Unsuspected Positive Intraoperative Cultures in Aseptic Revision Knee Arthroplasty: Prevalence, Management, and Infection-Free Survivorship.

BACKGROUND: The purpose of this study was to evaluate the management and outcomes of aseptic revision total knee arthroplasty (arTKA) with unsuspected positive cultures (UPCs) compared to those with sterile cultures. METHODS: The institutional database at a single tertiary center was retrospectively reviewed for arTKA from January 2013 to October 2023. Patients who met Musculoskeletal Infection Society criteria for periprosthetic joint infection (PJI) based on available preoperative infectious workup, received antibiotic spacers, or did not have at least 1 year of follow-up were excluded. Patients were stratified based on intraoperative cultures into 4 cohorts: sterile cultures, 1 UPC, ≥ 2 UPCs with different organisms, and ≥ 2 UPCs with the same organism. Univariable analyses were used to compare these groups. Kaplan-Meier survivorship analysis assessed infection-free survival at 5 years, and Cox proportional hazards regressions were used to evaluate factors that influence infection-free survival. A total of 691 arTKAs at a mean follow-up of 4.2 years were included in the study. Of these, 49 (7.1%) had 1 UPC with a new organism, 10 (1.4%) had ≥2 UPCs of the same organism, and 2 (0.2%) had ≥2 UPCs with different organisms. RESULTS: Postoperative antibiotics were prescribed to 114 (16.5%) patients-13 (26.5%) with 1 UPC, 6 (60.0%) with ≥2 UPCs of the same organism, and 0 (0.0%) of patients who had ≥2 UPCs of different organisms. There were no differences in infection-free survival at 5 years between patients who had sterile cultures and 1 UPC (96 versus 89%; P = .39) nor between sterile cultures and ≥2 UPCs of different organisms (96 versus 100%; P < .72). However, patients who had ≥2 UPCs of the same organism had significantly worse infection-free survival at 5 years compared to patients who had sterile cultures (58 versus 96%; P < .001). Cox proportional hazards regression suggested that when adjusting for covariates, an American Society of Anesthesiologists classification of ≥3 (hazard ratio [HR] = 3.1; P = .007), ≥2 UPCs of the same organism (HR = 11.0; P < .001), 1 UPC (HR = 4.2; P = .018), and arTKA with hinge constructs (HR = 4.1; P = .008) were associated with increased risk of rerevision for PJI. CONCLUSIONS: Patients who had 1 UPC or ≥2 UPCs with different organisms had similar infection-free survival at 5 years as patients who had sterile cultures. However, patients who had ≥2 UPCs of the same organism had significantly worse infection-free survival at 5 years. Overall, 1 UPC or ≥2 UPCs of the same organism at the time of arTKA may suggest the patient is at higher risk of rerevision for PJI. More studies are needed to determine what interventions can be implemented to mitigate this risk.

Comparing a robotic imageless second-generation system to traditional instrumentation in total knee arthroplasty: A matched cohort analysis.

Introduction: Robotic-assisted total knee arthroplasty (rTKA) has gained interest from patients and surgeons alike. Robotic systems assist with gap balancing and bone cut accuracy, which can theoretically minimize post-operative pain by decreasing soft tissue damage. This study compared perioperative results, 30- and 90-day complications, patient-reported outcomes (PROs), and survivorship to all-cause revisions between patients undergoing traditional versus rTKA. Methods: A total of 430 TKAs (215 rTKA, 215 traditional) by two fellowship trained arthroplasty surgeons were retrospectively reviewed from 2017 to 2022. All rTKAs were performed using the CORI Surgical System (Smith & Nephew, Memphis, Tennessee). Cohorts were propensity score matched by age, sex, body mass index, and American Society of Anesthesiologist classification. Blood loss, surgical times, length of stays, 30- and 90-day complications, pain scores and PROs were compared with univariable analyses. Cox regression analyses evaluated survival to all-cause revisions. Results: Patients undergoing rTKA had a higher incidence of discharge home (86.5 %-60.0 %) (p < 0.01). There was no difference in blood loss or surgical time. rTKA pain scores were lower in-hospital mean 2 (range, 0 to 9) vs 3 (range, 0 to 9) (p = 0.02) as well as at one-year post-operatively, mean 1 (range, 0 to 7) vs 2 (range, 0 to 10) (p = 0.02). Cox hazard ratio demonstrated no difference in survival to all-cause revisions (HR 1.3; CI 0.5 to 3.7) (p = 0.64). Conclusion: This matched cohort analysis demonstrated potential short-term benefits associated with imageless second generation rTKA including improved early post-operative pain, without compromising survivorship to all-cause revisions.

Continuing Home Oral Hypoglycemic Medications Was Associated With Superior Postoperative Glycemic Control Versus Initiating Sliding Scale Insulin After Total Hip Arthroplasty.

