Mini-Navigation Utilization in THA Results in Shorter Length of Stay, Increased Home Discharge, and Higher Physical Therapy Mobilization Scores Compared to THA Without Navigation.

BACKGROUND: As volume of total hip arthroplasty (THA) continues to increase, the utilization and availability of in-traoperative advanced technologies to arthroplasty surgeons continues to rise as well. Our primary goal was to determine whether the use of a mini navigation technology extended operative times and secondarily if it affected postoperative outcomes following elective THA. METHODS: A single-institution total joint arthroplasty da-tabase was utilized to identify adult patients who underwent elective THA from 2017 to 2019. Baseline demographic data along with surgical operative time, length of stay (LOS) and discharge disposition were collected. The Activity Measure for Post-Acute Care (AM-PAC) was used to determine physi-cal therapy progress. RESULTS: A total of 1,162 THAs were performed of which 69.1% (803) used navigation while 30.9% (359) did not. Baseline demographics including age, sex, body mass index (BMI), insurance, and smoking status were not statistically different between groups. The operative time was shorter in the navigation group compared to THA without navigation (115.1 vs. 118.9 min, p < 0.0001). Mean LOS was signifi-cantly shorter in the navigation THA group as compared to THA without navigation (2.1 vs. 2.6 days, p < 0.0001). Postoperative AM-PAC scores were higher in the navigation group on postoperative day 1 as compared to patients with-out navigation (18.87 vs. 17.52, p < 0.0001). Additionally, a greater percentage of patients were discharged directly home after THA with navigation as compared to THA without navigation (89.54% vs. 83.57%, p < 0.0001). CONCLUSION: Our study demonstrates that hip navigation technology in the setting of THA is associated with reduced operative times and higher AM-PAC mobilization scores. Hip mini navigation technology shortens operative times while improving early patient outcome scores in association with shorter LOS and greater home-based discharge.

Impact of Selective Posterior Cruciate Ligament Fiber Release on Femoral Rollback in Cruciate-Retaining Total Knee Arthroplasty: A Computational Study.

BACKGROUND: Partial or total release of the posterior cruciate ligament (PCL) is often performed intraoperatively in cruciate-retaining total knee arthroplasty (CR-TKA) to alleviate excessive femoral rollback. However, the effect of the release of selected fibers of the PCL on femoral rollback in CR-TKA is not well understood. Therefore, we used a computational model to quantify the effect of selective PCL fiber releases on femoral rollback in CR-TKA. METHODS: Computational models of 9 cadaveric knees (age: 63 years, range 47 to 79) were virtually implanted with a CR-TKA. Passive flexion was simulated with the PCL retained and after serially releasing each individual fiber of the PCL, starting with the one located most anteriorly and laterally on the femoral notch and finishing with the one located most posteriorly on the medial femoral condyle. The experiment was repeated after releasing only the central PCL fiber. The femoral rollback of each condyle was defined as the anterior-posterior distance between tibiofemoral contact points at 0° and 90° of flexion. RESULTS: Release of the central PCL fiber in combination with the anterolateral (AL) fibers, reduced femoral rollback a median of 1.5 [0.8, 2.1] mm (P = .01) medially and by 2.0 [1.2, 2.5] mm (P = .04) laterally. Releasing the central fiber alone reduced the rollback by 0.7 [0.4, 1.1] mm (P < .01) medially and by 1.0 [0.5, 1.1] mm (P < .01) laterally, accounting for 47 and 50% of the reduction when released in combination with the AL fibers. CONCLUSIONS: Releasing the central fibers of the PCL had the largest impact on reducing femoral rollback, either alone or in combination with the release of the entire AL bundle. Thus, our findings provide clinical guidance regarding the regions of the PCL that surgeons should target to reduce femoral rollback in CR-TKA.

Total knee arthroplasty survivorship and outcomes in young patients: a review of the literature and 40-year update to a longitudinal study.

