Factors influencing regional variability in the rate of total knee arthroplasty

Racial/ethnic and income-based differences in the use of surgery for cervical and lumbar disorders in New York State: a retrospective analysis

BACKGROUND CONTEXT

The extent to which use of spine surgeries for patients with cervical and lumbar disorders varies by their race/ethnicity and income is currently unknown.

PURPOSE

To assess racial/ethnic and income-based differences in use of spine surgery in New York State (NYS) from 2016 to 2019.

STUDY DESIGN

Retrospective observational analysis using 2016 to 2019 New York Statewide Planning and Research Cooperative System (SPARCS) data, direct standardization, and multivariable mixed-effects linear regression models.

METHODS

A dataset of patients who underwent surgery for cervical and spinal disorders in NYS in the period 2016 to 2019 was used to determine county-level age- and sex-standardized annual cervical and lumbar surgery rates expressed as number of surgeries per 10,000 individuals. Further sub-analysis was performed with the key independent variables being the combination of individual-level race/ethnicity (non-Hispanic White, non-Hispanic Black, and Hispanic individuals) and income (low-/high-income residing in zip codes below/above state median income); and year. We estimated multivariable mixed-effects linear regression models which controlled county-level variables to determine the adjusted rates of spine surgeries for patients belonging to various race/ethnicity and income group combinations.

RESULTS

The study included 29,650 and 42,498 patients in the cervical and lumbar cohorts, respectively. In 2019, the county-level mean cervical and lumbar surgery rates were 3.88 and 5.19 surgeries per 10,000 individuals, respectively. There was a five-fold rate variation across NYS. In 2019, the adjusted cervical rates were 4.59 (White low-income), 4.96 (White high-income), 7.20 (Black low-income), 3.01 (Black high-income), 4.37 (Hispanic low-income), and 1.17 (Hispanic high-income). The adjusted lumbar rates were 5.49 (White low-income), 6.31 (White high-income), 9.43 (Black low-income), 2.47 (Black high-income), 4.22 (Hispanic low-income), and 2.02 (Hispanic high-income). The rates for low-income Black or Hispanic patients were significantly higher than their high-income counterparts. Low-income Black patients had the highest rates. Over the study period, the gap/difference increased significantly between high-income Hispanic and White individuals by 2.19 (95% confidence interval [CI]: -4.27, -0.10, p=.04) for cervical surgery; and between low-income Black and White individuals by 2.82 (2.82, 95% CI: 0.59, 5.06, p=.01) for lumbar surgery.

CONCLUSION

There are differences in the rates of spine surgery in New York State, among identifiable groups. Black individuals from poorer zip codes experience relatively higher spine surgery rates. Understanding the drivers of surgical rate variation is key to improving the equitable delivery of spine care. A better understanding of such rate variations could inform health policy.

Hospital variation in revision rates after primary knee arthroplasty was not explained by patient selection: baseline data from 1452 patients in the Danish prospective multicenter cohort study, SPARK

PURPOSE

Revision rates following primary knee arthroplasty vary by country, region and hospital. The SPARK study was initiated to compare primary surgery across three Danish regions with consistently different revision rates. The present study investigated whether the variations were associated with differences in the primary patient selection.

METHODS

A prospective observational cohort study included patients scheduled Sep 2016 Dec 2017 for primary knee arthroplasty (total, medial/lateral unicompartmental or patellofemoral) at three high-volume hospitals, representing regions with 2-year cumulative revision rates of 1, 2 and 5%, respectively. Hospitals were compared with respects to patient demographics, preoperative patient-reported outcome measures, motivations for surgery, implant selection, radiological osteoarthritis and the regional incidence of primary surgery. Statistical tests (parametric and non-parametric) comprised all three hospitals.

RESULTS

Baseline data was provided by 1452 patients (89% of included patients, 56% of available patients). Patients in Copenhagen (Herlev-Gentofte Hospital, high-revision) were older (68.6 ± 9 years) than those in low-revision hospitals (Aarhus 66.6 ± 10 y. and Aalborg (Farsø) 67.3 ± 9 y., p = 0.002). In Aalborg, patients who had higher Body Mass Index (mean 30.2 kg/m² versus 28.2 (Aarhus) and 28.7 kg/m² (Copenhagen), p < 0.001), were more likely to be male (56% versus 45 and 43%, respectively, p = 0.002), and exhibited fewer anxiety and depression symptoms (EQ-5D-5L) (24% versus 34 and 38%, p = 0.01). The preoperative Oxford Knee Score (23.3 ± 7), UCLA Activity Scale (4.7 ± 2), range of motion (Copenhagen Knee ROM Scale) and patient motivations were comparable across hospitals but varied with implant type. Radiological classification ≥ 2 was observed in 94% (Kellgren-Lawrence) and 67% (Ahlbäck) and was more frequent in Aarhus (low-revision) (p ≤ 0.02), where unicompartmental implants were utilized most (49% versus 14 (Aalborg) and 23% (Copenhagen), p < 0.001). In the Capital Region (Copenhagen), the incidence of surgery was 15-28% higher (p < 0.001).