BACKGROUND: This retrospective study investigated the impact of continuing vs discontinuing home oral hypoglycemic medications for patients with diabetes undergoing total hip arthroplasty. MATERIALS AND METHODS: Patients who were not exclusively receiving home oral hypoglycemic regimens were excluded. Additionally, patients whose diabetes was not managed inpatient postoperatively were excluded. Included patients were retrospectively evaluated for early postoperative glycemic control, renal function, and metabolic abnormalities. Patients were then compared based on whether their home oral hypoglycemic regimen was continued vs discontinued in favor of initiating insulin while inpatient and analyzed using multivariable regression analysis. RESULTS: A total of 532 patients undergoing total hip arthroplasty met inclusion criteria, with 78.6% continuing their home oral hypoglycemic regimen. Those who continued showed significantly lower median maximum inpatient blood glucose (178.5 mg/dL vs 249.5 mg/dL; P<.001) and median average inpatient blood glucose (138.4 mg/dL vs 178.6 mg/dL; P<.001). Linear regression analysis, adjusting for various potential confounding factors, revealed a positive correlation between discontinuation of home hypoglycemic medications and higher maximum in-patient blood glucose (ß=70.15 [95% CI, 59.27-81.03]; P<.001). Patients in the continuation group had lower proportions of acute kidney injury (18.7% vs 41.2%; P<.001) and metabolic acidosis (4.3% vs 17.5%; P<.001), along with a shorter length of stay (1.0 d vs 2.0 d; P<.001). CONCLUSION: These findings suggest that continuing a home oral hypoglycemic regimen for patients with diabetes after total hip arthroplasty is associated with superior glycemic control without exacerbating renal abnormalities or increasing metabolic complications. [Orthopedics. 202x;4x(x):xx-xx.].

Defining Distinct Stress Curve Morphologies for Coronal Plane Alignment of the Knee Phenotypes Using an Imageless Navigation Robotic Platform in Total Knee Arthroplasty.

BACKGROUND: The coronal plane alignment of the knee (CPAK) classification system divides coronal knee anatomy into 9 phenotypes, suggesting different soft tissue balancing is needed for optimal outcomes. We investigated the interplay between CPAK phenotypes and gap stress curves throughout the knee's range of motion, aiming to understand their impact on total knee arthroplasty balancing. METHODS: There were 1,112 total knee arthroplasty cases from 2 imageless robotic assisted navigation systems using posterior stabilized implants that were classified into CPAK phenotypes. Medial and lateral initial gap values were measured throughout the knee flexion-extension arc, gap curve morphologies were generated, and mediolateral (ML) gap balance was calculated for each phenotype. The most common phenotypes were included in this study, CPAK I to VI. RESULTS: Each phenotype exhibited a distinct gap curve morphology. Type I maintained the largest ML gap difference (-3.6 to -2.1), with the medial compartment tightest in extension. Type II showed relative laxity in the lateral compartment compared to the medial gap (-1.0 to -1.9), with the medial compartment tightening through flexion. Type III had a looser medial and tighter lateral compartment in extension that inverts to a tighter medial compartment in deep flexion (2.1 to -0.8), while Type IV showed a decreasing compartment difference with increased flexion (-3.7 to 0.6). Type V had fluctuating tightness (-0.6 to 1.8), and Type VI had the medial compartment tightening more with flexion (0.6 to 1.8). CONCLUSIONS: The distinct stress curves and ML gap behavior provide a "fingerprint" for each corresponding CPAK phenotype. Investigating these morphologies can help determine the best phenotype-specific treatments, including alignment strategy, implant selection, and gap balance, for optimal functional and patient outcomes.

Validation of a Discharge Risk Calculator for Rural Patients Following Total Joint Arthroplasty.

INTRODUCTION: As the volume of total joint arthroplasty (TJA) in the US continues to grow, new challenges surrounding appropriate discharge surface. Arthroplasty literature has demonstrated discharge disposition to post-acute care facilities carries major risks regarding the need for revision surgery, patient co-morbidities, and financial burden. To quantify, categorize, and mitigaterisks, a decision tool that uses preoperative patient variables has previously been published and validated using an urban patient population. The aim of our investigation was to validate the same predictive model using patients in a rural setting undergoing total knee arthroplasty (TKA) and total hip arthroplasty (THA). METHODS: All TKA and THA procedures that were performed between January 2012 and September 2022 at our institution were collected. A total of 9,477 cases (39.6% TKA, 60.4% THA) were included for the validation analysis. There were nine preoperative variables that were extracted in an automated fashion from the electronic medical record. Included patients were then run through the predictive model, generating a risk score representing that patient's differential risk of discharge to a skilled nursing facility (SNF) versus home. Overall accuracy, sensitivity and specificity were calculated after obtaining risk scores. RESULTS: Score cutoff equally maximizing sensitivity and specificity was 0.23, and the proportion of correct classifications by the predictive tool in this study population was found to be 0.723, with an area under the curve (AUC) of 0.788-both higher than previously published accuracy levels. With the threshold of 0.23, sensitivity and specificity were found to be 0.720 and 0.723, respectively. CONCLUSION: The risk calculator showed very good accuracy, sensitivity, and specificity in predicting discharge location for rural patients undergoing TKA and THA, with accuracy even higher than in urban populations. The model provides an easy-to-use interface, with automation representing a viable tool in helping with shared decision-making regarding postoperative discharge plans.

