Implementation of the New Medicare-Mandated Patient-Reported Outcomes After Joint Arthroplasty Performance Measure.

A new mandatory hospital-level, risk-standardized performance measure for elective total hip arthroplasty (THA) and total knee arthroplasty (TKA) based on patient-reported outcomes (THA/TKA PRO-PM) has been implemented by the Centers for Medicare & Medicaid Services (CMS). All THA and TKA in Medicare fee-for-service beneficiaries at inpatient facilities are included. The THA/TKA PRO-PM is the proportion of risk-standardized THA or TKA patients meeting or exceeding the substantial clinical benefit threshold between preoperative and postoperative outcomes measures (Hip dysfunction and Osteoarthritis Outcome Score for Joint Replacement, Knee injury and Osteoarthritis Outcome Score for Joint Replacement). This binary outcome (yes/no) is then divided by all eligible patients creating a percentage of patients reaching substantial clinical benefit. The percentile score among hospitals will be reported. Following 2 voluntary reporting periods, mandatory reporting will begin in 2025. The CMS requires 50% reporting rates; failure leads to annual payment reduction in fiscal year 2028. The CMS intends the THA/TKA PRO-PM to be a patient-centered, meaningful, and relatable measure of hospital performance reported to the public. For surgeons, this is an opportunity to collaborate with hospitals for developing and implementing a THA/TKA data collection system to avoid penalties for the hospital. Further implementation for outpatient surgery and in ambulatory surgery centers has been announced by CMS. Major resources will be needed to succeed in the expected capture rates.

Oxidized Zirconium Versus Cobalt Chromium for Primary TKA: No Difference in Midterm Revision Rates From the American Joint Replacement Registry.

BACKGROUND: Cobalt chromium (CoCr) is the most commonly used material in TKA; however, the use of oxidized zirconium (OxZr) implants has increased. The advantages to this material demonstrated in basic science studies have not been borne out in clinical studies to date. QUESTION/PURPOSE: In the setting of the American Joint Replacement Registry (AJRR), how do revision rates differ between CoCr and OxZr after primary TKA? METHODS: The AJRR was accessed for all primary TKAs performed between 2012 and 2020 for osteoarthritis, resulting in 441,605 procedures (68,506 with OxZr and 373,099 with CoCr). The AJRR is the largest joint replacement registry worldwide and collects procedure-specific details, making it ideal for large-scale comparisons of implant materials in the United States. Competing risk survival analyses were used to evaluate the all-cause revision rates of primary TKAs, comparing CoCr and OxZr implants. Data from the Centers for Medicare and Medicaid Services claims from 2012 to 2017 were also cross-referenced to capture additional revisions from other institutions. Revision rates were tabulated and subclassified by indication. Multivariate Cox regression was used to account for confounding variables such as age, gender, region, and hospital size. RESULTS: After controlling for confounding variables, there were no differences between the OxZr and CoCr groups in terms of the rate of all-cause revision at a mean follow-up of 46 ± 23 months and 44 ± 24 months for CoCr and OxZr implants, respectively (hazard ratio 1.055 [95% confidence interval 0.979 to 1.137]; p = 0.16) The univariate analysis demonstrated increased rates of revisions for pain and instability in the OxZr group (p = 0.003 and p < 0.001, respectively). CONCLUSION: These findings suggest there is no difference in all-cause revision between OxZr and CoCr implants in the short-term to mid-term. However, further long-term in vivo studies are needed to monitor the safety and all-cause revision rate of OxZr implants compared with those of CoCr implants. OxZr implants may be favorable in patients who have sensitivity to metal. Despite similar short-term to mid-term all-cause revision rates to CoCr implants, because of the limitations of this study, definitive recommendations for or against the use of OxZr cannot be made. LEVEL OF EVIDENCE: Level III, therapeutic study.

Gout As a Predictor of Total Knee Arthroplasty Outcomes and Costs.