CONCLUSION

Patient-reported outcome measures prior to primary knee arthroplasty were comparable across hospitals with differing revision rates. While radiographic classifications and surgical incidence indicated higher thresholds for primary surgery in one low-revision hospital, most variations in patient and implant selection were contrary to well-known revision risk factors, suggesting that patient selection differences alone were unlikely to be responsible for the observed variation in revision rates across Danish hospitals.

LEVEL OF EVIDENCE

II, Prospective cohort study.

Explaining regional variation in elective hip and knee arthroplasties in Finland 2010 - 2017-a register-based cohort study

Background

A persistent research finding in industrialised countries has been regional variation in medical practices including elective primary hip and knee arthroplasty. The aim of the study was to examine regional variations in elective total hip and knee arthroplasties over time, and the proportions of these variations which can be explained by individual level or area-level differences in need.

Methods

We obtained secondary data from the Care Register for Health Care to study elective primary hip and knee arthroplasties in total Finnish population aged 25 + years between 2010 and 2017. Two-level Poisson regression models – individuals and hospital regions – were used to study regional differences in the incidence of elective hip and knee arthroplasties in two time periods: 2010 − 2013 and 2014 − 2017. The impact of several individual level explanatory factors (age, socioeconomic position, comorbidities) and area-level factors (need and supply of operations) was measured with the proportional change in variance. Predictions of incidence were measured with incidence rate ratios. The relative differences in risk of the procedures in regions were described with median rate ratios.

Results

We found small and over time relatively stable regional variation in hip arthroplasties in Finland, while the variation was larger in knee arthroplasties and decreased during the study period. In 2010 − 2013 individual socioeconomic variables explained 10% of variation in hip and 4% in knee arthroplasties, an effect that did not emerge in 2014 − 2017. The area-level musculoskeletal disorder index reflecting the need for care explained a further 44% of the variation in hip arthroplasties in 2010 − 2013, but only 5% in 2014 − 2017 and respectively 22% and 25% in knee arthroplasties. However, our final models explained the regional differences only partially.

Conclusions

Our results suggest that eligibility criteria in total hip and knee arthroplasty are increasingly consistent between Finnish hospital districts. Factors related to individual level and regional level need both had an important role in explaining regional variations. Further study is needed on the effect of health policy on equity in access to care in these operations.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-022-08305-7.

Relationship Between the Choice of Clinical Treatment, Gait Functionality and Kinetics in Patients With Comparable Knee Osteoarthritis

Objective: The objective of this study was to investigate the relationship between the choice of clinical treatment, gait functionality, and kinetics in patients with comparable knee osteoarthritis.

Design: This was an observational case-control study.

Setting: The study was conducted in a university biomechanics laboratory.

Participants: Knee osteoarthritis patients were stratified into the following groups: clinical treatment (conservative/total knee replacement (TKR) planned), sex (male/female), age (60–67/68–75), and body mass index (BMI) (&lt;30/≥30). All patients had a Kellgren–Lawrence score of 2 or 3 (N = 87).

Main Outcome Measures: All patients underwent gait analysis, and two groups of dependent variables were extracted:

• Spatiotemporal gait variables: gait velocity, stride time, and double-support time, which are associated with patient functionality.

• Kinetic gait variables: vertical, anterior–posterior, and mediolateral ground reaction forces, vertical free moment, joint forces, and moments at the ankle, knee, and hip. Multifactorial and multivariate analyses of variance were performed.

Results: Functionality relates to treatment decisions, with patients in the conservative group walking 25% faster and spending 24% less time in the double-support phase. However, these differences vary with age and are reduced in older subjects. Patients who planned to undergo TKR did not present higher knee forces, and different joint moments between clinical treatments depended on the age and BMI of the subjects.

Conclusions: Knee osteoarthritis is a multifactorial disease, with age and BMI being confounding factors. The differences in gait between the two groups were mitigated by confounding factors and risk factors, such as being a woman, elderly, and obese, reducing the variability of the gait compression loads. These factors should always be considered in gait studies of patients with knee osteoarthritis to control for confounding effects.

Recent trends in Medicare utilization and surgeon reimbursement for shoulder arthroplasty

BACKGROUND

Recent efforts to contain health care costs and move toward value-based health care have intensified, with a continued focus on Medicare expenditures, especially for high-volume procedures. As total shoulder arthroplasty (TSA) volume continues to increase, especially within the Medicare population, it is important for orthopedic surgeons to understand recent trends in the allocation of health care expenditures and potential effects on reimbursements. The purpose of this study was to evaluate trends in annual Medicare utilization and provider reimbursement rates for shoulder arthroplasty procedures between 2012 and 2017.

