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.

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.

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.

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 (MSIS) criteria for periprosthetic 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-Meyer 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 = 0.39) nor between sterile cultures and ≥ 2 UPCs of different organisms (96 versus 100%; P < 0.72). 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 < 0.001). Cox proportional hazards regression suggested that when adjusting for covariates, an American Society of Anesthesiologists classification of ≥ 3 (hazard ratio [HR] = 3.1; P = 0.007), ≥ 2 UPCs of the same organism (HR = 11.0; P < 0.001), 1 UPC (HR = 4.2; P = 0.018), and arTKA with hinge constructs (HR = 4.1; P = 0.008) were associated with increased risk of re-revision for PJI. CONCLUSION: 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 five 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 re-revision for PJI. More studies are needed to determine what interventions can be implemented to mitigate this risk.

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.

The Practice Patterns of American Association of Hip and Knee Surgeons for the Management of Chronic Periprosthetic Joint Infection After Total Knee Arthroplasty.

BACKGROUND: The management of periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) has considerable variation. In order to better capture current preferences for the management of PJI, this study sought to poll the current members of American Association of Hip and Knee Surgeons (AAHKS) first to characterize the distribution of practice patterns. METHODS: There were 32 questions in an online survey distributed to members of AAHKS. The questions were multiple choice regarding the management of PJI for TKA. There were 844 out of 2,752 members who completed the survey (response rate of 31%). RESULTS: Most of the members were in private practice (50%) compared to 28% being in an academic setting. On average, members were performing between 6 to 20 PJI cases per year. Two-stage exchange arthroplasty was performed in over 75% of the cases with either a cruciate retaining (CR) or posterior stabilized (PS) primary femoral component used in over 50% of the cases and 62% using an all-polyethylene tibial implant. Most of the members were using vancomycin and tobramycin. Typically, 2 to 3 grams of antibiotics were added per bag of cement regardless of the cement type. When indicated, amphotericin was the most often-used antifungal. Post-operative management had major variability with range of motion, brace use, and weight-bearing restrictions. CONCLUSION: There was variability in the responses from the members of AAHKS, but there was a preference toward performing a two-stage exchange arthroplasty with an articulating spacer using a metal femoral component and an all-polyethylene liner.

Failed 2-Stage Revision Knee Arthroplasty for Periprosthetic Joint Infection-Patient Characteristics and Outcomes.

BACKGROUND: Chronic prosthetic joint infection (PJI) is most frequently treated with 2-stage revision in conjunction with antibiotic treatment. The aims of this study were 1) to investigate the characteristics of patients who have recurrent infection following 2-stage revision for PJI and 2) to identify risk factors associated with treatment failure. METHODS: A multicenter retrospective review of 90 total knee arthroplasty (TKA) patients who underwent 2-stage revision for treatment of PJI from March 1, 2003 to July 31, 2019, and had recurrent PJI was conducted. The minimum follow-up was 12 months (median follow up of 2.4 years). Microorganisms, subsequent revision, PJI control status, and final joint status were collected. The infection-free survival after initial 2-stage revision was plotted utilizing the Kaplan-Meier method. RESULTS: Mean survival time to reinfection was 21.3 months (range, 0.3 to 160.5). There were 14 recurrent infections that were acute PJIs treated with debridement, antibiotics, and implant retention (DAIR), while 76 were chronic and treated with repeat 2-stage revision. The most common pathogen identified for both index and recurrent PJI was coagulase-negative Staphylococci. Pathogen persistence was observed in 14 (22.2%) of recurrent PJIs. In total, 61 (67.8%) patients possessed a prosthetic reimplantation at their most recent follow-up, and 29 (35.6%) patients required intervention following repeat 2-stage. CONCLUSION: Overall, 31.1% of the patients obtained infection control after treatment of a failed 2-stage revision due to PJI. The high rate of pathogen persistence and the relatively low survival time to recurrence suggests a need to more closely monitor PJIs cases within 2 years.

