary Total Joint Arthroplasty Patients?

BACKGROUND: Evaluation of total joint arthroplasty (TJA) patient-reported outcomes and survivorship requires that records of the index and potential revision arthroplasty procedure are reliably captured. Until the goal of the American Joint Replacement Registry (AJRR) of more-complete nationwide capture is reached, one must assume that patient migration from hospitals enrolled in the AJRR to nonAJRR hospitals occurs. Since such migration might result in loss to followup and erroneous conclusions on survivorship and other outcomes of interest, we sought to quantify the level of migration and identify factors that might be associated with migration in a specific AJRR population. QUESTIONS/PURPOSES: (1) What are the out-of-state and within-state migration patterns of U.S. Medicare TJA patients over time? (2) What patient demographic and institutional factors are associated with these patterns? METHODS: Hospital records of Medicare fee-for-service beneficiaries enrolled from January 1, 2004 to December 31, 2015, were queried to identify primary TJA procedures. Because of the nationwide nature of the Medicare program, low rates of loss to followup among Medicare beneficiaries, as well as long-established enrollment and claims processing procedures, this database is ideal for examining patient migration after TJA. We identified an initial cohort of 5.33 million TJA records from 2004 to 2016; after excluding patients younger than 65 years of age, those enrolled solely due to disability, those enrolled in a Medicare HMO, or residing outside the United States, the final analytical dataset consisted of 1.38 million THAs and 3.03 million TKAs. The rate of change in state or county of residence, based on Medicare annual enrollment data, was calculated as a function of patient demographic and institutional factors. A multivariate Cox model with competing risk adjustment was used to evaluate the association of patient demographic and institutional factors with risk of out-of-state or out-of-county (within-state) migration. RESULTS: One year after the primary arthroplasty, 0.61% (95% confidence interval [CI], 0.60-0.61; p < 0.001 for this and all comparisons in this Results section) of Medicare patients moved out of state and another 0.62% (95% CI, 0.60-0.63) moved to a different county within the same state. Five years after the primary arthroplasty, approximately 5.41% (95% CI, 5.39-5.44) of patients moved out of state and another 5.50% (95% CI, 5.46-5.54) Medicare patients moved to a different county within the same state. Among numerous factors of interest, women were more likely to migrate out of state compared with men (hazard ratios [HR], 1.06), whereas black patients were less likely (HR, 0.82). Patients in the Midwest were less likely to migrate compared with patients in the South (HR, 0.74). Patients aged 80 and older were more likely to migrate compared with 65- to 69-year-old patients (HR, 1.19). Patients with higher Charlson Comorbidity Index scores compared with 0 were more likely to migrate (index of 5+; HR, 1.19). CONCLUSIONS: Capturing detailed information on patients who migrate out of county or state, with associated changes in medical facility, requires a nationwide network of participating registry hospitals. At 5 years from primary arthroplasty, more than 10% of Medicare patients were found to migrate out of county or out of state, and the rate increases to 18% after 10 years. Since it must be assumed that younger patients might exhibit even higher migration levels, these findings may help inform public policy as a "best-case" estimate of loss to followup under the current AJRR capture area. Our study reinforces the need to continue aggressive hospital recruitment to the AJRR, while future research using an increasingly robust AJRR database may help establish the migration patterns of nonMedicare patients. LEVEL OF EVIDENCE: Level III, therapeutic study.

Are Ceramic Bearings Becoming Cost-Effective for All Patients Within a 90-Day Bundled Payment Period?

BACKGROUND: We analyzed whether the total hospital cost in a 90-day bundled payment period for ceramic-on-polyethylene (C-PE) and ceramic-on-ceramic (COC) total hip arthroplasty (THA) bearings was changing over time, and whether the cost differential between ceramic bearings and metal-on-polyethylene (M-PE) bearings was approaching the previously published tipping point for cost-effectiveness of US$325. METHODS: A total of 245,077 elderly Medicare patients (65+) who underwent primary THA between 2010 and 2015 were identified from the United States Medicare 100% national administrative hospital claims database. The total inpatient cost, calculated up to 90 days after index discharge, was computed using cost-to-charge ratios, and hospital payment was analyzed. The differential total inpatient cost of C-PE and COC bearings, compared to metal-on-polyethylene (M-PE), was evaluated using parametric and nonparametric models. RESULTS: After adjustment for patient and clinical factors, and the year of surgery, the mean hospital cost up to 90 days for primary THA with C-PE or COC was within ±1% of the cost for primary THA with M-PE bearings (P < .001). From the nonparametric analysis, the median total hospital cost was US$296-US$353 more for C-PE and COC than M-PE. Cost differentials were found to decrease significantly over time (P < .001). CONCLUSION: Patient and clinical factors had a far greater impact on the total cost of inpatient THA surgery than bearing selection, even when including readmission costs up to 90 days after discharge. Our findings indicate that the cost-effectiveness thresholds for ceramic bearings relative to M-PE are changing over time and increasingly achievable for the Medicare population.

