The Calpain Gene is Correlated With Metal-on-Metal Hip Replacement Failures.

BACKGROUND: Metal-on-metal (MOM) total hip arthroplasty is associated with unacceptable failure rates secondary to metal ion reactions. Efforts to identify which patients will go on to failure have been limited; recently, there has been a suggestion for a potential genetic basis for the increased risk of revision in MOM hip replacements (MOMHRs). The purpose of this study is to determine whether certain immunologic genotypes are predictive of the need for revision in patients with MOM total hip implants. METHODS: This is a case-control study of all patients undergoing primary MOMHR between September 2002 and January 2012 with a minimum of 5-year follow-up. Our investigational "case" cohort was comprised of patients who underwent revision for MOMHR for a reason other than infection. A single-nucleotide polymorphism (SNP) array analysis was performed to identify a potential genetic basis for failure. RESULTS: Thirty-two patients (15 case and 17 control) were included in our analysis. All patients in the revision group had a chief complain of pain; revision patients were more likely to have a posterior approach (P = .01) and larger head size (P = .04) than nonrevision patients. No patient or implant characteristics were independently associated with revision in a multivariate analysis. Patients with SNP kgp9316441 were identified as having an increased odds of revision for MOM failure (P < .001). CONCLUSION: This study identified an SNP, kgp9316441, encoding proteins associated with inflammation and macrophage activation. This SNP was associated with significantly increased odds of revision for MOMHR. Future studies are warranted to validate this gene target both in vitro and in vivo. LEVEL OF EVIDENCE: III.

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.].

A Preoperative Risk Prediction Tool for Discharge to a Skilled Nursing or Rehabilitation Facility After Total Joint Arthroplasty.

BACKGROUND: Discharge to rehabilitation or a skilled nursing facility (SNF) after total joint arthroplasty remains a primary driver of cost excess for bundled payments. An accurate preoperative risk prediction tool would help providers and health systems identify and modulate perioperative care for higher risk individuals and serve as a vital tool in preoperative clinic as part of shared decision-making regarding the risks/benefits of surgery. METHODS: A total of 10,155 primary total knee (5,570, 55%) and hip (4,585, 45%) arthroplasties performed between June 2013 and January 2018 at a single institution were reviewed. The predictive ability of 45 variables for discharge location (SNF/rehab vs home) was tested, including preoperative sociodemographic factors, intraoperative metrics, postoperative labs, as well as 30 Elixhauser comorbidities. Parameters surviving selection were included in a multivariable logistic regression model, which was calibrated using 20,000 bootstrapped samples. RESULTS: A total of 1786 (17.6%) cases were discharged to a SNF/rehab, and a multivariable logistic regression model demonstrated excellent predictive accuracy (area under the receiver operator characteristic curve: 0.824) despite requiring only 9 preoperative variables: age, partner status, the American Society of Anesthesiologists score, body mass index, gender, neurologic disease, electrolyte disorder, paralysis, and pulmonary circulation disorder. Notably, this model was independent of surgery (knee vs hip). Internal validation showed no loss of accuracy (area under the receiver operator characteristic curve: 0.8216, mean squared error: 0.0004) after bias correction for overfitting, and the model was incorporated into a readily available, online prediction tool for easy clinical use. CONCLUSION: This convenient, interactive tool for estimating likelihood of discharge to a SNF/rehab achieves excellent accuracy using exclusively preoperative factors. These should form the basis for improved reimbursement legislation adjusting for patient risk, ensuring no disparities in access arise for vulnerable populations. LEVEL OF EVIDENCE: III.

Synovial cell cross-talk with cartilage plays a major role in the pathogenesis of osteoarthritis.