INTRODUCTION: Growing numbers of younger patients are electing to undergo total knee arthroplasty (TKA) for end-stage osteoarthritis. The purpose of this study was to compare established literature regarding TKA outcomes in patients under age 55, to data from an ongoing longitudinal young patient cohort curated by our study group. Further, we aimed to provide a novel update on survivorship at 40 years post-TKA from our longitudinal cohort. METHODS: A literature search was conducted using the electronic databases PubMed, Embase, and Cochrane Library, using terms related to TKA, patients under age 55, and osteoarthritis. Demographic and outcome data were extracted from all studies that met the inclusion criteria. Data were divided into the "longitudinal study (LS) group," and the "literature review (LR) group" based on the patient population of the study from which it came. RESULTS: After screening, 10 studies met the inclusion criteria; 6 studies comprised the LR group, and 4 studies comprised the LS group. 2613 TKAs were performed among the LR group, and 114 TKAs were longitudinally followed in the LS group. The mean patient ages of the LR and LS groups were 46.1 and 51, respectively. Mean follow-up was 10.1 years for the LR group. Mean postoperative range of motion was 113.6° and 114.5° for the LR and LS groups, respectively. All-cause survivorship reported at 10 years or less ranged from 90.6% to 99.0%. The LS cohort studies reported survivorship ranges of 70.1-70.6% and 52.1-65.3% at 30 and 40 years, respectively. CONCLUSIONS: Young TKA patients demonstrated improved functionality at each follow-up time point assessed. Survivorship decreased with increasing lengths of follow-up, ultimately ranging from 52.1-65.3% at 40 years post-TKA. The paucity of literature on long-term TKA outcomes in this patient population reinforces the necessity of further research on this topic.

An Artificial Intelligence Chatbot is an Accurate and Useful Online Patient Resource Prior to Total Knee Arthroplasty.

BACKGROUND: Online information is a useful resource for patients seeking advice on their orthopaedic care. While traditional websites provide responses to specific frequently asked questions (FAQs), sophisticated artificial intelligence tools may be able to provide the same information to patients in a more accessible manner. Chat Generative Pretrained Transformer (ChatGPT) is a powerful artificial intelligence chatbot that has been shown to effectively draw on its large reserves of information in a conversational context with a user. The purpose of this study was to assess the accuracy and reliability of ChatGPT-generated responses to FAQs regarding total knee arthroplasty. METHODS: We distributed a survey that challenged arthroplasty surgeons to identify which of the 2 responses to FAQs on our institution's website was human-written and which was generated by ChatGPT. All questions were total knee arthroplasty-related. The second portion of the survey investigated the potential to further leverage ChatGPT to assist with translation and accessibility as a means to better meet the needs of our diverse patient population. RESULTS: Surgeons correctly identified the ChatGPT-generated responses 4 out of 10 times on average (range: 0 to 7). No consensus was reached on any of the responses to the FAQs. Additionally, over 90% of our surgeons strongly encouraged the use of ChatGPT to more effectively accommodate the diverse patient populations that seek information from our hospital's online resources. CONCLUSIONS: ChatGPT provided accurate, reliable answers to our website's FAQs. Surgeons also agreed that ChatGPT's ability to provide targeted, language-specific responses to FAQs would be of benefit to our diverse patient population.

The Financial Burden of Aspirin versus Oral Factor Xa Inhibitors for Thromboprophylaxis Following Total Knee Arthroplasty.

BACKGROUND: Aspirin and oral factor Xa inhibitor thromboprophylaxis regimens are associated with similarly low rates of venous thromboembolism following total knee arthroplasty (TKA). However, the rate of prosthetic joint infection (PJI) is lower with aspirin use. This study aimed to compare the cost differential between aspirin and factor Xa inhibitor thromboprophylaxis with respect to PJI management. METHODS: We used previously published rates of PJI following aspirin and factor Xa inhibitor thromboprophylaxis in primary TKA patients at a single, large institution. Prices for individual drugs were obtained from our hospital's pharmacy service. The cost of PJI included that of 2-stage septic revision, with or without the cost of 1-year follow-up. National data were obtained to determine annual projected TKA volume. RESULTS: The per-patient costs associated with a 28-day course of aspirin versus factor Xa inhibitor thromboprophylaxis were $17.36 and $3,784.20, respectively. Including cost of follow-up, per-patient costs for a 28-day course of aspirin versus factor Xa inhibitors increased to $73,358.76 and $77,125.60, respectively. The weighted average per-patient costs for a 28-day course were $237.38 and $4,370.93, respectively. The annual cost difference could amount to over $14.1 billion in the United States by 2040. CONCLUSIONS: The per-patient cost associated with factor Xa inhibitor thromboprophylaxis is as much as 1,980.6% higher than that of an aspirin regimen due to increased costs of primary treatment, differential PJI rates, and high costs of management. In an era of value-based care, the use of aspirin is associated with major cost advantages.