Trends in Total Knee Arthroplasty Cementing Technique Among Arthroplasty Surgeons-A Survey of the American Association of Hip and Knee Surgeons Members.

BACKGROUND: Aseptic loosening persists as one of the leading causes of failure following cemented primary total knee arthroplasty (TKA). Cement technique may impact implant fixation. We hypothesized that there is variability in TKA cement technique among arthroplasty surgeons. METHODS: A 28-question survey regarding variables in surgeons' preferred TKA cementation technique was distributed to 2,791 current American Association of Hip and Knee Surgeons (AAHKS) members with a response rate of 30.8% (903 respondents). Patterns of responses were analyzed by grouping respondents by their answers to certain questions including cementing technique, tibial cement location, and femoral cement location. RESULTS: A total of 73.5% reported performing at least 7 of 8 of the highest consensus techniques, including vacuum mixing (79.9%), using two bags (76.1%), tibial implant first (95.2%), single-stage cementing (96.9%), compression of the implants in extension (91.7%), and use of a tourniquet (84.3%). Medium and high viscosity cement was most commonly used (37.9 and 37.8%, respectively). Finger pressurization was most common (76.1%) compared to a gun (29.8%). There were 26.5% of respondents performing 6 or fewer of the most common majority techniques and seemed to perform other less common techniques (eg, use of a single bag of cement, trialing or closure prior to cement curing, and heating to accelerate cement curing). Cement was most commonly applied to the entire bone and implant surface on both the tibia (46.4%) and femur (47.7%), leaving much variation in the remaining cement application location responses. DISCUSSION: There appears to be variability in cemented TKA technique among arthroplasty surgeons. There were 26.5% of respondents performing less of the majority techniques and also performed other additional low-response rate techniques. Further studies that look at the impacts of variation in techniques on outcomes may be warranted. Our study demonstrates the need for defining best practices for cement technique given the substantial variability identified.

D-Dimer, Erythrocyte Sedimentation Rate, and C-Reactive Protein Sensitivities for Periprosthetic Joint Infection Diagnosis.

BACKGROUND: There is contradicting evidence on the diagnostic value of inflammatory biomarkers for periprosthetic joint infection (PJI). We sought to quantify the sensitivity of D-dimer for acute and chronic PJI diagnosis and evaluate D-dimer lab values in the 90-day postoperative window in a control cohort of primary joint arthroplasty patients for comparison. METHODS: An institutional database was queried for patients undergoing revision procedures for PJI after total hip arthroplasty (THA) and total knee arthroplasty (TKA) from 2014 to present. CRP, ESR, and D-dimer were collected within 90 days pre and postoperatively and sensitivities for the diagnosis of PJI were calculated. The control group included patients who underwent a negative diagnostic workup for deep venous thrombosis (DVT) or pulmonary embolus (PE) and had a D-dimer lab collected within 90 days postoperatively from primary total joint arthroplasty (TJA). RESULTS: A total of 604 PJI patients were identified, and 81 patients had D-dimer, ESR, and CRP collected. There were 50/81 acute PJI patients and 31/81 chronic PJI patients who had median D-dimer values of 2,136.5 ng/mL [interquartile range (IQR): 1,642-3,966.5] and 3,336 ng/mL [IQR: 1,976-5,594]. Only the chronic PJI group had significantly higher D-dimer values when compared to the control cohort (P = .009). The sensitivity of D-dimer was calculated to be 92% and 93.5% in the acute and chronic PJI groups, respectively. CONCLUSION: Serum D-dimer may not have high diagnostic utility for acute PJI, especially in the setting of recent surgery; however, it still may be useful for patients who have chronic PJI.

A Multicenter Prospective Investigation on Patient Physical and Mental Health After Girdlestone Resection Arthroplasty.

