In Kinematically Aligned Total Knee Arthroplasty, Failure to Recreate Native Tibial Alignment Is Associated With Early Revision.

BACKGROUND: The goal of kinematically aligned (KA) total knee arthroplasty (TKA) is to restore native knee anatomy. However, there are concerns about patellofemoral tracking problems with this technique that lead to early revision. We measured the differences between preoperative anatomic alignment and postoperative component alignment in a consecutive series of KA TKA and evaluated the association between alignment changes and the likelihood of early revision. METHODS: The charts of 219 patients who underwent 275 KA TKA procedures were reviewed. Preoperative anatomic alignment and postoperative tibial and femoral component alignment were measured radiographically. The difference in component alignment compared with preoperative anatomic alignment was compared between patients who underwent aseptic revision and those who did not at a minimum of 12 months of follow-up. Receiver operating characteristic curves were created for statistically significant variables, and the Youden index was used to determine optimal alignment thresholds with regard to likelihood of revision surgery. RESULTS: Change in tibial component alignment compared with native alignment was greater (P = .005) in the revision group (5.0° ± 3.7° of increased varus compared with preoperative anatomic tibial angle) than in the nonrevision group (1.3° ± 4.2° of increased varus). The Youden index indicated that increasing tibial varus by >2.2° or more is associated with increased likelihood of revision. Preoperative anatomic alignment and change in femoral alignment and overall joint alignment (ie, Q angle) were not associated with increased likelihood of revision. CONCLUSION: Small increases in tibial component varus compared with native alignment are associated with early aseptic revision in patients undergoing KA TKA.

Transfusion Thresholds for Major Orthopedic Surgery: A Systematic Review and Meta-analysis.

BACKGROUND: More than a million surgeries are performed annually in the United States for hip or knee arthroplasty or hip fracture stabilization. One-fifth of these patients have blood transfusions during their hospital stay. Increases in transfusion rates have caused concern about increased adverse events from unnecessary transfusions. METHODS: We systematically reviewed randomized trials examining the effect of restrictive vs liberal transfusion thresholds on patients having major orthopedic surgery. Study results were meta-analyzed with a random-effects model and heterogeneity was tested with the I2 statistic. Study risk of bias was assessed using a modified Jadad scale and evidence strength was measured using the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) system. RESULTS: A total of 504 published articles were screened, and 15 met inclusion criteria. The articles described 9 randomized trials, most comparing transfusion thresholds of 8 vs 10 g/dL hemoglobin. All involved hip or knee arthroplasty and/or hip fracture patients. Moderate-strength evidence suggested a reduction in need for transfusion (relative risk, 0.53; 95% confidence interval [CI], 0.39-0.71; I2 = 95%) and mean number of units transfused (-0.95 units, 95% CI, -1.48 to -0.41, I2 = 98%). There was a possible reduction in overall infections with more restrictive transfusion thresholds, although the result was not statistically significant (relative risk, 0.71; 95% CI, 0.47-1.06; I2 = 54%). Moderate-strength evidence suggested no differences in other clinical outcomes between the groups. Limitations included incomplete blinding, inconsistency, and imprecision. CONCLUSION: Moderate-strength evidence suggests that restrictive transfusion practices reduce utilization of transfusions and may decrease infections without increasing adverse outcomes in major orthopedic surgery.

Are Bundled Payments a Viable Reimbursement Model for Revision Total Joint Arthroplasty?

