Comparison of estimated glomerular filtration rate using five equations to predict acute kidney injury following hip fracture surgery.

BACKGROUND: Decreased estimated glomerular filtration rate (eGFR) is associated with acute kidney injury (AKI) following hip fracture surgery. Delaying surgery for preoperative treatment of comorbidities is controversial in this patient population. The purpose of this study was 1) to assess differences in demographics and comorbidities between AKI and non-AKI groups, 2) to analyze equations used in calculating eGFR, and 3) to identify the equation which best predicts the development of AKI following hip fracture surgery. We hypothesize that one of the equations used to calculate eGFR will be superior to the others. PATIENTS AND METHODS: 124,002 cases of hip fracture surgery were performed from 2012 to 2019, based upon a query of the National Surgical Quality Improvement Program (NSQIP). Preoperative eGFR was calculated using the following: Modification of Diet in Renal Disease (MDRD) II, re-expressed MDRD II, Chronic Kidney Disease Epidemiology Collaboration, Mayo quadratic, and Cockcroft-Gault equations. Independent associations between preoperative eGFR and postoperative renal failure were evaluated using multivariate regression analysis. The predictive ability of each equation was determined using the Akaike information criterion (AIC). RESULTS: AKI was diagnosed in 584 (0.71%) out of the 82,326 patients following hip fracture surgery. The AKI and no AKI cohorts differed significantly by patient sex (p = <0.001), race (p = <0.001), BMI (p = < 0.001), preoperative hematocrit (p = <0.001), preoperative albumin (p = <0.001), diabetes mellitus (p = <0.001), hypertension (p = <0.001), and congestive heart failure (p = <0.001). The Mayo equation (84.0 ± 23.7) was the equation with the highest calculated mean eGFR, followed by the CKD-EPI equation (83.6 ± 20.0), MDRD II equation (83.0 ± 38.9), CG equation (74.7 ± 35.5), and finally the re-expressed MDRD II equation (68.5 ± 36.0) which had the lowest calculated mean eGFR.. All five equations detected that a decrease in preoperative eGFR was associated with an increased risk of postoperative AKI. Lower preoperative eGFR, as calculated by each of the five equations, was significantly associated with an increased risk of AKI following surgical fixation of hip fracture. The AIC was the lowest in the Mayo equation, demonstrating the best fit of the equations to predict postoperative AKI CONCLUSIONS: We propose that using the equation that best identifies those at risk of developing postoperative AKI may help with perioperative decision making and treatment to improve outcomes, which we found to be the Mayo equation. The risk of postoperative AKI was independently associated with decreased preoperative eGFR. The results of this study may warrant further investigation utilizing prospective studies. LEVEL OF EVIDENCE: III; retrospective cohort study.

Routine Prescription of Proton Pump Inhibitors in the Perioperative Period is Associated with Decreased Rates of 2-Year Revision Surgery after Total Hip and Knee Arthroplasty.

INTRODUCTION: Proton Pump Inhibitors (PPIs) are often prescribed in conjunction with nonsteroidal anti-inflammatory drugs (NSAIDs) after total hip (THA) and total knee arthroplasty (TKA) due to their gastroprotective effects. In animal studies, it has been suggested that PPIs have immunosuppressive effects and impair fracture healing, however, the association between PPI use and adverse events following THA and TKA has not been well studied. METHODS: An administrative claims database was queried for patients who underwent elective THA from 2010 to 2019. The experimental group consisted of patients who did not have a prior history of gastrointestinal (GI) bleeding or gastroesophageal reflux disease (GERD) and who received a PPI prescription in the perioperative period. A 1:1 propensity score matching was used to create control cohorts of patients who did not have any PPI prescription filled, also matching for age, sex, and Charlson comorbidity index. This same cohort selection and matching procedure was then repeated for patients undergoing elective TKA. In total, 11,450 patients were studied (3,103 TKA+PPI, 2,622 THA+PPI, 3,103 TKA Controls, and 2,622 THA Controls). The mean age was 64 years (range, 38 to 94), and 57% were women. Significance was considered at P < 0.05. RESULTS: Perioperative PPI prescription in TKA patients was associated with significantly lower rates of all-cause revision (3.0 versus 4.1%, P < 0.01) and periprosthetic joint infection (1.0 versus 1.8%, P < 0.01). In THA patients, PPI prescription was associated with a lower all-cause revision rate (2.8 versus 4.0%, P = 0.02). No significant differences were found between PPI and non-PPI groups for aseptic loosening, periprosthetic fracture, gastrointestinal bleeding, or surgical site infection in either cohort. CONCLUSIONS: Patients receiving routine PPI prescriptions in the perioperative period surrounding TKA and THA have a lower risk of all-cause revision surgery, and perioperative PPI use is associated with a decreased risk of PJI in patients undergoing TKA. As these results conflict with the few previous studies performed on this topic, additional controlled studies are warranted to fully elucidate the relationship between PPI use and adverse events after THA and TKA.

