Metaphyseal Fixation Using Cones and Sleeves for Severe Proximal Tibial Bone Loss.

BACKGROUND: Tibial bone defects are commonly encountered in revision total knee arthroplasty (rTKA) and can be managed with metaphyseal cones or sleeves. Few studies have directly compared tibial cones and sleeves in rTKA, and none have limited this comparison to the most severe tibial defects. The purpose of this study was to evaluate and compare the outcomes of metaphyseal cones and sleeves for tibial reconstruction in rTKA regarding implant fixation and clinical outcomes. METHODS: A retrospective review was conducted on patients undergoing rTKA in which metaphyseal cones or sleeves were utilized for addressing metaphyseal bone loss (34 cones and 18 sleeves). Tibial bone loss was classified according to the Anderson Orthopaedic Research Institute bone defect classification, with types 2B and 3 being included. Patient-reported outcomes and postoperative complications were collected, and a radiographic evaluation of osseointegration or loosening was performed. RESULTS: There were 52 knees included (34 cones, 18 sleeves), with a median follow-up of 41.0 months. All-cause implant survival was 100% at 2 years and 96% (95% confidence interval: 76 to 99%) at 4 years, with 98% of tibial components demonstrating osseointegration at the final follow-up. During follow-up, there were a total 11 revisions, of which 1 sleeve was revised secondary to implant loosening. Tibial sleeves had a higher risk of revision compared to tibial cones (P < .01), and sleeves fixed with a hybrid technique were more likely to need revision than cones fixed by the same method (P = .01). CONCLUSIONS: Porous metaphyseal tibial cones and tibial metaphyseal sleeves both performed well at a 41-month median follow-up with no difference in aseptic survivorship between the 2 constructs. Both demonstrate high rates of osseointegration, low rates of aseptic failure, and significant improvement in Knee Society Scores in patients with severe tibial defects in rTKA.

Highly Cross-Linked Polyethylene in Patients 50 Years of Age and Younger: A 20-year Follow-Up Analysis.

BACKGROUND: Highly cross-linked polyethylene (HXLPE) has been an excellent bearing for total hip arthroplasty (THA) due to improved wear characteristics compared to conventional materials. Patients 50 years of age or younger are at high risk for wear-related complications of their THA, and few studies have followed these patients who have HXPLE into the third decade. METHODS: In a retrospective review of 88 consecutive THAs performed in 77 patients aged 50 years and younger (mean 41; range, 20 to 50), in which HXLPE was utilized, they were evaluated for their clinical and radiographic results at an average of 20-year follow-up (range, 18 to 24). The current study reports on longer-term follow-up from our previously published series at shorter follow-up times. Patients were categorized by femoral head material: cobalt chrome (n = 14), ceramic (n = 30), and oxidized zirconium (n = 22) and by femoral head size: 26 mm (n = 12), 28 mm (n = 46), and 32 mm (n = 8). Harris Hip Scores were collected preoperatively and at the most recent follow-up. Radiographs were evaluated for linear and volumetric wear, radiolucent lines, and osteolysis. RESULTS: Mean Harris Hip Scores improved from 47.1 (standard deviation [SD] 8.8) preoperatively to 92.0 (SD 7.7) (P < .0001) at 20-year follow-up. There was one hip that was revised for recurrent instability, and no hip demonstrated radiographic evidence of loosening or osteolysis. The mean polyethylene linear wear rate was 0.017 (SD 0.012) mm/y, and the mean polyethylene volumetric wear rate was 3.15 (SD 2.8) mm3/year, with no significant differences based on articulation type or head size. CONCLUSIONS: Total hip arthroplasty with HXLPE in patients ≤ 50 years of age continues to demonstrate excellent long-term clinical and radiographic outcomes with low wear characteristics at 20-year follow-up, regardless of femoral head material or size.

The Chitranjan S. Ranawat Award: Manipulation Under Anesthesia to Treat Postoperative Stiffness After Total Knee Arthroplasty: A Multicenter Randomized Clinical Trial.