Risk Factors of Failure to Discharge Before "Two Midnights" in Outpatient-Designated Total Hip Arthroplasty.

INTRODUCTION: The Centers for Medicare and Medicaid Services removed total hip arthroplasty (THA) from the inpatient-only list but continued to classify admissions as inpatient if they include two midnights, complicating care if an outpatient THA requires extended hospitalization. This study evaluates risk factors of patients undergoing outpatient-designated THA with a length of stay (LOS) ≥ 2 days. METHODS: A total of 17,063 THA procedures designated as outpatient in the National Surgical Quality Improvement Program database between 2015 and 2020 were stratified by LOS < 2 days (n = 2,294, 13.4%) and LOS ≥ 2 days (n = 14,765, 86.6%). Demographics, comorbidities, and outcomes were compared by univariate analysis. Multivariable regression analysis identified predictors of LOS ≥ 2 days. RESULTS: Outpatients with extended LOS were older (mean 65.3 vs. 63.5 years; P < 0.01); were more likely to have body mass index (BMI) > 35 (24.0 vs. 17.8%; P < 0.01); and had higher incidences of smoking (15.1% vs. 10.3%; P < 0.01), diabetes (15.4% vs. 9.9%; P < 0.01), chronic obstructive pulmonary disease (4.4% vs. 2.3%; P < 0.01), and hypertension (57.6% vs. 49.2%; P < 0.01). Patients with LOS ≥ 2 days had a higher incidence of surgical site infection (P < 0.01), hospital readmission (P < 0.01), and revision surgery (P < 0.01) over 30 days. Multivariable analysis demonstrated advanced age, female sex, African American race, Hispanic ethnicity, diabetes, smoking, and hypertension were independent risk factors for LOS ≥ 2 days. CONCLUSION: Despite removal from the inpatient-only list, a subset of outpatient THA remains at risk of an extended LOS. This study informs surgeons on the relevant risk factors of extended stay, enabling early inpatient preauthorization.

The relationship between pseudotumours and infected complications in patients who have undergone metal-on-metal total hip arthroplasty.

Aims: This study aims to assess the relationship between history of pseudotumour formation secondary to metal-on-metal (MoM) implants and periprosthetic joint infection (PJI) rate, as well as establish ESR and CRP thresholds that are suggestive of infection in these patients. We hypothesized that patients with a pseudotumour were at increased risk of infection. Methods: A total of 1,171 total hip arthroplasty (THA) patients with MoM articulations from August 2000 to March 2014 were retrospectively identified. Of those, 328 patients underwent metal artefact reduction sequence MRI and had minimum two years' clinical follow-up, and met our inclusion criteria. Data collected included demographic details, surgical indication, laterality, implants used, history of pseudotumour, and their corresponding preoperative ESR (mm/hr) and CRP (mg/dl) levels. Multivariate logistic regression modelling was used to evaluate PJI and history of pseudotumour, and receiver operating characteristic curves were created to assess the diagnostic capabilities of ESR and CRP to determine the presence of infection in patients undergoing revision surgery. Results: The rate of PJI for all identified MoM THAs was 3.5% (41/1,171), with a mean follow-up of 10.9 years (2.0 to 20.4). Of the patients included in the final cohort, 8.2% (27/328) had PJI, with a mean follow-up of 12.2 years (2.3 to 20.4). Among this cohort, 31.1% (102/328) had a history of pseudotumour. The rate of PJI in these patients was 14.7% (15/102), which was greater than those without pseudotumour, 5.3% (12/226) (p = 0.008). Additionally, logistic regression analysis showed an association between history of pseudotumour and PJI (odds ratio 4.36 (95% confidence interval 1.77 to 11.3); p = 0.002). Optimal diagnostic cutoffs for PJI in patients with history of pseudotumour versus those without were 33.1 mm/hr and 24.5 mm/hr for ESR and 7.37 mg/dl and 1.88 mg/dl for CRP, respectively. Conclusion: Patients with history of pseudotumour secondary to MoM THA had a higher likelihood of infection than those without. While suspicion of infection should be high for these patients, ESR and CRP cutoffs published by the European Bone and Joint Infection Society may not be appropriate for patients with a history of pseudotumour, as ESR and CRP levels suggestive of PJI are likely to be higher than for those without a pseudotumour. Additional investigation, such as aspiration, is highly recommended for these patients unless clinical suspicion and laboratory markers are low.