We elucidated the molecular cross-talk between cartilage and synovium in osteoarthritis, the most widespread arthritis in the world, using the powerful tool of single-cell RNA-sequencing. Multiple cell types were identified based on profiling of 10,640 synoviocytes and 26,192 chondrocytes: 12 distinct synovial cell types and 7 distinct articular chondrocyte phenotypes from matched tissues. Intact cartilage was enriched for homeostatic and hypertrophic chondrocytes, while damaged cartilage was enriched for prefibro- and fibro-, regulatory, reparative and prehypertrophic chondrocytes. A total of 61 cytokines and growth factors were predicted to regulate the 7 chondrocyte cell phenotypes. Based on production by > 1% of cells, 55% of the cytokines were produced by synovial cells (39% exclusive to synoviocytes and not expressed by chondrocytes) and their presence in osteoarthritic synovial fluid confirmed. The synoviocytes producing IL-1beta (a classic pathogenic cytokine in osteoarthritis), mainly inflammatory macrophages and dendritic cells, were characterized by co-expression of surface proteins corresponding to HLA-DQA1, HLA-DQA2, OLR1 or TLR2. Strategies to deplete these pathogenic intra-articular cell subpopulations could be a therapeutic option for human osteoarthritis.

Roadmap for Transforming Preoperative Assessment to Preoperative Optimization.

Preoperative assessment typically equates to evaluating and accepting the presenting condition of the patient (unless extreme) and commonly occurs only a few days before the planned surgery. While this timing enables a preoperative history and examination and mitigates unexpected findings on the day of surgery that may delay throughput, it does not allow for meaningful preoperative management of modifiable medical conditions. Evidence is limited regarding how best to balance efforts to mitigate modifiable risk factors versus the timing of surgery. Furthermore, while the concept of preoperative risk modification is not novel, evidence is lacking for successful and sustained implementation of such an interdisciplinary, collaborative program. A better understanding of perioperative care coordination and, specifically, implementing a preoperative preparation process can enhance the value of surgery and surgical population health. In this article, we describe the implementation of a collaborative preoperative clinic with the primary goal of improving patient outcomes.

Tranexamic acid or epsilon-aminocaproic acid in total joint arthroplasty? A randomized controlled trial.

AIMS: Antifibrinolytic agents, including tranexamic acid (TXA) and epsilon-aminocaproic acid (EACA), have been shown to be safe and effective for decreasing perioperative blood loss and transfusion following total hip arthroplasty (THA) and total knee arthroplasty (TKA). However, there are few prospective studies that directly compare these agents. The purpose of this study was to compare the benefits of intraoperative intravenous TXA with EACA. PATIENTS AND METHODS: A total of 235 patients (90 THA and 145 TKA) were enrolled in this prospective, randomized controlled trial at a single tertiary-care referral centre. In the THA cohort, 53.3% of the patients were female with a median age of 59.8 years (interquartile range (IQR) 53.3 to 68.1). In the TKA cohort, 63.4% of the patients were female with a median age of 65.1 years (IQR 59.4 to 69.5). Patients received either TXA (n = 119) or EACA (n = 116) in two doses intraoperatively. The primary outcome measures included change in haemoglobin level and blood volume, postoperative drainage, and rate of transfusion. Secondary outcome measures included postoperative complications, cost, and length of stay (LOS). RESULTS: TKA patients who received EACA had greater drainage (median 320 ml (IQR 185 to 420) vs 158 ml (IQR 110 to 238); p < 0.001), increased loss of blood volume (891 ml (IQR 612 to 1203) vs 661 ml (IQR 514 to 980); p = 0.014), and increased haemoglobin change from the preoperative level (2.1 ml (IQR 1.7 to 2.8) vs 1.9 ml (IQR 1.2 to 2.4); p = 0.016) compared with patients who received TXA. For the THA cohort, no statistically significant differences were observed in any haematological outcome measure. One patient in the EACA group required transfusion. No patient in the TXA group required transfusion. There were no statistically significant differences in number or type of postoperative complications or LOS for either THA or TKA patients regardless of whether they received TXA or EACA. CONCLUSION: For hip and knee arthroplasty procedures, EACA is associated with increased perioperative blood loss compared with TXA. However, there is no significant difference in transfusion rate. While further prospective studies are needed to compare the efficacy of each agent, we currently recommend orthopaedic surgeons to select their antifibrinolytic based on cost and regional availability. Cite this article: Bone Joint J 2019;101-B:1093-1099.