Are We Winning or Losing the Battle With Periprosthetic Joint Infection: Trends in Periprosthetic Joint Infection and Mortality Risk for the Medicare Population.

BACKGROUND: Periprosthetic joint infection (PJI) is a potentially deadly complication of total joint arthroplasty. This study was designed to address how the incidence of PJI and outcome of treatment, including mortality, are changing in the population over time. METHODS: Primary total hip arthroplasty (THA) and total knee arthroplasty (TKA) patients with PJI from the 100% Medicare inpatient data set (2005-2015) were identified. Cox proportional hazards regression models for risk of PJI after THA/TKA (accounting for competing risks) or risk of all-cause mortality after PJI were adjusted for patient and clinical factors, with year included as a covariate to test for time trends. RESULTS: The unadjusted 1-year and 5-year risk of PJI was 0.69% and 1.09% for THA and 0.74% and 1.38% for TKA, respectively. After adjustment, PJI risk did not change significantly by year for THA (P = .63) or TKA (P = .96). The unadjusted 1-year and 5-year overall survival after PJI diagnosis was 88.7% and 67.2% for THA and 91.7% and 71.7% for TKA, respectively. After adjustment, the risk of mortality after PJI decreased significantly by year for THA (hazard ratio = 0.97; P < .001) and TKA (hazard ratio = 0.97; P < .001). CONCLUSION: Despite recent clinical focus on preventing PJI, we are unable to detect substantial decline in the risk of PJI over time, although mortality after PJI has declined. Because PJI risk appears not to be changing over time, the incidence of PJI is anticipated to scale up proportionately with the demand for THA and TKA, which is projected to increase substantially in the coming decade.

Are Ceramic Bearings Becoming Cost-Effective for All Patients?

BACKGROUND: The purpose of this study is to analyze whether the cost for ceramic-on-polyethylene (C-PE) and ceramic-on-ceramic (COC) bearings used in primary total hip arthroplasty (THA) was changing over time, and if the cost differential between ceramic bearings and metal-on-polyethylene (M-PE) bearings was approaching the previously published tipping point for cost-effectiveness of $325. METHODS: A total of 245,077 elderly Medicare patients (65+) who underwent primary THA between 2010 and 2015 were identified from the United States Medicare 100% national administrative hospital claims database. The inpatient hospital cost, calculated using cost-to-charge ratios, and hospital payment were analyzed. The differential cost of C-PE and COC bearings, compared to M-PE, were evaluated using parametric and nonparametric models. RESULTS: After adjustment for patient and clinical factors, and the year of surgery, the mean hospital cost and payments for primary THA with a C-PE or COC was within ±1% of the cost for primary THA with M-PE bearings (P < .001). From the nonparametric analysis, the median hospital cost was $318-$360 more for C-PE and COC than M-PE. The differential in median Medicare payment for THA with ceramic bearings compared to M-PE was <$100. Cost differentials were found to decrease significantly over time (P < .001). CONCLUSION: Patient and clinical factors had a far greater impact on the cost of inpatient THA surgery than bearing selection. Because we found that costs and cost differentials for ceramic bearings were decreasing over time, and approaching the tipping point, it is likely that the cost-effectiveness thresholds relative to M-PE are likewise changing over time and should be revisited in light of this study.

Risk of Osteoporotic Fracture After Steroid Injections in Patients With Medicare.

