Allograft or Synthetic Mesh Extensor Mechanism Reconstruction After TKA Carries a High Risk of Infection, Revision, and Extensor Lag.

BACKGROUND: Extensor mechanism disruption is a devastating complication after TKA. Extensor mechanism reconstruction can be performed using an allograft or synthetic mesh. Recent studies have disagreed about the durability of these reconstructions. Evaluating a larger series of reconstructions that use current popular techniques and principles provides information to guide patient and surgeon expectations while bringing to light the potential fate of patients who experience an infection postoperatively. QUESTIONS/PURPOSES: (1) What was the 5-year survival free of repeat revision surgery or persistent extensor lag of more than 30° after allograft or synthetic mesh reconstruction of extensor mechanism disruptions after TKA, and did this differ between techniques? (2) What was the 5-year survival free of infection after allograft or mesh reconstruction, and what proportion of those patients experienced a secondary severe complication (arthrodesis or amputation)? METHODS: Between April 2008 and December 2020, 123 patients underwent extensor mechanism reconstruction after TKA at one center. Of those, 37% (45) were lost to follow-up before 2 years, had not been seen in the past 5 years, did not reach a study endpoint (repeat revision or extensor lag > 30°) before that time, or underwent primary repair and thus could not be analyzed, leaving 63% (78) for analysis here. During the study period, we considered extensor mechanism surgery when acute or chronic disruption of the patellar or quadriceps tendon was present or there was a fracture of the patella resulting in extensor lag. The decision to use either mesh or an allograft largely depended on surgeon experience and familiarity with either technique. We collected patient demographics, operative details (location of disruption and presence of a hinged prosthesis), subsequent periprosthetic joint infection (PJI), and postoperative SF-12 and Knee Injury and Osteoarthritis Outcome Score, Joint Replacement, scores. We used Kaplan-Meier survivorship analysis, with endpoints of extensor lag more than 30° or revision of the reconstruction and PJI. The mean follow-up duration was 5.3 ± 3.2 years. RESULTS: Survivorship free from revision or recurrent extensor lag was 54% (95% CI 44% to 66%) at 5 years. There was no difference between those undergoing reconstruction with allografts and those with mesh in terms of survivorship free from those endpoints at that timepoint (52% [95% CI 40% to 68%] versus 57% [95 CI% 41 to 78%]; p = 0.99). Survivorship free from PJI was 81% (95% CI 73% to 90%) at 2 years. There was no difference between those with allografts and those with mesh in terms of survivorship free from PJI at that timepoint (79% [95% CI 69% to 92%] versus 83% [95% CI 71% to 98%]; p = 0.75). Of the 17 patients who experienced PJI, four ultimately underwent arthrodesis and three more underwent transfemoral amputation. CONCLUSION: Allograft and synthetic mesh reconstructions commonly left patients with persistent limb dysfunction, while several patients had PJI and some underwent salvage procedures. Although improvements have been made with regard to treating extensor mechanism disruptions, patients and surgeons should be well aware of the potential adverse outcomes when determining management and use these findings to conduct risk-benefit analyses. There is a need for future studies to identify protocols that improve the durability of reconstructions and to determine whether interventions such as prolonged prophylactic antibiotic therapy have a role in minimizing the risk of PJI. LEVEL OF EVIDENCE: Level III, therapeutic study.

Operating Room Air May Harbor Pathogens: The Role of an Ultraviolet Air Filtration Unit.

BACKGROUND: One important factor for the prevention of surgical site infections is ultraclean air in the operating room (OR). Still, the direct sterilization potential of most technologies, especially in a dynamic clinical setting, is not well understood. We aimed to determine and compare the microbial presence from the inlet and outlet flow of a filtration unit with crystalline ultraviolet-C (C-UVC) light. METHODS: A prospective study was conducted at a single institution, where primary total joint arthroplasty and spine surgeries were performed. The OR was fitted with a positive ventilation system. In addition, a filtration unit with a C-UVC sterilizing light was placed in the OR. The inlet and outlet air flows were swabbed simultaneously and compared. Swabs were processed for culture and next-generation sequencing. RESULTS: The mean length of the surgical procedures sampled was 68 ± 13 minutes. Overall, 19 out of 200 (9.5%) swabs isolated microorganisms. Inlet air swabs were positive at a higher rate (16 versus 3%; P < .01) compared to the outlet air swabs. A wide variety of Gram-positive, Gram-negative, and anaerobic bacteria were isolated, but fungi were only recovered from inlet air swabs. The detection of microorganisms was also higher when more door openings were performed (32.5 ± 7.1 versus 27.9 ± 5.6; P < .01). CONCLUSIONS: Air swabs mainly isolated microorganisms from the inlet flow to the filtration unit with a C-UVC light. The sterilizing unit counteracted factors affecting the air quality in the OR, namely door openings, surgical personnel, and tissue combustion.