Early to Midterm Clinical and Radiographic Survivorship of the All-Polyethylene Versus Modular Metal-Backed Tibia Component in Primary Total Knee Replacement.

The purpose of this study was to compare the all-polyethylene tibial component with the modular metal-backed component in primary total knee arthroplasty. A retrospective review of 1064 patients recorded clinical failure, as determined by need for revision surgery, range of motion, and impending radiographic loosening, as evaluated by the presence of radiolucent lines. Mean follow-up was 1.2 and 3 years, respectively. Survival in the all-polyethylene group was 100%, with 95.5% (95% CI: 85.8-98.6) survival in the metal-backed component group at 4.3 years. Thin (<4 mm) radiolucent lines were present in one patient (0.7%) with an all-polyethylene implant and 24 (16.9%) patients with the metalbacked component (p < .001), while one (0.7%) and two (1.4%) patients had evidence of osteolysis, respectively (p = .621). While there were fewer radiolucent lines noted around the all-polyethylene implant on radiographs, the clinical implications of the finding are unknown. In this study population, the all-polyethylene tibial component appears appropriate. (Journal of Surgical Orthopaedic Advances 28(2):108-114, 2019).

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.

A Novel Risk Calculator Predicts 90-Day Readmission Following Total Joint Arthroplasty.

BACKGROUND: A reliable prediction tool for 90-day adverse events not only would provide patients with valuable estimates of their individual risk perioperatively, but would also give health-care systems a method to enable them to anticipate and potentially mitigate postoperative complications. Predictive accuracy, however, has been challenging to achieve. We hypothesized that a broad range of patient and procedure characteristics could adequately predict 90-day readmission after total joint arthroplasty (TJA). METHODS: The electronic medical records on 10,155 primary unilateral total hip (4,585, 45%) and knee (5,570, 55%) arthroplasties performed at a single institution from June 2013 to January 2018 were retrospectively reviewed. In addition to 90-day readmission status, >50 candidate predictor variables were extracted from these records with use of structured query language (SQL). These variables included a wide variety of preoperative demographic/social factors, intraoperative metrics, postoperative laboratory results, and the 30 standardized Elixhauser comorbidity variables. The patient cohort was randomly divided into derivation (80%) and validation (20%) cohorts, and backward stepwise elimination identified important factors for subsequent inclusion in a multivariable logistic regression model. RESULTS: Overall, subsequent 90-day readmission was recorded for 503 cases (5.0%), and parameter selection identified 17 variables for inclusion in a multivariable logistic regression model on the basis of their predictive ability. These included 5 preoperative parameters (American Society of Anesthesiologists [ASA] score, age, operatively treated joint, insurance type, and smoking status), duration of surgery, 2 postoperative laboratory results (hemoglobin and blood-urea-nitrogen [BUN] level), and 9 Elixhauser comorbidities. The regression model demonstrated adequate predictive discrimination for 90-day readmission after TJA (area under the curve [AUC]: 0.7047) and was incorporated into static and dynamic nomograms for interactive visualization of patient risk in a clinical or administrative setting. CONCLUSIONS: A novel risk calculator incorporating a broad range of patient factors adequately predicts the likelihood of 90-day readmission following TJA. Identifying at-risk patients will allow providers to anticipate adverse outcomes and modulate postoperative care accordingly prior to discharge. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Predicting Inpatient Dissatisfaction Following Total Joint Arthroplasty: An Analysis of 3,593 Hospital Consumer Assessment of Healthcare Providers and Systems Survey Responses.