BACKGROUND: Manipulation under anesthesia (MUA) occurs in 4% of patients after total knee arthroplasty (TKA). Anti-inflammatory medications may target arthrofibrosis pathogenesis, but the data are limited. This multicenter randomized clinical trial investigated the effect of adjuvant anti-inflammatory medications with MUA and physical therapy on range of motion (ROM) and outcomes. METHODS: There were 124 patients (124 TKAs) who developed stiffness after primary TKA for osteoarthritis enrolled across 15 institutions. All received MUA when ROM was < 90° at 4 to 12 weeks postoperatively. Randomization proceeded via a permuted block design. Controls received MUA and physical therapy, while the treatment group also received one dose of pre-MUA intravenous dexamethasone (8 mg) and 14 days of oral celecoxib (200 mg). The ROM and clinical outcomes were assessed at 6 weeks and 1 year. This trial was registered with ClinicalTrials.gov. RESULTS: The ROM significantly improved a mean of 46° from a pre-MUA ROM of 72 to 118° immediately after MUA (P < .001). The ROM was similar between the treatment and control groups at 6 weeks following MUA (101 versus 99°, respectively; P = .35) and at one year following MUA (108 versus 108°, respectively; P = .98). Clinical outcomes were similar at both end points. CONCLUSIONS: In this multicenter randomized clinical trial, the addition of intravenous dexamethasone and a short course of oral celecoxib after MUA did not improve ROM or outcomes. However, MUA provided a mean ROM improvement of 46° immediately, 28° at 6 weeks, and 37° at 1 year. Further investigation in regards to dosing, duration, and route of administration of anti-inflammatory medications remains warranted. LEVEL OF EVIDENCE: Level 1, RCT.

Novel Technique for the Identification of Hip Implants Using Artificial Intelligence.

BACKGROUND: The anticipated growth of total hip arthroplasty will result in an increased need for revision total hip arthroplasty. Preoperative planning, including identifying current implants, is critical for successful revision surgery. Artificial intelligence (AI) is promising for aiding clinical decision-making, including hip implant identification. However, previous studies have limitations such as small datasets, dissimilar stem designs, limited scalability, and the need for AI expertise. To address these limitations, we developed a novel technique to generate large datasets, tested radiographically similar stems, and demonstrated scalability utilizing a no-code machine learning solution. METHODS: We trained, validated, and tested an automated machine learning-implemented convolutional neural network to classify 9 radiographically similar femoral implants with a metaphyseal-fitting wedge taper design. Our novel technique uses computed tomography-derived projections of a 3-dimensional scanned implant model superimposed within a computed tomography pelvis volume. We employed computer-aided design modeling and MATLAB to process and manipulate the images. This generated 27,020 images for training (22,957) and validation (4,063) sets. We obtained 786 test images from various sources. The performance of the model was evaluated by calculating sensitivity, specificity, and accuracy. RESULTS: Our machine learning model discriminated the 9 implant models with a mean accuracy of 97.4%, sensitivity of 88.4%, and specificity of 98.5%. CONCLUSIONS: Our novel hip implant detection technique accurately identified 9 radiographically similar implants. The method generates large datasets, is scalable, and can include historic or obscure implants. The no-code machine learning model demonstrates the feasibility of obtaining meaningful results without AI expertise, encouraging further research in this area.

Granulocytic myeloid-derived suppressor cell activity during biofilm infection is regulated by a glycolysis/HIF1a axis.

Staphylococcus aureus is a leading cause of biofilm-associated prosthetic joint infection (PJI). A primary contributor to infection chronicity is an expansion of granulocytic myeloid-derived suppressor cells (G-MDSCs), which are critical for orchestrating the antiinflammatory biofilm milieu. Single-cell sequencing and bioinformatic metabolic algorithms were used to explore the link between G-MDSC metabolism and S. aureus PJI outcome. Glycolysis and the hypoxia response through HIF1a were significantly enriched in G-MDSCs. Interfering with both pathways in vivo, using a 2-deoxyglucose nanopreparation and granulocyte-targeted Hif1a conditional KO mice, respectively, attenuated G-MDSC-mediated immunosuppression and reduced bacterial burden in a mouse model of S. aureus PJI. In addition, single-cell RNA-Seq (scRNA-Seq) analysis of granulocytes from PJI patients also showed an enrichment in glycolysis and hypoxia-response genes. These findings support the importance of a glycolysis/HIF1a axis in promoting G-MDSC antiinflammatory activity and biofilm persistence during PJI.