High Incidence of Acute Kidney Injury Following Antibiotic-Loaded Spacer Insertion for Periprosthetic Joint Infection: An Updated Review of the Literature.

BACKGROUND: The use of antibiotic-impregnated cement during 2-stage revision arthroplasty for periprosthetic joint infection poses a risk of renal complications following spacer insertion. This systematic review aimed to investigate the rate of acute kidney injury (AKI) following antibiotic-loaded spacer insertion and to identify risk factors associated with this complication. METHODS: A systematic review was performed using PubMed, Cochrane Central, and Scopus databases. All clinical studies that documented renal complications following antibiotic-loaded spacer insertion for periprosthetic knee (total knee arthroplasty [TKA]) or hip (total hip arthroplasty [THA]) infection were included. Articles that combined THA and TKA outcomes were also included and labeled "THA + TKA." Descriptive statistics were analyzed when data were available. RESULTS: There were 24 studies (9 THA, 7 TKA, 8 THA + TKA) included. The mean incidences of spacer-related AKI across THA, TKA, and THA + TKA cohorts were 4.2 (range, 0 to 10%), 14 (range, 0 to 19%), and 27% (range, 0 to 35%), respectively. The most common patient-related risk factors for AKI were underlying chronic kidney disease or high baseline creatinine, low preoperative hemoglobin, and blood transfusion requirement. Spacer-related risk factors included high antibiotic dosage (>3.6 g/cement batch) and antibiotic type. While most recovered without complication, select patients required hemodialysis for acute management (2 THA, 18 THA + TKA) and/or developed chronic kidney disease (8 TKA, 8 THA). CONCLUSION: The rate of AKI following spacer insertion was high and likely under-reported in the literature. Surgeons should be cognizant of this devastating complication and should closely monitor at-risk patients for AKI following antibiotic-loaded spacer insertion.

Commercial Synovial Antigen Testing is Inferior to Traditional Culture for the Diagnosis of Periprosthetic Joint Infection in Patients Undergoing Revision Total Knee Arthroplasty.

BACKGROUND: Despite its limitations, a culture remains the "gold standard" for pathogen identification in patients who have periprosthetic joint infection (PJI). Recently, a synovial fluid antigen test has been introduced by a commercial entity. The purpose of this multicenter study was to determine the accuracy of the antigen test in the diagnosis of PJI. METHODS: This retrospective study identified 613 patients undergoing revision total knee arthroplasty who had undergone preoperative synovial fluid analysis. A PJI was defined using the 2018 International Consensus Meeting (ICM) criteria. Patients who had an extended period (> 180 days) from aspiration to revision procedure (n = 62), those presenting within 90 days of their index arthroplasty procedure (n = 17), and patients who had an inconclusive ICM score (n = 8) were excluded. Using receiver operator characteristic curve analyses, we examined the utility of the microbial identification (MID) antigen test and any positive culture (either preoperative or intraoperative) in the diagnosis of PJI. RESULTS: A total of 526 patients were included. Of these, 125 (23.8%) were ICM positive and 401 (76.2%) were ICM negative. Culture demonstrated an area under the curve (AUC) of 0.864, sensitivity of 75.2%, and specificity of 97.5%. On the other hand, the MID test exhibited an AUC of 0.802, sensitivity of 61.6%, and specificity of 98.8%. The AUC of culture was significantly higher than that of the MID test (P = .037). The MID test was positive in 41.9% of culture-negative PJI cases. We also observed a high rate of discordance (29.7%) when both culture and the MID test were positive in the ICM-positive group. CONCLUSIONS: Synovial fluid antigen testing does not provide additional clinical benefit when compared to traditional cultures for the diagnosis of PJI. The antigen test had low sensitivity in the diagnosis of PJI and a relatively high rate of discordance with culture. LEVEL OF EVIDENCE: Level III.