BACKGROUND: Alternative payment models, such as the Centers for Medicare & Medicaid Services (CMS) Bundled Payment for Care Improvement (BPCI) initiative, aim to decrease overall costs for hip and knee arthroplasties. QUESTIONS/PURPOSES: We asked: (1) Is there any difference in the CMS episode-of-care costs, hospital length of stay, and readmission rate from before and after implementation of our bundled-payment program? (2) Is there any difference in reimbursements and resource utilization between revision THA and TKA at our institution? (3) Are there any independent risk factors for patients with high costs who may not be appropriate for a bundled-payment system for revision total joint arthroplasty (TJA)? METHODS: Between October 2013 and March 2015, 218 patients underwent revision TKA or THA in one health system. Two hundred seventeen patients were reviewed as part of this study, and one patient with hemophilia was excluded from the analysis as an outlier. Our institution began a BPCI program for revision TJA during this study period. Patients' procedures done before January 1, 2014 at one hospital and January 1, 2015 at another hospital were not included in the bundled-care arrangement (70 revision TKAs and 56 revision THAs), whereas 50 revision TKAs and 41 revision THAs were performed under the BPCI initiative. Patient demographics, medical comorbidities, episode-of-care reimbursement data derived directly from CMS, length of stay, and readmission proportions were compared between the bundled and nonbundled groups. RESULTS: Length of stay in the group that underwent surgery before the bundled-care arrangement was longer than for patients whose procedures were done under the BPCI (mean 4.02 [SD, 3.0 days] versus mean 5.27 days [SD, 3.6 days]; p = 0.001). Index hospitalization reimbursement for the bundled group was less than for the nonbundled group (mean USD 17,754 [SD, USD 2741] versus mean USD 18,316 [SD, USD 4732]; p = 0.030). There was no difference, with the numbers available, in total episode-of-care CMS costs between the two groups (mean USD 38,107 [SD, USD 18,328] versus mean USD 37,851 [SD, USD 17,208]; p = 0.984). There was no difference, with the numbers available, in the total episode-of-care CMS costs between revision hip arthroplasties and revision knee arthroplasties (mean USD 38,627 [SD, USD 18,607] versus mean USD 37,414 [SD, USD 16,884]; p = 0.904). Disposition to rehabilitation (odds ratio [OR], 5.49; 95% CI, 1.97-15.15; p = 0.001), length of stay 4 days or greater (OR, 3.66; 95% CI, 1.60-8.38; p = 0.002), and readmission within 90 days (OR, 6.99; 95% CI, 2.58-18.91; p < 0.001) were independent risk factors for high-cost episodes. CONCLUSIONS: Bundled payments have the potential to be a viable reimbursement model for revision TJA. Owing to the unpredictable nature of the surgical procedures, inherent high risks of complications, and varying degrees of surgical complexity, future studies are needed to determine whether bundling patients having revision TJA will result in improved care and decreased costs. LEVEL OF EVIDENCE: Level IV, economic and decision analysis.

Predictors of the need for critical care after total joint arthroplasty: an update of our institutional risk stratification model.

Based on our previously published risk stratification model, 295 (19%) of a consecutive series of 1594 TJA patients were triaged to the ICU. However, only 67 patients (22%) required intensive care interventions. We identified 5 independent multivariate predictors (P < 0.001) including COPD, CAD, CHF (1 point each), EBL > 1000 mL, and intraoperative vasopressors (2 points each) to form the Penn Arthroplasty Risk Score (PARS). Patients with a score of 0 through 7 had a probability of requiring critical care of 7.0%, 13.2%, 23.5%, 38.1%, 55.4%, 71.4%, 83.4%, and 91.1% respectively. Based on these results, our previous risk stratification protocol is overly sensitive and non-specific. Any risk stratification algorithm for ICU admission should include intraoperative risk factors in order to be fully predictive.

The Impact of Femoral Component Cementation on Fracture and Mortality Risk in Elective Total Hip Arthroplasty: Analysis from a National Medicare Sample.