The Removal of Total Knee Arthroplasty From the Inpatient-Only List has Improved Patient Optimization.

INTRODUCTION: On January 1, 2018, the Centers for Medicare and Medicaid Services removed total knee arthroplasty (TKA) from the inpatient-only (IPO) list, expanding outpatient TKA (oTKA) to include patients with insurance coverage through their programs. These regulatory changes reinforced the need for preoperative optimization to ensure a safe and timely discharge after surgery. This study compared modifiable preoperative optimization metrics in patients who underwent oTKA pre-IPO and post-IPO removal. The authors hypothesized that patients post-IPO removal would demonstrate improvement in the selected categories. METHODS: Outpatient TKA in a national database was identified and stratified by surgical year (2015 to 2017 versus 2018 to 2020). Preoperative optimization thresholds were established for the following modifiable risk factors: albumin, hematocrit, sodium, smoking, and body mass index. The percentage of patients who did not meet thresholds pre-IPO and post-IPO removal were compared. RESULTS: In total, 2,074 patients underwent oTKA from 2015 to 2017 compared with 46,480 from 2018 to 2020. Patients undergoing oTKA after IPO removal were significantly older (67.0 versus 64.4 years; P < 0.01). A lower percentage of patients in the post-IPO cohort fell outside the threshold for all modifiable risk factors. Results were significant for preoperative sodium (10.7% versus 8.8%; P < 0.01), body mass index (12.4% versus 11.0% P = 0.05), and smoking history (9.9% versus 6.6%; P < 0.01). CONCLUSION: Outpatient TKA has increased considerably post-IPO removal. As this regulatory change has allowed older patients with increased comorbidities to undergo oTKA, the need for appropriate preoperative optimization has increased. The current data set demonstrates that surgeons have improved preoperative optimization efforts for select modifiable risk factors.

Subsequent total joint arthroplasty: Are we learning from the first stage?

BACKGROUND: With the increasing incidence of total joint arthroplasty (TJA), there is a desire to reduce peri-operative complications and resource utilization. As degenerative conditions progress in multiple joints, many patients undergo multiple procedures. AIM: To determine if both physicians and patients learn from the patient's initial arthroplasty, resulting in improved outcomes following the second procedure. METHODS: The institutional database was retrospectively queried for primary total hip arthroplasty (THA) and total knee arthroplasty (TKA). Patients with only unilateral THA or TKA, and patients undergoing same-day bilateral TJA, were excluded. Patient demographics, comorbidities, and implant sizes were collected at the time of each procedure and patients were stratified by first vs second surgery. Outcome metrics evaluated included operative time, length of stay (LOS), disposition, 90-d readmissions and emergency department (ED) visits. RESULTS: A total of 642 patients, including 364 undergoing staged bilateral TKA and 278 undergoing bilateral THA, were analyzed. There was no significant difference in demographics or comorbidities between the first and second procedure, which were separated by a mean of 285 d. For THA and TKA, LOS was significantly less for the second surgery, with 66% of patients having a shorter hospitalization (P < 0.001). THA patients had significantly decreased operative time only when the same sized implant was utilized (P = 0.025). The vast majority (93.3%) of patients were discharged to the same type of location following their second surgery. However, when a change in disposition was present from the first surgery, patients were significantly more likely to be discharged to home after the second procedure (P = 0.033). There was no difference between procedures for post-operative readmissions (P = 0.438) or ED visits (P = 0.915). CONCLUSION: After gaining valuable experience recovering from the initial surgery, a patient's perioperative outcomes are improved for their second TJA. This may be the result of increased confidence and decreased anxiety, and it supports the theory that enhanced patient education pre-operatively may improve outcomes. For the surgical team, the second procedure of a staged THA is more efficient, although this finding did not hold for TKA.

Total Joint Arthroplasty Is a Viable Treatment Option for Patients With Osteonecrosis and Osteoarthritis After Bone Marrow Transplantation.

Background: Long-term survival in patients who receive bone marrow transplantation (BMT) is increasing. However, osteonecrosis and secondary osteoarthritis (OA) of the hip and knee are common complications in this population due to post-transplant steroid treatment to prevent graft vs host disease. The purpose of this study was to evaluate the outcomes of total joint arthroplasty (TJA) in patients with prior BMT and compare them to those of patients undergoing TJA for primary OA. Methods: Patients with a history of BMT undergoing primary TJA from 2013 to 2021 were retrospectively reviewed. Patients were matched 1:1 by surgical site, sex, age, body mass index, American Society of Anesthesiologists score, and Elixhauser Comorbidity Index to patients undergoing TJA for primary OA. Demographics, intraoperative blood loss, perioperative transfusion requirements, hospital length of stay, 90-day emergency department visits and readmissions, all-cause revisions, and 2-year mortality were compared between cohorts. Results: There were 17 patients undergoing total knee arthroplasty (TKA) after BMT (TKA-BMT) and 43 patients undergoing total hip arthroplasty (THA) after BMT (THA-BMT). More TKA-BMT and THA-BMT patients were immunosuppressed preoperatively compared to 17 matched TKA-OA and 43 THA-OA patients (P = .018 and P < .001). There were no other significant perioperative differences between BMT and OA groups. Two-year patient and implant survivorship for TKA-BMT and THA-BMT patients were high and not statistically different from TKA-OA and THA-OA cohorts. Conclusions: TJA after BMT provides satisfactory perioperative and short-term outcomes and is a viable treatment option for patients with osteonecrosis and secondary OA after BMT treatment.

