Majority of ultra-high molecular weight polyethylene (UHMWPE) medical devices used in total joint arthroplasty are crosslinked using gamma radiation to improve wear resistance. Alternative methods of crosslinking are urgently needed to replace gamma radiation due to rapid decline in its supply. Peroxide crosslinking is a candidate method with widespread industrial applications. Oxidative stability and biocompatibility, which are critical requirements for medical device applications, can be achieved using vitamin-E as an additive and by removing peroxide by-products through high temperature melting, respectively. We investigated compression molded UHMWPE/vitamin-E/di-cumyl peroxide blends followed by high-temperature melting in inert gas as a material candidate for tibial knee inserts. Wear resistance increased and mechanical properties remained largely unchanged. Oxidation induction time was higher than most of the other clinically available formulations. The material passed the local-end point biocompatibility tests per ISO 10993. Compounds found in exhaustive extraction were of no concern with margin-of-safety values well above the accepted level, indicating a desirable toxicological risk profile. Peroxide crosslinked, vitamin-E stabilized, and high temperature melted UHMWPE has recently been cleared for clinical use in tibial knee inserts. With all the salient characteristics needed in a material that can provide superior long-term performance in total joint patients, peroxide crosslinking can replace gamma radiation crosslinking of UHMWPE for use in all total joint replacement implant including acetabular liners

Introduction. Patient demand for hip and knee arthroplasty continues to rise. Information sources providing data on the volume and cost of Medicare total joint arthroplasty by hospital are of use to patients and healthcare professionals. Data have demonstrated that higher volume surgeons are associated with lower cost, morbidity, and mortality. The current study assesses if the same is true for hospitals. Methods. The Limited Data Set (LDS) from the Centers for Medicare and Medicaid (CMS) were used for this study. All elective, DRG 470 Total Hip Arthroplasties (THA) reported by CMS from the first quarter of 2013 through the second quarter of 2016 were included. Volume and part A Medicare payments over a 90-day period for the 20 highest volume hospitals in the US were analyzed. Cost associated with initial hospital stay and post discharge skilled nursing, home health, long term acute care, inpatient rehabilitation facilities, and readmission was aggregated and analyzed. For each episode, demographic information (age, sex, and race), geographic location, and Elixhauser comorbidities were calculated to control for major confounding factors in the regression. Results. For the 20 highest volume centers in the US, total joint volume for CMS insured patients varied from 1104 to 5069. Average cost varied from $16,974 to $22,094. For the 20 highest volume cities in the US, total joint volume for CMS insured patients varied from 1,501 to 6,727. Average Medicare part A payment varied from $14,255 to $21,125. Readmission % varied from 3.9% to 8.2%. 90-day mortality varied from 0.0% to 0.57%. DISCUSSION AND CONCLUSION. The variation in volume between the top 20 centers in the US varies by more than a factor of 4 with the highest volume hospital having almost twice the volume as the second highest hospital. Part A payments, readmissions, and mortality also varied widely. Within the top 20 hospitals by volume, there does not appear to be a correlation between volume and cost

Due to limitations of existing pharmacological therapies for the management of chronic pain in osteoarthritis (OA), surgical interventions remain a major component of current standard of care, with total joint replacements (TJRs) considered for people who have not responded adequately to conservative treatment. This study aimed to quantify the economic burden of moderate-to-severe chronic pain in patients with OA in England prior to TJR. A retrospective, longitudinal cohort design was employed using Clinical Practice Research Datalink GOLD primary care data linked to Hospital Episode Statistics secondary care data in England. Patients (age ≥18 years) with an existing OA diagnosis of any anatomical site (Read/ICD-10) were indexed (Dec-2009 to Nov-2017) on a moderate-to-severe pain event (which included TJR) occurring within an episode of chronic pain. 5-year TJR rates from indexing were assessed via Kaplan-Meier estimates. All-cause healthcare resource utilisation and direct medical costs were evaluated in the 1–12 and 13–24 months prior to the first TJR experienced after index. Statistical significance was assessed via paired t-tests. The study cohort comprised 5,931 eligible patients (57.9% aged ≥65 years, 59.2% female). 2,176 (36.7%) underwent TJR (knee: 54.4%; hip: 42.8%; other: 2.8%). The 5-year TJR rate was 45.4% (knee: 24.3%; hip: 17.5%; other: 6.8%). Patients experienced more general practitioner consultations in 1–12 months pre-TJR compared with 13–24 months pre-TJR (means: 12.13 vs. 9.61; p<0.0001), more outpatient visits (6.68 vs. 3.77; p<0.0001), more hospitalisations (0.74 vs. 0.62; p=0.0032), and more emergency department visits (0.29 vs. 0.25, p=0.0190). Total time (days) spent as an inpatient was higher in 1–12 months pre-TJR (1.86 vs. 1.07; p<0.0001). Mean total per-patient cost pre-TJR increased from £1,771 (13–24 months) to £2,621 (1–12 months) (p<0.0001). Resource-use and costs incurred were substantially greater in the 12 months immediately prior to TJR, compared with 13–24 months prior. Reasons for increased healthcare and economic burden in the pre-TJR period deserve further exploration as potential targets for efforts to improve patient experience and efficiency of care