BACKGROUND: Complications following elective total hip arthroplasty (THA) are rare but potentially devastating. The impact of femoral component cementation on the risk of periprosthetic femoral fractures and early perioperative death has not been studied in a nationally representative population in the United States. METHODS: Elective primary THAs performed with or without cement among elderly patients were identified from Medicare claims from 2017 to 2018. We performed separate nested case-control analyses matched 1:2 on age, sex, race/ethnicity, comorbidities, payment model, census division of facility, and exposure time and compared fixation mode between (1) groups with and without 90-day periprosthetic femoral fracture and (2) groups with and without 30-day mortality. RESULTS: A total of 118,675 THAs were included. The 90-day periprosthetic femoral fracture rate was 2.0%, and the 30-day mortality rate was 0.18%. Cases were successfully matched. The risk of periprosthetic femoral fracture was significantly lower among female patients with cement fixation compared with matched controls with cementless fixation (OR = 0.83; 95% CI, 0.69 to 1.00; p = 0.05); this finding was not evident among male patients (p = 0.94). In contrast, the 30-day mortality risk was higher among male patients with cement fixation compared with matched controls with cementless fixation (OR = 2.09; 95% CI, 1.12 to 3.87; p = 0.02). The association between cement usage and mortality among female patients almost reached significance (OR = 1.74; 95% CI, 0.98 to 3.11; p = 0.06). CONCLUSIONS: In elderly patients managed with THA, cemented stems were associated with lower rates of periprosthetic femoral fracture among female patients but not male patients. The association between cemented stems and higher rates of 30-day mortality was significant for male patients and almost reached significance for female patients, although the absolute rates of mortality were very low. For surgeons who can competently perform THA with cement, our data support the use of a cemented stem to avoid periprosthetic femoral fracture in elderly female patients. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Prediction of Adverse Outcomes Within 90 Days of Surgery in a Heterogeneous Orthopedic Surgery Population.

INTRODUCTION: The LACE+ index has been shown to predict readmissions; however, LACE+ has not been validated for extended postoperative outcomes in an orthopedic surgery population. The purpose of this study is to examine whether LACE+ scores predict unplanned readmissions and adverse outcomes following orthopedic surgery. Use of the LACE1 index to proactively identify at-risk patients may enable actions to reduce preventable readmissions. METHODS: LACE+ scores were retrospectively calculated at the time of discharge for all consecutive orthopedic surgery patients (n = 18,893) at a multicenter health system over 3 years (2016-2018). Coarsened exact matching was used to match patients based on characteristics not assessed in the LACE+ index. Outcome differences between matched patients in different LACE quartiles (i.e. Q4 vs. Q3, Q2, and Q1) were analyzed. RESULTS: Higher LACE+ scores significantly predicted readmission and emergency department visits within 90 days of discharge and for 30-90 days after discharge for all studied quartiles. Higher LACE+ scores also significantly predicted reoperations, but only between Q4 and Q3 quartiles. CONCLUSIONS: The results suggest that the LACE+ risk-prediction tool may accurately predict patients with a high likelihood of adverse outcomes after a broad array of orthopedic procedures.

Association of Discharge to Home vs Institutional Postacute Care With Outcomes After Lower Extremity Joint Replacement.

Importance: Changes in financial incentives have led to more patients being discharged home than to institutional forms of postacute care, such as skilled nursing facilities (SNFs), after elective lower extremity total joint replacement (LEJR). Objective: To evaluate the association of this change with hospital readmissions, surgical complications, and mortality. Design, Setting, and Participants: This cohort study used cross-temporal propensity-matching to identify 104 828 adult patients who were discharged home following LEJR between 2016 and 2018 (after changes in financial incentives) and 84 121 adult patients discharged to institutional forms of postacute care (eg, SNFs) between 2011 and 2013 (before changes in financial incentives). A difference-in-differences design was used to compare differences in outcomes between these groups to a propensity-matched group of patients discharged to institutional postacute care in both periods. Data were collected from Pennsylvania all-payer claims database, which includes all surgical procedures and hospitalizations across payers and hospitals in Pennsylvania. Data were analyzed between August 2019 and February 2020. Exposures: Type of postacute care (home, including home with home health vs institutional postacute care, including SNF, inpatient rehabilitation facilities, and long-term acute care hospitals). Main Outcomes and Measures: Main outcomes were 30- and 90-day hospital readmissions, LEJR complication rates, and mortality rates. Results: Of 189 949 patients, 113 981 (60.0%) were women, and 83 444 (43.9%) were aged 40 to 64 years. The rate of discharge home increased from 63.6% (54 097 of 85 121) in 2011 to 2013 to 78.4% (82 199 of 104 828) in 2016 to 2018. In the adjusted difference-in-differences comparison, matched patients discharged home in 2016 to 2018 had significantly lower 30-day (difference, -2.9%; 95% CI, -4.2% to -1.6%) and 90-day (difference, -3.9%; 95% CI, -5.8% to -2.0%) readmission rates compared with similar patients sent to institutional postacute care in 2011 to 2013. Surgical complication and mortality rates were unchanged. Results were similar across payers and across hospital bundled payment participation status. Conclusions and Relevance: In this cohort study, increases in discharges home following LEJR surgery did not seem to be associated with increased harm during a period in which changes in financial incentives likely spurred observed changes in postacute care.