BACKGROUND: Girdlestone resection arthroplasty is a salvage procedure for hip periprosthetic joint infection (PJI) that controls infection and reduces chronic pain, but may result in limited postoperative joint function. The aim of this study was to assess physical function and mental health after Girdlestone. METHODS: This was a multicenter, prospective study evaluating patients with Girdlestone. The Prosthesis Evaluation Questionnaire (PEQ) and patient-reported outcomes measurement information system (PROMIS) global physical health and mental health surveys were administered postoperatively via telephone. The PEQ consists of four scales (ie, ambulation, frustration, perceived response, and social burden) with scores ranging from 0 to 10. The PROMIS measures generated T-scores (mean: 50, standard deviation: 10) that enable comparison to the general population. RESULTS: Thirty-five patients completed all surveys. The average time from procedure to survey completion was 6 years (range, 1 to 20). The median scores for the ambulation, frustration, perceived response, and social burden scales of the PEQ were 0.0 [interquartile range: 0-4.1], 6.0 [3.0-9.3], 9.0 [7.2-10.0], and 7.5 [4.3-9.5]. The median raw scores of the PROMIS global physical health and mental health were 11.91 [interquartile range: 9-14] and 14.0 [10.0-16.0]. These corresponded to average T scores of 39.7 (standard error : 4.3) for physical health and 46.1 (standard error: 3.8) for mental health, which were 10.3 points and 3.9 points below the average score in the United States general population, respectively. CONCLUSION: Girdlestone can have a substantial negative impact on physical functions; however, mental health and social interaction may be only moderately affected. These outcomes can be used to guide patient expectations, as this procedure may be necessary in certain salvage scenarios.

Cost Drivers in Two-Stage Treatment of Hip Periprosthetic Joint Infection With an Antibiotic Coated Cement Hip Spacer.

BACKGROUND: The current gold standard for treating chronic Periprosthetic Joint Infection (PJI) is a 2-stage revision arthroplasty. There has been little investigation into what specific patient and operative factors may be able to predict higher costs of this treatment. METHODS: An institutional electronic health record database was retrospectively queried for patients who developed a PJI after a total hip arthroplasty, and underwent removal of the prosthesis and implantation of an antibiotic-impregnated articulating hip cement spacer. Patient demographics, surgical variables, hospital readmissions, emergency department visits, and post-operative complications were collected. Total costs were captured through an internal accounting database through 2 years post-operatively. Negative binomial regressions were utilized for multivariable analyses. A total of 55 hips with PJI were available for cost analyses. RESULTS: A comorbidity index score was associated with a 70% increase (Odds Ratio (OR): 1.7 [1.18-2.5], P = .003) in total costs at 2-years. Illicit drug use was associated with a 70% increase in costs at 1-year post-operatively (OR 1.7 [1.18-2.5], P = .003). Metal-on-poly liners were associated with a 22% decrease in cost at 2-years post-operatively when compared to Cement-on-Bone articulating spacers, and Metal-on-poly -constrained liners accounted for 38% lower costs at 1-year (OR 0.62 [0.44-0.87], P = .004). Use of an intraoperative extended trochanteric osteotomy was associated with a 46 and 61% increase in cost at 1-year (OR 1.46 [1.14-1.89]) and 2-years (OR 1.61 [1.26-2.07], P < .001) post-operatively. CONCLUSION: Age, comorbidity index score, drug use, and extended trochanteric osteotomy were associated with increased costs of PJI treatment. This may be used to improve reimbursement models and target areas of cost savings.

Accelerated Discharge After Aseptic Revision Total Hip Arthroplasty Does Not Predict Inferior 30-Day Outcomes.

