Faculty Bibliography

BACKGROUND:Optimal femoral stem alignment and femoral canal fill have been associated with improved osteointegration in patients undergoing cementless total hip arthroplasty (THA). Direct anterior approach (DAA) has become more popular among new surgeons, and the ability to achieve appropriate stem alignment and canal fill due to limited surgical exposure may pose added risks. To mitigate these concerns, several modern tissue sparing stem designs have been designed. This study aimed to compare implant canal fill and alignment between two of the leading DAA-friendly femoral stems available. METHODS:This was a multi-center, retrospective study of patients who underwent DAA THA with either A (n = 149) or B stem (n = 85) between 2021 and 2023 and had a minimum one-year follow-up. Radiographic measures of proximal femoral morphology, including canal calcar ratio (CCR), Morphological Cortical Index (MCI), and Dorr Class (based on the CCR), as well as postoperative measures including femoral canal fill ratio (CFR), signs of osteointegration and stem alignment were analyzed and compared between stem types. RESULTS:, p = 0.082). Spot weld formation was significantly higher in stem A group (59.7% vs. 37.6%, P = 0.001). CONCLUSION/CONCLUSIONS:For patients with similar femoral morphology undergoing DAA THA, the stem A group demonstrated superior anatomical fit in the metaphyseal region, as evidenced by CFR, spot weld formation and implant positioning. Further longer follow up research is needed to elucidate these findings and their correlation to clinical outcomes.

BACKGROUND:Methylene blue (MB), a phenothiazine dye with antimicrobial activity, is used to stain soft tissues and guide thoroughness of debridement during revision total knee arthroplasty (rTKA) for periprosthetic joint infection (PJI). The purpose of this study was to determine if instillation of MB prior to arthrotomy impacts culture yield in TKA PJI. METHODS:We retrospectively reviewed 266 patients diagnosed with TKA PJIs according to the 2018 International Consensus Meeting (ICM) criteria from January 2018 - March 2023 at a single academic hospital. Demographics, perioperative outcomes, and preoperative and intraoperative culture positivity were compared between patients who received intraoperative MB (MB group; n = 26) and those who did not (nMB group; n = 241). A record of detected organisms was included in the analysis. RESULTS:There was no difference in preoperative aspiration culture positivity between groups. However, the MB group had a higher percentage of preoperative to intraoperative culture concordance (89.5 vs. 69.9%; P = 0.04). Although the overall rate of intraoperative culture positivity did not differ significantly between groups, the MB group had more intraoperative cultures obtained per patient (4.9 vs. 4.5; P = 0.02) and higher numbers of positive intraoperative cultures per patient. Concordance rates for patients in both groups with positive preoperative and negative intraoperative cultures were similar (10.5 vs. 16.5%, P = 0.50). Among patients with negative preoperative cultures, intraoperative culture positivity was more discordant in the MB group (0 vs. 18.8%; P = 0.03). There was no difference in the number of patients that received antibiotics following aspiration (68.4 vs. 49.6%; P = 0.12). CONCLUSION/CONCLUSIONS:While MB use did not affect overall culture positivity, it could interfere with intraoperative pathogen detection in patients with negative preoperative cultures. In these cases, MB should be avoided to decrease inaccuracies in intraoperative culture yield. If preoperative cultures are positive, MB may improve surgical debridement and likelihood of infection eradication.