Ankylosing spondylitis in patients undergoing total hip arthroplasty increases the risk of medical and implant-related complications: a case control analysis.

INTRODUCTION: Ankylosing spondylitis (AS) is an inflammatory spondyloarthropathy, often involving the spine and sacroiliac joints. Total hip arthroplasty (THA) has been shown to be effective in improving pain and function in patients with AS with hip involvement. However, extraskeletal manifestations and altered mechanics in those with AS leads to increased complications. Thus, the aims of this study were to assess the effects that AS has on medical and implant complications, falls, length of stay, and readmissions following THA. METHODS: A retrospective review of the Mariner private insurance claims database was conducted from 2010 to 2020. All cases of THA and those with AS were identified using Current Procedural Terminology, and International Classification of Disease 9th and 10th revision codes. Patients who underwent THA with a diagnosis of AS were matched to non-AS patients 1:5 based on demographic and comorbidity profiles. 90-day medical complications, falls, and readmission rates, as well as 2-year implant complications were compared between cohorts. RESULTS: A total of 6509 AS patients were matched to 32,489 control patients. The AS group had significantly higher rates of myocardial infarction, cerebrovascular accident, deep vein thrombosis, pulmonary embolism, urinary tract infection, wound complications, acute kidney injury, pneumonia, sepsis, transfusions, and falls when compared to the control group. The AS group had significantly higher rates of prosthetic joint infection, dislocation, mechanical loosening, and periprosthetic fracture (all p < 0.0001). Likewise, mean length of stay and readmissions were significantly greater in the AS group. CONCLUSIONS: Ankylosing spondylitis in patients undergoing THA is associated with significant risk of medical and implant complications, as well as fall risk, length of stay, and readmission rates. These findings may allow orthopaedic surgeons to be more attentive in identifying those patients at risk and allow for more educated patient counseling and perioperative planning.

Decreased Risk of Readmission and Complications With Preoperative GLP-1 Analog Use in Patients Undergoing Primary Total Joint Arthroplasty.

BACKGROUND: There has been considerable interest in the use of GLP-1 receptor analogs (GLP-1 RAs) for weight optimization in patients undergoing elective arthroplasty. As there is limited data regarding the implications of their use, our study aimed to evaluate the association between preoperative GLP-1 RA use and postoperative outcomes in patients undergoing primary total hip arthroplasty (THA) and total knee arthroplasty (TKA). METHODS: The TrinetX research network was queried to identify all patients undergoing primary THA or TKA between May 2005 and December 2023 across 84 health care organizations. Patients were stratified based on preoperative GLP-1 RA use. Propensity score matching (1:1) was performed to account for baseline differences in demographics, laboratory investigations, and comorbidities. Subsequently, risk ratios were evaluated for postoperative outcomes. RESULTS: A total of 268,504 and 386,356 patients underwent THA and TKA, of which 1,044 and 2,095 used preoperative GLP-1 RAs. After matching, GLP-1 RA use was associated with a decreased 90-day risk of periprosthetic joint infection (2.1 versus 3.6%, RR = 0.58, P = .042) and readmission (1.1 versus 2.0%, RR = 0.53, P = .017) following THA and TKA, respectively. There was no difference in the risk of all other outcomes between comparison groups. CONCLUSIONS: Preoperative GLP-1 RA use is associated with a 42% decreased risk of periprosthetic joint infection and 47% decreased risk of readmission in the 90-day postoperative period following THA and TKA, respectively, with no difference in other risks, including aspiration. Our findings indicate that GLP-1 RAs may be safe to use in patients undergoing elective arthroplasty; however, further studies are warranted to inform the routine use of GLP-1 RAs for weight management in THA and TKA patients.

Selective Use of Modern Cementless Total Knee Arthroplasty is Not Associated with Increased Risk of Revision in Patients Aged 65 or Greater: An Analysis from the American Joint Replacement Registry.