Introduction. There are several potential biological mechanisms that may influence aseptic implant failure including excessive innate and adaptive immune responses to implant debris. We investigated the hypothesis that patients with painful total joint replacements will exhibit elevated levels of metal reactivity and inflammatory markers compared to patients with well-performing TJA. We evaluated this hypothesis by testing for metal hypersensitivity using in vitro LTT assay and analyzing serum levels of selected inflammatory markers. Methods. Subject Groups: Blinded de-identified data from patients with TJR referred for metal hypersensitivity testing using a lymphocyte transformation test (LTT) and serum markers of inflammation using Luminex Multi-Analyte Assay was approved by Rush University IRB and retrospectively reviewed. None of the patients had radiographically identifiable osteolysis. Two groups of TJA patients were tested: Group 1: Well-functioning implant (<3 yrs. post-op), with no self-reported pain, i.e. <1 on 0–10 VAS scale (n=8) and Group 2: Painful TJR (<3 yrs. post-op), with self-determined pain of >8 on a 0–10 VAS scale at the time of blood draw (n=25). Metal-LTT: Peripheral blood mononuclear cells (PBMCs) were collected from 30mL of peripheral blood by Ficoll gradient separation. PBMCs were cultured with NiCl2. 3H Thymidine was added at day 5 of culture and 3H thymidine incorporation was analyzed using a beta scintillation counter at day 6. A stimulation index (SI) of reactivity was calculated by dividing scintillation counts per minute (cpms) of Ni challenged cells by those of untreated controls. A SI of <2 was considered nonreactive, 2 to <4 was mildly reactive and 4 to <8 was reactive. Luminex Assay: Serum samples were collected from whole blood and were analyzed according to manufacturer's protocols. Statistical analysis: Statistical differences were determined using unpaired t-test with Welch's correction with statistical significance at p≤0.1 (90% confidence interval). Results. To test if differences in metal sensitization exist among individuals with joint pain following TJR vs. well-functioning TJR (no pain), we analyzed each person-specific PBMC SI of reactivity to NiCl2. Painful TJR group exhibited greater sensitivity as demonstrated by significantly higher in vitro metal SI level. In general, inflammatory markers measured in serum among patients with pain following TJR were significantly increased compared to patients with no pain following TJR. Specifically, inflammatory markers that are classified as prototypical markers of a M1 inflammatory macrophage i.e. GMCSF, IL-12, IL-18, IL-1β and TNFα were significantly greater in TJR patients with pain compared to TJR patients with no pain. Due to this increase in inflammatory markers, IL-4, an anti-inflammatory marker was also significantly greater in TJR patients with pain in order to combat/mitigate the inflammatory microenvironment. While VEGF was the only marker that was significantly greater in TJR patients with no pain and is characteristic of M2 anti-inflammatory macrophage phenotype. Discussion. Metal sensitivity reactivity and serum markers of inflammation demonstrated significant differences between groups of patients with painful TJRs vs. well-functioning TJR. Classical markers of M1 phenotype were significantly greater in painful TJR group. Our data suggests that patients with self-reported pain following a TJR demonstrate active innate and adaptive immune responses that are significantly higher than patients with a well-performing TJR and that these differences are associated with detectable serum inflammatory markers. An important limitation of this study however, is that group subject numbers were low and that statistical differences found in these groups suggests these inflammatory markers may be more marked than was anticipated

Objectives

The primary objective of this study was to compare accuracy in restoring the native centre of hip rotation in patients undergoing conventional manual total hip arthroplasty (THA) versus robotic-arm assisted THA. Secondary objectives were to determine differences between these treatment techniques for THA in achieving the planned combined offset, component inclination, component version, and leg-length correction.