Long-term polyethylene wear rates and clinical outcomes of oxidized zirconium femoral heads on highly cross-linked polyethylene in total hip arthroplasty.

Aims: Oxidized zirconium (OxZi) and highly cross-linked polyethylene (HXLPE) were developed to minimize wear and risk of osteolysis in total hip arthroplasty (THA). However, retrieval studies have shown that scratched femoral heads may lead to runaway wear, and few reports of long-term results have been published. The purpose of this investigation is to report minimum ten-year wear rates and clinical outcomes of THA with OxZi femoral heads on HXLPE, and to compare them with a retrospective control group of cobalt chrome (CoCr) or ceramic heads on HXLPE. Methods: From 2003 to 2006, 108 THAs were performed on 96 patients using an OxZi head with a HXLPE liner with minimum ten-year follow-up. Harris Hip Scores (HHS) were collected preoperatively and at the most recent follow-up (mean 13.3 years). Linear and volumetric liner wear was measured on radiographs of 85 hips with a minimum ten-year follow-up (mean 14.5 years). This was compared to a retrospective control group of 45 THAs using ceramic or CoCr heads from October 1999 to February 2005, with a minimum of ten years' follow-up. Results: Average HHS improved from 50.8 to 91.9 and 51.0 to 89.8 in the OxZi group and control group, respectively (p = 0.644), with no osteolysis in either group. Linear and volumetric wear rates in the OxZi group averaged 0.03 mm/year and 3.46 mm3/year, respectively. There was no statistically significant difference in HHS scores, nor in linear or volumetric wear rate between the groups, and no revision for any indication. Conclusion: The radiological and clinical outcomes, and survivorship of THA with OxZi femoral heads and HXLPE liners, were excellent, and comparable to CoCr or ceramic heads at minimum ten-year follow-up. Wear rates are below what would be expected for development of osteolysis. OxZi-HXLPE is a durable bearing couple with excellent long-term outcomes.

Recurrent Periprosthetic Joint Infections: Diagnosis, Management, and Outcomes.

Periprosthetic joint infection (PJI) remains one of the most common complications after total joint arthroplasty. It is challenging to manage, associated with significant morbidity and mortality, and is a financial burden on the health care system. Failure of 2-stage management for chronic PJI is not uncommon. Repeat infections are oftentimes polymicrobial, multiple drug-resistant microorganisms, or new organisms. Optimizing the success of index 2-stage revision is the greatest prevention against failure of any subsequent management options and requires a robust team-based approach.

Management of Femoral Neck Fractures in Patients Age ≥50 Years by American Board of Orthopaedic Surgery Part II Examination Candidates.