Chondrocyte Invasion May Be a Mechanism for Persistent Staphylococcus Aureus Infection In Vitro.

BACKGROUND: Recurrent bone and joint infection with Staphylococcus aureus is common. S. aureus can invade and persist in osteoblasts and fibroblasts, but little is known about this mechanism in chondrocytes. If S. aureus were able to invade and persist within chondrocytes, this could be a difficult compartment to treat. QUESTION/PURPOSE: Can S. aureus infiltrate and persist intracellularly within chondrocytes in vitro? METHODS: Cell lines were cultured in vitro and infected with S. aureus. Human chondrocytes (C20A4) were compared with positive controls of human osteoblasts (MG63) and mouse fibroblasts (NIH3T3), which have previously demonstrated S. aureus invasion and persistence (human fibroblasts were not available to us). Six replicates per cell type were followed for 6 days after infection. Cells were treated daily with antibiotic media for extracellular killing. To determine whether S. aureus can infiltrate chondrocytes, fluorescence microscopy was performed to qualitatively assess the presence of intracellular bacteria, and intracellular colony-forming units (CFU) were enumerated 2 hours after infection. To determine whether S. aureus can persist within chondrocytes, intracellular CFUs were enumerated from infected host cells each day postinfection. RESULTS: S. aureus invaded human chondrocytes (C20A4) at a level (2.8 x 105 ± 5.5 x 104 CFUs/mL) greater than positive controls of human osteoblasts (MG63) (9.5 x 102 ± 2.5 x 102 CFUs/mL; p = 0.01) and mouse fibroblasts (NIH3T3) (9.1 x 104 ± 2.5 x 104 CFUs/mL; p = 0.02). S. aureus also persisted within human chondrocytes (C20A4) for 6 days at a level (1.4 x 103 ± 5.3 x 102 CFUs/mL) greater than that of human osteoblasts (MG63) (4.3 x 102 ± 3.5 x 101 CFUs/mL; p = 0.02) and mouse fibroblasts (NIH3T3) (0 CFUs/mL; p < 0.01). S. aureus was undetectable within mouse fibroblasts (NIH3T3) after 4 days. There were 0 CFUs yielded from cell media, confirming extracellular antibiotic treatment was effective. CONCLUSION: S. aureus readily invaded human chondrocytes (C20A4) in vitro and persisted viably for 6 days after infection, evading extracellular antibiotics. Chondrocytes demonstrated a greater level of intracellular invasion and persistence by S. aureus than positive control human osteoblast (MG63) and mouse fibroblast (NIH3T3) cell lines. CLINICAL RELEVANCE: Chondrocyte invasion and persistence may contribute to recurrent bone and joint infections. Additional research should assess longer periods of persistence and whether this mechanism is present in vivo.

Continuation of Oral Antidiabetic Medications Was Associated With Better Early Postoperative Blood Glucose Control Compared to Sliding Scale Insulin After Total Knee Arthroplasty.

BACKGROUND: This study evaluated blood glucose (BG), creatinine levels, metabolic issues, length of stay (LOS), and early postoperative complications in diabetic primary total knee arthroplasty (TKA) patients. It examined those who continued home oral antidiabetic medications and those who switched to insulin postoperatively. The hypothesis was that continuing home medications would lead to lower BG levels without metabolic abnormalities. METHODS: Patients who had diabetes who underwent primary TKA from 2013 to 2022 were evaluated retrospectively. Diabetic patients who were not on home oral antidiabetic medications or who were not managed as an inpatient postoperatively were excluded. Patient demographics and laboratory tests collected preoperatively and postoperatively as well as 90-day emergency department visits and 90-day readmissions, were pulled from electronic records. Patients were grouped based on inpatient diabetes management: continuation of home medications versus new insulin coverage. Acute postoperative BG control, creatinine levels, metabolic abnormalities, LOS, and early postoperative complications were compared between groups. Multivariable regression analyses were performed to measure associations. RESULTS: A total of 867 primary TKAs were assessed; 703 (81.1%) patients continued their home oral antidiabetic medications. Continuing home antidiabetic medications demonstrated lower median maximum inpatient BG (180.0 mg/dL versus 250.0 mg/dL; P < .001) and median average inpatient BG (136.7 mg/dL versus 173.7 mg/dL; P < .001). Logistic regression analyses supported the presence of an association (odds ratio = 17.88 [8.66, 43.43]; P < .001). Proportions of acute kidney injury (13.5 versus 26.7%; P < .001) were also lower. There was no difference in relative proportions of metabolic acidosis (4.4 versus 3.7%; P = .831), LOS (2.0 versus 2.0 days; P = .259), or early postoperative complications. CONCLUSIONS: Continuing home oral antidiabetic medications after primary TKA was associated with lower BG levels without an associated worsening creatinine or increase in metabolic acidosis. LEVEL III EVIDENCE: Retrospective Cohort Study.