Introduction

Opioids are an important component of multimodal analgesia, but improper utilization places patients at risk for overdose and addiction. The purpose of this randomized controlled trial is to determine whether the quantity of opioid pills prescribed at discharge is associated with the total amount of opioids consumed or unused by patients after total hip (THA) and knee (TKA) arthroplasty.

Aims. Despite declining frequency of blood transfusion and electrolyte supplementation following total joint arthroplasty, postoperative blood analyses are still routinely ordered for these patients. This study aimed to determine the rate of blood transfusion and electrolyte restoration in arthroplasty patients treated with a perioperative blood conservation protocol and to identify risk factors that would predict the need for transfusion and electrolyte supplementation. Patients and Methods. Patients undergoing primary total joint arthroplasty of the hip or knee between July 2016 and February 2017 at a single institution were included in the study. Standard preoperative and postoperative laboratory data were collected and reviewed retrospectively. A uniform blood conservation programme was implemented for all patients. Need for blood transfusion or potassium supplementation was determined through a coordinated decision by the care team. Rates of transfusion and supplementation were observed, and patient risk factors were noted. Results. The overall rate of blood transfusion was 1.06% in the study population of 1132 total joint arthroplasties performed in 1023 patients. Of the 12 patients requiring transfusion, 11 were female, ten occurred in patients undergoing total hip arthroplasty, and all 12 patients had a preoperative haemoglobin level less than 130 g/l. Operative duration and surgical blood loss were significantly greater in those patients requiring blood transfusion. Nearly all patients requiring transfusion had a history of, or risk factors for, cardiovascular disease. Potassium supplementation was required in 15.5% of the study cohort; 72% of these patients receiving potassium presented with a potassium level less than 4 mmol/l during preoperative testing, while the remaining 28% had a past medical history of either significant anaemia, cardiopulmonary, cardiovascular, or renal diseases that had required substantial medical management. Conclusion. A consistent blood-conserving perioperative strategy effectively minimized need for blood transfusion in total joint arthroplasty patients below previously reported rates in the literature. We suggest that postoperative full blood counts and basic metabolic panels should not routinely be ordered in these patients unless their preoperative haemoglobin and potassium is below 130 g/dl or 4 mmol/l respectively, and they have medical comorbidities

Both total joint arthroplasty (TJA) and Alzheimer's Disease (AD) are prevalent in elderly populations. It is the goal of this study to determine if the presence of implant metals originating from TJA correlates with the onset with higher implant metal content in the brain and AD pathology. Tissue samples from four brain regions of 701 (229 with TJA) participants from an ongoing longitudinal cohort study (Rush Memory and Aging Project) was analyzed including the inferior-temporal-cortex (ITC), which is associated with early onset of AD. Implant metal (Co, Cr, Mo, Ti, Al) content was determined by ICP-MS. Comparisons were conducted between the no-TJA-group and a TJA group. Due to the higher likelihood of Co release the TJA group was further differentiated in a THA (N=146) and a TKA/TSA (N=83) group. Diffuse and neuritic amyloid plaques and phosphorylated tau were assessed and summarized as standard measures of AD pathology. We used separate linear regression models adjusted for age, sex, education, and APOɛ4-status for the associations of all metals (log-transformed) with global AD pathology, amyloid plaques, and phosphorylated tau. The THA group had higher cobalt content across all brain regions (p=0.003) and within the ITC (p=0.051) compared to the no-TJA group, whereas the TKA/TSA group did not. Across all tissue samples, Co was associated with higher amyloid load (β=0.35, p=0.027), phosphorylated tau (β=0.47, p=0.011), and global AD pathology (β=0.19, 0.0004) in the ITC. The presence of TJA itself was not associated with AD pathology. We showed that only Co content was higher within the ITC in persons with THA. We found among all tested metals that Co was consistently associated with AD pathology. Although we found an association of cobalt with AD pathology, the cross-sectional nature of this study does not allow the determination of cause and effect