BACKGROUND: The Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) survey, created by the Centers for Medicare and Medicaid, is directly tied to hospital reimbursement. The purpose of this study is to identify factors that are predictive HCAHPS survey responses following primary hip and knee arthroplasty. METHODS: Prospectively collected HCAHPS responses from patients undergoing elective hip and knee arthroplasty between January 2013 and October 2017 at our institution were analyzed. Patient age, gender, race, marital status, body mass index, American Society of Anesthesiologists score, preoperative pain score, smoking status, alcohol use, illegal drug use, socioeconomic quartile, insurance type, procedure type, hospital type (academic vs community), distance to medical center, length of stay (LOS), and discharge disposition were obtained and correlated with HCAHPS inpatient satisfaction scores. RESULTS: Responses from 3593 patients were obtained: 1546 total hip arthroplasties, 1899 total knee arthroplasties, and 148 unicompartmental knee arthroplasties. Mean overall HCAHPS score was 79.2. Women had lower inpatient satisfaction than men (77.6 vs 81.6, P < .001). Alcohol consumers had lower inpatient satisfaction than abstainers (77.7 vs 81.6, P < .001). Inpatient satisfaction varied by socioeconomic quartile (P < .001) with patients in the highest quartile having lower satisfaction than patients in all other quartiles (P < .001). Patients discharged to a facility had lower inpatient satisfaction than those discharged home (71.2 vs 80.2, P < .001). An inverse correlation between inpatient satisfaction and LOS (r = -0.19, P < .001) and a direct correlation between satisfaction and distance to medical center (r = 0.06, P < .001) were seen. CONCLUSION: Patients more likely to report lower levels of inpatient satisfaction after total joint arthroplasty are female, affluent, and alcohol consumers, who are discharged to postacute care facilities. Inpatient satisfaction was inversely correlated with LOS and positively correlated with distance from patient home to medical center. These findings provide targets for improvements in TJA inpatient care.

Preoperative Optimization Checklists Within the Comprehensive Care for Joint Replacement Bundle Have Not Decreased Hospital Returns for Total Knee Arthroplasty.

BACKGROUND: The Comprehensive Care for Joint Replacement (CJR) model has resulted in the evolution of preoperative optimization programs to decrease costs and hospital returns. At the investigating institution, one center was not within the CJR bundle and has dedicated fewer resources to this effort. The remaining centers have adopted an 11 metric checklist designed to identify and mitigate modifiable preoperative risks. We hypothesized that this checklist would improve postoperative metrics that impact costs for total knee arthroplasty (TKA) patients eligible for participation in CJR. METHODS: Patients undergoing TKA from 2014 to 2018 were retrospectively reviewed. Only patients with eligible participation in CJR were included. Outcome variables including length of stay, disposition, 90-day emergency department visits, and hospital readmissions were explored. Analysis was performed to determine differences in outcomes between CJR participating and non-CJR participating hospitals within the healthcare system. RESULTS: In total, 2308 TKA patients including 1564 from a CJR participating center and 744 from a non-CJR center were analyzed. There was no significant difference in patient age or gender. Patients at the non-CJR hospital had significantly higher body mass index (P < .001) and American Society of Anesthesiologists scores (P < .001), while those in the CJR network had fewer skilled nursing facility discharges (P = .028) and shorter length of stay (P < .001). However, there was no reduction in 90-day emergency department visits or readmissions. CONCLUSION: The resources utilized at CJR participating hospitals, including patient optimization checklists, did not effectively alter patient outcomes following discharge. Likely, a checklist alone is insufficient for risk mitigation and detailed optimization protocols for modifiable risk factors must be investigated.

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.

Predicting Costs Exceeding Bundled Payment Targets for Total Joint Arthroplasty.

BACKGROUND: The Center for Medicare and Medicaid Services has instituted bundled reimbursement models for total joint arthroplasty (TJA), which includes target prices for each procedure. Some patients exceed these targets; however, currently there are no tools to accurately predict this preoperatively. We hypothesized that a validated comorbidity index combined with patient demographics would adequately predict excess cost-of-care prior to hospitalization. METHODS: Two thousand eighty-four primary unilateral TJAs performed at a single tertiary center were retrospectively examined. Data were extracted from medical records and a predictive model was built from 30 comorbidities and 7 patient demographic factors (age, gender, race, body mass index, American Society of Anesthesiologists score, smoking status, and marital status). Following parameter selection, a final multivariable model was created, with a corresponding nomogram for interactive visualization of probability for excess cost. RESULTS: Six hundred twelve patients (29%) had cost-of-care exceeding the target price. The final model demonstrated adequate predictive discrimination for cost-of-care exceeding the target price (area under the receiver operator characteristic curve: 0.747). Factors associated with excess cost included age, gender, marital status, American Society of Anesthesiologists score, body mass index, and race, as well as 7 Elixhauser comorbidities (alcohol use, rheumatoid arthritis, diabetes, electrolyte disorders, neurodegenerative disorders, psychoses, and pulmonary circulatory disorders). CONCLUSION: A novel patient model composed of a subset of validated comorbidities and demographic variables provides adequate discrimination in predicting excess cost within bundled payment models for TJA. This not only helps identify patients who would benefit from preoperative optimization, but also provides evidence for modification of future bundled reimbursement models to adjust for nonmodifiable risk factors.