BACKGROUND:High body mass index (BMI) is a risk factor for tibial baseplate loosening following total knee arthroplasty (TKA) but may not adequately correlate with stresses at the tibial baseplate. In this study, we aimed to determine an optimal cutoff of a weight-to-tibial baseplate surface-area ratio (weight/SA) for predicting aseptic tibial baseplate loosening. We further examined whether tibial stem extensions have a protective effect. METHODS:We identified 16,368 patients who underwent primary, elective TKA from June 2011 to March 2023. Patient demographics, including age, sex, and race, implants used, and revision surgeries were extracted. Revisions were manually reviewed to confirm revision indications. The exact surface areas of tibial baseplates were obtained from manufacturers. Receiver operating characteristic (ROC) analysis of patients without tibial stem extensions was utilized to examine the utility of BMI and weight/SA for predicting aseptic tibial baseplate loosening. Optimal weight/SA and BMI cutoffs for predicting loosening were determined. The effect of tibial stem extensions on loosening was then examined in patients at or above (n = 7,698; 3.7% with stem extension) and below (n = 8,670; 1.3% with stem extension) the determined weight/SA cutoff. RESULTS:There were 16,368 patients in the final sample (median age, 67 years; 68.9% female; 54.1% White). Weight/SA (area under the curve [AUC] = 0.653; p < 0.001) was a better predictor of aseptic tibial baseplate loosening requiring revision compared with patient BMI (AUC = 0.624; p < 0.001). The optimal weight/SA cutoff for predicting loosening was 0.0162 kg/mm2 (sensitivity = 0.747, specificity = 0.537). Multivariable logistic regression demonstrated that being at or above the weight/SA cutoff (odds ratio [OR] = 3.17; p < 0.001) but not the BMI cutoff (p = 0.911) was a significant predictor of revision for tibial baseplate loosening in patients without stem extensions. No cases of revision for aseptic tibial baseplate loosening in patients with stem extensions occurred either at or above or below the cutoff. The rate of revision for aseptic tibial baseplate loosening in patients without stem extensions was 0.3% for patients below and 1.0% for patients at or above the weight/SA cutoff. CONCLUSIONS:The ratio of weight-to-tibial baseplate surface area was more predictive of revision for aseptic tibial baseplate loosening following TKA compared with BMI alone. For patients with obesity with small tibial baseplate sizes, utilization of a tibial stem extension may protect against tibial loosening. LEVEL OF EVIDENCE/METHODS:Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

BACKGROUND:Modern surgical protocols, particularly the use of tranexamic acid (TXA), have reduced, but not eliminated, blood transfusions surrounding total hip arthroplasty (THA). Identifying patients at risk for transfusion remains important for risk reduction and to determine type and screen testing. METHODS:We reviewed 6,405 patients who underwent primary, unilateral THA between January 2014 and January 2023 at a single academic institution, received TXA, and had preoperative hemoglobin (Hgb) values. We compared demographics, baseline Hgb levels, and surgical details between patients who were and were not transfused. Data were analyzed utilizing multivariate regression and receiver operating characteristic curve analysis. RESULTS:The overall perioperative and intraoperative transfusion rates were 3.4 and 1.0%, respectively. Patients who were older, women, and American Society of Anesthesiologists class >II demonstrated an increased risk of transfusion. Risk of transfusion demonstrated an inverse correlation with preoperative Hgb levels, a bimodal association with body mass index, and a direct correlation with age, surgical time, and estimated blood loss on multivariate analysis. The receiver operating characteristic analysis demonstrated a preoperative Hgb cutoff of 12 g/dL for predicting any transfusion. Above the threshold of 12 g/dL, total and intraoperative transfusions were rare, with rates of 1.7 and 0.3%, respectively. Total and intraoperative transfusion rates with Hgb between 11 and 12 g/dL were 14.3 and 4.6%, respectively. Below 11 g/dL, total and intraoperative transfusion rates were 27.5 and 10.1%, respectively. CONCLUSIONS:In the age of TXA, blood transfusion is rare in THA when preoperative Hgb is >12 g/dL, challenging the need for universal type and screening. Conversely, patients who have Hgb < 11.0 g/dL, remain at substantial risk for transfusion. Between Hgb 11 and 12 g/dL, patient age, sex, body mass index, American Society of Anesthesiologists classification, anticipated estimated blood loss, and surgical time may help predict transfusion risk and the need for a perioperative type and screen. LEVEL OF EVIDENCE/METHODS:III.