Total joint arthroplasty (TJA) is one of the commonest and most successful orthopaedic procedures used for the management of end-stage arthritis. With the recent introduction of robotic-assisted joint replacement, Computed tomography (CT) has become part of required pre-operative planning. The aim of this study is to quantify and characterise incidental CT findings, their clinical significance, and their effect on the planned joint arthroplasty. All consecutive patients undergoing an elective TJA (total joint arthroplasty; hip or knee) were retrospectively identified, over a 4-year period (December 2019 and November 2023). Data documented and analysed included patient demographics, type of joint arthroplasty, CT findings, their clinical significance, as well as potential delays to the planned arthroplasty because of these findings and subsequent further investigation. A total of 987 patients (female: 514 patients (52.1%)) undergoing TJA were identified (THA: 444 patients (45.0%); TKA: 400 patients (40.5%); UKA: 143 patients (14.5%)). Incidental findings within imaged areas were identified in 227 patients (23.0%). Of these findings, 74 (7.5%) were significant, requiring further investigation or management, 40 (4.1%) of which represented potential malignancy and 4 (0.4%) resulting in a new cancer diagnosis. A single patient was found to have an aneurysm requiring urgent vascular intervention. Surgery was delayed for further investigation in 4 patients (0.4%). Significant findings were more frequent in THA patients (THA: 43 (9.7%) TKA/UKA: 31 (5.7%). Within our cohort, 74 (7.5%) patients had significant incidental findings that required further investigations or management, with 4 (0.4%) having a previously undiagnosed malignancy. We strongly advocate that all robotic arthroplasty planning CTs are reviewed and reported by a specialist, to avoid missing undiagnosed malignancies and other significant diagnoses

Introduction. Elective surgery elicits a systemic immune response and may result in immunosuppression in certain patients. It is currently unknown whether patients are at an increased risk for viral infection and associated illness in the immediate postoperative period following total joint arthroplasty. This question has become more important given the ongoing coronavirus disease 2019 (COVID-19) pandemic. Methods. We analyzed 3 large administrative datasets (Medicare 5% and 100% standard analytic files, Humana claims database) to identify patients who underwent total knee arthroplasty (TKA) and total hip arthroplasty (THA) from 2005 to 2013. The influenza vaccination status of each patient was defined using the presence or absence of a code for vaccination. The incidence of a flu diagnosis was recorded in both vaccinated and unvaccinated patients at 1 month, 3 months, and 6 months following the date of surgery and was compared to a cohort of vaccinated patients who did not undergo surgery. Results. The incidence of postoperative influenza diagnoses codes in TKA and THA patients were similar to that of vaccinated patients who did not undergo TJA at all time points. The results were largely consistent across all three datasets. Conclusion. Large administrative databases fail to show an increased incidence of influenza codes in patients who have recently undergone total joint arthroplasty. While the lack of signal is reassuring and provides evidence, these findings are limited by the nature of large administrative datasets and the accuracy of coding for influenza. Further studies will be necessary to fully understand an individual patient's postoperative risk for contracting a viral illness

Introduction. Total joint arthroplasty rates have increased dramatically in recent decades. However, a comprehensive analysis of trends in revision total hip arthroplasty has not been performed recently to address the changing volume, costs, and location of these complex cases. We sought to identify trends in volume of these procedures, geographic distribution changes, and cost trends using a national sample. Materials and methods. The National Inpatient Sample, a representative sample of all hospital discharges within the United States, was used to determine the volume of revision total hip arthroplasty (THA) from 1993 to 2014. Procedures were identified by ICD-9 codes corresponding to revision THA. Annual incidence of revision THA was compared to annual incidence of primary THA to determine whether relative growth of revisions differed proportionally from the primary procedure. State-specific data was analyzed where available to develop geographic trend maps in the incidence of revision THA procedures using the estimated state population for years under review. Trends were also reviewed for hospital location (urban versus rural; teaching versus non-teaching) and total hospital charges. Analysis of trends was performed using linear regression models. Results. Volume of revision THA increased slower than primary THA from 1993 to 2014. Revision THA volume increased from 28,429 in 1993 to 48,295 in 2014. However, the relative proportion of revision compared to primary THA during this time period decreased from 21.3% in 1993 to 13.0% in 2014. While revision THA grew significantly at 925 additional procedures per year (p <0.001), the revision/primary proportion declined at a rate of −0.4 percentage points annually (p <0.001). Nationally, only one state demonstrated statewide incidence rate of revision THA >100 / 100,000 residents in 2001, while 31 of 36 states reporting in 2014 demonstrated statewide incidence rate of revision THA >100 / 100,000 residents. Revision THA shifted dramatically away from rural and urban non-teaching hospitals to urban teaching hospitals. In the year 2000, 52.3% of revision THA was performed in urban teaching hospitals, which had increased to 71.2% by 2014. Only 5.2% of revision THA was performed in rural hospitals in 2014. Similarly, hospital charges for revision THA increased significantly from a mean of $32,007 in 2000 to $83,927 in 2014. Discussion. Dramatic changes in the geographic distribution, hospital type, and cost of revision THA have occurred over the past two decades. The importance of this cannot be overstated, especially within the context of shifting payment models including mandated and voluntary bundles that have been applied to total joint arthroplasty procedures. With the burden of these costly, complex surgical cases falling predominantly on urban teaching hospitals, there must be a mechanism for adequately valuing these procedures to allow surgeons to be able to properly care for these patients. For any tables or figures, please contact the authors directly

