Comparison of the hospital cost of primary and revision total hip arthroplasty after cost containment

Inpatient Hospital Costs, Emergency Department Visits, and Readmissions for Revision Hip and Knee Arthroplasty

BACKGROUND

Revision total hip arthroplasty (THA) and total knee arthroplasty (TKA) tremendously burden hospital resources. This study evaluated factors influencing perioperative costs, including emergency department (ED) visits, readmissions, and total costs-of-care within 90 days following revision surgery.

METHODS

A retrospective analysis of 772 revision TKAs and THAs performed on 630 subjects at a single center between January 2007 and December 2019 was conducted. Cost data were available from January 2015 to December 2019 for 277 patients. Factors examined included comorbidities, demographic information, preoperative Anesthesia Society of Anesthesiologists score, implant selection, and operative indication using mixed-effects linear regression models.

RESULTS

Among 772 revisions (425 THAs and 347 TKAs), 213 patients required an ED visit, and 90 required hospital readmission within 90 days. There were 22.6% of patients who underwent a second procedure after their initial revision. Liver disease was a significant predictor of ED readmission for THA patients (multivariable odds ratio [OR]: 3.473, P = .001), while aseptic loosening, osteolysis, or instability significantly reduced the odds of readmission for TKA patients (OR: 0.368, P = .014). In terms of ED visits, liver disease increased the odds for THA patients (OR: 1.845, P = .100), and aseptic loosening, osteolysis, or instability decreased the odds for TKA patients (OR: 0.223, P < .001). Increased age was associated with increased costs in both THA and TKA patients, with significant cost factors including congestive heart failure for TKA patients (OR: $7,308.17, P = .004) and kidney disease for THA patients. Revision surgeries took longer than primary ones, with TKA averaging 3.0 hours (1.6 times longer) and THA 2.8 hours (1.5 times longer).

CONCLUSIONS

Liver disease increases ED readmission risk in revision THA, while aseptic loosening, osteolysis, or instability decreases it in revision TKA. Increased age and congestive heart failure are associated with increased costs. These findings inform postoperative care and resource allocation in revision arthroplasty.

LEVEL OF EVIDENCE

Economic and Decision Analysis, Level IV.

The role of preoperative aspartate aminotransferase-to-platelet ratio index in predicting complications following total hip arthroplasty

BACKGROUND

The purpose of this study was to investigate the relationship between preoperative aspartate aminotransferase-to-platelet ratio index (APRI) and postoperative complications following total hip arthroplasty (THA).

METHODS

All THA for osteoarthritis patients from 2007 to 2020 within the American College of Surgeons (ACS) National Surgical Quality Improvement Program (NSQIP) database were included in this study. Subjects were subsequently divided into cohorts based on APRI. Four groups, including normal range, some liver damage, significant fibrosis, and cirrhosis groups, were created. Comparisons between groups were made for demographics, past medical history, and rate of major and minor complications. Other outcomes included readmission, reoperation, discharge destination, mortality, periprosthetic fracture, and postoperative hip dislocation. Multivariate logistic regression analysis was performed to determine the role of preoperative APRI in predicting adverse outcomes. Statistical significance was set at p < 0.05.

RESULTS

In total, 104,633 primary THA patients were included in this study. Of these, 103,678 (99.1%) were in the normal APRI group, 444 (0.4%) had some liver damage, 256 (0.2%) had significant fibrosis, and 253 (0.2%) had cirrhosis. When controlling for demographics and relevant past medical history, the abnormal APRI groups had a significantly higher likelihood of major complication, minor complication, intraoperative or postoperative bleeding requiring transfusion, readmission, and non-home discharge (all p < 0.05) compared to normal APRI individuals.

CONCLUSIONS

Abnormal preoperative APRI is linked with an increasing number of adverse outcomes following THA for osteoarthritis for patients across the United States.

LEVEL OF EVIDENCE

Level I.

Revision total knee arthroplasty results in financial deficits within the Swiss healthcare system

PURPOSE

Revision total knee arthroplasty (RTKA) results in high costs with inadequately low reimbursement in different healthcare systems. Therefore, a financial analysis was performed comparing costs and reimbursements of primary total knee arthroplasty (PTKA) versus RTKA using financial and total knee arthroplasty-register data from a large tertiary hospital, the Cantonal Hospital of St. Gallen (KSSG), Switzerland.

METHODS

All PTKA and RTKA performed between January 2012 and September 2019 at the KSSG were included. Financial and TKA-register data for each case were collected, including detailed cost allocation, reimbursement, patients' insurance status, type and indication for surgery and length of hospital stay. RTKA was further subdivided in one-stage and two-stage RTKA. Direct hospital costs were analyzed and compared to reimbursement in both groups. Cost-coverage ratios were calculated.

RESULTS

730 PTKA and 106 RTKA were included. The RTKA group contained 66 one-stage and 40 two-stage RTKA. Cost-coverage ratio for PTKA and RTKA showed to be 110.9% and 81.3%, respectively. Cost-coverage ratio was lower for two-stage RTKA than for one-stage RTKA with 74.1% and 92.3%, respectively.

CONCLUSION

RTKA leads to financial deficits especially for tertiary hospitals within the Swiss healthcare system. Restructuring of the reimbursements for PTKA and RTKA should be considered in favor of RTKA. Otherwise, tertiary hospitals will face a growing financial burden with the constantly increasing annual number of RTKA procedures, predominantly performed in this type of hospitals.

LEVEL OF EVIDENCE

III.