Gout is the most common inflammatory arthritis and affects approximately 4% of the U.S. population. As the prevalence of gout and the number of total knee arthroplasties (TKAs) performed continue to increase, the literature on TKA in patients with gout remains scant. The purpose of this study was to evaluate the outcomes of patients with gout following TKA at a population level, that is, how patient with gout fair after TKA. We hypothesized that patients with gout have higher rates of complications and higher costs compared with controls. A case-control study was designed to evaluate two cohorts of Medicare patients who underwent TKA whose only distinguishing feature was the presence or absence of gout. Matching was performed to decrease confounding at a 1:1 ratio based on age, gender, and Charlson comorbidity index (CCI), (10-year survival predictor). The Medicare standard analytical files were queried through International Classification of Disease and current procedural terminology codes. A total of 15,238 patients were evaluated with 7,619 in each cohort. There were no age, gender, or CCI differences and 57.4% were females. Day of surgery and 90-day post-surgery costs were both significantly greater in those with gout (p < 0.001 for both). Multivariate analysis revealed that gout patients had increased odds of infection (odds ratio [OR] 1.229, p = 0.019), cardiac arrest (OR 1.354, p = 0.002), pneumonia (OR 1.161, p < 0.001), hematoma (OR 1.204, p = 0.002), and development of capsulitis (OR 1.208, p = 0.012). Nonetheless these patients had a decreased risk of pulmonary emboli (OR 0.835, p = 0.016). Our results support our hypothesis that patients with gout have higher rates of postoperative complications and increased day of surgery and 90-day costs of care after TKA. Given the high prevalence of gout in the United States, additional study on the utility of preoperative gout optimization for TKA patients is warranted. The level of evidence of this study is III, and it is a retrospective case-control study.

Economic impact of orthopaedic care for non-fatal gunshot wounds: analysis of a public health crisis.

BACKGROUND: The purpose of this study was to perform an epidemiological evaluation and an economic analysis of 90-day costs associated with non-fatal gunshot wounds (GSWs) to the extremities, spine and pelvis requiring orthopaedic care in the United States. METHODS: A retrospective epidemiological review of the Medicare national patient record database was conducted from 2005 to 2014. Incidence, fracture location and costs associated where evaluated. Those patients identified through International Classification of Disease (ICD)-9 revision codes and Current Procedural Terminology (CPT) Codes who sustained a fracture secondary to a GSW. Any type of surgical intervention including incision and drainage, open reduction with internal fixation, closed reduction and percutaneous fixation, etc. were identified to analyze, and evaluate costs of care as seen by charges and reimbursements to the payer. The 90-day period after initial fracture care was queried. RESULTS: A total of 9,765 patients required surgical orthopaedic care for GSWs. There was a total of 2,183 fractures due to GSW treated operatively in 2,201 patients. Of these, 22% were femur fractures, 18.3% were hand/wrist fractures and 16.7% were ankle/foot fractures. A majority of patients were male (83.3%) and under 65 years of age (56.3%). Total charges for GSW requiring orthopedic care were $513,334,743 during the 10-year study period. Total reimbursement for these patients were $124,723,068. Average charges per patient were highest for fracture management of the spine $431,021.33, followed by the pelvis $392,658.45 and later by tibia/fibula fractures $342,316.92. CONCLUSIONS: The 90-day direct charges and reimbursements of orthopedic care for non-fatal GSWs are of significant amounts per patient. While the number of fatal GSWs has received much attention, non-fatal GSWs have a large economic and societal impact that warrants further research and consideration by the public and policy makers.

A Matched Control Analysis on the Effects of Alcohol Use Disorder After Primary Total Knee Arthroplasty in Medicare Patients.

