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

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

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

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

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

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

Versatility and accuracy of a novel image-free robotic-assisted system for total knee arthroplasty.

INTRODUCTION: Technological advances alongside increased demand for knee replacement surgery have led to the development of a novel image-free bed rail-mounted robotic-assisted system for total knee arthroplasty (TKA). The device is capable of real-time tracking to accommodate for leg motion during bone resection allowing for precise control and positioning of the bone saw in the planned resection plane. The purpose of this study is to discuss the versatility and accuracy of this novel image-free robotic-assisted technology in TKA. METHODS AND MATERIALS: The novel robotic-assisted system underwent a stepwise assessment to verify its versatility and accuracy. First, functional accuracy was bench tested to evaluate predetermined surgical plans independent of user variability and anatomic variability compared to conventional instrumentation. This was followed by assessments utilizing cadaveric specimens for resection accuracy, implant positioning, and soft tissue involvement. RESULTS: Test bench accuracy revealed overall pooled linear positional accuracy of 0.326 ± 0.249 mm and pooled angular positional accuracy of 0.365 ± 0.611°. Resection errors for both robotic and conventional cohorts ranged between 0.6° and 1.9°. Concerning coronal alignment, 33/40 robotic specimen were within ± 1° and 38/40 within ± 3° of the femoral varus-valgus target, compared with 17/40 and 37/40 with conventional instrumentation, respectively. Twenty-four of the 40 robotic specimens were within ± 1° and 40/40 within ± 3° of the tibial varus-valgus target compared with 15/40 and 32/40 with conventional instrumentation, respectively. Soft tissue structures were uncompromised in all robotic-assisted cases. Conventional instruments revealed two cases of partial cleavage of the posterior cruciate ligament and two instances of a compromised posterior medial capsule. There were no significant differences between the two techniques concerning the samples that were uncompromised and fully functional (40/40 vs. 38/40, p = 0.49). CONCLUSION: The novel image-free robotic-assisted surgical system demonstrates excellent benchtop accuracy to aid bony resection in cadaveric specimens. It offers notable improvement in coronal implant alignment compared to conventional instrumentation.

Does the Organism Profile of Periprosthetic Joint Infections Change With a Topical Vancomycin Powder and Dilute Povidone-Iodine Lavage Protocol?

BACKGROUND: While vancomycin powder and dilute povidone-iodine (VIP) is associated with fewer total joint arthroplasty (TJA) periprosthetic joint infections (PJI), its effect on PJI organism profiles is unclear. This study evaluates primary TJA PJI organism profiles before and after the implementation of a VIP protocol. METHODS: In total, 18,299 primary TJAs performed at a university-affiliated, not-for-profit orthopedic hospital from before (1/2012-12/2013) and after (1/2016-12/2019) a VIP protocol was initiated were reviewed to identify deep PJIs that occurred within 90 days of the index arthroplasty as defined by the Musculoskeletal Infection Society guidelines. Demographics, overall organism incidence (n/TJAs), and relative organism incidence (n/PJIs) from the two cohorts were compared. RESULTS: In total, 103 TJA PJIs were identified (pre-VIP: 32/3982; VIP: 71/14,317). Following the introduction of VIP, the overall and relative incidence of coagulase-negative staphylococcal TJA PJIs significantly decreased (overall: 0.20% to 0.04%, P = .004; relative: 25.00% to 8.45%, P = .031). In response, the relative incidence of MSSA TJA PJIs significantly increased (18.75% to 40.85%, P = .042). Broken down by arthroplasty type, VIP was associated with a significantly lower overall incidence of coagulase-negative staphylococcal total knee arthroplasty (TKA) PJIs (0.27% to 0.06%, P = .015), a significantly lower overall incidence of MRSA TKA PJIs (0.18% to 0.03%, P = .031), and a nonsignificant decrease in the overall incidence of gram-negative TKA PJIs (0.18% to 0.04%, P = .059). No organism profile changes were found in total hip arthroplasty PJIs. CONCLUSION: VIP is not associated with more difficult to treat primary TJA PJIs. While promising, these findings require a prospective randomized controlled trial for confirmation. LEVEL OF EVIDENCE: Level III, Retrospective cohort study.

Lack of small tibial component size availability for females in a highly utilized total knee arthroplasty system.