Porous Metal Augments Have Comparable Outcomes to Other Constructs for Severe Acetabular Bone Loss at Mid-Term Follow-up.

BACKGROUND: Acetabular reconstruction options in the setting of severe bone loss remain limited, with few comparative studies published to date. The purpose of this study was to compare the outcomes of revision total hip arthroplasty (THA) for severe bone loss using porous metal augments to cup cage and triflange prostheses. METHODS: We reviewed a consecutive series of 180 patients who had Paprosky 3A or 3B acetabular defects and underwent revision THA. Patients treated with porous augments (n = 141) were compared with those who received cup cages or triflange constructs (n = 39). Failure of the acetabular construct was defined as undergoing acetabular revision surgery or radiographic evidence of loosening. RESULTS: There was no difference in acetabular component survivorship in patients undergoing revision THA with porous augments or a cage or triflange prosthesis (92.2 versus 87.2%, P = .470) at a mean follow-up of 6.6 ± 3.4 years. Overall, survivorship free from any revision surgery was comparable between the 2 groups (78.7 versus 79.5%, P = .720). There was also no difference in dislocation (5.7 versus 10.3%, P = .309) or periprosthetic joint infection rates (7.8 versus 10.3%, P = .623). In a subgroup analysis of patients who had pelvic discontinuity (n = 47), survivorship free from any revision surgery was comparable between the 2 groups (79.5 versus 72.2%, P = .543). CONCLUSIONS: Porous metal augments in the setting of severe acetabular bone loss demonstrated excellent survivorship at intermediate-term (mean 6.6 years follow-up, even in cases of pelvic discontinuity, with comparable outcomes to cup cages and triflanges. Instability and infection remain major causes of failure in this patient population, and long-term follow-up is needed.

Finding the Optimal Screening Test for Periprosthetic Joint Infection: A Prospective Study.

BACKGROUND: No single test has demonstrated absolute accuracy in the diagnosis of periprosthetic joint infection (PJI). Serological markers are often used as screening tools to avoid unnecessary joint aspiration in cases with a low probability of infection. This study aimed to determine the utility of standard-of-care serological tests as a screening tool for PJI in patients undergoing revision arthroplasty. METHODS: This prospective study enrolled 502 patients undergoing revision hip or knee arthroplasty between May 2017 and August 2021. A PJI was defined using a modified definition of the 2018 International Consensus Meeting criteria. Plasma D-dimer, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and fibrinogen were measured preoperatively. There were 82 patients undergoing reimplantation who were excluded. Additionally, 8 patients who had an inconclusive International Consensus Meeting score were also excluded. Of the 412 included patients, 317 (76.9%) underwent revision for aseptic failure, and 95 (23.1%) had PJI. Receiver operating characteristic curves were used to assess the diagnostic utility of each serological test. A pairwise comparison with Bonferroni correction was performed to determine whether the differences in areas under the curve (AUCs) between the tests were significant. Additional analyses were performed to find the threshold for each test that offered 100% sensitivity, allowing it to be the optimal screening test. RESULTS: All 4 serological markers, D-dimer (AUC 0.860, sensitivity 81.3%, specificity 81.7%), CRP (AUC 0.862, sensitivity 90.4%, specificity 70.0%), ESR (AUC 0.833, sensitivity 73.9%, specificity 85.2%), and fibrinogen (AUC 0.798, sensitivity 74.7%, specificity 75.4%), demonstrated comparable accuracy for the diagnosis of PJI (all P > .05). When maximizing sensitivity to 100%, D-dimer demonstrated the highest specificity (AUC 0.860, specificity 40.2%), outperforming ESR (AUC 0.833, specificity 3.3%), fibrinogen (AUC 0.798, specificity 2.3%), and CRP (AUC 0.862, specificity 0%). A plasma D-dimer level of ≥ 244 ng/mL was identified as the optimal cutoff for use as a screening test. CONCLUSIONS: Although plasma D-dimer demonstrated similar diagnostic accuracy as CRP, ESR, and fibrinogen, it outperformed all 3 aforementioned serological markers when used as a screening test for PJI. LEVEL OF EVIDENCE: Level II.