Modern highly porous surfaces have increased confidence and use of cementless total knee arthroplasty (TKA) in the United States. As cementless TKA use increases, there remains a paucity of literature regarding associated risk of revision in patients aged ≥65 years. We analyzed the American Joint Replacement Registry (AJRR) data from January 2012 to March 2020 identifying patients aged ≥65 years undergoing primary TKA with linked cases to supplemental centers for Medicare and Medicaid data. Patients with hybrid fixation, reverse hybrid fixation, missing component data, highly constrained implants, and stem extension/augmentation were excluded. We identified 442,745 cemented TKAs and 19,841 modern cementless TKAs with a minimum of 2-year follow-up. Cumulative incident function (CIF) curves and cause-specific Cox models evaluated the risk of all-cause revision and revision for mechanical loosening, adjusting for body mass index (BMI), sex, age, cruciate retaining (CR) versus posterior stabilized (PS) femoral design, patellar resurfacing, and Charlson's comorbidity index (CCI). Patients with cementless compared with cemented TKA were younger (mean age: 71.9 vs. 73.2 years, p < 0.001), more likely to be male sex (48.8 vs. 39.0%, p < 0.001), more likely to have a CR femoral design (81.1 vs. 45.7%, p < 0.001), less likely to have patellar resurfacing (92.7 vs. 95.0%, p < 0.001), and had a lower CCI (mean: 2.9 vs. 3.1, p < 0.001). Adjusted hazard ratios (HRs) showed no difference in associated risk for all-cause revision (HR: 1.07; 95% confidence interval [CI]: 0.92-1.24; p = 0.382) or revision for mechanical loosening (HR: 1.38; 95% CI: 0.9-2.12; p = 0.14) for cementless versus cemented TKA. Our results suggest that current selective use of cementless fixation for TKA in patients aged ≥65 years in the United States is not associated with an increased risk of revision. While encouraging, further study is necessary to establish indications for use in this age group prior to broader adoption in this patient population. LEVEL OF EVIDENCE: Therapeutic Level III.

Over the Past Decade, Preoperative Anemia Has Become a Greater Predictor of Transfusions After Total Knee Arthroplasty.

BACKGROUND: With advancements in perioperative blood management and the use of tranexamic acid, the rate of transfusions after total knee arthroplasty (TKA) has substantially decreased. As these principles are refined, other modifiable risk factors, such as preoperative anemia, may play an increasingly important role in transfusion risk for patients undergoing TKA. METHODS: A multicenter, national database was utilized to identify patients undergoing TKA from 2010 to 2021. Anemia was defined by World Health Organization definitions as < 12 g/dL for women and < 13 g/dL for men. A predictive model was created using backwards elimination logistic regression to predict transfusion risk, controlling for demographic and medical covariates. The coefficient of anemia was then analyzed for each year. The trend over time was fitted with a best-fit linear regression equation. RESULTS: There were 509,117 patients who underwent TKA, and had a mean age of 67 years (range, 18 to 89). There were 57,716 (11%) patients who were anemic preoperatively, and 15,426 (3%) of patients required a transfusion. Rate of transfusion decreased from 10.6% in 2010 to 0.6% in 2021. The odds ratio associated with anemia as a predictor of transfusion increased from 3.1 (95% confidence interval: 2.1 to 4.6) in 2010 to 14.0 (95% confidence interval: 8.9 to 24) in 2021. CONCLUSIONS: The results of this study demonstrate that the importance of preoperative anemia as a predictor of transfusion has increased over the past decade as rates of transfusion have decreased. As perioperative blood management protocols improve, preoperative anemia should be considered an important focus of intervention to reduce the risk of transfusion prior to TKA. LEVEL OF EVIDENCE: III.

Cemented Stem Design in Total Hip Arthroplasty: Fixation Philosophies, Biomechanics, and an Updated Classification System.

There is renewed interest in cemented femoral fixation in total hip arthroplasty in the United States, and to fully appreciate the evolution of cemented femoral stem designs, an understanding of their history and design rationale is essential. To adequately study the outcomes of modern-day designs, a comprehensive classification system is also necessary. The biomechanical principles, failure mechanisms, and clinical outcomes associated with various cemented femoral stems are described in this comprehensive review. In addition, an updated version of an existing classification system is described that incorporates the primary design characteristics which differentiate implants currently in use. In this classification, implants are categorized as taper-slip (Type I), which are subdivided by Anatomic (IA), Double-Taper (IB), and Triple-Taper (IC) with subclassification for Traditional and Line-to-Line implants. Composite beam (Type II) implants are similarly divided into Anatomic (IIA), Straight (IIB), and Wedge (IIC) with subclassification for Polished, Satin, or Roughened finish. This classification system provides a basis for comparing cemented femoral stems, thereby improving our understanding of the effect of design characteristics on survivorship to guide future advancements and improve clinical outcomes.