OBJECTIVE: Assess associations between fellowship training, procedure, and performance in femoral neck fracture (FNF) surgery on adults by American Board of Orthopaedic Surgery (ABOS) Part II Examination candidates. SETTING: ABOS SCRIBE database exam years 2007-2020. PARTICIPANTS: 6,777 candidates performing 39,283 FNF surgeries on adults age ≥ 50 years. INTERVENTION: Fellowship training. MAIN OUTCOME MEASUREMENTS: Case volume; procedure performed: internal fixation (IF), hemiarthroplasty (HA), or total hip arthroplasty (THA); complications; readmission; reoperation. RESULTS: Over the observation period, fewer candidates reported FNF surgery (68% overall, -0.6%/year, R2=0.80) while more candidates reported fellowship training (87% overall, +1.4%/year, R2=0.81). The rate of any complication was significantly associated with fellowship training (32% overall, p<0.001). Readmission (12%, p=0.080) and reoperation (5%, p=0.531) were not significantly associated with fellowship training. The odds of any complication (odds ratio [OR]=-0.03 [95% CI -0.07 to -0.001] per 10 cases) and surgical complication (OR=-0.12 [95% CI -0.17 to -0.07] per 10 cases) were negatively associated with candidate FNF case volume. 3,396 THA for FNF were performed (8% of cases). THA use increased 25 cases/year (R2=0.83) and was associated with adult reconstruction (p<0.001) and oncology (p<0.001) fellowship training. Any complication of THA for FNF (32%, p=0.261), readmission (9% overall, p=0.321), and reoperation (5%, p=0.200) were not significantly associated with fellowship training. CONCLUSIONS: Between 2007-2020, femoral neck fracture surgery was performed by fewer ABOS Part II Examination candidates and there was greater use of THA. Over this time period there was a greater prevalence of fellowship training but complications were not associated with fellowship training. Complications were associated with FNF case volume. LEVEL OF EVIDENCE: Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Wear, Osteolysis, and Aseptic Loosening Following Total Hip Arthroplasty in Young Patients with Highly Cross-Linked Polyethylene: A Review of Studies with a Follow-Up of over 15 Years.

Total hip arthroplasty (THA) has in recent years trended toward a younger, more physically demanding patient population. Mid- to long-term studies of all ages of THA patients using highly cross-linked polyethylene (HXLPE) have been favorable, but concerns about its long-term failure and wear-related complications remain for young THA patients. In this narrative review, a search of the PubMed/MEDLINE and Cochrane databases was performed, and we identified six studies with a minimum 15-year follow-up of HXLPE with various femoral head materials. Wear-related revisions were exceedingly low for patients under the age of 55, with variable reports of non-clinically significant osteolysis. Higher activity levels, a larger femoral head size, and femoral head material were not associated with greater long-term wear rates. Young THA with metal or ceramic on HXLPE is exceedingly durable with favorable outcomes at follow-ups of over 15 years.

Do Articular Surfaces of Dual Mobility Hips Have More Wear and Friction? An In Vitro Investigation.

BACKGROUND: Larger head-to-neck ratio of dual mobility (DM) hip arthroplasties provide greater range of motion/less risk of dislocation, but raise concerns for high wear and friction. We measured in vitro, the wear rates of contemporary DM hips with highly cross-linked ultra high molecular weight polyethylene (UHWMPE), where it came from, and their frictional torques. METHODS: Hip simulators were used to compare the wear of DM to fixed-bearing (FB) designs of 2 different implants. Each of 8 different configurations underwent millions of simulated walking cycle tests, some as full DM, some as FB controls, some DM with the outer-articulation deliberately immobilized, and some the inner. Wear and 3-dimensional-frictional torques were measured and friction independent of size was deduced. RESULTS: The DM hips produced lower wear and friction-torque than the FB hips. The DM wear during walking gait comes mostly from the smaller inner articular surface. If the outer surface was immobilized, the wear and torque of the inner alone would be small, but the full DM (inner and outer free-to-move) wear and torque were smallest of all. Friction measurements expectedly showed larger hips having higher frictional torques, but the DM showed the lowest, again because its motion was mostly the smaller inner articulation; smaller than even a modern fixed-bearing hip. CONCLUSION: The DM hips appear to combine the benefits of greater range of motion and less impingement of larger hips, with the lower wear and friction of smaller FB hips, with some benefits compromised if the outer or inner articulations are immobilized.

The Challenge of Emerging Resistant Gram-Positive Pathogens in Hip and Knee Periprosthetic Joint Infections.