Prior Authorization Leads to Administrative Burden and Delays in Treatment in Primary Total Joint Arthroplasty Patients.

BACKGROUND: The prior authorization (PA) process is often criticized by physicians due to increased administrative burden and unnecessary delays in treatment. The effects of PA policies on total hip arthroplasty (THA) and total knee arthroplasty (TKA) have not been well described. The purpose of this study was to analyze the use of PA in a high-volume orthopaedic practice across 4 states. METHODS: We prospectively collected data on 28,725 primary THAs and TKAs performed at our institution between 2020 and 2023. Data collected included patient demographics, payer approval or denial, time to approval or denial, the number of initial denials, the number of peer-to-peer (P2P) or addenda, and the reasons for denial. RESULTS: Seven thousand five hundred twenty eight (56.4%) patients undergoing THA and 8,283 (54%) patients undergoing TKA required PA, with a mean time to approval of 26.3 ± 34.6 and 33.7 ± 41.5 days, respectively. Addenda were requested in 608 of 7,528 (4.6%) THA patients and 737 of 8,283 (8.9%) TKA patients. From a total of 312 (4.1%) THA patients who had an initial denial, a P2P was requested for 50 (0.7%) patients, and only 27 (0.4%) were upheld after the PA process. From a total of 509 (6.1%) TKA patients who had an initial denial, a P2P was requested for 55 (0.7%) patients, and only 26 (0.3%) were upheld after the PA process. The mean time to denial in the THA group was 64.7 ± 83.5, and the most common reasons for denial were poor clinical documentation (25.9%) and lack of coverage (25.9%). The mean time to denial in the TKA group was 63.4 ± 103.9 days, and the most common reason for denial was not specified by the payer (46.1%). CONCLUSIONS: The use of PA to approve elective THA and TKA led to increased surgical waiting times and a high administrative burden for surgeons and healthcare staff.

AAHKS Surgical Techniques & Technologies Award: Inferior Screw Fixation Decreases Acetabular Component Failure Following Revision Total Hip Arthroplasty.

BACKGROUND: Adjunctive screw fixation has been shown to be reliable in achieving acetabular component stability in revision total hip arthroplasty (THA). The purpose of this study was to assess the effect of inferior screw placement on acetabular component failure following revision THA. We hypothesized that inferior screw fixation would decrease acetabular failure rates. METHODS: We reviewed 250 patients who had Paprosky Type II or III defects who underwent acetabular revision between 2001 and 2021 across three institutions. Demographic factors, the number of screws, location of screw placement (superior versus inferior), use of augments and/or cup-cage constructs, Paprosky classification, and presence of discontinuity were documented. Multivariate regression was performed to identify the independent effect of inferior screw fixation on the primary outcome of aseptic rerevision of the acetabular component. RESULTS: At a mean follow-up of 53.4 months (range, 12 to 261), 16 patients (6.4%) required re-revision for acetabular loosening. There were 140 patients (56.0%) who had inferior screw fixation, all of whom did not have neurovascular complications during screw placement. Patients who had inferior screws had a lower rate of acetabular rerevision than those who only had superior screw fixation (2.1 versus 11.8%, P = .0030). Multivariate regression demonstrates that inferior screw fixation decreased the likelihood of rerevision for acetabular loosening when compared to superior screw fixation alone (odds ratio: 0.1, confidence interval: 0.03 to 0.5; P = .0071). No other risk factors were identified. CONCLUSIONS: Inferior screw fixation is a safe and reliable technique to reduce acetabular component failure following revision THA in cases of severe acetabular bone loss.

2022 American Association of Hip and Knee Surgeons Symposium: Periprosthetic Joint Infection.

Periprosthetic joint infection (PJI) is the leading cause of failure in patients undergoing total joint arthroplasty. This article is a brief summary of a symposium on PJI that was presented at the annual AAHKS meeting. It will provide an overview of current technqiues in the prevention, diagnosis, and management of PJI. It will also highlight emerging technologies in this setting.

Should We Aim to Help Patients "Feel Better" or "Feel Good" After Total Hip Arthroplasty? Determining Factors Affecting the Achievement of the Minimal Clinically Important Difference and Patient Acceptable Symptom State.