INTRODUCTION: Several studies have found the negative impact of alcohol use disorder (AUD), most notably coagulation derangements. We sought to investigate the effects of AUD after primary total knee arthroplasty (TKA) for (1) postoperative complications, (2) lengths of stay, and (3) costs of care. METHODS: This was a retrospective database analysis of Medicare patients with AUD undergoing primary TKA performed between 2005 and 2014. Patients with AUD were matched to controls in a 1:5 ratio by age, sex, and medical comorbidities. The query yielded 354,690 TKA patients: 59,126 with AUD and 295,564 without AUD. RESULTS: Patients with AUD had significantly greater odds ratio (OR) of medical complications, including venous thromboembolism (VTE) within 90 days (OR: 1.41, P < 0.0001) and at 1 year (OR: 1.51, P < 0.0001) and greater 2-year implant-related complications after primary TKA. Furthermore, patients with AUD had significantly longer lengths of stay (4 versus 3 days, P < 0.0001) and incurred a significantly higher episode of care costs ($15,569.76 versus $13,763.06, P < 0.0001). DISCUSSION: The present study demonstrated a significant association between AUD and the development of VTE. We hope this research will aid in risk stratification and tailoring of VTE chemoprophylaxis and postoperative management in this at-risk group after TKA. LEVEL OF EVIDENCE: Level III.

A Case Complexity Modifier Is Warranted for Primary Total Knee Arthroplasty.

BACKGROUND: The Center for Medicare and Medicaid Services is faced with a challenge of decreasing the cost of care for total knee arthroplasty (TKA) but must make efforts to prevent patient selection bias in the process. Currently, no appropriate modifier codes exist for primary TKA based on case complexity. We sought to determine differences in perioperative parameters for patients with complex primary TKA with the hypothesis that they would require increased cost of care, prolonged care times, and have worse postoperative outcome metrics. METHODS: We performed a single-center retrospective review from 2015 to 2018 of all primary TKAs. Patient demographics, medial proximal tibial angle (mPTA), lateral distal femoral angle (lDFA), flexion contracture, cost of care, and early postoperative outcomes were collected. Complex patients were defined as those requiring stems or augments, and multivariable logistic regression analysis and propensity score matching were performed to evaluate perioperative outcomes. RESULTS: About 1043 primary TKAs were studied, and 84 patients (8.3%) were deemed complex. For this cohort, surgery duration was greater (P < .001), cost of care higher (P < .001), and patients had a greater likelihood for 90-day hospital return. Deviation of mPTA and lDFA was significantly greater preoperatively before and after propensity score matching. Cut point analysis demonstrated that preoperative mPTA <83o or >91o, lDFA <84o or >90o, flexion contracture >10o, and body mass index >35.7 were associated with complex procedures. CONCLUSION: Complex primary TKA may be identifiable preoperatively and those cases associated with prolonged operative time, excess hospital cost of care, and increased 90-day hospital returns. This should be considered in future reimbursement models to prevent patient selection bias, and a complexity modifier is warranted.

All-Polyethylene Tibia: An Opportunity for Value-Based Care in Bundled Reimbursement Initiatives.

Surgeons play a critical role in making cost-effective decisions that maintain high-quality patient outcomes, which is the current focus of the Centers for Medicare & Medicaid Services. All-polyethylene tibial (APT) components often cost less during total knee arthroplasty (TKA). The authors sought to determine the relative cost savings of APT, as well as their effect on 90-day quality outcome metrics. This was a retrospective review of primary TKAs performed at a single tertiary referral center participating in the Comprehensive Care for Joint Replacement model, by 2 surgeons, from 2015 to 2017. Patient demographic data and direct hospital costs were collected, and patients were stratified by APTs vs metal-backed components. Univariable and multivariable analyses were performed for all outcome metrics. A total of 188 primary TKAs were included (92 APT, 96 metal-backed). Patients receiving APT components were older (P<.001) and had a lower body mass index (P<.001), but there was no difference in sex or American Society of Anesthesiologists score between groups. Operative time was significantly less (mean, 13 minutes) and direct surgery costs were significantly lower for APTs (P<.001). A multivariable regression model for surgical costs demonstrated significant savings (P<.001), and total hospital cost demonstrated a 6.2% average savings with APT. There was no difference in 90-day emergency department visits or re-admissions. This study demonstrates that the use of an APT is able to significantly affect not only the surgical cost but also the total hospital admission cost while maintaining equivalent 90-day outcome metrics. Strategies like this should be considered in appropriately selected patients as the incidence of TKA continues to expand. [Orthopedics. 2021;44(1):e114-e118.].