INTRODUCTION/BACKGROUND:Discharge disposition after total joint arthroplasty may be predictable. Previous literature has attempted to improve upon models such as the Risk Assessment and Prediction Tool (RAPT) in an effort to optimize postoperative planning. The purpose of this study was to determine whether preoperative laboratory values and other previously unstudied demographic factors could improve the predictive accuracy of the RAPT. METHODS:All patients included had RAPT scores in addition to the following preoperative laboratory values: red blood cell count, albumin, and vitamin D. All values were recorded within 90 days of surgery. Demographic variables including marital status, American Society of Anesthesiologists (ASA) scores, body mass index, Charlson Comorbidity Index, and depression were also evaluated. Binary logistic regression was used to determine the significance of each factor in association with discharge disposition. RESULTS:Univariate logistic regression found significant associations between discharge disposition and all original RAPT factors as well as nonmarried patients (P < 0.001), ASA class 3 to 4 (P < 0.001), body mass index >30 kg/m2 (P = 0.065), red blood cell count <4 million/mm3 (P < 0.001), albumin <3.5 g/dL (P < 0.001), Charlson Comorbidity Index (P < 0.001), and a history of depression (P < 0.001). All notable univariate models were used to create a multivariate model with an overall predictive accuracy of 90.1%. CONCLUSIONS:The addition of preoperative laboratory values and additional demographic data to the RAPT may improve its PA. Orthopaedic surgeons could benefit from incorporating these values as part of their discharge planning in THA. Machine learning may be able to identify other factors to make the model even more predictive.

INTRODUCTION/BACKGROUND:The role of advanced imaging in diagnosing aseptic implant loosening following total hip arthroplasty (THA) remains unclear. This study aimed to assess the diagnostic value of magnetic resonance imaging (MRI) in detecting aseptic loosening. METHODS:This was a retrospective review of 342 consecutive patients who underwent revision THA between July 2011 and April 2023 and had a pelvis MRI as part of the preoperative diagnostic evaluation. Among them, 62 patients had an intraoperative diagnosis of aseptic loosening of either the femoral or acetabular component. Patients were stratified based on the concordance between their MRI and radiographs findings. RESULTS:Preoperative MRI showed signs of aseptic loosening in 25/62 patients (sensitivity = 40.3%). Similarly, preoperative radiographs demonstrated signs of aseptic loosening in 27 patients (43.5%). Twelve patients (19.4%) had both MRI and radiographs predictive of aseptic loosening, 22 patients (35.5%) did not show signs of aseptic loosening in either MRI or radiographs, and for 28 patients (45.2%), the results were discordant. Among the patients with a negative radiograph for aseptic loosening (n = 35), 13 patients (37.1%) showed signs of aseptic loosening on MRI. CONCLUSION/CONCLUSIONS:Aseptic loosening remains an elusive diagnosis, and the findings of this study suggest that the utility of MRI and radiographs as part of the diagnostic process is limited. However, in cases of presumed aseptic loosening with inconclusive radiographs findings, MRI may play a role in improving the diagnostic process. LEVEL OF EVIDENCE/METHODS:III.

INTRODUCTION/BACKGROUND:Previous studies have attempted to validate the risk assessment and prediction tool (RAPT) in primary total hip arthroplasty (THA) patients. The purpose of this study was to: (1) identify patients who had an extended length of stay (LOS) following THA; and (2) compare the accuracy of 2 previously validated RAPT models. METHODS:We retrospectively reviewed all primary THA patients from 2014 to 2021 who had a completed RAPT score. Youden's J computational analysis was used to determine the LOS where facility discharge was statistically more likely. Based on the cut-offs proposed by Oldmeadow and Dibra, patients were separated into high- (O: 1 to 5 versus D: 1 to 3), medium- (O: 6 to 9 versus D: 4 to 7), and low- (O: 10 to 12 versus D: 8 to 12) risk groups. RESULTS:We determined that an LOS of greater than 2 days resulted in a higher chance of facility discharge. In these patients (n = 717), the overall predictive accuracy (PA) of the RAPT was 79.8%. The Dibra model had a higher PA in the high-risk group (D: 68.2 versus O: 61.2% facility discharge). The Oldmeadow model had a higher PA in the medium-risk (O: 78.7 versus D: 61.4% home discharge) and low-risk (O: 97.0 versus D. 92.5% home discharge) groups. CONCLUSIONS:As institutions continue to optimize LOS, the RAPT may need to be defined in the context of a patient's hospital stay. In patients requiring an LOS of greater than 2 days, the originally established RAPT cut-offs may be more accurate in predicting discharge disposition. LEVEL OF EVIDENCE/METHODS:III Retrospective Cohort Study.