Patient Perceptions and Interest in Robotic-Assisted Total Joint Arthroplasty.

Background: Robotic-assisted total joint arthroplasty (rTJA) has growing interest among patients and surgeons. However, patient interest in and perceptions of rTJA have not been well explored. We sought to investigate the influence of patient demographics on interest in rTJA and patient perceptions regarding rTJA. Methods: Patients presenting for their initial adult reconstruction consultation received an optional anonymous survey prior to seeing the provider. Patient sociodemographic parameters were recorded. Additional questions assessed interest in and perceptions surrounding rTJA. Results were analyzed to determine whether patient factors correlated with survey responses. Results: A total of 360 patients participated. Analysis of responses revealed 77.8% of patients were interested in rTJA. Interest level positively correlated with patient age (Rs = 0.139, P = .010), education level (Rs = 0.168, P = .002), household income (Rs = 0.274, P < .001), and White race (F = 4.157, P = .016). At least 100 patients believed rTJA was easier and more accurate, but more expensive and had a significant learning curve for the surgeon. Over 100 patients believed robots were capable of independently performing most or all of the rTJA operation. Conclusions: Patient interest in rTJA varies between patients. Many patients have an incomplete understanding of rTJA, and orthopaedic surgeons should address patient perceptions during surgical consultation. Level of Evidence: IV, Cross-sectional study.

Timing of Renal Transplant Prior to Total Knee Arthroplasty Impacts 90-Day Postoperative Outcomes.

BACKGROUND: Renal transplant (RT) patients are at increased risk for complications after total knee arthroplasty (TKA); however, it is unknown if the time from RT to TKA influences such risks. This study evaluated RT patients undergoing primary TKA at various time intervals after transplant. We hypothesized that increased time between RT and TKA would decrease the risk of complications after TKA. METHODS: There were 499 RT patients in a national database undergoing subsequent primary TKA from 2010 to 2020. Patients were stratified by intervals of less than 1 year, between 1 and 2 years, and more than 2 years from RT to TKA. Medical complications up to 90 days, readmissions, and 2-year revisions were compared via univariable and multivariable analyses. RESULTS: Patients who underwent TKA less than 1 year after RT were associated with higher 90-day medical complications when compared to those who underwent TKA 1 to 2 years after RT (odds ratio [OR] 0.4, confidence interval [CI] 0.2 to 0.8, P = .01) and more than 2 years (OR 0.3, CI 0.2 to 0.7, P < .01) after RT. Acute kidney injury and blood transfusion were the most common complications. The TKAs performed 2 years after RT were less likely to have 90-day readmissions when compared to TKAs performed less than 1 year after RT (OR 0.4, CI: 0.2 to 0.9, P < .01). However, time from RT to TKA did not increase the risk of revision at 2 years (P > .30). CONCLUSIONS: Patients undergoing TKA within 1 year of RT have an increased risk of 90-day postoperative medical complications and readmissions, but the time interval from RT does not appear to affect revision risk. These findings suggest waiting 1 year after RT before proceeding with TKA may be advantageous.

Outcomes After Pseudomonas Prosthetic Joint Infections.

BACKGROUND: Pseudomonas species are a less common but devastating pathogen family in prosthetic joint infections (PJIs). Despite advancements in management, Pseudomonas PJIs remain particularly difficult to treat because of limited antibiotic options and robust biofilm formation. This study aimed to evaluate Pseudomonas PJI outcomes at a single institution and review outcomes reported in the current literature. METHODS: All hip or knee PJIs at a single institution with positive Pseudomonas culture were evaluated. Forty-two patients (24 hips, 18 knees) meeting inclusion criteria were identified. The primary outcome of interest was infection clearance at 1 year after surgical treatment, defined as reassuring aspirate without ongoing antibiotic treatment. Monomicrobial and polymicrobial infections were analyzed separately. A focused literature review of infection clearance after Pseudomonas PJIs was performed. RESULTS: One-year infection clearance was 58% (n = 11/19) for monomicrobial PJIs and 35% (n = 8/23) for polymicrobial PJIs. Among monomicrobial infections, the treatment success was 63% for patients treated with DAIR and 55% for patients treated with two-stage exchange. Monotherapy with an oral or intravenous antipseudomonal agent (minimum 6 weeks) displayed the lowest 1-year clearance of 50% (n = 6/12). Resistance to antipseudomonal agents was present in 16% (n = 3/19), and two of eight patients with monomicrobial and polymicrobial PJIs developed resistance to antipseudomonal therapy in a subsequent Pseudomonas PJI. Polymicrobial infections (55%) were more common with a mortality rate of 44% (n = 10/23) at a median follow-up of 3.6 years. CONCLUSION: Pseudomonas infections often present as polymicrobial PJIs but are difficult to eradicate in either polymicrobial or monomicrobial setting. A review of the current literature on Pseudomonas PJI reveals favorable infection clearance rates (63 to 80%) after DAIR while infection clearance rates (33 to 83%) vary widely after two-stage revision.