The Use of Computer Navigation and Robotic Technology in Complex Total Hip Arthroplasty.

Computer assisted surgical (CAS) navigation and robotic-assisted total hip arthroplasty (THA) have the potential to improve the reproducibility of accurate component positioning and facilitate complex cases, including revision and preoperative deformity. Numerous studies, including multiple comparing technology with conventional THA control groups, suggest that CAS navigation may improve component accuracy in cases of deformity such as hip dysplasia and significant leg length discrepancy. Revision THA data is also encouraging but limited. The functional benefits compared to conventional techniques remain unclear. The evidence for robot-assisted THA in complex cases is more limited but also demonstrates utility. For complex cases, studies comparing results with conventional THA are not yet available. The limitations of these systems, including cost, operative time, learning curves, and possible complications, require further study. The available data for CAS navigation and robotic-assisted THA indicates that they may play a role in complex deformity and revision cases. Further high-quality randomized studies should be undertaken.

Exposure to Extended Reality and Artificial Intelligence-Based Manifestations: A Primer on the Future of Hip and Knee Arthroplasty.

BACKGROUND: Software-infused services, from robot-assisted and wearable technologies to artificial intelligence (AI)-laden analytics, continue to augment clinical orthopaedics - namely hip and knee arthroplasty. Extended reality (XR) tools, which encompass augmented reality, virtual reality, and mixed reality technology, represent a new frontier for expanding surgical horizons to maximize technical education, expertise, and execution. The purpose of this review is to critically detail and evaluate the recent developments surrounding XR in the field of hip and knee arthroplasty and to address potential future applications as they relate to AI. METHODS: In this narrative review surrounding XR, we discuss (1) definitions, (2) techniques, (3) studies, (4) current applications, and (5) future directions. We highlight XR subsets (augmented reality, virtual reality, and mixed reality) as they relate to AI in the increasingly digitized ecosystem within hip and knee arthroplasty. RESULTS: A narrative review of the XR orthopaedic ecosystem with respect to XR developments is summarized with specific emphasis on hip and knee arthroplasty. The XR as a tool for education, preoperative planning, and surgical execution is discussed with future applications dependent upon AI to potentially obviate the need for robotic assistance and preoperative advanced imaging without sacrificing accuracy. CONCLUSION: In a field where exposure is critical to clinical success, XR represents a novel stand-alone software-infused service that optimizes technical education, execution, and expertise but necessitates integration with AI and previously validated software solutions to offer opportunities that improve surgical precision with or without the use of robotics and computed tomography-based imaging.

Spine or Hip First? Outcomes in Patients Undergoing Sequential Lumbar Spine or Hip Surgery.

BACKGROUND: Lumbar spine pathology frequently coexists in patients who have hip arthrosis. There is controversy on whether lumbar or hip pathology should be first addressed. The purpose of this study was to evaluate the outcomes of sequential lumbar spine (LSP) or hip arthroplasty (THA). METHODS: Using a large national database from 2010 to 2020, we reviewed the records of 241,279 patients who had concurrent hip arthritis and lumbar spine disease defined as spinal stenosis, lumbar radiculopathy, or degenerative disc disease. During the study period, 6,458 (2.7%) patients with concurrent hip/spine disease underwent sequential operative treatment of either the hip joint or lumbar spine within 2 years. The rates of subsequent surgery in either the hip or the spine, opioid requirements, and rates of hip dislocation were determined and analyzed using compared Chi-squared analyses. RESULTS: Patients undergoing THA first had lower risk of subsequent spinal procedure compared to patients who had spinal procedures first (5.7 versus 23.7%, P < .001). This disparity was maintained up to 5 years (P < .001). Opioid requirements at 1 year were highest in patients who underwent spinal procedures only (836 pills/patient) compared to any other group THA only (566 pills/patient), LSP and then THA (564 pills/patient), THA and LSP (586 pills/patient). Also, THA following LSP was associated with significantly higher rates of dislocation compared to patients undergoing THA first (3.2 versus 1.9%, P < .001). CONCLUSION: Total hip arthroplasty first in patients who have concurrent spine disease was associated with lower risk of subsequent surgery, opioid requirement, and risk of postoperative instability compared to patients having lumbar procedure first.