In-Bundle Surgeons More Likely Select Cemented Femoral Fixation in Total Hip Arthroplasty for At-Risk Patients: The Medicare Comprehensive Care for Joint Replacement Bundled Model.

Background: Bundled payment models for lower-extremity arthroplasty have been shown to lower costs but have not reliably improved quality. It is unknown how the bundled payment model may affect surgeons' decisions that impact the quality of arthroplasty care. The purpose of this study was to compare the utilization of femoral component fixation modes by surgeons performing total hip arthroplasties (THAs) in at-risk patients in areas subject to Medicare's Comprehensive Care for Joint Replacement (CJR) bundled payment model compared with patients treated by surgeons in areas exempt from the policy. Methods: Elective, primary THAs among elderly persons were identified from Medicare claims during 2017 and 2018, including the use of cemented or cementless femoral fixation. Multivariable regression models, applied to samples stratified by sex, were used to assess the association between CJR bundle participation and the use of femoral fixation mode. Analyses were adjusted for patient age, race or ethnicity, comorbidity burden, low-income status, and Census division of the hospital. Results: Of 118,676 Medicare patients who underwent THA, 9.1% received cemented femoral components, and use of cement varied significantly by geographic region (p < 0.001). Patients who received cemented fixation, compared with patients who received cementless fixation, had significant differences in mean age (and standard deviation) at 78.3 ± 6.9 years compared with 74.5 ± 6.1 years (p < 0.001) for female patients and 77.3 ± 6.8 years and 74.2 ± 5.9 years (p < 0.001) for male patients; were more likely to be White at 94.0% compared with 92.7% (p < 0.001) for female patients and 95.1% compared with 93.8% (p = 0.046) for male patients; and had higher mean Elixhauser comorbidity index at 2.6 ± 2.2 compared with 2.3 ± 2.0 (p < 0.001) for female patients and 2.8 ± 2.4 compared with 2.4 ± 2.1 (p < 0.001) for male patients. In adjusted analyses, female patients in the CJR bundled payment model were more likely to have cemented fixation compared with female patients not in the CJR model (odds ratio [OR], 1.11 [95% confidence interval (CI), 1.05 to 1.16]; p < 0.001), whereas male patients in the CJR bundled payment model were less likely to have cemented fixation compared with male patients not in the CJR model (OR, 0.91 [95% CI, 0.83 to 0.99]; p = 0.029). Conclusions: In the bundled environment, surgeons were more likely to choose cemented femoral fixation for elderly female patients. This may be due to in-bundle surgeons being more risk-averse and avoiding cementless fixation in patients at risk for fracture or implant-related complications. Further research is needed to directly examine the impact of the bundle on surgeon decision-making.

Composite score for prediction of 30-day orthopedic surgery outcomes.

The LACE+ (Length of stay, Acuity of admission, Charlson Comorbidity Index score, and Emergency department visits in the past 6 months) risk-prediction tool has never been tested in an orthopedic surgery population. LACE+ may help physicians more effectively identify and support high-risk orthopedics patients after hospital discharge. LACE+ scores were retrospectively calculated for all consecutive orthopedic surgery patients (n = 18 893) at a multi-center health system over 3 years (2016-2018). Coarsened exact matching was employed to create "matched" study groups with different LACE+ score quartiles (Q1, Q2, Q3, Q4). Outcomes were compared between quartiles. In all, 1444 patients were matched between Q1 and Q4 (n = 2888); 2079 patients between Q2 and Q4 (n = 4158); 3032 patients between Q3 and Q4 (n = 6064). Higher LACE+ scores significantly predicted 30D readmission risk for Q4 vs Q1 and Q4 vs Q3 (P < .001). Larger LACE+ scores also significantly predicted 30D risk of ED visits for Q4 vs Q1, Q4 vs Q2, and Q4 vs Q3 (P < .001). Increased LACE+ score also significantly predicted 30D risk of reoperation for Q4 vs Q1 (P = .018), Q4 vs Q2 (P < .001), and Q4 vs Q3 (P < .001).