BACKGROUND: Recent attempts have been made to use preoperative patient-reported outcome measure (PROM) thresholds as prior authorization criteria based on the assumption that patients who have higher baseline scores are less likely to achieve the minimal clinically important difference (MCID). This study aimed to identify factors affecting the achievement of MCID and patient acceptable symptom state (PASS) after total hip arthroplasty (THA), and to determine the overlap between the two outcomes. METHODS: We identified 3,581 primary, unilateral THAs performed at a single practice in 2015-2019. PROMs including Hip Disability and Osteoarthritis Outcome Score for Joint Replacement (HOOS-JR) and 12-item Short Form Health Survey were collected preoperatively and 1-year postoperatively. The likelihood of attaining PASS according to attainment of MCID was assessed. Multivariable regression was used to identify independent predictors of MCID and PASS. RESULTS: In total, 79.8% achieved MCID and 73.6% achieved PASS for HOOS-JR. Approximately 1 in 7 patients who achieved MCID did not eventually achieve PASS. Worse preoperative HOOS-JR (odd ratio 0.933) was associated with MCID attainment. Better preoperative HOOS-JR (odd ratio 1.015) was associated with PASS attainment. Men, lower body mass index, better American Society of Anesthesiologists score, and better preoperative 12-item Short Form Health Survey mental score were predictors of MCID and PASS. Age, race, ethnicity, Charlson Comorbidity Index, and smoking status were not significant predictors. CONCLUSION: Preoperative PROMs were associated with achieving MCID and PASS after THA, albeit in opposite directions. Clinicians should strive to help patients "feel better" and "feel good" after surgery. Preoperative PROMs should not solely be used to prioritize access to care.

Plasma D-Dimer Is a Promising Marker to Guide Timing of Reimplantation: A Prospective Cohort Study.

BACKGROUND: Two-stage exchange arthroplasty remains the preferred surgical treatment for chronic periprosthetic joint infection. Currently, there is no single reliable marker to determine the optimal timing for reimplantation. The purpose of this prospective study was to assess the diagnostic utility of plasma D-dimer and other serological markers in predicting successful control of infection following reimplantation. METHODS: This study enrolled 136 patients undergoing reimplantation arthroplasty between November 2016 and December 2020. Strict inclusion criteria were applied including the need for a two-week "antibiotic holiday" prior to reimplantation. A total of 114 patients were included in the final analysis. Plasma D-dimer, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and fibrinogen were measured preoperatively. Treatment success was defined using the Musculoskeletal Infection Society Outcome-Reporting Tool. Receiver operating characteristic curves were used to assess the prognostic accuracy of each biomarker in predicting failure following reimplantation at a minimum 1-year follow-up. RESULTS: Treatment failure occurred in 33 patients (28.9%) at a mean follow-up of 3.2 years (range, 1.0 to 5.7). Median plasma D-dimer was significantly higher in the treatment failure group (1,604 versus 631 ng/mL, P < .001), whereas median CRP, ESR, and fibrinogen were not significantly different between the success and failure groups. Plasma D-dimer demonstrated the best diagnostic utility (area under the curve [AUC] 0.724, sensitivity 51.5%, specificity 92.6%), outperforming ESR (AUC 0.565, sensitivity 93.3%, specificity 22.5%), CRP (AUC 0.541, sensitivity 87.5%, specificity 26.3%), and fibrinogen (AUC 0.485, sensitivity 30.4%, specificity 80.0%). Plasma D-dimer level of ≥1,604 ng/mL was identified as the optimal cutoff that predicted failure following reimplantation. CONCLUSION: Plasma D-dimer was superior to serum ESR, CRP, and fibrinogen in predicting failure after the second stage of a two-stage exchange arthroplasty for periprosthetic joint infection. Based on the findings of this prospective study, plasma D-dimer may be a promising marker in assessing the control of infection in patients undergoing reimplantation surgery. LEVEL OF EVIDENCE: Level II.

Mark Coventry Award: Human Knee Has a Distinct Microbiome: Implications for Periprosthetic Joint Infection.