BACKGROUND: Perioperative advancements have made outpatient primary total hip arthroplasty (THA) a viable option for patients. This study evaluated the feasibility of expedited discharge after revision THA and compared 30-day outcomes to patients who had prolonged inpatient hospitalizations. The authors hypothesized that expedited discharge would not result in inferior 30-day outcomes. METHODS: Aseptic revision THAs in a national database were reviewed from 2013 to 2020. THAs were stratified by hospital length of stay (LOS) more or less than 24 hours. Demographics, comorbidities, preoperative laboratory values, American Society of Anesthesiology (ASA) scores, operative times, components revised, 30-day readmissions, and reoperations were compared. Multivariable analyses evaluated predictors of discharge prior to 24 hours, 30-day readmissions, and reoperations. Of 17,044 aseptic revision THAs, 211 were discharged within 24 hours. RESULTS: Accelerated discharge patients were younger, mean age 63 years (range, 20-92) versus 66 years (range, 18-94) (P < .01) had lower body mass index, mean 28.7 (range, 18.3-46.4) versus 29.9 (range, 17.3-52.5) (P = .01), and ASA scores (ASA, 1-2; 40.4-57.8%) (P < .01). Components revised had no association with LOS (P = .39); however, operative times were shorter and mean 100 minutes (range, 35-369) versus 139 minutes (range, 24-962) (P < .01) in accelerated discharge patients. Accelerated discharge patients had lower readmission rates (P < .01) but no difference in reoperation rates (P = .06). CONCLUSION: Discharge less than 24 hours after revision THA is a feasible option for the correct patient and further efforts to decrease LOS should be evaluated.

Does Preoperative Weight Loss Within 6 Months or 1 Year Change the Risk of Adverse Outcomes in Total Knee Arthroplasty by Initial Body Mass Index Classification?

BACKGROUND: High body mass index (BMI) is associated with adverse outcomes after total knee arthroplasty (TKA). Thus, many patients are advised to lose weight before TKA. This study examined how weight loss before TKA is associated with adverse outcomes depending on patients' initial BMI. METHODS: This was a retrospective study of 2,110 primary TKAs at a single academic center. Data on preoperative BMIs, demographics, comorbidities, and incidences of revision or prosthetic joint infection (PJI) were obtained. Multivariable logistic regressions segmented by patients' initial (1-year preoperative) BMI classifications were performed to determine if a > 5% BMI decrease from 1 year or 6 months preoperatively predicted PJI and revision controlling for patient age, race, sex, and Elixhauser comorbidity index. RESULTS: Preoperative weight loss did not predict adverse outcomes for patients who had Obesity Class II or III. 6-month weight loss had greater odds of adverse outcomes than 1-year weight loss and most significantly predicted the occurrence of 1-year PJI (adjusted odds ratio: 6.55, P < .001) for patients who had Obesity Class 1 or lower. CONCLUSION: This study does not show a statistically significant effect to patients who had Obesity Class II and III losing weight preoperatively with respect to PJI or revision. For patients who have Obesity Class I or lower pursuing TKA, future research should consider potential risks associated with weight loss. Further study is needed to determine if weight loss can be implemented as a safe and effective risk reduction strategy for specific BMI classes of TKA patients.

The Removal of Total Hip Arthroplasty From the Inpatient-Only List has Improved Patient Selection and Expanded Optimization Efforts.

BACKGROUND: On January 1, 2020, the Centers for Medicare and Medicaid Services removed total hip arthroplasty (THA) from the Inpatient-Only (IPO) list. This study evaluated patient demographics and comorbidities, preoperative optimization efforts, and 30-day outcomes of patients undergoing outpatient THA before and after IPO removal. The authors hypothesized that patients undergoing THA post-IPO removal would have improved optimization of modifiable risk factors and equivalent 30-day outcomes. METHODS: There were 17,063 outpatient THAs in a national database stratified by surgery performed before (2015 to 2019: 5,239 patients) and after IPO (2020: 11,824 patients) removal. Demographics, comorbidities, and 30-day outcomes were compared with univariable and multivariable analyses. Preoperative optimization thresholds were established for the following modifiable risk factors: albumin, creatinine, hematocrit, smoking history, and body mass index. The percentage of patients who fell outside the thresholds in each cohort were compared. RESULTS: Patients undergoing outpatient THA post-IPO removal were significantly older; mean age 65 years (range, 18 to 92) versus 62 (range, 18 to 90) years (P < .01), with a higher percentage of American Society of Anesthesiologists scores 3 and 4 (P < .01). There was no difference in 30-day readmissions (P = .57) or reoperations (P = 1.00). A significantly lower percentage of patients fell outside the established threshold for albumin (P < .01) post-IPO removal, and trended towards lower percentages for hematocrit and smoking status. CONCLUSION: The removal of THA from the IPO list expanded patient selection for outpatient arthroplasty. Preoperative optimization is critical to minimize postoperative complications, and the current study demonstrates that 30-day outcomes have not worsened post-IPO removal.