PURPOSE: Surgeons must rely on manufacturers to provide an appropriate distribution of total knee arthroplasty (TKA) sizes. There is a lack of literature regarding current appropriateness of tibial sizing schemes according to sex. As such, a study was devised assessing the adequacy of off-the-shelf tibial component size availability according to sex. METHODS: A search was conducted to identify all primary TKAs between July 2012 and June 2019 performed using a single implant. Baseline patient characteristics were collected (age, weight, height, BMI, and race). Two cohorts were created according to patient sex. Tibial sizes for each cohort were collected. Tibial component bar graph and histogram were created according to component sizes. Skewness and kurtosis were calculated for each distribution. Overhang was noted and measured radiographically. RESULTS: A total of 864 patients were identified, 38.7% males and 61.3% females. Most patients were Caucasian, and BMI was similar between cohorts. Tibial size distribution for males was as follows: 0.3% C, 4.8% D, 16.5% E, 40.1% F, 31.4% G, 6.9% H. Tibial size distribution for females was as follows: 30.8% C, 42.8% D, 23.0% E, 2.6% F, 0.8% G, 0.0% H. Histograms and normal curves demonstrated a fairly symmetric distribution of sizes for males (skewness = - 0.31, kurtosis = - 0.03). The distribution for females was positively skewed (skewness = 0.57, kurtosis = 0.12). Overall, overhang was noted in 16.6% of all size C tibias. CONCLUSIONS: The results of this study highlight an implant-specific discrepancy in size availability affecting female patients which could result in inferior outcomes. The authors urge manufacturers to critically assess current implant size distribution availability to ensure both genders are adequately, and equally represented. LEVEL OF EVIDENCE: IV.

Topical Vancomycin Powder and Dilute Povidone-Iodine Lavage Reduce the Rate of Early Periprosthetic Joint Infection After Primary Total Knee Arthroplasty.

BACKGROUND: Vancomycin powder and dilute povidone-iodine lavage (VIP) was introduced to reduce the incidence of periprosthetic joint infection (PJI) in high-risk total knee arthroplasty (TKA) patients. We hypothesize that VIP can reduce the incidence of early PJI in all primary TKA patients, regardless of preoperative risk. METHODS: An infection database of primary TKAs performed before a VIP protocol was implemented (January 2012-December 2013), during a time when only high-risk TKAs received VIP (January 2014-December 2015), and when all TKAs received VIP (January 2016-September 2019) at an urban, university-affiliated, not-for-profit orthopedic hospital was retrospectively reviewed to identify patients with PJI. Criteria used for diagnosis of PJI were the National Healthcare Safety Network and Musculoskeletal Infection Society guidelines. RESULTS: VIP reduced early primary TKA PJI incidence in both the high-risk and all-risk cohorts compared with the pre-VIP cohort by 44.6% and 56.4%, respectively (1.01% vs 0.56% vs 0.44%, P = .0088). In addition, after introducing VIP to all-risk TKA patients, compared with high-risk TKA patients, the relative risk of PJI dropped an additional 21.4%, but this finding did not reach statistical significance (0.56% vs 0.44%, P = .4212). There were no demographic differences between the 3 VIP PJI cohorts. CONCLUSION: VIP is associated with a reduced early PJI incidence after primary TKA, regardless of preoperative risk. With the literature supporting its safety and cost-effectiveness, VIP is a value-based intervention, but given the nature of this historical cohort study, a multicenter randomized controlled trial is underway to definitively confirm its efficacy.

Differences in Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) Scores for a Single Surgeon Comparing Two Institutions: An Unfair Reimbursement Metric.

BACKGROUND: Emphasis on value-based purchasing links physician financial remuneration to patient-derived outcome scores. Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) surveys aim to provide a uniform comparison tool. Of the 22 different survey questions, only 3 (13.6%) focus on experience related to doctors. We sought to determine how HCAHPS scores differ for a single surgeon performing more than 500 total joint arthroplasties annually, divided almost equally between two centers. METHODS: HCAHPS data from 2015 to 2018 for a single, fellowship-trained arthroplasty surgeon were collected from two different hospitals. More than 200 cases were performed at each center with the same staff. One center is a large metropolitan academic-teaching hospital, and the other is a suburban private hospital. The purpose of the study was to determine if differences existed regarding HCHAPS scores between the two institutions. RESULTS: A significant difference was found between institutions regarding questions pertaining to "hospital environment," "admission process," and "hospital staff concern for pain," with more patients responding favorably in Institution Two than Institution One. CONCLUSION: Patient perceptions and ratings of overall experience differ significantly between hospitals even when surgery is performed by a single surgeon. These results lend credence to the fact that surgeons should not be unduly penalized for the hospital in which they operate, and financial remuneration involving HCAHPS scores must be approached with caution. This unfair system could potentially drive surgeons to perform the majority of their cases in the hospital system with higher scores in the nonphysician related domains as this would affect overall patient satisfaction, and thus, financial compensation.