Introduction. Recent literature has sought to quantify pre-operative work associated with total joint arthroplasty. These studies have utilized surveys or self-reported time logs to estimate the Pre-op Optimization Work (POW) completed by the surgical team. The purpose of this study was to objectively quantify POW associated with total hip arthroplasty (THA) using electronic medical record (EMR) activity audit logs. Methods. Retrospective analysis of EMR activity for 4 arthroplasty surgeons and their clinical staff was collected for 100 consecutive THA cases (25 per surgeon). Clinical informatics data was generated using EMR activity audit logs for pre-THA activity. Every action and mouse-click within a patient's chart was recorded for each team member. The time between mouse-clicks was calculated and summed for each user. Times exceeding five minutes without activity were assumed to reflect inactivity and excluded. Descriptive statistics were used to estimate the POW associated with THA preparation. Results. The mean number of days for pre-THA time period was70.7 (SD43.9; range: 8–175days). During this period, the mean time spent in each patient's chart was 75.5 minutes (SD50.75) minutes. Surgeon's POW in the medical record accounted for 7.3(SD6.7) of these minutes. Much of the work was conducted by nurses (47.0 minutes, SD43.4), physician extenders (10.8 minutes, SD 13.1), and qualified office staff/technicians (10.4 minutes, SD14.9). The majority of work captured in the EMR activity log was associated with medication review, patient optimization, documentation of necessary medical clearances, ordersets, patient communication, and prior authorization requests. Conclusion. A considerable amount of preoperative work is required between the clinic date a patient decides to pursue THA and the day prior to surgery. These retrospective electronic time stamp measurements should represent the absolute minimum time required for surgical preparation

Aims. The aim of this study was to investigate the differences in 30-day outcomes between patients undergoing revision for an infected total hip arthroplasty (THA) compared with an aseptic revision THA. Patients and Methods. This was a retrospective review of prospectively collected data from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database, between 2012 and 2017, using Current Procedural Terminology (CPT) codes for patients undergoing a revision THA (27134, 27137, 27138). International Classification of Diseases Ninth Revision/Tenth Revision (ICD-9-CM, ICD-10-CM) diagnosis codes for infection of an implant or device were used to identify patients undergoing an infected revision THA. CPT-27132 coupled with ICD-9-CM/ICD-10-CM codes for infection were used to identify patients undergoing a two-stage revision. A total of 13 556 patients were included; 1606 (11.8%) underwent a revision THA due to infection and there were 11 951 (88.2%) aseptic revisions. Results. Patients undergoing an infected revision had a significantly greater length of stay of more than three days (p < 0.001), higher odds of any 30-day complication (p < 0.001), readmission within 30 days (p < 0.001), 30-day reoperations (p < 0.001), and discharge to a destination other than the patient’s home (p < 0.001). Conclusion. The findings suggest the need for enhanced risk adjustment based on the indication of revision THA prior to setting prices in bundled payment models of total joint arthroplasty. This risk adjustment should be used to reduce the chance of financial disincentives in clinical practice. Cite this article: Bone Joint J 2019;101-B:547–551