Complications and Costs Are Not Increased After Total Hip Arthroplasty in Patients With a History of Prostate Cancer.

BACKGROUND: Prostate cancer (PCa) is a largely prevalent disease in the United States. Moreover, it is unclear whether the thromboembolic burden of disease remains present after the cancer has been treated and whether such state impacts the short-term outcomes of orthopedic procedures. Therefore, the purpose of this study is to assess 90-day postoperative complications and costs after total hip arthroplasty (THA) for osteoarthritis in patients with a history of PCa. METHODS: Two groups of patients who underwent THA for osteoarthritis in the Medicare Standard Analytical Files were identified through the PearlDiver server. Both groups were matched based on age, diabetes, smoking status, chronic kidney disease, alcohol abuse, chronic liver disease, and obesity in order to create a case-control study comparison. The 90-day complication rates after THA were compared using univariate regressions (odds ratio). We hypothesized that patients with a history of PCa would develop increased rates of thromboembolic complications based on a prolonged procoagulative state. RESULTS: After matching, each group was comprised of 62,571 patients. Our findings identified greater 90-day pneumonia rates for those without a history of PCa (3.26% vs 2.68%; odds ratio, 0.82). All other complications including thromboembolic diseases were clinically comparable in both groups during the 90-day postoperative period. The charges and reimbursements for the 90-day period were also comparable. CONCLUSION: In our large case-control study of 125,142 patients, we found that patients with a history of PCa do not have increased risk of short-term complications after THA and that the mean 90-day reimbursements were similar for both groups at $14,153 for PCa patients and $14,033 for those without (P = .114).

No Changes in Patient Selection and Value-Based Metrics for Total Hip Arthroplasty After Comprehensive Care for Joint Replacement Bundle Implementation at a Single Center.

BACKGROUND: Alternative payment models for total hip arthroplasty (THA) were initiated by the Center for Medicare and Medicaid Services to decrease overall healthcare cost. The associated shift of financial risk to participating institutions may negatively influence patient selection to avoid high cost of care ("cherry picking," "lemon dropping"). This study evaluated the impact of the Comprehensive Care for Joint Replacement (CJR) model on patient selection, care delivery, and hospital costs at a single care center. METHODS: Patients undergoing a primary THA from 2015-2017 were stratified by insurance type (Medicare and commercial insurance) and whether care was provided before (pre-CJR) or after (post-CJR) CJR bundle implementation. Patient age, gender, and body mass index, Elixhauser comorbidities and American Society of Anesthesiologists scores, were analyzed. Delivery of care variables including surgery duration, discharge disposition, length of stay, and direct hospital costs were compared pre- and post-CJR. RESULTS: A total of 751 THA patients (273 Medicare and 478 commercial Insurance) were evaluated pre-CJR (29%) and post-CJR (71%). Patient demographics were similar (age, gender, BMI); however, commercially insured patients had less comorbidities pre-CJR (P = .033). Medicare patient post-CJR length of stay (P = .010) was reduced with a trend toward discharge to home (P = .019). Surgical time, operating room service time, 90-day readmissions and direct hospital costs were similar pre- and post-CJR. CONCLUSION: There was no differential patient selection after CJR bundle implementation and value-based metrics (surgical time, operating room service time) were not affected. Patients were discharged sooner and more often to home. However, overall direct hospital expenses remained unchanged revealing that any cost savings were for insurance providers, not participating hospitals.

Value-Based Care Has Not Resulted in Biased Patient Selection: Analysis of a Single Center's Experience in the Care for Joint Replacement Bundle.