Aspirin Thromboprophylaxis Following Primary Total Knee Arthroplasty Is Associated With a Lower Rate of Early Prosthetic Joint Infection Compared With Other Agents.

BACKGROUND: Patients undergoing total knee arthroplasty (TKA) are at increased risk of venous thromboembolism (VTE). Aspirin has been shown to be effective at reducing rates of VTE. In select patients, more potent thromboprophylaxis is indicated, which has been associated with increased rates of bleeding and wound complications. This study aimed to evaluate the effect of thromboprophylaxis choice on the rates of early prosthetic joint infection (PJI) following TKA. METHODS: A review of 11,547 primary TKA patients from 2013 to 2019 at a single academic orthopaedic hospital was conducted. The primary outcome measure was PJI within 90 days of surgery as measured by Musculoskeletal Infection Society criteria. There were 59 (0.5%) patients diagnosed with early PJI. Chi-square and Welch-2 sample t-tests were used to determine statistically significant relationships between thromboprophylaxis and demographic variables. Significance was set at P < .05. Multivariate logistic regression adjusted for age, body mass index, sex, and Charlson comorbidity index was performed to identify and control for independent risk factors for early PJI. RESULTS: There was a statistically significant difference in the rates of early PJI between the aspirin and non-aspirin group (0.3 versus 0.8%, P < .001). Multivariate logistic regressions revealed that patients given aspirin thromboprophylaxis had significantly lower odds of PJI (odds ratios = 0.51, 95% confidence interval = 0.29-0.89, P = .019) compared to non-aspirin patients. CONCLUSION: The use of aspirin thromboprophylaxis following primary TKA is independently associated with a lower rate of early PJIs. Arthroplasty surgeons should consider aspirin as the gold standard thromboprophylaxis in all patients in which it is deemed medically appropriate and should carefully weigh the morbidity of PJI in patients when non-aspirin thromboprophylaxis is considered. LEVEL OF EVIDENCE: Retrospective, Therapeutic Level III.

Role of non-ASA VTE prophylaxis in risk for manipulation following primary total knee arthroplasty.

INTRODUCTION: Stiffness and decreased range of motion frequently lead to hindrance of activities of daily living and dissatisfaction follow total knee arthroplasty (TKA). This study aims to evaluate the effect of non-aspirin (ASA) chemoprophylaxis and determine patient-related risk factors for stiffness and need for manipulation under anesthesia (MUA) following primary TKA. MATERIALS AND METHODS: A review of all patients undergoing primary TKA from 2013 to 2019 at a single academic orthopedic hospital was conducted. The primary outcome measure was MUA performed post-operatively. Chi-square analysis and Mann-Whitney U test were used to determine statistically significant relationships between risk factors and outcomes. Significance was set at p < 0.05. Univariate logistic regression was performed to control for identified independent risk factors for MUA. RESULTS: A total of 11,550 patients undergoing primary TKA from January 2013 to September 2019 at an academic medical center were included in the study. Increasing age and Charlson Comorbidity Index were associated with statistically significant decreased odds of MUA (0.93, 95% CI: 0.92-0.94, p < 0.001, OR 0.71, 95% CI 0.63-0.79, p < 0.001). Active smokers had a 2.01 increased odds of MUA (OR 2.01, 95% CI 1.28, 3.02, p < 0.001). There was no significant difference in rates of MUA between ASA and non-ASA VTE prophylaxis (p 0.108). CONCLUSIONS: Younger age, lower CCI, and history of smoking are associated with a higher rate, while different chemical VTE prophylaxis does not influence rate of MUA after TKA. Arthroplasty surgeons should consider these risk factors when counseling patient preoperatively. Understanding each patients' risk for MUA allows surgeons to appropriately set preoperative expectations and reasonable outcome goals.

Impact of preoperative opioid use on patient-reported outcomes following primary total knee arthroplasty.