Conversion Total Hip Arthroplasty in the Era of Bundled Care Payments: Impacts on Costs of Care

BACKGROUND

Conversion hip arthroplasty is defined as a patient who has had prior open or arthroscopic hip surgery with or without retained hardware that is removed and replaced with arthroplasty components. Currently, it is classified under the same diagnosis-related group as primary total hip arthroplasty (THA); however, it frequently requires a higher cost of care.

METHODS

A retrospective study of 228 conversion THA procedures in an orthopaedic specialty hospital was performed. Propensity score matching was used to compare the study group to a cohort of 510 primary THA patients by age, body mass index, sex, and American Society of Anesthesiologists score. These matched groups were compared based on total costs, implants used, operative times, length of stay (LOS), readmissions, and complications.

RESULTS

Conversion THA incurred 25% more mean total costs compared to primary THA (P < .05), longer lengths of surgery (154 versus 122 minutes), and hospital LOS (2.1 versus 1.56 days). A subgroup analysis showed a 57% increased cost for cephalomedullary nail conversion, 34% increased cost for sliding hip screw, 33% for acetabular open reduction and internal fixation conversion, and 10% increased costs in closed reduction and percutaneous pinning conversions (all P < .05). There were 5 intraoperative complications in the conversion group versus none in the primary THA group (P < .01), with no statistically significant difference in readmissions.

CONCLUSION

Conversion THA is significantly more costly than primary THA and has longer surgical times and greater LOS. Specifically, conversion THA with retained implants had the greatest impact on cost.

Current Trends in Revision Hip Arthroplasty: Indications and Types of Components Revised

BACKGROUND

The materials and techniques for both primary and revision total hip arthroplasty (THA) have changed over time. This study evaluated if the indications for revision THA, rates of components utilized (femoral or acetabulum, both, or head/liner exchange), length of stay (LOS), and payments to surgeons and facilities have also changed.

METHODS

A retrospective study, utilizing the PearlDiver database, of 38,377 revision THA patients from January 2010 through December 2018 was performed. Data included the indication for revision, components revised (femoral or acetabulum, both, or head/liner exchange), LOS, and payments. Indications and components were analyzed by logistic regression (Dunnett's post hoc test). Revision totals were analyzed with a linear regression model. Analysis of variance assessed changes in LOS and payments.

RESULTS

Patients' median age was 67 years (Q1-Q3: 59-74), and 58.7% were female. Revisions for dislocation decreased between 2010 and 2018 (odds ratio [OR] 0.82, 95% confidence interval [CI] 0.68-0.98). Revisions for component loosening increased (OR 1.54, 95% CI 1.25-1.91). Dislocation remained the most common indication (19.3%), followed by PJI (17.3%) and loosening (17.1%). Both-component (OR:1.45; 95% CI:1.25-1.67) and femoral component only revisions increased; acetabular component only and head/liner exchanges decreased. Acetabular (OR 0.57, 95% CI 0.47-0.70) and head/liner exchange (OR 0.29, 95% CI 0.20-0.43) revisions decreased, while both component exchange (OR 1.45, 95% CI 1.25-1.67) and femoral revisions (OR 1.17, 95% CI 0.99-1.37) increased. Average LOS (-0.68 days; P < .001) and surgeon payments decreased (-$261.8; P < .001) while facility payments increased ($4,211; P < .001).

CONCLUSION

Indications for revision THA in this database study changed over time, with revision for dislocation decreasing and revision for loosening increasing over time. Both component and femoral revisions increased, and acetabular component and head/liner exchanges decreased. It is possible that these associations could be attributed to a number of details, the method of femoral fixation, surgical approach, and cementing, all of which require additional study.

Optimal surgical component alignment minimizes TKR wear - An in silico study with nine alignment parameters

Currently, preclinical mechanical wear testing of total knee replacements (TKRs) is done using ideally aligned components using standardized TKR level walking under either force or displacement-control regimes. To understand the influence of implant alignment and testing control regime, we studied the effect of nine component alignment parameters on TKR volumetric wear in silico. We used a computational framework combining Latin Hypercube sampling design of experiments, finite element analysis, and a numerical model of polyethylene wear, to create a predictive model of how component alignment affects wear rate for each control regime. Nine component alignment parameters were investigated, five femoral variables and four tibial variables. To investigate perturbations of the nine implant alignment variables, two separate 300-point designs were executed, one for each control regime. The results were then used to generate surrogate statistical models using stepwise multiple linear regression. Wear at the neutral position was 4.5mm3/million cycle and 8.6mm3/million cycle for displacement and force-control, respectively. Stepwise multiple linear regression surrogate models were highly significant for each control regime, but force-control generated a stronger predictive model, with a higher R2, more included terms, and a lower RMSE. Both models predicted transverse plane rotational mismatch can lead to large changes in predicted wear; a transverse plane alignment mismatch of 15° can elicit a change in wear of up to 5mm3/million cycle, almost double that of neutral alignment. Therefore, transverse plane alignment is particularly important when considering failure of the implant due to wear.