Preoperative weight loss before total hip arthroplasty negatively impacts postoperative outcomes.

BACKGROUND: Obesity adversely impacts outcomes of total hip arthroplasty (THA), leading surgeons to impose body mass index cutoffs for patient eligibility and encourage preoperative weight loss. This study aimed to determine if preoperative weight loss impacts outcomes of THA in the general patient population and if it mitigates poor outcomes in obese patients. METHODS: Patients who underwent THA from 2013-2020 were identified in the National Surgical Quality Improvement Program (NSQIP) database. Patients were stratified by weight loss of >10% of body weight over the preceding 6 months. We used multivariable linear and logistic regression models, adjusted for age, sex, race/ethnicity, and comorbidities, to examine the effect of significant preoperative weight loss on 30-day outcomes after THA in the general and obese patient populations. RESULTS: In the overall population, patients who lost significant weight preoperatively had significantly increased length of stay, were more likely to have a non-home discharge, return to the operating room, or be readmitted, and were more likely to experience numerous medical complications. In the obese population, patients who lost significant weight preoperatively had significantly increased length of stay and were more likely to require a transfusion or experience any medical complication. DISCUSSION: Rapid significant preoperative weight loss is not associated with improved postoperative outcomes after THA in the obese population and is associated with worse outcomes in the general population. Arthroplasty surgeons should balance these risks with the risks of obesity when advising patients about preoperative weight loss prior to THA. LEVEL OF EVIDENCE: III.

The weight of complications: high and low BMI have disparate modes of failure in total hip arthroplasty.

BACKGROUND: Body mass index (BMI) has been shown to influence risk for revision total hip arthroplasty (rTHA), but few studies have specifically examined which causes of rTHA are most likely in different BMI classes. We hypothesized that patients in different BMI classes would undergo rTHA for disparate reasons. METHODS: Ninety-eight thousand six hundred seventy patients undergoing rTHA over 2006-2020 were identified in the National Inpatient Sample. Patients were classified as underweight, normal-weight, overweight/obese, or morbidly obese. Multivariable logistic regression was used to analyze the impact of BMI on rTHA for periprosthetic joint infection (PJI), dislocation, periprosthetic fracture (PPF), aseptic loosening, or mechanical complications. Analyses were adjusted for age, sex, race/ethnicity, socioeconomic status, insurance, geographic region, and comorbidities. RESULTS: Compared to normal-weight patients, underweight patients were 131% more likely to have a revision due to dislocation and 63% more likely due to PPF. Overweight/obese patients were 19% less likely to have a revision due to dislocation and 10% more likely due to PJI. Cause for revision in morbidly obese patients was 4s1% less likely to be due to dislocation, 8% less likely due to mechanical complications, and 90% more likely due to PJI. CONCLUSIONS: Overweight/obese and morbidly obese patients were more likely to undergo rTHA for PJI and less likely for mechanical reasons compared to normal weight patients. Underweight patients were more likely to undergo rTHA for dislocation or PPF. Understanding the differences in cause for rTHA among the BMI classes can aid in patient-specific optimization and management to reduce postoperative complications. LEVEL OF EVIDENCE: III.

Impact of Postoperative COVID-19 Infection Status on Outcomes in Elective Primary Total Joint Arthroplasty.

BACKGROUND: Although Coronavirus disease 2019 (COVID-19) infection causes major morbidity and mortality, it is unclear what the impact of postoperative COVID-19 infection is on 30-day outcomes after total joint arthroplasty (TJA). METHODS: There were 2,340 patients who underwent TJA in 2021, identified using the National Surgical Quality Improvement Program database, with 925 total hip arthroplasty (THA) patients (39.5%) and 1,415 total knee arthroplasty (TKA) patients (60.5%), overall. Propensity score matching was implemented using patient demographics and preoperative medical conditions to compare outcomes for postoperative COVID-19-positive and COVID-19-negative patients who underwent TKA or THA. RESULTS: Postoperative COVID-19-positive THA patients were found to have a significantly increased risk of pneumonia (odds ratio [OR] 42.57), sepsis (OR 12.77), readmission (OR 12.06), non-home discharge (OR 3.78), and longer length of stay (hazard ratio 1.62). Postoperative COVID-19-positive TKA patients had an increased risk of 30-day mortality (OR 14.17), superficial infection (OR 3.17), pneumonia (OR 34.68), unplanned intubation (OR 18.31), ventilator use for more than 48 hours (OR 18.31), pulmonary embolism (OR 11.98), urinary tract infection (OR 5.16), myocardial infarction (OR 16.02), deep vein thrombosis (OR 4.69), non-home discharge (OR 1.79), reoperation (OR 3.17), readmission (OR 9.61), and longer length of stay (hazard ratio 1.49). CONCLUSIONS: Patients who contracted COVID-19 within 30 days after TJA were at increased risk of mortalities, medical complications, readmissions, reoperations, and non-home discharges. It is important for orthopedic surgeons to understand these adverse outcomes to better counsel patients and mitigate these risks, particularly in higher risk populations.