PURPOSE: The previous literature suggests that 25-30% of patients who undergo total knee arthroplasty (TKA) are using opioids prior to their surgery. This study aims to investigate the effect of preoperative opioid use on clinical outcomes and patient-reported outcome measures (PROMs) following TKA. METHODS: We retrospectively reviewed 329 patients who underwent primary TKA from 2019 to 2020, answered the preoperative opioid survey, and had available PROMs. Patients were stratified into two groups based on whether they were taking opioids preoperatively or not: 26 patients with preoperative opioid use (8%) and 303 patients without preoperative opioid use (92%) were identified. Demographics, clinical data, and PROMs [Forgotten Joint Score (FJS-12), Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR), and Veterans RAND-12 Physical and Mental components (VR-12 PCS and MCS)] were collected. Demographic differences were assessed with Chi-square and independent sample t-tests. Outcomes were compared using multilinear regression analysis, controlling for demographic differences. RESULTS: Preoperative opioid users had a significantly longer length-of-stay (2.74 vs. 2.10; p = 0.010), surgical time (124.65 vs. 105.69; p < 0.001), and were more likely to be African-American (38.5 vs. 14.2%; p = 0.010) compared to preoperative opioid-naive patients. Postoperative FJS-12 did not statistically differ between the two groups. While preoperative KOOS, JR scores were significantly lower for preoperative opioid users (41.10 vs. 46.63; p = 0.043), they did not significantly differ postoperatively. Preoperative VR-12 PCS did not statistically differ between the groups; however, both 3-month (33.87 vs. 38.41; p = 0.049) and 1-year (36.01 vs. 44.73; p = 0.043) scores were significantly lower for preoperative opioid users. Preoperative VR-12 MCS was significantly lower for preoperative opioid users (46.06 vs. 51.06; p = 0.049), though not statistically different postoperatively. CONCLUSION: At 8%, our study population had a lower percentage of opioid users than previously reported in the literature. Preoperative opioid users had longer operative times and length of stay compared to preoperatively opioid-naive patients. While both cohorts achieved similar clinical benefits following TKA, preoperative opioid users reported lower postoperative scores with respect to VR-12 PCS scores. LEVEL III EVIDENCE: Retrospective Cohort.

Outcomes of isolated head-liner exchange versus full acetabular component revision in aseptic revision total hip arthroplasty.

INTRODUCTION: Isolated head and liner exchange in aseptic revision total hip arthroplasty (rTHA) is an appealing option rather than full acetabular component revision; however, early outcome reports suggest high rates of complications requiring re-revision. This study seeks to compare the outcomes of these procedures. METHODS: This retrospective study assessed 124 head and liner exchanges and 59 full acetabular cup revisions conducted at a single center between 2011 and 2019 with at least 2 years of follow-up. Baseline demographics did not vary by group. Mean follow-up was 3.7 (range 2.0-8.6) years. RESULTS: In the head and liner exchange group, re-revision-free survivorship at 2 years was 79% for all-causes and 84% for aseptic reasons. In the full acetabular revision group, it was 80% for all causes (p > 0.99) and 83% for aseptic reasons (p > 0.99). The 2-year survivorship of head and liner exchange was non-inferior to that of full acetabular revision, correcting for surgical indication and history of prior revision (adj-OR 0.1.39, 95% CI, 0.62-3.28, p = 0.99). A best-fit multivariable model found that revision for instability (adj-OR=3.03, 95% CI 1.40-6.66, p = 0.005), prior revision (adj-OR 2.15; 95% CI, 0.87-5.32; p = 0.10), current smoking (adj-OR 2.07; 95% CI, 0.94-4.57; p = 0.07), and obesity (adj-OR 0.58; 95% CI, 0.24-1.36; p = 0.22) were associated with failure within 2 years. CONCLUSIONS: In this analysis, 2-year outcomes for isolated head and liner exchange were non-inferior to full acetabular component revision. A future randomised prospective study should be conducted to better assess the optimal approach to revision in an aseptic failed hip arthroplasty.

Indications for Conversion of Spinal into General Anesthesia During Total Joint Arthroplasty.