To further evaluate the relationship between steroid injections and osteoporotic fracture risk, we analyzed Medicare administrative claims data on both large-joint steroid injections (LJSIs) into knee and hip and transforaminal steroid injections (TSIs), as well as osteoporotic hip and wrist fractures. Our hypothesis was that a systemic effect of steroid injections would increase fracture risk in all skeletal locations regardless of injection site, whereas a local effect would produce a disproportionate increased risk of spine fracture with spine injection. Patients treated with an LJSI, a TSI, or an epidural steroid injection (ESI) were identified from 5% Medicare claims data. Patients under age 65 years and patients with prior osteoporotic fracture were excluded. Analyses were performed to determine fracture risk (adjusted hazard ratio) for each type of injection. Analysis of the Medicare data revealed that ESIs were associated with decreased osteoporotic spine fracture risk, but the effect was small and might not be clinically relevant. ESIs did not influence osteoporotic hip or wrist fracture risk, but LJSIs reduced the risk.

Has Health Care Reform Legislation Reduced the Economic Burden of Hospital Readmissions Following Primary Total Joint Arthroplasty?

BACKGROUND: The purpose of this study was to determine whether the cost of readmissions after primary total hip and knee arthroplasty (THA and TKA) has decreased since the introduction of health care reform legislation and what patient, clinical, and hospital factors drive such costs. METHODS: The 100% Medicare inpatient dataset was used to identify 1,654,602 primary THA and TKA procedures between 2010 and 2014. The per-patient cost of readmissions was evaluated in general linear models in which the year of surgery and patient, clinical, and hospital factors were treated as covariates in separate models for THA and TKA. RESULTS: The year-to-year risk of 90-day readmission was reduced by 2% and 4% (P < .001) for THA and TKA, respectively. By contrast, the cost of readmissions did not change significantly over time. The 5 most important variables associated with the cost of 90-day THA readmissions (in rank order) were the nature of the readmission (ie, due to medical or procedure-related reasons), the length of stay, hospital's teaching status, discharge disposition, and hospital's overall total joint arthroplasty volume. The top 5 factors associated with the cost of 90-day TKA readmissions were (in rank order) the length of stay, hospital's teaching status, discharge disposition, patient's gender, and age. CONCLUSION: Although readmission rates declined slightly, the results of this study do not support the hypothesis that readmission costs have decreased since the introduction of health care reform legislation. Instead, we found that clinical and hospital factors were among the most important cost drivers.

Which Clinical and Patient Factors Influence the National Economic Burden of Hospital Readmissions After Total Joint Arthroplasty?

BACKGROUND: The Affordable Care Act of 2010 advanced the economic model of bundled payments for total joint arthroplasty (TJA), in which hospitals will be financially responsible for readmissions, typically at 90 days after surgery. However, little is known about the financial burden of readmissions and what patient, clinical, and hospital factors drive readmission costs. QUESTIONS/PURPOSES: (1) What is the incidence, payer mix, and demographics of THA and TKA readmissions in the United States? (2) What patient, clinical, and hospital factors are associated with the cost of 30- and 90-day readmissions after primary THA and TKA? (3) Are there any differences in the economic burden of THA and TKA readmissions between payers? (4) What types of THA and TKA readmissions are most costly to the US hospital system? METHODS: The recently developed Nationwide Readmissions Database from the Healthcare Cost and Utilization Project (2006 hospitals from 21 states) was used to identify 719,394 primary TJAs and 62,493 90-day readmissions in the first 9 months of 2013 based on International Classification of Diseases, 9th Revision, Clinical Modification codes. We classified the reasons for readmissions as either procedure- or medical-related. Cost-to-charge ratios supplied with the Nationwide Readmissions Database were used to compute the individual per-patient cost of 90-day readmissions as a continuous variable in separate general linear models for THA and TKA. Payer, patient, clinical, and hospital factors were treated as covariates. We estimated the national burden of readmissions by payer and by the reason for readmission. RESULTS: The national rates of 30- and 90-day readmissions after THA were 4% (95% confidence interval [CI], 4.2%-4.5%) and 8% (95% CI, 7.5%-8.1%), respectively. The national rates of 30- and 90-day readmissions after primary TKA were 4% (95% CI, 3.8%-4.0%) and 7% (95% CI, 6.8%-7.2%), respectively. The five most important variables responsible for the cost of 90-day THA readmissions (in rank order, based on the Type III F-statistic, p < 0.001) were length of stay (LOS), all patient-refined diagnosis-related group (APR DRG) severity, type of readmission (that is, medical- versus procedure-related), hospital ownership, and age. Likewise, the five most important variables responsible for the cost of 90-day TKA readmissions were LOS, APR DRG severity, gender, hospital procedure volume, and hospital ownership. After adjusting for covariates, mean 90-day readmission costs reimbursed by private insurance were, on average, USD 1324 and USD 1372 greater than Medicare (p < 0.001) for THA and TKA, respectively. In the 90 days after TJA, two-thirds of the total annual readmission costs were covered by Medicare. In 90 days after THA, more readmissions were still associated with procedure-related complications, including infections, dislocations, and periprosthetic fractures, which in aggregate account for 59% (95% CI, 59.1%-59.6%) of the total readmission costs to the US healthcare system. For TKA, 49% of the total readmission cost (95% CI, 48.8%-49.6%) in 90 days for the United States was associated with procedure issues, most notably including infections. CONCLUSIONS: Hospital readmissions up to 90 days after TJA represent a massive economic burden on the US healthcare system. Approximately half of the total annual economic burden for readmissions in the United States is medical and unrelated to the joint replacement procedure and half is related to procedural complications. CLINICAL RELEVANCE: This national study underscores LOS during readmission as a primary cost driver, suggesting that hospitals and doctors further optimize, to the extent possible, the clinical pathways for the hospitalization of readmitted patients. Because patients readmitted as a result of infection, dislocation, and periprosthetic fractures are the most costly types of readmissions, efforts to reduce the LOS for these types of readmissions will have the greatest impact on their economic burden. Additional clinical research is needed to determine the extent to which, if any, the LOS during readmissions can be reduced without sacrificing quality or access of care.