Skilled Nursing Facilities After Total Knee Arthroplasty: The Time for Selective Partnerships Is Now!

BACKGROUND: Bundled payment initiatives for total knee arthroplasty (TKA) patients are dramatically impacted by discharges to skilled nursing facilities (SNFs), making target prices set by the Center for Medicare and Medicaid Services difficult to achieve. However, we hypothesized that a granular examination of SNF discharges would reveal that some may disproportionately increase costs compared to others. METHODS: The institutional database was retrospectively queried for primary TKA patients under bundled payment initiatives. The 4 most common SNFs utilized by our patient population (A, B, C, and D) were investigated for length of stay, cost of care, and whether the overall target price for the episode of care (EOC) was reached. RESULTS: In total, 1223 TKA patients were analyzed, with 378 (30.9%) discharged to an SNF and 246 patients selecting one of the 4 most common SNFs (A: 198, B: 21, C: 15, D: 12). Each SNF represented a significant fiscal portion of the total EOC; however, SNF D had significantly longer length of stay (21 vs 13 days, P < .001) and cost of care ($11,805 vs $6015, P < .001) relative to the others, resulting in no EOC under the target price. SNF costs >24.6% of the total EOC were predictive of exceeding the target price. CONCLUSION: Bundled payment models are significantly impacted by SNF disposition; however, select facilities disproportionately impact this system. In order to maintain free patient selection for disposition, post-acute care facilities must be held accountable for controlling cost, or a separate bundled payment provided.

Preoperative Patient Profile in Total Hip and Knee Arthroplasty: Predictive of Increased Medicare Payments in a Bundled Payment Model.

BACKGROUND: The shift toward value-based bundled payment models in total joint arthroplasty highlights the need for identification of modifiable risk factors for increased spending as well as opportunities to mitigate perioperative treatment of chronic disease. The purpose of this study was to identify preoperative comorbidities that result in an increased financial burden using institutional data at a single institution. METHODS: We conducted a retrospective review of total joint arthroplasty patients and collected payment data from the Center for Medicare and Medicaid Services for each patient up to 90 days after surgery in accordance with the regulations of the Comprehensive Care for Joint Replacement initiative. Statistical analysis and comparison of preoperative profile and Medicare payments as a surrogate for cost were completed. RESULTS: Six hundred ninety-four patients were identified over a 4-year time period who underwent surgery before adoption of the Comprehensive Care for Joint Replacement but that met criteria for inclusion. The median total payment per patient episode of care was $20,048. Preoperative diagnosis of alcoholism, anemia, diabetes, and obesity was found to have a statistically significant effect on total payments. The model predicted a geometric mean increase from $1425 to $9308 for patients bearing these comorbidities. CONCLUSION: With Medicare payments as a surrogate for cost, we demonstrate that specific patient comorbidities and a cumulative increase in comorbidities predict increased costs. This study was based on institutional data rather than administrative data to gain actionable information on an institutional level and highlight potential flaws in research based on administrative data.

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.

Association Between Pseudotumor Formation and Patient Factors in Metal-on-Metal Total Hip Arthroplasty Population.