Defining the Key Parts of a Procedure: Implications for Overlapping Surgery.

INTRODUCTION: The American College of Surgeons' Statements on Principles requires attending surgeons to be present for the "key parts" of surgical procedures, but the term is not defined. The research question addressed in this study is whether a functional definition of the critical or key steps of common orthopaedic surgical procedures can be reliably constructed. We used the examples of hip and knee arthroplasty because these procedures are highly structured and divisible into distinct subroutines. METHODS: We surveyed 100 experienced orthopaedic surgeons regarding whether particular steps in knee and hip arthroplasty procedures were considered "key." The patterns of individual surgeons' responses were compared among surgeons for overall reliability. The steps frequently cited as key were also identified. RESULTS: The agreement rates among surgeons for the definitions of the key parts of hip and knee arthroplasty were 3.2% and 8.6%, respectively. For both procedures, five steps were identified as key by >90% of the respondents. DISCUSSION: The agreement rate on what constitutes the key parts of hip and knee arthroplasty was poor, despite the fact that these are highly structured procedures. Accordingly, defining the key parts for a given procedure must rely on either the operating surgeon's discretion or a consensus definition. Imposing a single surgeon's standard on others is not the optimal approach because such a standard is likely to be idiosyncratic. CONCLUSION: A consensus standard articulated by the orthopaedic surgery community may be the best means for identifying the key parts of orthopaedic surgical operations. The data presented here suggest a foundation upon which a consensus definition for the key parts of arthroplasty procedures may be built.

Can an arthroplasty risk score predict bundled care events after total joint arthroplasty?

BACKGROUND: The validated Arthroplasty Risk Score (ARS) predicts the need for postoperative triage to an intensive care setting. We hypothesized that the ARS may also predict hospital length of stay (LOS), discharge disposition, and episode-of-care cost (EOCC). METHODS: We retrospectively reviewed a series of 704 patients undergoing primary total hip and knee arthroplasty over 17 months. Patient characteristics, 90-day EOCC, LOS, and readmission rates were compared before and after ARS implementation. RESULTS: ARS implementation was associated with fewer patients going to a skilled nursing or rehabilitation facility after discharge (63% vs 74%, P = .002). There was no difference in LOS, EOCC, readmission rates, or complications. While the adoption of the ARS did not change the mean EOCC, ARS >3 was predictive of high EOCC outlier (odds ratio 2.65, 95% confidence interval 1.40-5.01, P = .003). Increased ARS correlated with increased EOCC (P = .003). CONCLUSIONS: Implementation of the ARS was associated with increased disposition to home. It was predictive of high EOCC and should be considered in risk adjustment variables in alternative payment models.

The effect of a 5-day space flight on the immature rat spine.

BACKGROUND CONTEXT: Spaceflight has many reported effects upon the musculoskeletal system structure and function. This study was designed to determine the effect of a 5-day flight on the rat spine. METHODS: In September 1991, 8 neonatal rats were flown aboard the Space Shuttle Columbia flight STS-48 during a 5-day mission. Upon return to earth, the spines were dissected, frozen and shipped to our laboratory. Matched ground-based rats were used as controls. The spines were radiographed and then slowly thawed. Individual vertebrae were subjected to compressive biomechanical testing using an Instron tester (Instron Corp, Canton, MA, USA) and then processed for determination of calcium and phosphorus content. The intervertebral discs were placed in physiological saline and the stress-relaxation characteristics measured. The discs were then lyophilized and assayed for collagen and proteoglycan content. Disc height on radiographs was measured by image analysis. RESULTS: After space flight, the heights of the discs were found to be 150 to 200 microns greater, although the values were not statistically significant. There was no difference in the resiliency of the thoracic discs as determined by stress-relaxation. However, in the lumbar discs, space flight increased the resiliency (p<.01). There was no difference in water content. In both the thoracic and lumbar discs there was a 3.3-fold increase in hydroxyproline-proteoglycan ratio after space flight. However, because of the small sample size, these values were not statistically significant. In the vertebrae, there was no difference in calcium-phosphate ratio or compressive strength. CONCLUSIONS: These data suggest that even after a short 5-day flight, the spine begins to undergo biomechanical and biochemical changes. In addition, the weightless environment in space may provide a good model to study the effects of immobilization on earth.