A Permanent Articulating Spacer Versus Two-Stage Exchange for Chronic Periprosthetic Joint Infection: A Propensity Score-Matched Study.

BACKGROUND: Although 2-stage revision has been proposed as gold standard for periprosthetic joint infection treatment, limited evidence exists for the role of articulating spacers as definitive management. The purpose of this study was to compare clinical outcomes and costs associated with articulating spacers (1.5-stage) and a matched 2-stage cohort. METHODS: A retrospective review was performed for patients who had chronic periprosthetic joint infections after total knee arthroplasty defined by Musculoskeletal Infection Society criteria and were matched via propensity score matching using cumulative Musculoskeletal Infection Society scores and a comorbidity index. Patients who maintained an articulating spacer (cemented cobalt-chrome femoral component and all-poly tibia) were included in the 1.5-stage cohort. Patients who underwent a 2-stage reimplantation procedure were included in the 2-stage cohort. Outcomes included visual analog scale pain scores, 90-day emergency department visits, 90-day readmission, unplanned reoperation, reinfection, as well as cost at 1 and 2-year intervals. A total of 116 patients were included for analyses. RESULTS: The 90-day pain scores were lower in the 1.5-stage cohort compared to the 2-stage cohort (2.9 versus 4.6, P = .0001). There were no significant differences between readmission and reoperation rates. Infection clearance was equivalent at 79.3% for both groups. Two-stage exchange demonstrated an increased cost difference of $26,346 compared to 1.5-stage through 2 years (P = .0001). Regression analyses found 2 culture-positive results with the same organism decreased the risk for reinfection [odds ratio: 0.2, 95% confidence interval 0.04-0.8, P = .03]. CONCLUSION: For high-risk candidates, articulating spacers can preserve knee function, reduce morbidity from second-stage surgery, and lower the costs with similar rates of infection clearance as 2-stage exchange. LEVEL OF EVIDENCE: Level III, therapeutic study.

A Validated Pre-operative Risk Prediction Tool for Extended Inpatient Length of Stay Following Primary Total Hip or Knee Arthroplasty.

BACKGROUND: As value-based reimbursement models mature, understanding the potential trade-off between inpatient lengths of stay and complications or need for costly postacute care becomes more pressing. Understanding and predicting a patient's expected baseline length of stay may help providers understand how best to decide optimal discharge timing for high-risk total joint arthroplasty (TJA) patients. METHODS: A retrospective review was conducted of 37,406 primary total hip (17,134, 46%) and knee (20,272, 54%) arthroplasties performed at two high-volume, geographically diverse, tertiary health systems during the study period. Patients were stratified by 3 binary outcomes for extended inpatient length of stay: 72 + hours (29%), 4 + days (11%), or 5 + days (5%). The predictive ability of over 50 sociodemographic/comorbidity variables was tested. Multivariable logistic regression models were created using institution #1 (derivation), with accuracy tested using the cohort from institution #2 (validation). RESULTS: During the study period, patients underwent an extended length of stay with a decreasing frequency over time, with privately insured patients having a significantly shorter length of stay relative to those with Medicare (1.9 versus 2.3 days, P < .0001). Extended stay patients also had significantly higher 90-day readmission rates (P < .0001), even when excluding those discharged to postacute care (P < .01). Multivariable logistic regression models created from the training cohort demonstrated excellent accuracy (area under the curve (AUC): 0.755, 0.783, 0.810) and performed well under external validation (AUC: 0.719, 0.743, 0.763). Many important variables were common to all 3 models, including age, sex, American Society of Anesthesiologists (ASA) score, body mass index, marital status, bilateral case, insurance type, and 13 comorbidities. DISCUSSION: An online, freely available, preoperative clinical decision tool accurately predicts risk of extended inpatient length of stay after TJA. Many risk factors are potentially modifiable, and these validated tools may help guide clinicians in preoperative patient counseling, medical optimization, and understanding optimal discharge timing.