Preoperative COVID-19 infection status negatively impacts postoperative outcomes of geriatric hip fracture surgery.

OBJECTIVES: Compare outcomes for patients with recently diagnosed COVID-19 infection to those without COVID-19 infection undergoing operative treatment of hip fractures using the American College of Surgeons National Surgical Quality Improvement Program (NSQIP) database. DESIGN: Retrospective propensity score matched cohort. METHODS: Patients who received surgery for an acute hip fracture (intramedullary nail (IMN), open reduction internal fixation (ORIF) or hemiarthroplasty) in 2021 were identified from the NSQIP database. Propensity score matching was implemented using patient demographics and preoperative medical conditions to compare outcomes for COVID-19-positive and COVID-19-negative cohorts. RESULTS: After matching, COVID-19-positive patients exhibited a higher risk of 30-day mortality (Odds ratio (OR) 1.48, 95 % confidence interval (CI) 1.01 - 2.04), pneumonia (OR 2.90, 95 % CI: 1.91 - 4.33), unplanned intubation (OR 2.53, 95 % CI: 1.39 - 4.39), and septic shock (OR 2.51, 95 % CI: 1.10 - 4.67). COVID-19-positive patients were also more likely to have a longer length of hospital stay (Hazard Ratio 1.3, 95 % CI: 1.20 - 1.41) and were more likely to be discharged to an acute care hospital (OR 1.90, 95 % CI: 1.03 - 3.06). CONCLUSIONS: Active COVID-19 infection is an independent risk factor for complications as well as increased resource utilization in patients undergoing surgical treatment of acute hip fracture. Using the results of this multicenter study, quantification of these risks can help inform practice and treatment protocols for this population. LEVEL OF EVIDENCE: III.

The Definition of Anemia Matters When Using Preoperative Hemoglobin as a Screening Tool Prior to Total Hip and Knee Arthroplasty.

BACKGROUND: Preoperative anemia is common in patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA). Several definitions of anemia have been described, with no clear consensus on the optimal one for preoperative screening. We hypothesized that depending on the definition used preoperatively, the proportion of anemic patients identified who would require a postoperative allogeneic blood transfusion would vary significantly. METHODS: A total of 681,141 patients were identified in a national database who underwent either THA or TKA. Preoperative anemia was classified according to the World Health Organization (WHO) definition, Cleveland Clinic (CC) definition, or race, age, and sex-specific definition described by Beutler et al in 2006. The optimal preoperative (OP) hemoglobin thresholds to predict perioperative transfusions were also calculated using receiver operating characteristic curves. RESULTS: When using the WHO definition, 18% of anemic patients required a transfusion versus 14% (OP definition), 12% (CC definition), and 16% (Beutler definition). Similarly, 0.69% of anemic patients sustained a periprosthetic joint infection within 30 days using the WHO definition versus 0.59% (OP definition), 0.60% (CC definition), or 0.66% (Beutler definition). Using the WHO definition, 5.3% of patients would have sustained a major complication versus 4.5% (OP definition), 4.4% (CC definition), and 5.0% (Beutler definition). CONCLUSIONS: Variation in the definition of anemia for preoperative screening in THA and TKA results in substantial differences in discriminative ability to predict perioperative transfusions. The WHO definition identified the largest proportion of patients who ultimately received a perioperative transfusion.

Mapping the course to recovery: a prospective study on the anatomic distribution of early postoperative pain after total knee arthroplasty.