The use of clopidogrel (Plavix) in patients undergoing nonelective orthopaedic surgery.

OBJECTIVE: To assess the effects of Plavix on patients requiring nonelective orthopaedic surgery. DESIGN: Retrospective cohort study. SETTING: University-affiliated teaching institutions. PATIENTS AND PARTICIPANTS: The orthopaedic trauma registry was used to retrospectively identify all patients taking clopidogrel (Plavix; Bristol-Myers Squibb/Sanofi Pharmaceuticals, Bridgewater, NJ) who required nonelective orthopaedic surgery from 2004 to 2008. Twenty-nine patients were identified on Plavix (PG) and 32 matched patients in the control group not taking Plavix (NPG). The Plavix group was separated into those with a surgical delay less than 5 days of the last dose (PG < 5) (n = 28) and a delay greater than 5 days (PG > 5) (n = 1). A randomized age- and injury-matched control group not on Plavix was separated with surgical delay less than 5 days (NPG < 5) (n = 29) and delay greater than 5 days (NPG > 5) (n = 3). INTERVENTION: A retrospective review was performed comparing pre- and postoperative hemoglobin, blood transfusion requirements, surgical delay, 30-day mortality, and postoperative complications. MAIN OUTCOME MEASUREMENTS: Statistical analyses were performed using the Student t test and chi square test to identify differences between the groups. RESULTS: : The mean preoperative hemoglobin of the PG and the NPG was 11.2 g/dL and 12.3 g/dL (P = 0.03). Transfusion rates were similar with 18 of 28 in the PG compared with 13 of 29 in the NPG (P = 0.22). The mean surgical delay between the PG and NPG was 1.88 and 1.68 days (P = 0.64). Overall complications between the PG and NPG was nine of 28 and nine of 29 (P = 0.92). In both groups, two patients had postoperative wound drainage, which resolved without intervention. One patient in each group required revision surgery for nonunion. The 30-day mortality in the Plavix group was zero of 28 (0%) compared with one of 29 (3%) in the control group (cardiac arrest) (P = 0.32). CONCLUSIONS: In this study, there were no serious complications or increased transfusion requirements in the Plavix group. Avoiding surgical delay for patients on Plavix requiring nonelective orthopaedic surgery appears to be safe. The goal should be early operative intervention to decrease the morbidity and mortality of surgical delay. This is especially true for patients with hip fractures, which was the most common nonelective orthopaedic surgery required of patients on Plavix in this study.

Phenotypic characterization of inflammatory cells from osteoarthritic synovium and synovial fluids.

Osteoarthritis (OA) is considered a degenerative joint disorder caused by mechanical wear to the articular surface. However, while joint injury, obesity, and mutations in collagen increase the risk of developing OA, evidence implicates inflammatory mechanisms in disease progression and chronicity. To address this question we used FACS analysis, immunohistochemistry, and in vitro cell culture to evaluate inflammatory mechanisms in synovial fluids and joint tissues obtained after arthrocentesis or knee replacement surgery. Immunohistochemistry revealed a significant T cell infiltrate in six of nine tissue specimens. T cells were present throughout the synovial membrane and were particularly localized around vasculature and in large cellular aggregates. Cells within the aggregates expressed markers associated with immune activation and antigen presentation. T cells from OA synovial fluids expressed an activated phenotype and synthesized interferon-gamma following in vitro stimulation. These data support the hypothesis that inflammatory cells play a significant role in OA disease progression and chronicity.