METHODS

This study tracked annual Medicare claims and payments to shoulder arthroplasty surgeons via publicly available databases and aggregated data at the county level. Descriptive statistics were used to evaluate trends in procedure volume, utilization rate (per 10,000 Medicare beneficiaries), and reimbursement rate. We used adjusted multiple linear regression models to examine associations between county-specific variables (ie, urban or rural, average household income, poverty rate, percentage Medicare population, and race and ethnicity demographics) and procedure volume, utilization rate, and reimbursement rate.

RESULTS

Between 2012 and 2017, there was an 81.3% increase in primary TSA volume and 55.5% increase in primary TSA utilization. The Midwest and South had higher utilization rates than the Northeast and West (P < .001). TSA utilization rates in metropolitan areas were significantly higher than in rural areas (P < .001). Utilization rates for primary TSA procedures also had a significant negative association with poverty rate (P < .001). Regarding reimbursements, the Medicare payment per TSA case decreased from 2012 to 2017, with overall inflation-adjusted decreases of 7.1% and 11.8% for primary and revision cases, respectively. TSAs performed in metropolitan areas received significantly higher reimbursements per case than TSAs performed in rural areas ($1108.05 and $1066.40, respectively; P = .002). Furthermore, reimbursements per case were on average higher in the Northeast and West than in the South and Midwest (P < .001).

CONCLUSIONS

Our study confirms that although TSA volume and per capita utilization have increased dramatically since 2012, Medicare Part B reimbursements to surgeons have continued to fall even after the adoption of bundled-payment models for orthopedic procedures. Cost-containment efforts continue to focus on Medicare reimbursements to surgeons, although other expenditures such as hospital payments and operational and implant costs must also be evaluated as part of an overall transition to value-based health care.

Bacterial and fungal biofilm formation on anodized titanium alloys with fluorine

Orthopaedic device-related infections are closely linked to biofilm formation on the surfaces of these devices. Several modified titanium (Ti-6Al-4V) surfaces doped with fluorine were studied in order to evaluate the influence of these modifications on biofilm formation by Gram-positive and Gram-negative bacteria as well as a yeast. The biofilm studies were performed according to the standard test method approved by ASTM (Designation: E2196-12) using the Rotating Disk Reactor. Four types of Ti-6Al-4V samples were tested; chemically polished (CP), two types of nanostructures containing fluorine, nanoporous (NP) and nanotubular (NT), and non-nanostructured fluorine containing samples (fluoride barrier layers, FBL). Different species of Gram-positive cocci, (Staphylococcus aureus and epidermidis), Gram-negative rods (Escherichia coli, Pseudomonas aeruginosa), and a yeast (Candida albicans) were studied. For one of the Gram-positive (S. epidermidis) and one of the Gram-negative (E. coli) species a statistically-significant decrease in biofilm accumulation for NP and NT samples was found when compared with the biofilm accumulation on CP samples. The results suggest an effect of the modified materials on the biofilm formation.

Predicting the Burden of Revision Knee Arthroplasty: Simulation of a 20-Year Horizon

OBJECTIVES

To estimate future utilization scenarios for knee arthroplasty (KA) revision in the Spanish National Health System in the short- and long-term and their impact on primary KA utilization.

METHODS

A discrete-event simulation model was built to represent KA utilization for 20 years (2012-2031) in the Spanish National Health System. Data on KA utilization from 1997 to 2011 were obtained from the minimum data set. Three scenarios of future utilization of primary KA (1, fixed number since 2011; 2, fixed age- and sex-adjusted rates since 2011; and 3, projection using a linear regression model) were combined with two prosthesis survival functions (W [worse survival], from a study including primary KA from 1995 to 2000; and B [better survival], from the Catalan Registry of Arthroplasty, including primary KA from 2005 to 2013). The simulation results were analyzed in the short-term (2015) and the long-term (2030).

RESULTS

Variations in the number of revisions depended on both the primary utilization rate and the survival function applied, ranging from increases of 8.3% to 31.6% in the short- term and from 38.3% to 176.9% in the long-term, corresponding to scenarios 1-B and 3-W, respectively. The prediction of increases in overall surgeries ranged from 0.1% to 22.3% in the short-term and from 3.7% to 98.2% in the long-term.

CONCLUSIONS

Projections of the burden of KA provide a quantitative basis for future policy decisions on the concentration of high-complexity procedures, the number of orthopedic surgeons required to perform these procedures, and the resources needed.