INTRODUCTION: Early postoperative pain following total knee arthroplasty significantly impacts outcomes and patient satisfaction. However, the characteristics and sources of early pain after total knee arthroplasty remain unclear. Therefore, the purpose of this study was to determine the anatomic distribution and course of postoperative pain in the acute and subacute period following total knee arthroplasty. METHODS: A prospective observational study of primary, elective unilateral total knee arthroplasty cases was conducted at our academic tertiary care medical center from January 2021 to September 2021. Preoperative variables were extracted from institutional electronic medical records. Postoperatively, patients utilized a knee pain map to identify the two locations with the most significant pain and rated it using the visual analog scale (VAS). The data were collected on day 0, at 2 weeks, 2 months, and 6 months after operation. RESULTS: This study included 112 patients, with 6% of patients having no pain at postoperative day 0, 22% at 2 weeks, 46% at 2 months, and 86% at 6 months after operation. In those who reported pain, the VAS score (mean ± standard deviation) was 5.8 ± 2.4 on postoperative day 0 and decreased at each follow-up time point (5.4 ± 2.3 at 2 weeks, 3.9 ± 2.2 at 2 months, and 3.8 ± 2.7 at 6 months). The majority of patients were able to identify distinct loci of pain. The most common early pain loci were patellae, thigh, and medial joint line, and this distribution dissipated by 6 months. CONCLUSION: At 2 postoperative weeks, pain was primarily at the medial joint, and at 6 months postoperatively, pain was more likely to be at the lateral joint. No relationship was found between pain at six months and pain scores or location at postoperative day 0 or 2 weeks. Understanding the distribution and progression of knee pain following total knee arthroplasty may benefit patient education and targeted interventions. LEVEL OF EVIDENCE: Level II, prospective observational study.

Ultracongruent Designs Compared to Posterior-Stabilized and Cruciate-Retaining Tibial Inserts - What Does the Evidence Tell Us? A Systematic Review and Meta-Analysis.

BACKGROUND: Posterior-stabilized (PS) and cruciate-retaining (CR) have been the most common tibial designs used in total knee arthroplasty. Ultra-congruent (UC) inserts are becoming popular because they preserve bone without relying on the posterior cruciate ligament balance and integrity. Despite increasing use, there is no consensus on how UC inserts perform versus PS and CR designs. METHODS: A comprehensive literature search of 5 online databases was performed for articles from January 2000 to July 2022 comparing the kinematic and clinical outcomes of PS or CR tibial inserts to UC inserts. There were nineteen studies included. There were 5 studies comparing UC to CR and 14 comparing UC to PS. Only one randomized controlled trial (RCT) was rated "good quality". RESULTS: For CR studies, pooled analyses showed no difference in knee flexion (n = 3, P = .33) or Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores (n = 2, P = .58). For PS studies, meta-analyses showed better anteroposterior stability (n = 4, P < .001) and more femoral rollback (n = 2, P < .001) for PS but no difference in knee flexion (n = 9, P = .55) or medio-lateral stability (n = 2, P = .50). There was no difference with WOMAC (n = 5, P = .26), Knee Society Score (n = 3, P = .58), Knee Society Knee Score (n = 4, P = .76), or Knee Society Function Score (n = 5, P = .51). CONCLUSION: Available data demonstrates there are no clinical differences between CR or PS and UC inserts in small short-term studies ending around 2 years after surgery. More importantly, high-quality research comparing all inserts is lacking, demonstrating a need for more uniform and longer-term studies beyond 5 years after surgery to justify increased UC usage.

Body Mass Index and Revision Total Knee Arthroplasty: Does Cause for Revision Vary by Underweight or Obese Status?

BACKGROUND: Body mass index (BMI) impacts risk for revision total knee arthroplasty (rTKA), but the relationship between BMI and cause for revision remains unclear. We hypothesized that patients in different BMI classes would have disparate risk for causes of rTKA. METHODS: There were 171,856 patients who underwent rTKA from 2006 to 2020 from a national database. Patients were classified as underweight (BMI < 19), normal-weight, overweight/obese (BMI 25 to 39.9), or morbidly obese (BMI > 40). Multivariable logistic regressions adjusted for age, sex, race/ethnicity, socioeconomic status, payer status, hospital geographic setting, and comorbidities were used to examine the effect of BMI on risk for different rTKA causes. RESULTS: Compared to normal-weight controls, underweight patients were 62% less likely to undergo revision due to aseptic loosening, 40% less likely due to mechanical complications, 187% more likely due to periprosthetic fracture, 135% more likely due to periprosthetic joint infection (PJI). Overweight/obese patients were 25% more likely to undergo revision due to aseptic loosening, 9% more likely due to mechanical complications, 17% less likely due to periprosthetic fracture, and 24% less likely due to PJI. Morbidly obese patients were 20% more likely to undergo revision due to aseptic loosening, 5% more likely due to mechanical complications, and 6% less likely due to PJI. CONCLUSION: Mechanical reasons were more likely to be the cause of rTKA in overweight/obese and morbidly obese patients, compared to underweight patients, for whom revision was more likely to be infection or fracture related. Increased awareness of these differences may promote patient-specific management to reduce complications. LEVEL OF EVIDENCE: III.