BACKGROUND: Bundled reimbursement models for total knee arthroplasty (TKA) by the Center for Medicare and Medicaid Services have resulted in an effort to decrease the cost of care. However, these models may incentivize bias in patient selection to avoid excess cost of care. We sought to determine the impact of the Comprehensive Care for Joint Replacement (CJR) model at a single center. METHODS: This is a retrospective review of primary TKA patients from July 2015 to December 2017. Patients were stratified by whether or not their surgery was performed before or after implementation of the CJR bundle. Patient demographic data including age, sex, and body mass index were collected in addition to Elixhauser comorbidities and American Society of Anesthesiologists score. In-hospital outcomes were then examined including surgery duration, length of stay, discharge disposition, and direct cost of care. RESULTS: A total of 1248 TKA patients (546 Medicare and 702 commercial insurance) were evaluated, with 27.0% undergoing surgery before the start of the bundle. Compared to patients following implementation of the bundle, there was no significant difference in age, gender, or body mass index. However, pre-CJR Medicare patients were more likely to have fewer Elixhauser comorbidities (P < .001), prolonged length of stay (P < .001), and greater discharges to inpatient facilities (P = .019). There was no significant difference in direct hospital costs or operative service time comparing pre-bundle and post-bundle patients. CONCLUSION: Implementation of the bundled reimbursement model did not result in biased patient selection at our institution; importantly, it also did not result in decreased hospital costs despite apparent improvement in value-based outcome metrics. This should be taken into consideration as future adaptations to reimbursement are made by the Center for Medicare and Medicaid Services.

Should Medical Severity-Diagnosis Related Group Classification Be Utilized for Reimbursement? An Analysis of Elixhauser Comorbidities and Cost of Care.

BACKGROUND: The Center for Medicare and Medicaid Services (CMS) classifies reimbursement for total hip arthroplasty (THA) and total knee arthroplasty (TKA) based on Medical Severity-Diagnosis Related Groups (MS-DRGs) 469 (with major complication/comorbidity) and 470 (without major complication/comorbidity). The validated Elixhauser comorbidity index includes 31 variables that may be associated with MS-DRG 469. However, we hypothesized that these comorbidities may not be the most predictive of increased cost of care. METHODS: Elixhauser comorbidities were retrospectively examined for 1243 TKAs and 897 THAs from 2013 to 2017 at a single center. Comorbidities were investigated in univariable analysis and significant variables associated with MS-DRG 469, and cost of care was further investigated in a multivariable regression to determine which were most predictive of the increased complexity classification assigned by CMS vs true increased cost of care. RESULTS: Thirty-nine patients (1.8%) were classified as MS-DRG 469. Univariable and multivariable logistic analysis revealed that coagulopathy, electrolyte disorders, neurodegenerative disorders, and psychosis were significantly associated with an increased complexity classification. These 4 comorbidities were also associated with increased cost of care; however, 13 additional comorbidities were also predictive of increased cost but not MS-DRG classification. CONCLUSIONS: Patient comorbidities have been shown to increase complications and cost of care for arthroplasty patients. To date, however, the only risk adjustment provided has been the 469 DRG code. This study demonstrates little correlation to the current system with the most expensive diagnoses. Consequently, an expansion of the current risk adjustment system for THA and TKA provided by CMS appears greatly needed.

Utilization of an Electronic Patient Portal Following Total Joint Arthroplasty Does Not Decrease Readmissions.

BACKGROUND: At the investigating institution, an electronic messaging portal (MyChart) allows patients to directly communicate with their healthcare provider. As reimbursement models evolve, there is an increasing effort to decrease 90-day hospital resource utilization and patient returns, and secure messaging portals have been proposed as one way to achieve this goal. We sought to determine which patients utilize this portal, and to determine the impact of secure messaging on emergency department (ED) visits and readmissions within 90 days postoperatively. METHODS: The institutional database was used to analyze 6426 procedures including 3297 primary total knee and 3129 primary total hip arthroplasties. Patient demographics, comorbidities, and secure communication activity status were recorded. Subsequently, statistical analysis was performed to determine which patients utilized MyChart, as well as to correlate patient outcomes to the utilization of secure messaging portals. RESULTS: Active MyChart users were significantly more likely to be young, healthy (American Society of Anesthesiologists 1 or 2), Caucasian, married, employed, have private insurance, and be discharged to home. Decreased utilization was seen in patients who were unhealthy (American Society of Anesthesiologists 3 or 4), were African American, unmarried, unemployed, had Medicare or Medicaid insurance, and were discharged to a skilled nursing facility; these characteristics were also independent significant risks for returning to the ED. Active MyChart status was not significantly associated with 90-day ED return (P = .781) or readmission (P = .512). However, if multiple messages to providers were sent, and the provider response rate was <75%, patients had significantly more readmissions (P = .004). CONCLUSION: Primary total joint arthroplasty patients who were at high risk for ED returns were less likely to utilize MyChart. However, MyChart use did not decrease the 90-day rate of return to the ED or readmissions. A low provider response rate to the secure messages may lead to increased resource utilization in patients using secure messaging as their preferred communication tool. Alternative means of communication with the most vulnerable patients must be investigated to effectively decrease postoperative complications and resource utilization.