➤: An increase in resistant bacterial pathogens has occurred over the last 4 decades. ➤: Careful patient selection and improving or correcting risk factors for periprosthetic joint infection (PJI) before elective surgical treatment are strongly recommended. ➤: Appropriate microbiological methods, including those used to detect and grow Cutibacterium acnes, are recommended. ➤: Antimicrobial agents used in the prevention or management of infection should be selected appropriately and the duration of therapy should be carefully considered in order to mitigate the risk of developing bacterial resistance. ➤: Molecular methods including rapid polymerase chain reaction (PCR) diagnostics, 16S sequencing, and/or shotgun and/or targeted whole-genome sequencing are recommended in culture-negative cases of PJI. ➤: Expert consultation with an infectious diseases specialist (if available) is recommended to assist with the appropriate antimicrobial management and monitoring of patients with PJI.

Failure of a Highly Cross-Linked Polyethylene Liner After Spine Fusion.

A 73-year-old woman, 11 years after total hip arthroplasty and 2 years after a multilevel lumbar spine fusion, presented with a 2-month history of anterior hip and gluteal pain. She was diagnosed with an acetabular liner fracture that occurred through the high wall, likely related to repetitive impingement on the neck of the femoral implant, as notable burnishing was observed on the explanted femoral head. The acetabulum was successfully revised to a dual-mobility articulation. Spinal fusion after total hip arthroplasty can alter the acetabular implant position and was seen in our patient whose previously functional high-walled liner failed. Surgeons may consider alternative techniques, including a change in acetabular implant's anteversion to mitigate the need for a high-walled liner or the use of a dual-mobility bearing.

Increased Incidence of Methicillin-Resistant Staphylococcus aureus in Knee and Hip Prosthetic Joint Infection.

BACKGROUND: Periprosthetic joint infection (PJI) is a devastating complication of knee and hip arthroplasty. Past literature has shown that gram-positive bacteria are commonly responsible for these infections, although limited research exists studying the changes in the microbial profile of PJIs over time. This study sought to analyze the incidence and trends of pathogens responsible for PJI over three decades. METHODS: This is a multi-institutional retrospective review of patients who had a knee or hip PJI from 1990 to 2020. Patients with a known causative organism were included and those with insufficient culture sensitivity data were excluded. There were 731 eligible joint infections from 715 patients identified. Organisms were divided into multiple categories based on genus/species and 5-year increments were used to analyze the study period. The Cochran-Armitage trend tests were used to evaluate linear trends in microbial profile over time and a P-value <.05 was considered statistically significant. RESULTS: There was a statistically significant positive linear trend in the incidence of methicillin-resistant Staphylococcus aureus over time (P = .0088) as well as a statistically significant negative linear trend in the incidence of coagulase-negative staphylococci over time (P = .0018). There was no statistical significance between organism and affected joint (knee/hip). CONCLUSION: The incidence of methicillin-resistant Staphylococcus aureus PJI is increasing over time, whereas, coagulase-negative staphylococci PJI is decreasing, paralleling the global trend of antibiotic resistance. Identifying these trends may help with the prevention and treatment of PJI through methods such as remodeling perioperative protocols, modifying prophylactic/empiric antimicrobial approaches, or transitioning to alternative therapeutic strategies.

Total Joint Arthroplasty in Patients With an Implanted Left Ventricular Assist Device.

Left ventricular assist devices (LVADs) may be used as bridge therapy or destination therapy in heart failure patients. Total joint arthroplasty may improve the functional status of patients limited by arthritis. This retrospective case series evaluated patients with an implanted LVAD who underwent a total joint arthroplasty at 1 institution from 2012 to present. Five patients underwent 12 surgeries with 7 primary arthroplasties and 5 revisions. Their mortality, length of stay, coagulopathic events, incidence of infection or revision arthroplasty, and heart transplantation were evaluated, and is the largest study to date of this population. Two patients expired from thrombotic events while 3 progressed to heart transplantation. Joint arthroplasty is feasible in patients with an implanted LVAD with expected risk and perioperative multidisciplinary collaboration.

American Board of Orthopaedic Surgery's Initiatives Toward Competency-Based Education.