Body Mass Index and American Society of Anesthesiologists Score Predict Perioperative Delays in Different Phases for Total Hip Arthroplasty.

Perioperative efficiency has become increasingly important with cost constraints and expanding indications for total hip arthroplasty (THA). We chose to analyze body mass index (BMI) and American Society of Anesthesiologists (ASA) score, in predicting perioperative efficiency. We retrospectively reviewed the institutional database for primary THAs from July 2015 to January 2018. Patient demographics and perioperative times lines were collected. A multivariable model was utilized to evaluate BMI (< 30, ≥ 30) and ASA (< 3, ≥ 3) for all outcomes. A total of 2,934 patients were included with mean age 62.0 (12.2) years, and 1,599 (54.5%) were female. A BMI ≥ 30 was associated with prolonged operative time (p < 0.001) while an ASA ≥ 3 was predictive of post-anesthesia care unit time (p < 0.001), physical therapy hours (p < 0.001), and length of stay (p < 0.001). Both BMI (p = 0.004) and ASA (p < 0.001) were associated with skilled nursing/rehabilitation dispositions. While BMI predicts prolonged operative time, ASA predicts perioperative delays for anesthesia, nursing, and physical therapy. (Journal of Surgical Orthopaedic Advances 32(3):169-172, 2023).

Risk Factors for Delayed Discharge and Adverse Outcomes Following Outpatient Billed Total Knee Arthroplasty.

BACKGROUND: The volume of outpatient total knee arthroplasty (TKA) has increased with advances in perioperative protocols, patient selection, and recent policy changes regarding insurance authorization. This study analyzed 30-day outcomes from a national database to better understand risk factors for delayed discharge (length of stay [LOS] ≥1), readmission, and reoperation after outpatient TKA. METHODS: The National Surgical Quality Improvement Program (NSQIP) database was utilized to collect TKA (CPT 27447) billed as outpatient surgery performed from 2013 to 2018. Patient demographics, comorbidities, and short-term outcomes were collected and compared in LOS 0 versus LOS ≥1 cohorts. Subgroup analysis was completed for TKA performed in 2018, after the Center for Medicare Services removal of TKA from the inpatient-only list. RESULTS: A total of 13,669 patients had outpatient TKA performed from 2013 to 2018. Most patients had LOS ≥1 day (77.1%). The LOS 0 cohort demonstrated a lower 30-day readmission rate (1.8%) compared to LOS ≥1 (2.8%), P > .01. Both groups demonstrated a low 30-day reoperation rate, LOS 0 (0.7%) and LOS ≥1 (1.1%), P = .05. Regression analysis demonstrated risk factors for LOS ≥1 day included COPD, ASA ≥3, age >75, and BMI >35 kg/m2. Regression analysis demonstrated male gender, age >75, ASA ≥3, and albumin <3.5 g/dL were risk factors for readmission. Hypertension was a risk factor for 30-day reoperation. CONCLUSION: Risk factors for LOS ≥1 day include age >75, ASA ≥3, BMI >35 kg/m2. In addition, BMI >35 kg/m2 was a risk factor for readmission and reoperation. These findings reinforce appropriate patient selection when considering outpatient TKA.