Cementless versus Cemented Fixation in Total Knee Arthroplasty: Usage, Costs, and Complications during the Inpatient Period.

Cemented fixation has been the gold standard in total knee arthroplasty (TKA). However, with younger and more active patients requiring TKA, cementless (press-fit) fixation has sparked renewed interest. Therefore, we investigated differences in (1) patient demographics, (2) inpatient costs, (3) short-term complications, and (4) discharge disposition between patients who underwent TKA with cemented and cementless fixation. The National Inpatient Sample database was queried for TKA patients with cement or cementless fixation between October 1 and December 31, 2015. Primary outcomes of interest included complications, length of stay (LOS), discharge disposition, and inpatient costs. Student's t-test and chi-square analysis were used to assess continuous and categorical data, respectively. Multivariable analysis evaluated the effects of fixation type on the continuous and categorical dependent variables. Patients who received cementless fixation were more often younger (63.5 vs. 65.9 years), male (47.4 vs. 40.3%), Black (10.7 vs. 7.7%), from the Northeast census region (29.1 vs. 17.1%), and under private insurance (49.2 vs. 40.3%; p < 0.001 for all). Cementless fixation involved higher inpatient hospital costs (US$17,357 vs. US$16,888) and charges (US$67,366 vs. US$64,190; p < 0.001 for both), lower mean LOS (2.63 vs. 2.71 days; p < 0.001), and higher odds of being discharged to home (odds ratio = 1.99; p = 0.002). This study revisited the outcomes of TKA with cementless fixation and demonstrated higher inpatient charges and costs, shorter mean LOS, and higher odds of being discharged home. Future studies should investigate patient outcomes and complications past the inpatient period, evaluate long-term survivorship and failure rates, and implement a prospective study design.

Medicaid Insurance Correlates With Increased Resource Utilization Following Total Hip Arthroplasty.

BACKGROUND: With increased restraints and efforts to contain costs in total hip arthroplasty (THA), an emphasis has been placed on risk stratification. The purpose of this study was to determine whether Medicaid patients have increased resource utilization (including 90-day emergency department [ED] visits and readmissions) compared to Medicare or commercial insurance carriers. The study hypothesized that the Medicaid population would represent a high-risk cohort with increased resource utilization. METHODS: The institutional database was retrospectively queried for primary THAs from 2013 to 2017 based on Current Procedural Terminology codes and patients undergoing revision surgery were excluded. Demographic information including age, sex, and body mass index (BMI) and medical comorbidities including American Society of Anesthesiologists (ASA) scores were evaluated. Patients were stratified by insurance type and length of stay (LOS), and 90-day ED visits and 90-day readmissions were assessed in univariable and multivariable analysis. RESULTS: A total of 3674 primary THA patients were included in the analysis (including 116 with Medicaid, 1713 with Medicare, and 1845 with other insurance providers). Medicaid patients had significantly higher ASA scores (P < .001) and BMI (P < .001), with corresponding increase in procedure duration (115 vs 99 vs 105 minutes; P < .001). They had a prolonged LOS (2.5 vs 2.5 vs 1.5 days; P < .001) compared with other insurances, but similar to Medicare patients. Following discharge, in multivariable analysis controlling for age, BMI, and ASA score, Medicare patients were significantly more likely to return to the ED (odds ratio, 3.15; 95% confidence interval, 1.88-5.27; P < .001) and be readmitted (odds ratio, 2.46; 95% confidence interval, 1.26-4.81; P = .009). CONCLUSION: Medicaid patients represent a higher risk cohort with increased resource utilization perioperatively, including longer LOS, and more 90-day ED visits and readmissions. This should be considered in outcome assessments and alternative expectations for the episode of care should be set for this population.