BACKGROUND: Pathogens causing prosthetic joint infection (PJI) are thought to gain access to the knee during surgery or from a remote site in the body. Recent studies have shown that there is a distinct microbiome in various sites of the body. This prospective study, and first of its kind, was set up to investigate the presence of possible microbiome in human knee and compare the profile in different knee conditions. METHODS: We obtained synovial fluid from 65 knees (55 patients) with various conditions that included normal knee, osteoarthritis (OA), aseptic revision, and those undergoing revision for PJI. The contralateral knee of patients who had a PJI were also aspirated for comparison. A minimum of 3 milliliters of synovial fluid was collected per joint. All samples were aliquoted for culture and next-generation sequencing analysis. RESULTS: The highest number of species was found in native osteoarthritic knees (P ≤ .035). Cutibacterium, Staphylococcus, and Paracoccus species were dominant in native nonosteoarthritic knees, and meanwhile a markedly high abundance of Proteobacteria was observed in the osteoarthritic joints. Moreover, the contralateral and aseptic revision knees showed a similar trend in bacterial composition (P = .75). The sequencing analysis of patients who had PJI diagnosis, confirmed the culture results. CONCLUSION: Distinct knee microbiome profiles can be detected in patients who have OA and other knee conditions. The distinct microbiome in the knee joint and the close host-microbe relationships within the knee joint may play a decisive role in the development of OA and PJI.

Synovial C-Reactive Protein is a Useful Adjunct for Diagnosis of Periprosthetic Joint Infection.

BACKGROUND: The diagnostic utility of synovial C-reactive protein (CRP) has been debated for a while. Existing studies are limited by small sample sizes and using outdated criteria for periprosthetic joint infection (PJI). Furthermore, the relationship between synovial and serum CRP has rarely been investigated in the setting of PJI. This study aimed to evaluate the diagnostic utility of synovial CRP and to assess its relationship with serum CRP and other common biomarkers. METHODS: We reviewed 621 patients who underwent evaluation for PJI prior to revision arthroplasty from 2014 to 2021. Biomarkers, including serum CRP and erythrocyte sedimentation rate, synovial CRP, polymorphonuclear leukocyte percentage, white blood cell count, and alpha-defensin, were evaluated using the 2018 International Consensus Meeting criteria. RESULTS: In total, 194 patients had a PJI; 394 were considered aseptic failures and 33 were inconclusive. Synovial CRP showed an area under the curve (AUC) of 0.951 (95% CI, 0.932-0.970) with 74.2% sensitivity and 98.0% specificity, whereas, serum CRP had an AUC of 0.926 (95% CI, 0.903-0.949) with 83.5% sensitivity and 88.3% specificity. There was a good correlation between synovial and serum CRP (R = 0.703; 95% CI, 0.604-0.785). The combination of serum and synovial CRP yielded a significantly higher AUC than that obtained when using serum CRP alone (AUC 0.964 versus 0.926, P = .016). CONCLUSION: Synovial CRP demonstrated excellent accuracy when used to determine the presence of PJI. There was a good correlation between serum and synovial CRP levels in revision arthroplasty patients and the combined use of serum and synovial CRP proved to be more accurate than the serum test alone. These findings support the use of synovial CRP as an adjunct in the workup of PJI.

Surgical Helmets Used During Total Joint Arthroplasty Harbor Common Pathogens: A Cautionary Note.

BACKGROUND: The use of personal-protection surgical helmet/hood systems is now a part of the standard surgical attire during arthroplasty in North America. There are no protocols for the disinfection of these helmets. METHODS: This is a prospective, single-center, observational study. Helmets worn by 44 members of the surgical team and foreheads of 44 corresponding surgical personnel were swabbed at three distinct time points. In addition, 16 helmets were treated with hypochlorite spray to determine if pathogens could be eliminated. Swabs obtained were processed for culture and next-generation sequencing (NGS). RESULTS: Of the 132 helmet samples, 97 (73%) yielded bacteria on culture and 94 (71%) had evidence of bacterial-deoxyribonucleic acid (DNA) on NGS. Of the swabs sent for bacterial identification at the three time points, at least one from each helmet was positive for a pathogen(s). Of the 132 forehead samples, 124 (93%) yielded bacteria on culture and 103 (78%) had evidence of bacterial-DNA on NGS. The most commonly identified organism from helmets was Cutibacterium acnes (86/132) on NGS and Staphylococcus epidermidis (47/132) on culture. The most commonly identified organism from the foreheads of surgical personnel was Cutibacterium acnes (100/132) on NGS and Staphylococcus epidermidis (70/132) on culture. Sanitization of helmets was totally effective; no swabs taken the following morning for culture and NGS identified any bacteria. CONCLUSION: This study demonstrates that surgical helmets worn during orthopedic procedures are contaminated with common pathogens that can potentially cause surgical site infections. The findings of this study should at the minimum compel us to develop protocols for the disinfection of these helmets.