Revision Total Joint Arthroplasty: Final Stop Tertiary Referral Center

High complication rates associated with revision total knee arthroplasty (TKA) and total hip arthroplasty (THA) may unequally burden tertiary referral centers, which manage medically complex patients. The authors aimed to quantify TKA and THA referral patterns at a tertiary referral center based on travel distance and patient comorbidities. All patients who underwent primary or revision TKA or THA at the investigating institution from 2012 to 2016 were identified. Travel distance was calculated using each patient's home address and stratified into less than 25 miles, 25 to 74 miles, and 75 miles or more. Age, body mass index, Charlson Comorbidity Index, and postoperative clinical data were identified. Patients were analyzed based on procedure performed and travel distance. A total of 4245 procedures were included for analysis (1754 primary TKAs, 432 revision TKAs, 1503 primary THAs, and 556 revision THAs). Patients living 75 miles or more away had significantly higher odds of undergoing revision arthroplasty compared with patients living within 25 miles (knee: odds ratio [OR], 2.43; hip: OR, 2.61; P<.001). Charlson Comorbidity Index did not increase with travel distance. Patients traveling 75 miles or more were more likely to have periprosthetic fracture (OR, 3.91; P=.011) and less likely to have dislocation (OR, 0.54; P=.026) as the surgical indication for revision. Patients referred to a tertiary center were more likely to necessitate revision total joint arthroplasty but did not differ in comorbidity profile compared with local patients. Periprosthetic fracture, a particularly high-risk surgical indication, was overrepresented among referral patients. These data suggest that factors such as underlying diagnosis, but not preoperative medical comorbidities, may influence referral patterns. [Orthopedics. 2021;44(4):e477-e481.].

Financial analysis of revision knee surgery at a tertiary referral centre as classified according to the Revision Knee Complexity Classification (RKCC)

BACKGROUND

Revision total knee arthroplasty (rTKA) can be complex, with greater costs to the treating hospital than primary TKA. A rTKA regional network has been proposed in England. The aim of this work was to accurately quantify current costs and reimbursement for the rTKA service and to assess whether costs are proportional to case complexity at a tertiary referral centre within the National Health Service (NHS).

METHODS

A review of all rTKA performed at our institution over two consecutive financial years (2017-2019) was performed. Cases were classified according to the Revision Knee Complexity Classification (RKCC) and by mode of failure; "infected" and "non-infected". Financial data was acquired through Patient-Level Information and Costing System (PLICS). The primary outcome was the financial difference between tariff and cost per episode. Comparisons between groups were analysed using analysis of variance and two-tailed unpaired t-test as appropriate.

RESULTS

159 patients underwent 188 rTKA procedures. Length of stay and cost significantly increased between complexity groups (p < 0.0001) and for infected revisions (p < 0.0001). All groups sustained a mean deficit but this significantly increased with revision complexity (from £1,903 to £5,269 per case) and for infected revisions. The total deficit to the Trust for the two-year rTKA service was £667,091.

CONCLUSIONS

The current level of NHS reimbursement are inadequate for centres that offer rTKA and should be more closely aligned to case complexity. An increase in the most complex rTKA at major revision centres will undoubtedly place an even greater strain on the finances of these units.

Bundled Payment "Creep": Institutional Redesign for Primary Arthroplasty Positively Affects Revision Arthroplasty

BACKGROUND

Revision total joint arthroplasty (TJA) is associated with increased readmissions, complications, and expense compared to primary TJA. Bundled payment methods have been used to improve value of care in primary TJA, but little is known of their impact in revision TJA patients. The purpose of this study is to evaluate the impact of a care redesign for a bundled payment model for primary TJA on quality metrics for revision patients, despite absence of a targeted intervention for revisions.

METHODS

We compared quality metrics for all revision TJA patients including readmission rate, use of post-acute care facility after discharge, length of stay, and cost, between the year leading up to the redesign and the 2 years following its implementation. Changes in the primary TJA group over the same time period were also assessed for comparison.

RESULTS

Despite a volume increase of 37% over the study period, readmissions declined from 8.9% to 5.8%. Use of post-acute care facilities decreased from 42% to 24%. Length of stay went from 4.84 to 3.92 days. Cost of the hospital episode declined by 5%.

CONCLUSION

Our health system experienced a halo effect from our bundled payment-influenced care redesign, with revision TJA patients experiencing notable improvements in several quality metrics, though not as pronounced as in the primary TJA population. These changes benefitted the patients, the health system, and the payers. We attribute these positive changes to an altered institutional mindset, resulting from an invested and aligned care team, with active physician oversight over the care episode.

Conversion vs Primary Total Hip Arthroplasty: Increased Cost of Care and Perioperative Complications

BACKGROUND

With the increasing incidence of hip fractures and hip preservation surgeries, there has been a concomitant rise in the number of conversion total hip arthroplasties (THAs) performed. Prior studies have shown higher complication rates in conversion THA. However, there is a paucity of data showing differences in cost between these 2 procedures. Currently, the Center for Medicare and Medicaid Services bundles primary and conversion THA in the same Medicare Severity-Diagnosis Related Group for hospital reimbursement. More evidence is needed to support the reclassification of conversion THA.

METHODS

The cohort provided by the institutional database included 163 conversion THAs between January 1, 2012 and December 31, 2015. Intraoperative complications, estimated blood loss, operative time, postoperative complications, and perioperative cost data were analyzed for 163 primary THA patients matched to the conversion THA cohort.

RESULTS

Compared with primary THA, conversion THA had significantly (P < .05) greater cost for direct labor, other direct costs, intermediate nursing services, other diagnostic/therapy, surgery services, physical/occupational/speech therapy, radiology, laboratories, blood, medical/surgical supply, and total direct costs. In addition, the conversion THA group had significantly greater operative times, estimated blood loss, length of stay, intraoperative complications, and postoperative complications.

CONCLUSION

Conversion THA, as compared with primary THA, is associated with greater costs (approximately 19% greater), increased surgical times, and perioperative complications. To prevent these additional expenses from creating patient selection bias and a barrier to care, the conversion THA Medicare Severity-Diagnosis Related Group should be reclassified, or modifiers created.

Increasing Burden of Total Hip Arthroplasty Revisions in Patients Between 45 and 64 Years of Age

BACKGROUND

This study provides a comprehensive analysis of total hip arthroplasty (THA) revisions in the U.S. from 2007 to 2013.