Compressed Sensing SEMAC MRI of Hip, Knee, and Ankle Arthroplasty Implants: A 1.5-T and 3-T Intrapatient Performance Comparison for Diagnosing Periprosthetic Abnormalities.

BACKGROUND. The utility of 3-T MRI for diagnosing joint disorders is established, but its performance for diagnosing abnormalities around arthroplasty implants is unclear. OBJECTIVE. The purpose of this study was to compare 1.5-T and 3-T compressed sensing slice encoding for metal artifact correction (SEMAC) MRI for diagnosing peri-prosthetic abnormalities around hip, knee, and ankle arthroplasty implants. METHODS. Forty-five participants (26 women, 19 men; mean age ± SD, 71 ± 14 years) with symptomatic lower extremity arthroplasty (hip, knee, and ankle, 15 each) prospectively underwent consecutive 1.5- and 3-T MRI examinations with intermediate-weighted (IW) and STIR compressed sensing SEMAC sequences. Using a Likert scale, three radiologists evaluated the presence or absence of periprosthetic abnormalities, including bone marrow edema-like signal, osteolysis, stress reaction/fracture, synovitis, and tendon abnormalities and collections; image quality; and visibility of anatomic structures. Statistical analysis included nonparametric comparison and interchangeability testing. RESULTS. For diagnosing periprosthetic abnormalities, 1.5-T and 3-T compressed sensing SEMAC MRI were interchangeable. Across all three joints, 3-T MRI had lower noise than 1.5-T MRI (median IW and STIR scores at 3 T vs 1.5 T, 4 and 4 [range, 2-5 and 3-5] vs 3 and 3 [range, 2-5 and 2-4]; p < .01 for both), sharper edges (median IW and STIR scores at 3 T vs 1.5 T, 4 and 4 [both ranges, 2-5] vs 3 and 3 [range, 2-4 and 2-5]; p < .02 and p < .05), and more effective metal artifact reduction (median IW and STIR scores at 3 T vs 1.5 T, 4 and 4 [range, 3-5 and 2-5] vs 4 and 4 [both ranges, 3-5]; p < .02 and p = .72). Agreement was moderate to substantial for image contrast (IW and STIR, 0.66 and 0.54 [95% CI, 0.41-0.91 and 0.29-0.80]; p = .58 and p = .16) and joint capsule visualization (IW and STIR, 0.57 and 0.70 [range, 0.32-0.81 and 0.51-0.89]; p = .16 and p = .19). The bone-implant interface was more visible at 1.5 T (median IW and STIR scores, 4 and 4 [both ranges, 2-5] at 1.5 T vs 3 and 3 [both ranges, 2-5] at 3 T; p = .08 and p = .58), but periprosthetic tissues had superior visibility at 3 T (IW and STIR, 4 and 4 [both ranges, 3-5] at 3 T vs 4 and 4 [ranges, 2-5 and 3-5] at 1.5 T; p = .07 and p = .19). CONCLUSION. Optimized 1.5-T and 3-T compressed sensing SEMAC MRI are interchangeable for diagnosing periprosthetic abnormalities, although metallic artifacts are larger at 3 T. CLINICAL IMPACT. With compressed sensing SEMAC MRI, lower extremity arthroplasty implants can be imaged at 3 T rather than 1.5 T.

Comparing Pain and Pain Coping Mechanisms in Patients Undergoing Total Joint Arthroplasty as Part of a Mission Trip to Those in the United States.

BACKGROUND: Access to total joint arthroplasty can be difficult in low-resource settings. Service trips are conducted to provide arthroplasty care to populations in need around the world. This study aimed to compare the pain, function, surgical expectations, and coping mechanisms of patients from one such service trip to the United States. METHODS: In 2019, the Operation Walk program conducted a service trip in Guyana during which 50 patients had hip or knee arthroplasties. Patient demographics, patient-reported outcome measures, questionnaires assessing pain attitudes and coping, and pain visual analog scales were collected preoperatively and at 3 months postoperatively. These outcomes were compared with a matched cohort of elective total joint arthroplasty at a US tertiary care medical center. There were 37 patients matched between the 2 cohorts. RESULTS: The mission cohort had significantly lower preoperative self-reported function scores than the US cohort (38.3 versus 47.5, P = .003), as well as a significantly larger improvement at 3 months (42.4 versus 26.4, P = .014). The mission cohort had significantly higher initial pain (8.0 versus 7.0, P = .015), but there were no differences with regard to pain at 3 months (P = .420) or change in pain (P = .175). The mission cohort had significantly greater preoperative scores in pain attitude and coping responses. CONCLUSION: Patients in low-resource settings were more likely to have preoperative functional limitations and pain, and they coped with pain through prayer. Understanding the key differences between these 2 types of populations and how they approach pain and functional limitations may help improve care for each group. LEVEL OF EVIDENCE: II, prospective study.