The Paradox of Patient-Reported Outcome Measures: Should We Prioritize "Feeling Better" or "Feeling Good" After Total Knee Arthroplasty?

BACKGROUND: The use of preoperative patient-reported outcome measure (PROM) thresholds for patient selection in arthroplasty care has been questioned recently. This study aimed to identify factors affecting achievement of the minimal clinically important difference (MCID) and patient acceptable symptom state (PASS) after total knee arthroplasty (TKA) and determine the overlap between the two outcomes. METHODS: We identified 1,239 primary, unilateral TKAs performed at a single institution in 2015-2019. PROMs including the Knee injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) and 12-item Short Form Health Survey (SF-12) were collected preoperatively and 1-year postoperatively. The likelihood of attaining PASS as per attainment of MCID was assessed. A multivariable regression was used to identify predictors of MCID and PASS. RESULTS: In total, 71.3% achieved MCID and 75.5% achieved PASS for KOOS-JR. Only 7.7% achieved MCID but not PASS, whereas almost twice this number did not achieve MCID but did achieve PASS (11.9%). Poorer preoperative KOOS-JR (OR 0.925), better SF-12 physical (OR 1.025), and mental (OR 1.027) were associated with MCID attainment. In contrast, better preoperative KOOS-JR (OR 1.030) and SF-12 mental (OR 1.025) were associated with PASS attainment. Age, gender, race, ethnicity, body mass index, Charlson index, American Society of Anesthesiologists classification, and smoking status were not significant predictors. CONCLUSION: Preoperative PROMs were associated with achieving MCID and PASS after TKA, albeit some positively and some negatively. In the era of value-based care, clinicians should not only strive to help patients "feel better" but also ensure that patients "feel good" after surgery. This study does not support the use of PROMs in prioritizing access to care.

Positive Cultures Can Be Safely Ignored in Revision Arthroplasty Patients That Do Not Meet the 2018 International Consensus Meeting Criteria.

BACKGROUND: During aseptic revision total joint arthroplasty (TJA), one or more cultures may occasionally isolate an organism. The hypothesis of this study was that in a portion of patients undergoing revision arthroplasty for aseptic failure, culture may isolate an organism(s) that can be left untreated. METHODS: All patients undergoing revision TJA from 2000 to 2017 at two institutions were retrospectively reviewed. Patients were categorized as aseptic if they were appropriately investigated preoperatively and did not meet the 2018 International Consensus Meeting criteria. In the aseptic revision cohort, patients with a single positive culture or multiple cultures positive for different organisms ("organism-positive") and patients who had negative intraoperative cultures ("organism-negative") were compared based on demographics, comorbidities, operative details, subsequent reoperations, and periprosthetic joint infection (PJI). RESULTS: In total, 3,234 International Consensus Meeting-negative aseptic revision TJAs were included, of which 215 patients (6.6%) were organism-positive, 196 (91.2%) had a single positive culture, and 19 (8.8%) were positive for 2 or more distinct organisms (ie, polymicrobial). The most prevalent organisms were coagulase-negative Staphylococci (37.5%), Staphylococcus epidermidis (9.6%), and Cutibacterium acnes (8.0%). Demographics and operative details were comparable between the groups. Using multiple regressions there was no association between culture positivity and the rate of reoperation or PJI. CONCLUSION: Isolation of organisms by culture in patients undergoing revision for aseptic failure was not uncommon. As long as these patients were appropriately investigated preoperatively and PJI was excluded, these findings suggest that culture results may be ignored without subjecting patients to additional antimicrobial treatment.

Robotic-Assisted Versus Manual Unicompartmental Knee Arthroplasty: A Time-Driven Activity-Based Cost Analysis.