METHODS

International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes were used to identify all THA revisions in the Nationwide Inpatient Sample (NIS) from 2007 to 2013. The diagnoses leading to the revisions, types of revisions, major inpatient complications, and hospital and patient characteristics were compared between 2007 and 2013. Multivariable logistic regression models were used to calculate adjusted odds ratios (ORs) for complications in 2013 versus 2007.

RESULTS

This study identified 320,496 THA revisions performed between 2007 and 2013. From 2007 to 2013, the THA revision rate adjusted for U.S. population growth increased by 30.4% in patients between 45 and 64 years of age and decreased in all other age groups. The rate of surgically treated THA dislocations decreased by 14.3% from 2007 to 2013 (p < 0.0001). The mean length of the hospital stay and hospital costs for THA revision were significantly lower in 2013 than in 2007 (4.6 versus 5.8 days and $20,463 versus $25,401 both p < 0.0001). A multivariable model showed that the odds of a patient undergoing THA revision having the following inpatient complications were significantly lower in 2013 than in 2007: deep vein thrombosis (OR = 0.57, p = 0.004), pulmonary embolism (OR = 0.45, p = 0.047), myocardial infarction (OR = 0.52, p = 0.003), transfusion (OR = 0.64, p < 0.0001), pneumonia (OR = 0.56, p < 0.0001), urinary tract infection (OR = 0.66, p < 0.0001), and mortality (OR = 0.50, p = 0.0009). Notably, the odds of being discharged to a skilled nursing facility were also lower in 2013 than in 2007 (OR = 0.71, p < 0.0001).

CONCLUSIONS

The THA revision rate has significantly increased in patients between 45 and 64 years of age. However, the rate of surgically treated THA dislocations has decreased significantly. This may indicate that evolving techniques and implants are improving stability. The rate of inpatient complications following THA revision also decreased significantly from 2007 to 2013.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Do Conversion Total Hip Arthroplasty Yield Comparable Results to Primary Total Hip Arthroplasty?

BACKGROUND

The incidence of hip fractures is growing with the increasing elderly population. Typically, hip fractures are treated with open reduction internal fixation, hemiarthroplasty, or total hip arthroplasty (THA). Failed hip fracture fixation is often salvaged by conversion THA. The total number of conversion THA procedures is also supplemented by its use in treating different failed surgical hip treatments such as acetabular fracture fixation, Perthes disease, slipped capital femoral epiphysis, and developmental dysplasia of the hip. As the incidence of conversion THA rises, it is important to understand the perioperative characteristics of conversion THA. Some studies have demonstrated higher complication rates in conversion THAs than primary THAs, but research distinguishing the 2 groups is still limited.

METHODS

Perioperative data for 119 conversion THAs and 251 primary THAs were collected at 2 centers. Multivariable linear regression was performed for continuous variables, multivariable logistic regression for dichotomous variables, and chi-square test for categorical variables.

RESULTS

Outcomes for conversion THAs were significantly different (P < .05) compared to primary THA and had longer hospital length of stay (average 3.8 days for conversion THA, average 2.8 days for primary THA), longer operative time (168 minutes conversion THA, 129 minutes primary THA), greater likelihood of requiring metaphysis/diaphysis fixation, and greater likelihood of requiring revision type implant components.

CONCLUSION

Our findings suggest that conversion THAs require more resources than primary THAs, as well as advanced revision type components. Based on these findings, conversion THAs should be reclassified to reflect the greater burden borne by treatment centers.

Primary vs Conversion Total Hip Arthroplasty: A Cost Analysis

INTRODUCTION

Increasing hip fracture incidence in the United States is leading to higher occurrences of conversion total hip arthroplasty (THA) for failed surgical treatment of the hip. In spite of studies showing higher complication rates in conversion THA, the Centers for Medicare and Medicaid services currently bundles conversion and primary THA under the same diagnosis-related group. We examined the cost of treatment of conversion THA compared with primary THA. Our hypothesis is that conversion THA will have higher cost and resource use than primary THA.

METHODS

Fifty-one consecutive conversion THA patients (Current Procedure Terminology code 27132) and 105 matched primary THA patients (Current Procedure Terminology code 27130) were included in this study. The natural log-transformed costs for conversion and primary THA were compared using regression analysis. Age, gender, body mass index, American Society of Anesthesiologist, Charlson comorbidity score, and smoker status were controlled in the analysis. Conversion THA subgroups formed based on etiology were compared using analysis of variance analysis.

RESULTS

Conversion and primary THAs were determined to be significantly different (P<.05) and greater in the following costs: hospital operating direct cost (29.2% greater), hospital operating total cost (28.8% greater), direct hospital cost (24.7% greater), and total hospital cost (26.4% greater).

CONCLUSIONS

Based on greater hospital operating direct cost, hospital operating total cost, direct hospital cost, and total hospital cost, conversion THA has significantly greater cost and resource use than primary THA. In order to prevent disincentives for treating these complex surgical patients, reclassification of conversion THA is needed, as they do not fit together with primary THA.

Variations in hospital billing for total joint arthroplasty

Although regional variations in Medicare spending are known, it is not clear whether regional variations exist in hospital charges for total joint arthroplasty. Data from Centers for Medicare and Medicaid Services (CMS) on Diagnosis Related Groups 469 and 470 (Major Joint with and without Major Complicating or Comorbid Condition) from 2011 were analyzed for variation by region. Drastic variations in charges between institutions were apparent with significant differences between regions for hospital charges and payments. The median hospital charge nationwide was $71,601 and $46,219 for Diagnosis Related Groups 469 and 470, respectively, with corresponding median payments of $21,231 and $13,743. Weak to no correlation was found between hospital charges and payments despite adjustments for wage index, cost of living, low-income care and teaching institution status.