Not All Patients Need Supervised Physical Therapy After Primary Total Knee Arthroplasty: A Systematic Review and Meta-Analysis.

Although postoperative physical therapy (PT) has long been considered essential to successful total knee arthroplasty (TKA) recovery, recent literature has suggested that unsupervised home exercise regimens may offer similar benefits to formal supervised sessions. We aimed to compare objectively measured physical function and subjective patient-reported outcomes (PROs) between primary TKA patients who received formal supervised physical therapy sessions and those who received unsupervised home exercise regimens after discharge. Six electronic databases were queried to identify randomized controlled trials comparing supervised physical therapy to unsupervised home exercise regimens in primary TKA patients after discharge. Outcomes of interest included change from baseline in objective measures (knee flexion range of motion (ROM), lower extremity strength, and aerobic capacity) and PROs (physical function and quality of life scores). These outcomes were subdivided into short-term (<6 months from surgery; closest data point to three months is used if multiple measurements were made in this time period) and long-term (≥6 months from surgery; closest data point to 12 months is used if multiple measurements were made in this time period) assessments. A total of 1,884 cases performed in 11 studies were included in this review. There were no significant differences between cohorts with regard to short-term knee flexion ROM (p = 0.7), lower extremity strength (p = 0.6), or patient-reported quality of life (p = 0.5), as well as long-term knee flexion ROM (p = 0.7), patient-reported quality of life (p = 0.2), or patient-reported physical outcome scores (p = 0.3). A small difference in short-term patient-reported physical outcomes was observed in favor of the supervised cohort (standardized mean difference (SMD): 0.3 (95% confidence interval (CI): 0.01, 0.6); I2 = 82%; p = 0.04). Formal supervised physical therapy regimens do not confer clinically significant benefits over unsupervised home exercise regimens following primary TKA. The routine use of supervised physical therapy after discharge may not be warranted. Further study is needed to determine the subset of patients that may benefit from supervised care.

Comparing five equations to calculate estimated glomerular filtration rate to predict acute kidney injury following total joint arthroplasty.

BACKGROUND: Acute kidney injury (AKI) following total joint arthroplasty (TJA) is associated with increased morbidity and mortality. Estimated glomerular filtration rate (eGFR) is used as an indicator of renal function. The purpose of this study was (1) to assess each of the five equations that are used in calculating eGFR, and (2) to evaluate which equation may best predict AKI in patients following TJA. METHODS: The National Surgical Quality Improvement Program (NSQIP) was queried for all 497,261 cases of TJA performed from 2012 to 2019 with complete data. The Modification of Diet in Renal Disease (MDRD) II, re-expressed MDRD II, Cockcroft-Gault, Mayo quadratic, and Chronic Kidney Disease Epidemiology Collaboration equations were used to calculate preoperative eGFR. Two cohorts were created based on the development of postoperative AKI and were compared based on demographic and preoperative factors. Multivariate regression analysis was used to assess for independent associations between preoperative eGFR and postoperative renal failure for each equation. The Akaike information criterion (AIC) was used to evaluate predictive ability of the five equations. RESULTS: Seven hundred seventy-seven (0.16%) patients experienced AKI after TJA. The Cockcroft-Gault equation yielded the highest mean eGFR (98.6 ± 32.7), while the Re-expressed MDRD II equation yielded the lowest mean eGFR (75.1 ± 28.8). Multivariate regression analysis demonstrated that a decrease in preoperative eGFR was independently associated with an increased risk of developing postoperative AKI in all five equations. The AIC was the lowest in the Mayo equation. CONCLUSIONS: Preoperative decrease in eGFR was independently associated with increased risk of postoperative AKI in all five equations. The Mayo equation was most predictive of the development of postoperative AKI following TJA. The mayo equation best identified patients with the highest risk of postoperative AKI, which may help providers make decisions on perioperative management in these patients.