Cost Analysis of Sending Routine Pathology Specimens following Total Joint Arthroplasty in the Age of Bundled Payments.

Bundled payment plans are being developed as a means to curb healthcare spending. Routine histology following total hip arthroplasties (THA) and total knee arthroplasties (TKA) is standard practice at many institutions. Recently, the value of this practice has been questioned as histologic diagnoses in THA and TKA rarely differ from the clinical diagnoses. The goal of this study is to identify discrepant and discordant diagnoses following THA and TKA at an academic medical center and to calculate the cost-saving potential in the setting of a bundled payment plan. A retrospective chart review was conducted on 1,213 primary THA and TKA performed by two orthopaedic surgeons from 2012 to 2014. The clinical and histologic diagnoses were compared and classified as concordant, discrepant, or discordant. Cost information was obtained from the institutional billing office. One thousand one hundred and sixty-six THA and TKA were analyzed in the final cohort. Nineteen (1.6%) diagnoses were classified as discrepant while none were discordant. The cost of histologic examination per specimen was estimated to be $48.56. The total cost of all arthroplasties was $14,999,512.46, of which histologic examination made up 0.31% of the total cost. The results of this study corroborate the results of previous studies and support the proposition that routine histologic examination is not cost-effective. The cost incurred to perform histologic examination will become a cost deduction from future bundled payments. The practice of sending routine histologic specimens following TJA should be decided upon by the operating orthopaedic surgeon.

Patient Factors and Cost Associated with 90-Day Readmission Following Total Hip Arthroplasty.

This study sought to identify specific costs for 90-day readmissions following total hip arthroplasty in a bundled payment system. Hospital billing records revealed 139 readmissions (8.93%) in 1781 patients. Mean costs for surgical readmissions were greater (P=0.002) compared with medical reasons, but similar for Medicare/Medicaid and private payers (P=0.975). Costs for imaging, laboratory workup, medication and transfusions, and hospital cost correlated with increasing SOI (P<0.05). Patients transferred from outside hospitals or rehabilitation had higher hospital (P=0.006) and operating room costs (P=0.001) compared to patients admitted from ED or clinic. Hospitals that care for complex patients with Medicare/Medicaid may experience increased costs for unplanned 90-day readmissions highlighting considerations for payer mix.

Assessment of accuracy of robotically assisted unicompartmental arthroplasty.

PURPOSE: The purpose of this study was to analyse the accuracy of component placement during unicompartmental knee arthroplasty (UKA) using a robotic-assisted system. METHODS: Two hundred and six patients (232 knees) who underwent medial robotic-assisted UKA were retrospectively studied. Femoral and tibial sagittal and coronal alignments were measured in the post-operative radiographs and were compared with the equivalent measurements collected during the intra-operative period by the robotic system. Mismatch between pre-planning and post-operative radiography was assessed against accuracy of the prosthesis insertion. RESULTS: Robotic-assisted surgery for medial UKA resulted in an average difference of 2.2° ± 1.7° to 3.6° ± 3.3° depending on the component and radiographic view between the intra-operatively planned and post-operative measurements. Mismatch between pre-planning and post-operative radiography (inaccuracy) was related to improper cementing technique of the prosthesis in all measurements (except for tibial sagittal axis) rather than wrong bony cuts performed by the robotic arm. CONCLUSION: Robotic-assisted medial UKA results in accurate prosthesis position. Inaccuracy may be attributed to suboptimal cementing technique.