INTRODUCTION: Spinal anesthesia (SA) is the preferred method of anesthesia at many centers for total joint arthro- plasty (TJA). However, a small subset of patients fails SA, necessitating a conversion to general anesthesia (GA). This report assesses the patient characteristics associated with failed SA. METHODS: A retrospective study was conducted on patients who underwent SA during their primary TJA between Janu- ary 2015 and December 2016 at our institution. A subset of this group required a conversion from SA to GA. Anesthesia reports were reviewed for the number of attempts at SA and the documented reason for failure. The SA failure cohort was then subdivided into failure categories based on the reasons that had been provided. RESULTS: A total of 5,706 patients were included in this study, 78 of which experienced SA failure. The number of attempts was most strongly associated with SA failure, with three attempts resulting in a five times increased failure rate (OR = 4.73, p = 0.010) and four attempts resulting in 12 times increased failure rate compared to the no failure cohort (OR = 12.3, p < 0.001). Greater than two attempts occurred in 87.5% of the "technical failure" sub-group of the SA failure cohort (p < 0.001). No difference was demon- strated among the other patient characteristics, such as age, sex, body mass index, race, American Society of Anesthesia (ASA) score, and surgical time. CONCLUSIONS: The results suggest that the major predic- tor influencing spinal to general anesthesia conversion was the number of attempts at SA, especially among technical failure cases. Based on the results, it may be appropriate for anesthesiologists to convert to GA after two failed spi- nal attempts. Further studies are warranted to assess this relationship for firm clinical recommendations.

The Effects of Patient Point of Entry and Medicaid Status on Postoperative Opioid Consumption and Pain After Primary Total Hip Arthroplasty.

INTRODUCTION: Medicaid expansion has allowed more patients to undergo total hip arthroplasty (THA). Given the continued focus on the opioid epidemic, we sought to determine whether patients with Medicaid insurance differed in their postoperative pain and narcotic requirements compared with privately or Medicare-insured patients. METHODS: A single-institution database was used to identify adult patients who underwent elective THA between 2016 and 2019. Patients in the Medicaid group received Medicaid insurance, while the non-Medicaid group was insured commercially or through Medicare. Subgroup analysis was done, separating the private pay from Medicare patients. RESULTS: A total of 5,845 cases were identified: 326 Medicaid (5.6%) and 5,519 non-Medicaid (94.4%). Two thousand six hundred thirty-five of the non-Medicaid group were insured by private payors. Medicaid patients were younger (56.1 versus 63.28 versus 57.4 years; P < 0.001, P < 0.05), less likely to be White (39.1% versus 78.2% versus 76.2%; P < 0.001), and more likely to be active smokers (21.6% versus 8.8% versus 10.5%; P < 0.001). Surgical time (113 versus 96 versus 98 mins; P < 0.001) and length of stay (2.7 versus 1.7 versus 1.4 days; P < 0.001) were longer for Medicaid patients, with lower home discharge (86.5% versus 91.8% versus 97.2%; P < 0.001). Total opioid consumption (178 morphine milligram equivalents [MMEs] versus 89 MME versus 82 MME; P < 0.001) and average MME/day in the first 24 hours and 24 to 48 hours (52.3 versus 44.7 versus 44.45; P < 0.001 and 73.8 versus 28.4 versus 29.8; P < 0.001) were higher for Medicaid patients. This paralleled higher pain scores (2.71 versus 2.31 versus 2.38; P < 0.001) and lower Activity Measure for Post-Acute Care scores (18.77 versus 20.98 versus 21.61; P < 0.001). CONCLUSIONS: Medicaid patients presenting for THA demonstrated worse postoperative pain and required more opioids than their non-Medicaid counterparts. This highlights the need for preoperative counseling and optimization in this at-risk population. These patients may benefit from multidisciplinary intervention to ensure that pain is controlled while mitigating the risk of continuation to long-term opioid use.

Increased Rate of Early Periprosthetic Joint Infection in Total Hip Arthroplasty With the Use of Alternatives to Cefazolin Despite Additional Gram-Negative Coverage.