Redefining revision total hip arthroplasty based on hospital admission status

This study examined patient demographics, length of hospital stay, and discharge disposition in those undergoing nonelective revision total hip arthroplasty (rTHA) vs elective rTHA. Data from 23 000 patients with hip revisions from 2005 through 2007 were extracted from the Healthcare Cost and Utilization Project Nationwide Inpatient Sample database. We examined patient admission status, demographics, length of stay, and discharge location. We found that patients undergoing nonelective rTHA were older, were female, had more comorbidities, stayed an excess of 1.61 days in the hospital, and required a skilled care facility after discharge compared with those undergoing elective rTHA. We found that rTHA outcomes varied based on patient hospital admission status. Patients who elected to have rTHA had less comorbidities, cost, and likelihood of being discharged into a skilled care facility.

Hospital economics of primary THA decreasing reimbursement and increasing cost, 1990 to 2008

BACKGROUND

The introduction of new technology has increased the hospital cost of THA. Considering the impending epidemic of hip osteoarthritis in the United States, the projections of THA prevalence, and national cost-containment initiatives, we are concerned about the decreasing economic feasibility of hospitals providing THA.

QUESTIONS/PURPOSES

We compared the hospital cost, reimbursement, and profit/loss of THA over the 1990 to 2008 time period.

METHODS

We reviewed the hospital accounting records of 104 patients in 1990 and 269 patients in 2008 who underwent a unilateral primary THA. Hospital revenue, hospital expenses, and hospital profit (loss) for THA were evaluated and compared in 1990, 1995, and 2008.

RESULTS

From 1990 to 2008, hospital payment for primary THA increased 29% in actual dollars, whereas inflation increased 58%. Lahey Clinic converted a $3848 loss per case on Medicare fee for service, primary THA in 1990 to a $2486 profit per case in 1995 to a $2359 profit per case in 2008. This improvement was associated with a decrease in inflation-adjusted revenue from 1995 to 2008 and implementation of cost control programs that reduced hospital expenses. Reduction of length of stay and implant costs were the most important drivers of expense reduction. In addition, the managed Medicare patient subgroup reported a per case profit of only $650 in 2008.

CONCLUSIONS

If hospital revenue for THA decreases to managed Medicare levels, it will be difficult to make a profit on THA. The use of technologic enhancements for THA add to the cost problem in this era of healthcare reform. Hospitals and surgeons should collaborate to deliver THA at a profit so it will be available to all patients. Government healthcare administrators and health insurance payers should provide adequate reimbursement for hospitals and surgeons to continue delivery of high-quality THAs.

LEVEL OF EVIDENCE

Level III, economic and decision analysis. See Guidelines for Authors for a complete description of levels of evidence.

Acrylic bone cements: influence of time and environment on physical properties

Acrylic bone cements are in extensive use in joint replacement surgery. They are weight bearing and load transferring in the bone-cement-prosthesis complex and therefore, inter alia, their mechanical properties are deemed to be crucial for the overall outcome. In spite of adequate preclinical test results according to the current specifications (ISO, ASTM), cements with inferior clinical results have appeared on the market. The aim of this study was to investigate whether it is possible to predict the long term clinical performance of acrylic bone cement on the basis of mechanical in vitro testing. We performed in vitro quasistatic testing of cement after aging in different media and at different temperatures for up to 5 years. Dynamic creep testing and testing of retrieved cement were also performed. Testing under dry conditions, as required in current standards, always gave higher values for mechanical properties than did storage and testing under more physiological conditions. We could demonstrate a continuous increase in mechanical properties when testing in air, while testing in water resulted in a slight decrease in mechanical properties after 1 week and then levelled out. Palacos bone cement showed a higher creep than CMW3G and the retrieved Boneloc specimens showed a higher creep than retrieved Palacos. The strength of a bone cement develops more slowly than the apparent high initial setting rate indicates and there are changes in mechanical properties over a period of five years. The effect of water absorption is important for the physical properties but the mechanical changes caused by physical aging are still present after immersion in water. The established standards are in need of more clinically relevant test methods and their associated requirements need better definition. We recommend that testing of bone cements should be performed after extended aging under simulated physiological conditions. Simple quasistatic and dynamic creep tests seem unable to predict clinical performance of acrylic bone cements when the products under test are chemically very similar. However, such testing might be clinically relevant if the cements exhibit substantial differences.

An analysis of medicare payment policy for total joint arthroplasty

Medicare facility payment policy for lower extremity total joint arthroplasty (TJA) has undergone extensive changes since 2005. The purpose of this study was to compare patient and procedure characteristics and resource use among TJA procedures and to identify predictors of resource use in TJA. Clinical, demographic, and economic data were analyzed from 6483 primary or revision TJA patients from 4 high-volume centers between October 2005 and June 2006. Descriptive analyses were conducted to evaluate differences between procedure types, and multivariable linear regression analyses were undertaken to identify predictors of resource use. Both patient severity of illness and surgical complexity influenced resource use associated with TJA procedures. As the primary goal of Medicare payment policy is to set payment rates proportional to relative resource use, both severity of illness and surgical complexity should be incorporated for payment equity and to minimize incentives for selection bias among hospitals that perform TJA procedures.