Ultracongruent Polyethylene Liners Do Not Affect Survival of Total Knee Arthroplasty for Valgus Deformity.

BACKGROUND: Valgus knee deformity is observed in nearly 10% of patients undergoing total knee arthroplasty (TKA). The degree of polyethylene constraint required to balance a valgus knee remains controversial, and historically, posterior-stabilized (PS) designs have been favored. This study evaluated the survivorship of TKA done in valgus knees based on implant design and specifically compared posterior-stabilized (PS) and ultracongruent (UC) liners. METHODS: A total of 549 primary TKAs performed on valgus knees by fellowship-trained arthroplasty surgeons from 2013 to 2019 were reviewed. Demographics, comorbidities, degrees of preoperative deformity, implants used, and all-cause revisions until final follow-up were recorded. Cox regression analyses evaluated survival to all-cause revision in each cohort. The mean follow-up was 4.9 years (range, 2 to 9). RESULTS: There were 403 UC liners compared to 146 PS liners. There was no difference in patient age (68 versus 67 years; P = .30), body mass index (30.9 versus 30.4; P = .36), or degree of deformity (8.6 versus 8.8 degrees; P = .75) between the cohorts. At final follow-up, there were 5 revisions in the PS cohort (3.4%) versus 11 revisions in the UC cohort (2.7%) (P = .90). The most common reason for revision in both cohorts was periprosthetic joint infection (4 PS; 8 UC). Multivariable regression analyses controlling for age, body mass index, Elixhauser comorbidity score, sex, and degree of deformity demonstrated UC polyethylene liners were not associated with revision (hazard ratio 0.76; 95% confidence interval [CI] 0.26 to 2.21; P = .62). There was no difference in eight-year survivorship to all-cause revision, including aseptic and septic failure. CONCLUSIONS: Alternative polyethylene liners from the historically utilized PS liners for TKA for valgus deformity did not reduce survivorship. With modern polyethylene designs, UC inserts can be utilized for this deformity without increasing the risk of failure.

Revision Total Knee Arthroplasty With an Imageless, Second-Generation Robotic System.

BACKGROUND: Robotic-assisted total knee arthroplasty is increasingly used in revision total knee arthroplasty (rTKA), with imageless systems recently receiving Food and Drug Administration (FDA) approval. However, there remains a paucity of literature on the use of robotic assistance in revision total knee arthroplasty (TKA). This paper describes the imageless surgical technique for robotic revision TKA using a second-generation robotic system and details both intraoperative and 90-day outcomes. METHODS: This was a retrospective review of 115 robotic revision TKAs from March 2021 to May 2023 at 3 tertiary academic centers. Patient demographics, perioperative surgical data, and 90-day outcomes were collected. Pain and Patient-Reported Outcomes Measurement Information System scores preoperatively and postoperatively were recorded. All-cause reoperations at the final follow-up were detailed. The mean patient age was 65 years (range, 43 to 88), and 58% were women. The mean follow-up time was 13 months (range, 3 to 51). RESULTS: The most common indications for rTKA were instability (n = 37, 32%) and aseptic loosening (n = 42, 37%). There were 83 rTKAs to a posterior-stabilized liner, 22 to a varus-valgus constrained liner, and 5 to a hinged construct. The median polyethylene size was 11 (interquartile range, 10 to 13), and 93% of patients had their joint line restored within 5 millimeters of the native contralateral knee. Within the 90-day postoperative window, there were 8 emergency department visits and 2 readmissions. At the final follow-up, there were 5 reoperations and 2 manipulations under anesthesia. There were 4 patients who required irrigation and debridement after superficial wound dehiscence, and one had an arthrotomy disruption after a fall. CONCLUSIONS: This review demonstrates favorable intraoperative and 90-day outcomes and suggests that imageless robotic surgery is a promising modality in rTKA. Further studies comparing the longitudinal outcomes after robotic and conventional rTKA are warranted.

Gender Trends in Authorship in 6 Major Orthopaedic Journals.