Is There a Difference in Revision Risk Between Metal and Ceramic Heads on Highly Crosslinked Polyethylene Liners?

BACKGROUND: The most common bearing surface used among primary THAs worldwide is a metal or ceramic femoral head that articulates against a highly crosslinked ultrahigh-molecular-weight polyethylene (HXLPE) acetabular liner. Despite their widespread use, relatively little is known about the comparative effectiveness of ceramic versus metal femoral heads with respect to risk of revision and dislocation as well as the role of head size in this relationship. QUESTIONS/PURPOSES: The purpose of this study was to evaluate the risk of (1) all-cause revision in metal versus ceramic femoral heads when used with an HXLPE liner, including an evaluation of the effect of head size; and (2) dislocation in metal versus ceramic femoral heads when used with an HXLPE liner as well as an assessment of the effect of head size. METHODS: Data were collected as part of the Kaiser Permanente Total Joint Replacement Registry between 2001 and 2013. Patients in this study were on average overweight (body mass index = 29 kg/m2), 67 years old, mostly female (57%), and had osteoarthritis (93%) as the primary indication for surgery. The material of the femoral head (metal, ceramic) was crossed with head size (< 32, 32, 36, > 36 mm), yielding eight device groupings. Only uncemented devices were evaluated. The primary outcome was all-cause revision (n = 28,772) and the secondary outcome was dislocation within 1 year (n = 19,623). Propensity scores were used to adjust for potential confounding at the implant/patient level using between-within semiparametric survival models that control for surgeon and hospital confounding and adjust estimates for the within-cluster correlation among observations on the response. RESULTS: For all-cause revision, there was no difference between ceramic versus metal (reference) heads in combination with an HXLPE liner (hazard ratio [HR] = 0.82 [0.65-1.04], p = 0.099). Smaller metal head sizes of < 32 mm were associated with increased risk of revision relative to 36 mm (HR = 1.66 [1.20-2.31], p = 0.002, adjusted p = 0.025). For dislocation, ceramic heads increased risk relative to metal at < 32 mm only (HR = 4.39 [1.72-11.19], p = 0.002, adjusted p = 0.020). Head sizes < 32 mm were associated with increased risk of dislocation relative to 36 mm for metal (HR = 2.99 [1.40-6.39], p = 0.005, adjusted p = 0.047) and ceramic heads (HR = 15.69 [6.07-40.55], p < 0.001, adjusted p < 0.001). CONCLUSIONS: The results did not provide evidence for use of one femoral head material over another when used with HXLPE liners for the outcome of revision, but for dislocation, metal performed better than ceramic with < 32-mm heads. Overall, the findings suggest increased risk of revision/dislocation with head sizes < 32 mm. LEVEL OF EVIDENCE: Level III, therapeutic study.