Background: Periprosthetic joint infection (PJI) remains one of the most devastating complications following total joint arthroplasty. Appropriate prophylactic antimicrobial administration and antibiotic stewardship are major factors impacting the risk of PJI in total hip arthroplasty (THA). The purpose of our study was to evaluate whether cefazolin administration was superior to noncefazolin antibiotics in prevention of PJI after primary THA. Material and methods: A review of 9910 patients undergoing primary THA from 2013 to 2019 at a single institution was conducted. The primary outcome was PJI within 90 days of surgery. The Musculoskeletal Infection Society definition of PJI was used for this analysis. Groups were those receiving cefazolin + expanded gram-negative antimicrobial prophylaxis (EGNAP) and those receiving an alternative to cefazolin + EGNAP. Chi-square tests were conducted to determine statistical significance. Multivariate logistic regression was performed to eliminate confounders. Results: 9028 patients received cefazolin + EGNAP, and 882 patients received an alternative to cefazolin + EGNAP. PJI rate using the Musculoskeletal Infection Society criteria was 0.82% (81/9910). PJI rate in the cefazolin + EGNAP group was 0.75% (68/9028). In the group receiving an alternative to cefazolin + EGNAP, the PJI rate was 1.47% (13/882). This difference was statistically significant (P = .023). On multivariate analysis, the odds ratio for developing PJI when an alternative to cefazolin was used was 2.05 (P = .022). When comparing alternatives, there remained a statistically significant increased PJI rate when the alternative used was clindamycin (odds ratio 2.65, P = .007). Conclusion: Our data demonstrate that in the presence of EGNAP in THA, there was a higher PJI rate when clindamycin was given as an alternative to cefazolin. The number of THA patients receiving alternatives to cefazolin must be minimized. Level of Evidence: III, Retrospective Cohort Study.

Increased Rates of Tibial Aseptic Loosening in Primary Cemented Total Knee Arthroplasty With a Short Native Tibial Stem Design.

BACKGROUND: Emerging evidence has suggested that both obesity and a short, native tibial stem (TS) design may be associated with early aseptic loosening in total knee arthroplasty. The use of short, fully cemented stem extensions may mitigate this risk. As such, we devised a multicenter study to confirm or negate these claims. METHODS: A search of our institutional research databases was done. A minimum 2-year time from index procedure was selected. Cohorts were created according to patient body mass index and the presence (stemmed tibia [ST]) or absence (nonstemmed tibia [NST]) of a short TS extension. Kaplan-Meier survival analyses for aseptic loosening and log-rank tests were done. RESULTS: A total of 1,350 patients were identified (ST = 500, NST = 850). The mean time to the final follow-up in cases without aseptic loosening for the ST cohort was 3.5 years (2.8-6.3) and 5.0 years (2.9-6.3) for the NST cohort (P < 0.001). Kaplan-Meier survival analysis at 6 years was superior for the ST cohort (100%, 98.5%; P = 0.025), and a trend toward superior 5-year survival was observed for body mass index <40 kg/m2 (99.1%, 93.2%; P = 0.066). The mean time to aseptic loosening was 2.4 years (0.9-4.5), with approximately 40% occurring within the first 2 years. CONCLUSIONS: Short, native TS design is associated with early aseptic loosening in primary cemented total knee arthroplasty. This can be mitigated through the use of an ST. More cost-effective solutions include (1) use of implants with longer native stem designs or (2) redesign of short TS implants.

A Novel Machine Learning Predictive Tool Assessing Outpatient or Inpatient Designation for Medicare Patients Undergoing Total Knee Arthroplasty.

BACKGROUND: Removal of total joint arthroplasty from the inpatient-only list has created significant confusion regarding which patients qualify for an inpatient designation. The purpose of this study is to develop and validate a novel predictive tool for assessing who will be an outpatient vs inpatient after total knee arthroplasty (TKA). METHODS: A cohort of Medicare patients undergoing primary TKA between January 2018 and September 2019 were retrospectively reviewed. Baseline demographics and patient characteristics were obtained, and their distributions for outpatient (less than 2 midnights) and inpatient stay were assessed. Subsequently, a XGBoost machine learning model was trained using 80% of the TKA patients, and the remaining 20% of patients were involved in testing the model's performance in terms of accuracy and the average area under the receive operating characteristic curve. RESULTS: Eight hundred ninety-nine Medicare patients underwent TKA at our institution between January 2018 and September 2019. Of which, 625 patients had outpatients stays, and 274 qualified for inpatient designation. Significant associations were demonstrated between inpatient visits and the following factors: higher body mass index, increased age, better functional scores, multidimensional fatigue inventory, Charlson Comorbidity Index, American Society of Anesthesiologists score, female gender, cardiac history, and the Revised Cardiac Risk Index. The XGBoost model for predicting an inpatient or outpatient stay was 63.3% accurate, with area under the receive operating characteristic curve of 68.8%. CONCLUSIONS: Using readily available key baseline characteristics, functional scores, and comorbidities, this machine-learning model accurately predicts the probability of an "outpatient" vs "inpatient" stay after TKA in the Medicare population. body mass index, age, VR12 functional scores, and multidimensional fatigue inventory scores had the highest influence on this predictive model.