BACKGROUND: Historically, orthopaedic surgery has had low female representation, with <6% of practicing surgeons identifying as female. Although prior literature has illustrated gender disparities in first and last authorship as well as changes in gender representation over time, less attention has been paid to middle authorship. We hypothesized that trends in female authorship would reflect increasing female participation in orthopaedic surgery and orthopaedic subspecialties coinciding with an overall increase in female authorship. METHODS: Bibliometric information from articles published between 2011 and 2021 in 6 orthopaedic journals was extracted with use of the Web of Science. Collected data included author order, author names, affiliation, and corresponding author address. A gender was assigned with the use of Genderize.io, which is validated software, on the basis of author first name. Statistical analysis was performed with use of an analysis of variance for each journal, and linear regression was performed to determine trends, controlling for year. RESULTS: Among all included orthopaedic journals, female middle authorship increased by 5 percentage points, female first authorship increased by 4 percentage points, and female last authorship increased by 1 percentage point. Over the study period, the highest rate of female middle authorship (28%) was seen in the Journal of Pediatric Orthopaedics, whereas the lowest rate (16%) was seen in The Journal of Arthroplasty . We found that the 5 highest-producing female last authors were, on average, cited significantly less per publication than their male counterparts in all but 2 journals. CONCLUSIONS: Gender gaps exist within orthopaedic surgery as well as within its body of literature. Although this study highlights areas of growth, it also promotes further inquiry into research productivity and the availability of opportunity within orthopaedic surgery as a whole. The increase in female middle authorship overall and in each journal demonstrates momentum for future growth for women in the field of orthopaedic surgery.

Dual Mobility Articulation in Total Hip Arthroplasty: Mixed Femoral and Acetabular Components are a Feasible Option.

BACKGROUND: The utilization of a different manufacturer for the prosthetic femoral head and the polyethylene insert in dual mobility (DM) for total hip arthroplasty (THA) may be necessary, especially in the revision setting. However, there is no data in the literature about this application. This study evaluated the outcomes of mixed manufacturer components, with the hypothesis that there would be no difference in measured outcomes compared to matched components. METHODS: The DM articulations implanted during THA revision were retrospectively reviewed from 2011 to 2017. The study group was then stratified into 2 cohorts: matching components or mixed components. Of 130 hips included in the study with DM articulations with average follow-up of 7 years, 103 had mixed and 27 had matching manufacturer components. Rates of all cause reoperation and revision, intraprosthetic dislocation, dislocation, and aseptic loosening were compared using Chi-squared and Fisher's exact test; survival analysis was also performed. RESULTS: Matched and mixed manufacturer implants had no significant difference between all cause reoperation (33 versus 25.2%), dislocation (14.8 versus 7.7%), and aseptic loosening (3.7 versus 3.9%), respectively. Higher rates of intraprosthetic dislocation (11 versus 0.97%) were observed in the matching component cohort. Survival analysis showed similar outcomes at 2, 5, and 10 years. CONCLUSIONS: Mixed-component DM articulations show similar results compared to matching components. The off-label use of mixed manufacture DM articulation in THA is a feasible and safe option in the correct patient. Furthermore, when encountering a well-fixed femoral stem or acetabular shell, the use of a mixed component DM articulations may reduce the morbidity for the patient and prevent revision of all components.

Risk factors for failure after rotational muscle flap coverage for prosthetic knee infections.

INTRODUCTION: Soft tissue defects are a devastating complication of prosthetic joint infections (PJI) after total knee arthroplasty (TKA). Rotational flaps are commonly utilized to address these defects with variable reports of success. This study aimed to identify predictors of poor outcomes in rotational muscle flap placement after prosthetic knee infections. The authors hypothesized that outcomes may vary based on infecting pathogen and treatment characteristics. METHODS: 44 cases of rotational muscle flaps for prosthetic knee infection were retrospectively evaluated at a tertiary referral hospital from 2007 to 2020. Muscle flap types included 39 medial and four lateral gastrocnemius, and one anterior tibialis. Minimum follow-up was 1 year (median: 3.4 years). Primary outcome was flap-related complications. Secondary outcomes included recurrent infection requiring additional surgery, final joint outcomes, and mortality. RESULTS: One-year complication-free flap survivorship was 83.9%, recurrent infection-free survivorship was 65.7%, and amputation-free survivorship was 79%. Multivariable cox regression revealed that rheumatoid arthritis diagnosis (HR: 3.4; p = .028) and methicillin-resistant Staphylococcus aureus-positive culture (HR: 4.0; p = .040) had increased risk, while Coagulase-negative Staphylococcus infections had reduced risk for recurrent or persistent infection (HR: 0.2; p = .023). Final joint outcome was retained TKA implant in 18 (40.9%), amputation in 15 (34.1%) patients, and definitive treatment with articulating spacer in 10 (22.7%). 5-years survivorship from death was 71.4%. CONCLUSION: Rotational muscle flaps for soft tissue coverage of the knee are often performed in limb salvage situations with poor survivorship from flap complications, reinfections, and amputation. When considering surgical options for limb salvage, patients should be counseled on these risks.