BACKGROUND: Pseudotumor formation from metal-on-metal (MoM) hip implants is associated with implant revision. The relationship between pseudotumor type and patient outcomes is unknown. METHODS: We retrospectively reviewed patients with a MoM total hip arthroplasty and metal artifact reduction sequence magnetic resonance imaging. Pseudotumors were graded using a validated classification system by a fellowship-trained radiologist. Patient demographics, metal ion levels, and implant survival were analyzed. RESULTS: Pseudotumors were present in 49 hips (53%). Thirty-two (65%) pseudotumors were cystic thin walled, 8 (16%) were cystic thick walled, and 9 (18%) were solid masses. Patients with pseudotumors had high offset stems (P = .030) but not higher metal ion levels. Patients with thick-walled cystic or solid masses were more likely to be symptomatic (P = .025) and were at increased risk for revision (P = .004) compared to patients with cystic lesions. CONCLUSION: Pseudotumor formation is present in 53% of patients with a MoM total hip arthroplasty, of which 40% were asymptomatic. Patients with thick-walled cystic and solid lesions were more likely to be symptomatic and undergo revision.

Saphenous Nerve Block From Within the Knee Is Feasible for TKA: MRI and Cadaveric Study.

BACKGROUND: Surgeon-performed periarticular injections and anesthesiologist-performed femoral nerve or adductor canal blocks with local anesthetic are in common use as part of multimodal pain management regimens for patients undergoing TKA. However, femoral nerve blocks risk causing quadriceps weakness and falls, and anesthesiologist-performed adductor canal blocks are costly in time and resources and may be unreliable. We investigated the feasibility of a surgeon-performed saphenous nerve ("adductor canal") block from within the knee at the time of TKA. QUESTIONS/PURPOSES: (1) Can the saphenous nerve consistently be identified distally on MRI studies, and is there a consistent relationship between the width of the femoral transepicondylar axis (TEA) and the proximal (cephalad) location where the saphenous nerve emerges from the adductor canal? With these MRI data, we asked the second question: (2) Can we utilize this anatomic relationship to simulate a surgeon-performed intraoperative block of the distal saphenous nerve from within the knee with injections of dyes after implantation of trial TKA components in cadaveric lower extremity specimens? METHODS: A retrospective analysis of 94 thigh-knee MRI studies was performed to determine the relationship between the width of the distal femur at the epicondylar axis and the proximal location of the saphenous nerve after its exit from the adductor canal and separation from the superficial femoral artery. These studies, obtained from one hospital's MRI library, had to depict the saphenous nerve in the distal thigh and the femoral epicondyles and excluded patients younger than 18 years of age or with metal implants. These studies were performed to evaluate thigh and knee trauma or unexplained pain, and 55 had some degree of osteoarthritis. After obtaining these data, TKA resections and trial component implantation were performed, using a medial parapatellar approach, in 11 fresh cadaveric lower extremity specimens. There were six male and five female limbs from cadavers with a mean age of 70 years (range, 57-80 years) and mean body mass index of 20 kg/m (range, 15-26 kg/m) without known knee arthritis. Using a blunt-tipped 1.5-cm needle, we injected 10 mL each of two different colored solutions from inside the knee at two different locations and, after 30 minutes, dissected the femoral and saphenous nerves and femoral artery from the hip to the knee. Our endpoints were whether the saphenous nerve was bathed in dye and if the dye or needle was located in the femoral artery or vein. RESULTS: Based on the MRI analysis, the mean ± SD TEA was 75 ± 4 mm in females and 87 ± 4 mm in males. The saphenous nerve exited the adductor canal and was located at a mean of 1.5 ± 0.16 times the TEA width in females and a mean of 1.3 ± 0.13 times the TEA width in males proximal to the medial epicondyle. After placement of TKA trial components and injection, the proximal injection site solution bathed the saphenous nerve in eight of 11 specimens. In two cachectic female cadaver limbs, the dye was located posteriorly to the nerve in hamstring muscle. The proximal blunt needle and colored solution were directly adjacent to but did not penetrate the femoral artery in only one specimen. CONCLUSIONS: This study indicates, based on MRI measurements, cadaveric injections, and dissections, that a surgeon-performed injection of the saphenous nerve from within the knee after it exits from the adductor canal seems to be a feasible procedure. CLINICAL RELEVANCE: This technique may be a useful alternative to an ultrasound-guided block. A trial comparing surgeon- and anesthesiologist-performed nerve block should be considered to determine the clinical efficacy of this procedure.