Changes in surgical loads and economic burden of hip and knee replacements in the US: 1997-2004

OBJECTIVE

A major component of the economic burden associated with the treatment of arthritis relates to surgical joint replacements of the hips/knees. The purpose of this study was to describe the recent trend of hip/knee replacements and the associated economic burden.

METHODS

The Nationwide Inpatient Survey from 1997 to 2004 was analyzed. The International Classification of Diseases, Ninth Revision, Clinical Modification procedure coding was used to identify joint replacement cases.

RESULTS

During 2004, approximately 225,900 (95% confidence interval [95% CI] 201,782-250,018) primary hip replacements and 431,485 (95% CI 397,454-465,516) primary knee replacements were performed. This was a 37% increase in primary hip replacements and a 53% increase in primary knee replacements compared with 2000. The number of primary replacement procedures increased equally for males and females; however, the number of procedures increased excessively among persons age 45-64 years. While Medicare remained the major source of payment (55.4% for primary hip replacements, 59.3% for primary knee replacements), private insurance payment experienced a steeper increase. In 2004, the national bill of hospital charges for hip/knee replacements was $26.0 billion, the hospital cost was $9.1 billion, and the amount of reimbursement was $7.2 billion (28% of hospital charges or 79% of hospital cost). Nearly 600,000 hip replacements and 1.4 million knee replacements will be performed in the year 2015.

CONCLUSION

The number of joint replacement procedures performed is growing faster than ever. The health care community should consider and prepare for this upcoming demand of surgical loads and its associated economical burden.

Economic considerations in minimally invasive total joint arthroplasty

Minimally invasive techniques for hip and knee arthroplasty have been gaining popularity in recent years. Despite the apparent widespread enthusiasm for these procedures, there is little published evidence demonstrating superior quality of life outcomes directly attributable to the surgical technique. The current debate regarding the value of minimally invasive surgery extends beyond the demonstrated or potential clinical benefits of these procedures. Economic considerations of patients, surgeons, hospitals, and payers are prominent factors in this debate and will continue to influence the adoption of minimally invasive surgical procedures. Developing an understanding of the barriers posed by our healthcare delivery system to minimally invasive surgical procedures and how these barriers impact each of the stakeholders in the healthcare system will foster a rational deployment of these promising new approaches to hip and knee arthroplasty in the future.

Implant selection and cost for total joint arthroplasty: conflict between surgeons and hospitals

Total joint arthroplasty is a successful surgical treatment for painful, arthritic hips and knees. The prevalence of total joint arthroplasty is increasing, and it is consuming an increasing proportion of health care dollars. Payers, especially Centers for Medicare and Medicaid Services, have targeted total joint arthroplasty for cost control, and joint implants, the greatest expense in total joint arthroplasty, have been identified as an opportunity for cost control. Hospitals seek to control the cost of joint implants because the rate of increase in the price of implants is rising faster than the rate of increase in hospital payment for total joint arthroplasty. As joint implants consume more of the hospital payment for total joint arthroplasty, hospitals are encouraging surgeons to use less expensive implants. Several methods for controlling the cost of implants have been described, but no method has succeeded without the cooperation and involvement of surgeons. Gainsharing programs may help align the incentives of hospitals and surgeons relative to the selection and cost of implants. We have implemented a Single-price/Case-price Purchasing program with considerable savings on the cost of implants without adversely affecting the patient outcome of total joint arthroplasty.

Economic burden of revision hip and knee arthroplasty in Medicare enrollees

The economic burden to Medicare due to revision arthroplasty procedures has not yet been studied systematically. The economic burden of revisions was calculated as annual reimbursements for revision arthroplasties relative to the sum total reimbursements of primary and revision arthroplasties. We evaluated this revision burden for total hip and knee arthroplasties through investigation of trends in charges and reimbursements in the Medicare population (Parts A and B claims from 1997-2003), while taking into account age and gender effects. Mean annual economic revision burdens were 18.8% (range, 17.4-20.2%) and 8.2% (range, 7.5-9.2%) for total hip arthroplasties and total knee arthroplasties, respectively. Procedural charges increased while reimbursements decreased over the study period, with higher charges observed for revisions than primary arthroplasties. Reimbursements per procedure were 62% to 68% less than associated charges for primary and revision total hip and knee arthroplasties. The effect of age and gender on reimbursements varied by procedure type. Unless some limiting mechanism is implemented to reduce the incidence of revision surgeries, the diverging trends in reimbursements and charges for total hip and knee arthroplasties indicate that the economic impact to the Medicare population and healthcare system will continue to increase.

LEVEL OF EVIDENCE

Prognostic study, level II-1 (retrospective study). See Guidelines for Authors for a complete description of levels of evidence.

Reducing the risk of deep wound infection in primary joint arthroplasty with antibiotic bone cement

Despite significant advances in intraoperative antimicrobial procedures, deep wound infection remains the most serious complication associated with primary, cemented total joint arthroplasty. A systematic review was conducted to evaluate studies of antibiotic bone cement prophylaxis for reducing the risk of deep wound infection. The literature included 22 articles providing estimates of the prophylactic effectiveness of antibiotic cement. In reducing deep wound infection, antibiotic cement was consistently superior to plain cement, similar to systematic antiobiotics, and independent and additive in effect when combined with other prophylactic measures. Randomized controlled trials in particular had important methodological limitations. However, the collective results nearly unanimously favored prophylactic use of antibiotic cement in primary arthoplasty procedures.