Surgical Approach to Total Hip Arthroplasty Affects the Organism Profile of Early Periprosthetic Joint Infections.

The optimal approach for total hip arthroplasty (THA) remains hotly debated. While wound complications following the direct anterior approach are higher than with other approaches, the organism profile of periprosthetic joint infections (PJIs) by approach remains unknown. Our goal was to compare the organism profiles of PJIs following direct anterior and non-anterior THA. METHODS: We retrospectively reviewed 12,549 primary THAs (4,515 direct anterior and 8,034 non-anterior) that had been performed between January 2012 and September 2019 at a university-affiliated single-specialty orthopaedic hospital to identify patients with an early postoperative PJI. Criteria used for the diagnosis of a PJI were the National Healthcare Safety Network, which screens for PJI that occurs within 90 days of index arthroplasty, and the Musculoskeletal Infection Society guidelines. Patient demographic information and organism characteristics were recorded for analysis. RESULTS: We identified 84 patients (38 who underwent the direct anterior approach and 46 who underwent the non-anterior approach) with an early postoperative PJI following primary THA (0.67% total THA PJI rate, 0.84% direct anterior THA PJI rate, and 0.57% non-anterior THA PJI rate). The direct anterior THA cohort had a significantly lower body mass index and American Society of Anesthesiologists score than the non-anterior THA cohort (29.5 versus 35.2 kg/m2, p < 0.0001; 2.29 versus 2.63, p = 0.016, respectively). Regarding organism profile, patients in the direct anterior THA cohort had significantly more monomicrobial gram-negative infections than the non-anterior THA cohort (4 versus 0, p = 0.038). We did not identify any demographic risk factors other than approach for gram-negative PJI. There were no significant differences in methicillin-resistant Staphylococcus aureus, methicillin-sensitive Staphylococcus aureus, coagulase-negative Staphylococcus, obligate anaerobes, polymicrobial, or PJIs due to other organisms by approach. CONCLUSIONS: Direct anterior THA approaches have a greater risk of monomicrobial gram-negative PJI, likely due to the unique microbiome of the inguinal region. While targeted infection prophylaxis may reduce these infections, it is not entirely effective on its own. Future studies with larger sample sizes are required to help us develop more targeted perioperative infection prophylaxis. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Reduced Aseptic Loosening With Fully Cemented Short-Stemmed Tibial Components in Primary Cemented Total Knee Arthroplasty.

BACKGROUND: Recently, the use of short tibial stems in the obese population undergoing total knee arthroplasty (TKA) has been proposed. Thus, we designed a study to assess tibial component survivorship after primary TKA using a single implant both with and without a fully cemented stem extension performed by a single surgeon. METHODS: A search of our institutional research database was performed. A minimum 2-year follow-up was selected. Cohorts were created according to patient body mass index (BMI; >40 kg/m2 and <40 kg/m2) and the presence (stemmed tibia [ST]) or absence (non-stemmed tibia [NST]) of a short tibial stem extension. Kaplan-Meier survival analyses for aseptic loosening and log-rank tests were performed. RESULTS: A total of 236 patients were identified (ST = 162, NST = 74). Baseline patient characteristics were statistically similar between cohorts with the exception of BMI which was greater in the ST cohort (32.9 kg/m2, 30.6 kg/m2; P = .01). Kaplan-Meier survival analysis at 5 years was superior for the BMI < 40 kg/m2 cohort (98.9%, 93.1%; P = .045), the ST cohort (100%, 94.5%; P = .006), and the BMI > 40 kg/m2 with ST cohort at 4 years (71.4%, 100%; P = .008). CONCLUSION: Morbid obesity and a short native tibial stem design appear to be associated with aseptic loosening in primary TKA. This appears to be mitigated through the use of an ST. As such, the use of ST may be considered in at-risk patients. Alternatively, implants with longer native stem designs can be employed. Modern short-stemmed tibial components may need to be redesigned.