Cefazolin remains the linchpin for preventing acute periprosthetic joint infection following primary total knee arthroplasty.

AIMS: Despite recent literature questioning their use, vancomycin and clindamycin often substitute cefazolin as the preoperative antibiotic prophylaxis in primary total knee arthroplasty (TKA), especially in the setting of documented allergy to penicillin. Topical povidone-iodine lavage and vancomycin powder (VIP) are adjuncts that may further broaden antimicrobial coverage, and have shown some promise in recent investigations. The purpose of this study, therefore, is to compare the risk of acute periprosthetic joint infection (PJI) in primary TKA patients who received cefazolin and VIP to those who received a non-cephalosporin alternative and VIP. METHODS: This was a retrospective cohort study of 11,550 primary TKAs performed at an orthopaedic hospital between 2013 and 2019. The primary outcome was PJI occurring within 90 days of surgery. Patients were stratified into two groups (cefazolin vs non-cephalosporin) based on their preoperative antibiotic. All patients also received the VIP protocol at wound closure. Bivariate and multiple logistic regression analyses were performed to control for potential confounders and identify the odds ratio of PJI. RESULTS: In all, 10,484 knees (90.8%) received cefazolin, while 1,066 knees (9.2%) received a non-cephalosporin agent (either vancomycin or clindamycin) as preoperative prophylaxis. The rate of PJI in the cefazolin group (0.5%; 48/10,484) was significantly lower than the rate of PJI in the non-cephalosporin group (1.0%; 11/1,066) (p = 0.012). After controlling for confounding variables, the odds ratio (OR) of developing a PJI was increased in the non-cephalosporin cohort compared to the cefazolin cohort (OR 2.389; 1.2 to 4.6); p = 0.01). CONCLUSION: Despite the use of topical irrigant solutions and addition of local antimicrobial agents, the use of a non-cephalosporin perioperative antibiotic continues to be associated with a greater risk of TKA PJI compared to cefazolin. Strategies that increase the proportion of patients receiving cefazolin rather than non-cephalosporin alternatives must be emphasized. Cite this article: Bone Jt Open 2022;3(1):35-41.

Inaccuracy of the intramedullary femoral guide: traditional instrumentation lacks precision and accuracy.

PURPOSE: The purpose of the study was to utilize a large-scale biomorphometric computer tomography (CT) database to determine the desirable starting point and angle for placement of the femoral intramedullary rod in the sagittal plane. METHODS: A CT-based modeling and analytics system (SOMA, Stryker, Mahwah, NJ) was used to evaluate 1029 entire-femur CT scans. From this, 19,464 simulations were run to test whether a 20 cm intramedullary rod, with a radius of 4 mm, would successfully pass through the femoral canal before contacting cortical bone. First, modelling included varying angles from 0-6 degrees in the sagittal plane, at 1-degree intervals. Next, the start point was adjusted with an assumed 3 degrees of induced flexion in comparison to the mechanical axis. RESULTS: A total of 5012 simulations were able to place the femoral intramedullary rod 20 cm into the canal. The angle of the rod that created the highest proportion of successful jig placement was at a 3-degree angle of induced flexion to the orthogonal plane of the transepicondylar axis (TEA), with 33.7% successful jig placements. The starting point for the greatest proportion of successful guide placements was 48.5% along the distance between the sTEA, slightly closer to the lateral side. In the AP plane, the average distance to the ideal start point was 12.1 mm anterior to the PCL. CONCLUSION: By examining over a thousand femoral CT scans, an angle of 3 degrees of induced flexion was identified in the sagittal plane with the highest proportion of successful placement of an intramedullary rod before cortical contact. It is important to note the high rate of failure in completely inserting the 20 mm rod. LEVEL OF EVIDENCE: This is a prospective computer based model.