Differences in patient and procedure characteristics and hospital resource use in primary and revision total joint arthroplasty: a multicenter study

A multicenter retrospective cost-identification cohort study was undertaken to analyze clinical, demographic, and economic data for 4533 consecutive total hip arthroplasty (THA) and 3508 consecutive total knee arthroplasty (TKA) procedures performed during a 3-year period in 1 of 3 hospitals. Statistically significant differences were found between primary and revision procedures with respect to patient age, sex, payer type, mean total operative time, use of allograft, average length of hospital stay, discharge disposition, and hospital costs. Significant differences were also found between different types of revision total joint arthroplasty (TJA) procedures. Our findings could be used to help improve the accuracy of administrative claims data related to primary and revision TJA procedures to identify relevant differences in patient characteristics, procedure characteristics, and hospital resource use.

Minimally invasive outpatient total hip arthroplasty: a financial analysis

Costs of outpatient total hip arthroplasties were compared with costs of a matched group of patients having inpatient total hip arthroplasties. Ten patients were in each group and had surgery by the same surgeon in the same hospital. The average hospital bill for the outpatients was $4000 less than for the inpatients. The total average charge including prehospital, intrahospital, and posthospital care for the outpatients was approximately $2500 less than for the inpatients. The total average reimbursement was $1155 less for the outpatients. Results of this pilot study show that outpatient total hip arthroplasty is financially advantageous.

LEVEL OF EVIDENCE

Economic and decision analyses, Level IV (no sensitivity analyses). See the Guidelines for Authors for a complete description of levels of evidence.

Hospital resource utilization for primary and revision total hip arthroplasty

BACKGROUND

Previous reports have suggested that hospital resource utilization for revision total hip arthroplasty is substantially higher than that for primary total hip arthroplasty. However, current United States Medicare hospital-reimbursement policy does not distinguish between the two procedures. The purpose of this study was to compare primary and revision total hip arthroplasties with regard to actual hospital resource utilization and to identify clinical and demographic factors that are predictive of higher resource utilization associated with these procedures.

METHODS

We evaluated the clinical, demographic, and economic data associated with 491 consecutive unilateral primary or revision total hip arthroplasties performed by two surgeons at a single institution between January 2000 and December 2002. The distributions of various demographic, clinical, and utilization characteristics were compared between the two types of arthroplasty procedures, and multivariable linear regression techniques were used to determine independent patient characteristics that were predictive of higher costs for both the primary and the revision procedures.

RESULTS

The mean total hospital cost was $31,341 for the revision procedures compared with $24,170 for the primary procedures (p < 0.0001). The mean operative time was 41% longer for the revisions than for the primary procedures (4.5 hours compared with 3.2 hours, p < 0.0001), the mean estimated blood loss was 160% higher (1348 mL compared with 518 mL, p < 0.0001), the mean complication rate was 32% higher (29% compared with 22%, p = 0.072), and the mean length of the hospital stay was 16% longer (6.5 days compared with 5.6 days, p = 0.0005). A higher severity-of-illness score (a measure of preoperative medical health) was predictive of higher resource utilization for both primary and revision arthroplasty even after adjustment for other factors. Preoperative femoral and ace-tabular bone loss and a diagnosis of periprosthetic fracture were predictive of higher resource utilization associated with revision procedures.

CONCLUSIONS

At one institution, hospital resource utilization for revision total hip arthroplasty was found to be significantly higher than that for primary arthroplasty. This information is not reflected by current United States Medicare hospital reimbursement, which is the same for all lower-extremity arthroplasty procedures, regardless of the diagnosis, the complexity of the procedure, or the patient's baseline medical health. If these findings are generalizable to other institutions, appropriate reimbursement formulas should be developed to accurately reflect the true costs of caring for patients with a failed total hip arthroplasty.

In-hospital cost of total hip arthroplasty in Canada and the United States

BACKGROUND

There is little information comparing the costs of specific surgical procedures performed in Canada and those done in the United States. The objective of this study was to compare the in-hospital costs associated with primary total hip arthroplasty performed in the two countries.

METHODS

In-hospital costs of 1679 consecutive patients (940 Canadian and 739 American patients) who underwent total hip arthroplasty were extracted from three Canadian and three United States teaching hospitals between 1997 and 2001. Participating hospitals used the same cost accounting system to provide per-patient demographic, clinical, and cost data. Canadian dollar costs were converted to United States dollar costs with use of purchasing power parities.

RESULTS

The baseline clinical characteristics of patients undergoing total hip arthroplasty in Canada and the United States were similar. The American patients were a mean of 4.6 years older than the Canadian patients (mean [and standard deviation], 67.8 +/- 12.4 years compared with 63.2 +/- 14.9 years). The median cost for the primary arthroplasty was $6080 (mean [and standard error of the mean], $6766 +/-$119) at the three Canadian hospitals and $12,846 (mean, $13,339 +/-$131) at the United States hospitals (p < 0.0001). The mean length of stay (and standard deviation) was 7.2 +/- 4.7 days for the Canadian patients and 4.2 +/- 2.0 days for the American patients. Implants at one hospital in the United States were found to be four times more costly than those in a Canadian hospital.

CONCLUSIONS

Higher in-hospital costs were found for the American hospitals despite the fact that they had a significantly shorter patient length of stay compared with Canadian centers (p < 0.0001). Canadian hospitals should follow the lead of their counterparts in the United States and implement strategies to decrease the length of stay in the hospital, while institutions in the United States should revisit their ability to better manage the costs related to a primary total hip arthroplasty, particularly by controlling unit costs.