BACKGROUND: The cost-effectiveness of robotic-assisted unicompartmental knee arthroplasty (RA-UKA) remains unclear. Time-driven activity-based costing (TDABC) has been shown to accurately reflect true resource utilization. This study aimed to compare true facility costs between RA-UKA and conventional UKA. METHODS: We identified 265 consecutive UKAs (133 RA, 132 conventional) performed at a specialty hospital in 2016-2020. Itemized facility costs were calculated using TDABC. Separate analyses including and excluding implant costs were performed. Multiple regression was performed to determine the independent effect of robotic assistance on facility costs. RESULTS: Due to longer operative time, RA-UKA patients had higher personnel costs and total facility costs ($2,270 vs $1,854, P < .001). Controlling for demographics and comorbidities, robotic assistance was associated with an increase in personnel costs of $399.25 (95% confidence interval [CI] $343.75-$454.74, P < .001), reduction in supply costs of $55.03 (95% CI $0.56-$109.50, P = .048), and increase in total facility costs of $344.27 (95% CI $265.24-$423.31, P < .001) per case. However, after factoring in implant costs, robotic assistance was associated with a reduction in total facility costs of $235.87 (95% CI $40.88-$430.85, P < .001) per case. CONCLUSION: Using TDABC, overall facility costs were lower in RA-UKA despite a longer operative time. To facilitate wider adoption of this technology, implant manufacturers may negotiate lower implant costs based on volume commitments when robotic assistance is used. These supply cost savings appear to offset a portion of the increased costs. Nonetheless, further research is needed to determine if RA-UKA can improve clinical outcomes and create value in arthroplasty.

Clinical and Radiographic Outcomes of Novel 3D-Printed Highly Porous Knee Cone Design.

INTRODUCTION: Metaphyseal bone defects seen at revision total knee replacement (TKA) have traditionally been treated with bone graft or cement. Recently, metal augments have surfaced as viable alternatives to conventional methods previously used in these patients. Newer 3D-printed metal cones offer better biological fixation as a means of improving construct stability. This study aimed to determine clinical and radiographic outcomes of the novel 3D-printed titanium cone augments for femoral and tibial metaphyseal bone defects. MATERIALS AND METHODS: A retrospective review was undertaken of 72 patients who underwent revision TKA with metaphyseal cones (Stryker) and stemmed implants from 2015-2017. Knee Injury and Osteoarthritis Outcome Scores (KOOS Jr) and VR/SF-12 scores were recorded. Knee Society radiographic scores were calculated at latest follow up to evaluate for radiolucency and biological fixation. Loosening noted on radiographs and reoperation for any reason were the endpoints to determine survivorship. RESULTS: A total of 68 patients with 78 cones (58 tibial, 20 femoral) met inclusion criteria. Mean follow up was 3.4 years (range 2-5.4 years). The average KOOS Jr score increased from 38 preoperatively to 66 at two years. The average VR/SF-12 PH score increased from 33 preoperatively to 37 at two years. The average VR/SF-12 MH score increased from 46 preoperatively to 54 at two years. Twelve percent of tibial implants and 10% of femoral implants with cones were found to have lucency in at least one radiographic zone. Overall survivorship at latest follow up was 93% with two patients requiring revision for infection, two revised following mechanical complications, and one patient who underwent polyethylene exchange after experiencing mechanical complications. When considering only aseptic loosening, survivorship was 100%. CONCLUSION: This 3D-printed titanium femoral and tibial cone augment system showed excellent survivorship, biological fixation, clinical outcomes, and radiographic outcomes in the setting of TKA. Further studies are needed for assessment of long-term survivorship.

Editorial: Management of PJI/SSI after joint arthroplasty.

The management of periprosthetic joint infection (PJI) and surgical site infection (SSI) after joint arthroplasty poses a major challenge in orthopedic surgery. This Editorial provides an overview of the studies published in the special issue "Management of PJI/SSI after Joint Arthroplasty", summarizing the key findings from these studies, which cover a wide range of topics, including stringent preventive strategies, comprehensive diagnostic methods, and personalized treatment modalities. The authors concluded the editorial with their perspectives regarding the status quo of research in this field and future directions for research, such as the development of novel antibiotics, biofilm research, patient-specific risk factors, and the integration of technological advancements (such as machine learning and artificial intelligence) into clinical practice. The authors emphasized the need for continued research, interdisciplinary collaboration, and the application of innovative technologies to enhance patient outcomes and mitigate the burden of these infections on healthcare systems.