BACKGROUND:As worldwide utilization of total knee arthroplasty (TKA) broadens, demographic trends can help make projections to inform access to care. This study aimed to assess the temporal trends in the socioeconomic and medical demographics of patients undergoing TKA. METHODS:A retrospective review of 15,848 patients who underwent primary, elective TKA at an urban, New York City-based academic medical center between January 2013 and September 2022 was performed. Trends in patients' age, body mass index (BMI), socioeconomic status (SES) (based on median income by patients' ZIP code), race, and Charlson comorbidity index were evaluated using the Mann-Kendall test. RESULTS:In the last decade, mean patient age (65 to 68 years, P < .001) and Charlson comorbidity index (1.4 to 2.3, P < .001) increased significantly. The proportion of patients who had a BMI ≥ 30 and < 40 increased (43.8 to 51.2%, P = .002), while the proportion of patients who had a BMI ≥ 40 (13.7 to 12.1%, P = .015) and BMI < 30 (42.5 to 36.8%, P = .020) decreased. The distribution of patients' race and SES did not change from 2013 to 2022; Black (18.1 to 16.8%, P = .211) and low SES (12.9 to 11.3%, P = .283) patients consistently represented a minority of TKA patients. CONCLUSIONS:Over the last decade, the average age and comorbidity burden of TKA patients at our institution have increased. This portends the need for higher levels of preoperative optimization and postoperative management for TKA patients. A decreased prevalence of BMI ≥40 could reflect optimization efforts. However, the consistently low prevalence of Black and low-SES patients suggests that recent payment models did not improve access to care for these populations. LEVEL OF EVIDENCE/METHODS:IV.

INTRODUCTION/BACKGROUND:The direct anterior approach (DAA) and posterior approach (PA) for total hip arthroplasty (THA) have advantages and disadvantages, but their physiologic burden to the surgeon has not been quantified. This study was conducted to determine whether differences exist in surgeon physiological stress and strain during DAA in comparison to PA. METHODS:We evaluated a prospective cohort of 144 consecutive cases (67 DAA and 77 PA). There were five, high-volume, fellowship-trained arthroplasty surgeons who wore a smart-vest that recorded cardiorespiratory data while performing primary THA DAA or PA. Heart rate (beats/minute), stress index (correlates with sympathetic activations), respiratory rate (respirations/minute), minute ventilation (liters/min), and energy expenditure (calories) were recorded, along with patient body mass index and operative time. Continuous data was compared using T-tests or Mann Whitney U tests, and categorical data was compared with Chi-square or Fischer's exact tests. RESULTS:There were no differences in patient characteristics. Compared to PA, performing THA via DAA had a significantly higher surgeon stress index (17.4 versus 12.4; P < 0.001), heart rate (101 versus 98.3; P = 0.007), minute ventilation (21.7 versus 18.7; P < 0.001), and energy expenditure per hour (349 versus 295; P < 0.001). However, DAA had a significantly shorter operative time (71.4 versus 82.1; P = 0.001). CONCLUSION/CONCLUSIONS:Surgeons experience significantly higher physiological stress and strain when performing DAA compared to PA for primary THA. This study provides objective data on energy expenditure that can be factored into choice of approach, case order, and scheduling preferences, and provides insight into the work done by the surgeon.