Economic evaluation in total hip arthroplasty: analysis and review of the literature

We performed a bibliographic search of MEDLINE databases from January 1966 to July 2002 to identify English language articles that contained either "cost" or "economic" in combination with "total hip arthroplasty" (THA) in the abstract or title. Each study was then critically reviewed for content, technique, and adherence to established healthcare economic principles. Only 81 of the 153 studies retrieved contained actual economic data. Only 6% of studies adhered to established criteria for a comprehensive health care economic analysis. Although the number of publications regarding economic evaluation of THA is on the rise, the methodologic quality of many of these studies remains inadequate. Future studies should employ sound healthcare economic techniques to properly evaluate and assess the true social and economic value of THA.

Long stemmed total knee arthroplasty with interlocking screws: a computational bone adaptation study

The ability of an interlocking screw fixation technique to minimize bone loss related to stress shielding in the tibia was investigated and compared to the abilities of cement and press-fit fixation. Full bony ingrowth has been associated with greater stress shielding than partial ingrowth; therefore, the effect of intimate bonding of the stem to bone on subsequent bone loss was also studied. A damage- and disuse-based remodeling theory was coupled with a two-dimensional finite element model of the tibia to predict changes in bone remodeling following long stemmed total knee arthroplasty (TKA) for four different fixation techniques (cement, press-fit, interlock with bony ingrowth, and interlock without bony ingrowth). Remodeling changes commenced with the model state variables--bone area fraction, mechanical stimulus, damage, and remodeling activity--at steady-state values predicted by the intact tibia simulation. After TKA and irrespective of fixation technique, the model predicted elevated remodeling due to disuse, in which more bone was removed than replenished. In regions below the tibial tray and along the cortices, the interlocking stem with full bony ingrowth and the cemented stem caused the least amount of bone loss. An interlocking stem with a smooth, matted finish did not reduce the bone loss associated with interlocking fixation.

Functional outcome after revision hip arthroplasty: a metaanalysis

The current study systematically reviews the literature describing patient outcomes after revision total hip arthroplasties using conventional global hip score ratings. Two thousand one hundred thirty-seven English-language articles published from 1966 through 2000 were identified through a computerized literature search and bibliography review. A three-step filter process was used to identify articles to be included in the metaanalysis. Forty-two articles with 2578 patients had data abstracted for the analysis. Metaanalysis of global hip scores was done using a fixed effects model with the assumption that the variances of each measurement were identical across studies. Thirty-nine articles reporting on 46 cohorts progressed through three filters and went to data extraction and analysis. Revision total hip arthroplasty is a reasonably safe and effective procedure for failed hip replacement Based on this exploratory analysis revision hip procedures seem to have comparable longevity, to primary hip replacement but appear to have slightly lower functional outcome (as measured by global hip scores), and slightly higher morbidity and mortality rates than primary procedures. Inconsistent reporting in the original studies limited exploration of other factors that may have affected outcomes.

Revision total hip arthroplasty: hospital cost and reimbursement analysis

Revision total hip arthroplasty is a complex surgical procedure that frequently requires high levels of hospital resources. The purpose of the current study was to report the actual costs and reimbursement to the hospital for a stratified group of patients having revision total hip arthroplasty based on a severity index. The clinical and financial records of 49 patients (51 hips) stratified by complexity of revision were reviewed. Clinical variable included age, length of stay, operating time, estimated blood loss, number of transfusions, implant type, metallic augmentation, use of bone graft, and time spent in the postanesthesia care unit. Financial review included the actual fixed and variable costs associated with each procedure. Hospital costs associated with revision total hip arthroplasty were significantly greater in the most complex revisions and in older patients. The use of bone grafting techniques on the femur resulted in significantly greater costs. The average loss to the hospital was $5402 US dollars per procedure with a range of $5657 (US dollars) profit to $28,780 (US dollars) loss. Procedures in patients younger than 65 years has an average loss of $1133 US dollars. All procedures in patients who were 65 years or older resulted in a loss to the hospital, with the average loss being $8617 US dollars. Despite improvements in length of stay, use of clinical pathways, and negotiated discounts on implants, the hospital loss on each hip revision procedure averaged $5402 US dollars.

Functional outcome after total knee arthroplasty revision: a meta-analysis

The objective of this study was to perform a systematic literature review to describe patient outcome after total knee arthroplasty revision procedures using various global knee score ratings. English language articles published from 1966 through 2000 were identified through a computerized literature search and bibliography review. A multistage assessment was used to determine the articles containing data that could meet our objective. Meta-analyses of global knee scores were undertaken using a fixed effects model with the assumption that the variances of each individual measurement were identical across studies. The initial inclusion criteria were met by 58 articles with a total of 1965 patients. There were 42 articles comprising 45 unique patient cohorts and a total of 1515 patients that had sufficient global knee score data for analysis and were used in the meta-analyses. Revision total knee arthroplasty is an effective procedure for failed knee arthroplasties based on global knee rating scales.

Activity level and wear in total knee arthroplasty: a study of autopsy retrieved specimens

We assessed the correlation between activity level, length of implantation (LOI), and wear in total knee arthroplasty. Twenty-eight implants were retrieved at autopsy from 8 men and 15 women. Linear, volumetric, and visual wear and the presence or absence of creep were quantitated. Functional level was classified using the Knee Society, the standard Charnley classification, and the UCLA activity level scale. The average age at surgery was 68 years +/- 14.0 SD and average LOI was 74 months +/- 38 SD. The average linear and volumetric wear rates were 0.127 mm/y +/- 0.104 SD and 31.80 mm3/y +/- 42.8 SD. LOI (B coefficient = -0.656 +/- 0.0 SE; P<.001) correlated with linear, volumetric, and visual wear rates. Charnley C patients showed decreased volumetric wear in the lateral compartment (P=.01). Decreased activity level (UCLA) correlated with areas of less extent and severity of creep (P=.001 and P<.001).