The American Board of Orthopaedic Surgery (ABOS) is the national organization charged with defining education standards for graduate medical education in orthopaedic surgery. The purpose of this article is to describe initiatives taken by the ABOS to develop assessments of competency of residents to document their progress toward the independent practice of orthopaedic surgery and provide feedback for improved performance during training. These initiatives are called the ABOS Knowledge, Skills, and Behavior Program. Web-based assessment tools have been developed and validated to measure competence. These assessments guide resident progress through residency education and better define the competency level by the end of training. The background and rationale for these initiatives and how they serve as steps toward competency-based education in orthopaedic residency education in the United States will be reviewed with a vision of a hybrid of time and competency-based orthopaedic residency education that will remain 5 years in length, with residents assessed using standardized tools.

Predictors of Reinfection in Prosthetic Joint Infections Following Two-Stage Reimplantation.

BACKGROUND: Two-stage reimplantation is an effective treatment for periprosthetic joint infection (PJI). Many factors are involved in the variable success of this procedure. The purpose of this study is to examine the relationship between patient risk factors, comorbidities, and the pathogen on reinfection rates following two-stage reimplantation. METHODS: We evaluated 158 patients treated for PJI from 2008-2019. Only patients who had completed a two-stage exchange were included. Patient demographics, comorbidities, laboratory values, time-to-reimplantation, pathogen, antibiotic sensitivities, host status, and reinfection rates were assessed. Multivariate analysis was performed to identify correlation between risk factors and reinfection. A P-value < .05 was considered statistically significant. RESULTS: 31 patients experienced a reinfection (19.6%). There was a statistically significant association between infection with Methicillin Sensitive Staphylococcus Aureus (MSSA) and reinfection (P = .046). Patients with a reinfection also had a significantly greater median serum C-reactive protein (CRP) level (12.65 g/dL) at the time of diagnosis compared to patients without a reinfection (5.0 g/dL) (P = .010). Median Erythrocyte Sedimentation Rate (ESR) (56 in no re-infection and 69 in re-infection) and time-to-reimplantation (101 days in no reinfection and 141 days in reinfection) demonstrated a trend toward an association with re-infection but were not statistically significant (P = .055 and P = .054 respectively). CONCLUSION: As the number of arthroplasties continue to rise, PJIs are increasing proportionately and represent a significant revision burden. Elevated C-reactive protein (CRP) levels and Methicillin Sensitive Staphylococcus aureus (MSSA) infection were strongly associated with failure of a two-stage reimplantation. While not statistically significant with our numbers, there were strong trends toward an association between elevated Erythrocyte Sedimentation Rate (ESR), longer time-to-reimplantation, and reinfection.

Long Term Results of Two-Stage Revision for Chronic Periprosthetic Hip Infection: A Multicenter Study.

BACKGROUND: Two-stage exchange arthroplasty remains the gold standard in the United States for treatment of chronic periprosthetic joint infection (PJI). Long-term reinfection rates and clinical outcomes with sufficient subject numbers remain limited. The purpose was to evaluate the long-term outcomes following two-stage exchange following hip arthroplasty. METHODS: Retrospective review of 221 patients who underwent two-stage exchange hip arthroplasty for chronic PJI at three large tertiary referral institutions from 1990-2015. Outcomes including reinfection, mortality, and all-cause revision were calculated. Cumulative incidence of reinfection with death as competing factor was also calculated. Risk factors for reinfection were determined using Cox multivariate regression analysis. RESULTS: Rate of infection eradication and all-cause revision was 88.24% and 22.6%, respectively. Overall mortality rate was 40.72%. Patients with minimum five-year follow-up (n = 129) had a success rate of 91.47% with mortality rate of 41.1%. Major risk factors for reinfection included polymicrobial infection (HR = 2.36, 95% CI: 1.08-5.14) and antibiotic resistant organism (HR = 2.36, 95% CI: 1.10-5.04). CONCLUSION: This is the largest series with greater than 5-year follow-up evaluating outcomes of two-stage exchange hip arthroplasty. This technique resulted in a relatively high infection eradication, however, the mortality rate is alarmingly high. Antibiotic resistant organisms appear to be highest risk factor for failure.

Randomised comparative effectiveness trial of Pulmonary Embolism Prevention after hiP and kneE Replacement (PEPPER): the PEPPER trial protocol.

INTRODUCTION: More than 1 million elective total hip and knee replacements are performed annually in the USA with 2% risk of clinical pulmonary embolism (PE), 0.1%-0.5% fatal PE, and over 1000 deaths. Antithrombotic prophylaxis is standard of care but evidence is limited and conflicting. We will compare effectiveness of three commonly used chemoprophylaxis agents to prevent all-cause mortality (ACM) and clinical venous thromboembolism (VTE) while avoiding bleeding complications. METHODS AND ANALYSIS: Pulmonary Embolism Prevention after HiP and KneE Replacement is a large randomised pragmatic comparative effectiveness trial with non-inferiority design and target enrolment of 20 000 patients comparing aspirin (81 mg two times a day), low-intensity warfarin (INR (International Normalized Ratio) target 1.7-2.2) and rivaroxaban (10 mg/day). The primary effectiveness outcome is aggregate of VTE and ACM, primary safety outcome is clinical bleeding complications, and patient-reported outcomes are determined at 1, 3 and 6 months. Primary data analysis is per protocol, as preferred for non-inferiority trials, with secondary analyses adherent to intention-to-treat principles. All non-fatal outcomes are captured from patient and clinical reports with independent blinded adjudication. Study design and oversight are by a multidisciplinary stakeholder team including a 10-patient advisory board. ETHICS AND DISSEMINATION: The Institutional Review Board of the Medical University of South Carolina provides central regulatory oversight. Patients aged 21 or older undergoing primary or revision hip or knee replacement are block randomised by site and procedure; those on chronic anticoagulation are excluded. Recruitment commenced at 30 North American centres in December 2016. Enrolment currently exceeds 13 500 patients, representing 33% of those eligible at participating sites, and is projected to conclude in July 2024; COVID-19 may force an extension. Results will inform antithrombotic choice by patients and other stakeholders for various risk cohorts, and will be disseminated through academic publications, meeting presentations and communications to advocacy groups and patient participants. TRIAL REGISTRATION: NCT02810704.

Long Term Results of Two-Stage Revision for Chronic Periprosthetic Knee Infection: A Multicenter Study.

BACKGROUND: Long-term reinfection and mortality rates and clinical outcomes with sufficient subject numbers remain limited for patients undergoing two-stage exchange arthroplasty for chronic periprosthetic knee infections. The purpose of this study was to determine the long-term reinfection, complication, and mortality following reimplantation for two-stage exchange following knee arthroplasty. METHODS: Retrospective review of 178 patients who underwent two-stage exchange knee arthroplasty for chronic PJI at three large tertiary referral institutions with an average of 6.63-year follow-up from reimplantation from 1990 to 2015. Rates of reinfection, mortality, and all-cause revision were calculated along with the cumulative incidence of reinfection with death as a competing factor. Risk factors for reinfection were determined using Cox multivariate regression analysis. RESULTS: Overall rate of infection eradication was 85.41%, with a mortality rate of 30.33%. Patients with minimum 5-year follow-up (n = 118, average 8.32 years) had an infection eradication rate of 88.98%, with a mortality rate of 33.05%. CONCLUSION: This is a large series with long-term follow-up evaluating outcomes of two-stage exchange knee arthroplasty resulting in adequate infection eradication and high mortality. Results were maintained at longer follow-up. This technique should be considered in patients with chronic PJI; however, realistic expectations regarding long-term outcomes must be discussed with patients.

Ten-Year Survivorship and Risk of Periprosthetic Fracture of a Cementless Tapered Stem.

This article is a retrospective review of a consecutive series of 401 primary total hip arthroplasties with the use of cementless, ream and broach Synergy stem (Smith & Nephew, Memphis, TN, USA) with minimal 10-year follow-up. We report an overall 10-year survivorship of 99.6% with a total of 15 fractures during the study period. Six of these fractures occurred intraoperatively. This is the largest series to our knowledge reporting greater than 10-year follow-up. This stem has excellent survivorship with overall low risk of periprosthetic fracture.