Introduction. Wound complications following revision total hip arthroplasty (THA) are associated with an increased risk of superficial and deep infections. Closed incision negative-pressure therapy (ciNPT) has been reported to decrease this risk. This study's purpose was to assess if ciNPT decreases the rate of wound complications following revision THA versus a conventional, silver-impregnated dressing. Methods. This was a single center, randomized controlled trial of patients undergoing both septic and aseptic revision THA. Patients received either ciNPT or a silver-impregnated dressing (control) for 7 days. Wound complications within 90 days of the procedure were recorded, including: surgical site infection (SSI), periprosthetic joint infection (PJI), prolonged drainage greater than 5 days, erythema requiring antibiotics, and hematoma formation. An a priori power analysis determined 201 patients per cohort were necessary to demonstrate a 10% decrease in wound complication rate. Results. Between 2017 and 2020, 113 patients have been enrolled: 57 (50.4%) to ciNPT and 56 (49.6%) to the control dressing. Two revisions (1.8%) were performed via a direct lateral approach; all others via a posterior approach. There were no differences in age, BMI, ASA score, revision performed, wound closure method (staples, superficial nylons, subcuticular), or postoperative anti-coagulation (p=0.2–0.8). Seven (12.3%) patients in the ciNPT cohort sustained a wound complication versus 4 (7.1%) in the control cohort (p=0.2). There was no difference in type of wound complication sustained (p=0.4). Four (7.0%) patients in the ciNPT cohort underwent re-operation for wound-related complications (2 PJI, 1 SSI, 1 prolonged drainage) versus zero in the control cohort (p=0.04). Conclusion. Prior studies have shown ciNPT to be effective in decreasing the rate of wound complications in total joint arthroplasty. Preliminary results of this randomized trial of revision THA patients do not corroborate these prior reports. Continued enrollment is required to confirm these initial findings

Introduction. Patients with aseptic loosening, a cause of failure in uncemented total joint arthroplasty (TJA), often present with fibrous tissue at the bone-implant interface. 1. In this study, we characterize the presence of neutrophil extracellular traps (NETs) in the intramedullary fibrotic membrane of aseptic loosening patients. We further explore the role of NETs, mediated by peptidyl arginine deiminase (PAD4), in peri-implant fibrosis and osseointegration failure through a murine model of unstable tibial implantation. 2–4. Methods. Peri-implant membrane was retrieved from five patients during total hip revision surgery and analyzed for the presence of NETs (citH3+ with extracellular DNA) via immunofluorescence. A Ti-6Al-4V implant was inserted in an oversized drill-hole in the right proximal tibia of 8-week-old C57BL/6J and PAD4 knockout mice (n=3 per group). Fourteen days later, all mice were euthanized, and implanted tibias were dissected. Fibrosis and osseointegration at the bone-implant interface were assessed by micro-computed tomography (microCT) and hematoxylin and eosin (H&E) staining. H&E samples were scored blindly by the investigator and another observer for signs of poor (score=0) to excellent osseointegration (score=3) using a rubric established in our lab. Results. NETs were found in peri-implant membrane collected from aseptic loosening patients (Figure 1a) and at the bone-implant interface in a murine model (Figure 1b). Unstable implants in wild type mice failed to osseointegrate, indicated by presence of fibroblast-like cells (dashed arrow), immature bone matrix (Figure 1c), low bone volume fraction (BV/TV) and bone surface area (BS) (Figure 1e). Unstable implants in PAD4. −/−. mice showed signs of good osseointegration such as mature trabeculae (solid arrow) (Figure 1d), higher BV/TV (p<0.10) and BS (p<0.05) (Figure 1f). Histological osseointegration scoring indicated wildtype mice exhibited an average score of 0.83 and PAD4. −/−. exhibited an average score of 2.5 (p<0.05, weighted Cohen's kappa = 0.714) (Figure 1g). Conclusion. NETs were characterized in fibrotic tissue in both aseptic loosening patients and in a murine model of unstable tibial implantation. NET inhibition was able to successfully prevent peri-implant fibrosis and osseointegration failure, leading the way for a potential novel non-invasive therapeutic approach for the treatment of aseptic loosening. For any figures, tables, or references, please contact the authors directly

Total joint arthroplasty (TJA) is a high value elective orthopaedic procedure, the indications for which may vary among surgeons as well as patients. The utilization of other discretionary procedures is known to be influenced by the availability of qualified surgeons. We investigated the existence of a correlation between geographic variation in TJA utilization and the regional density of arthroplasty surgeons. The number of Medicare-funded total hip (THA) and total knee (TKA) arthroplasties performed in predetermined geographic referral regions were obtained from the Dartmouth Atlas for 2012. The number of surgeons specializing in total joint arthroplasty in each respective region was derived from the AAHKS membership list. Linear regression was used to assess the relationship between number of arthroplasties performed per 1000 Medicare beneficiaries and the number of AAHKS-members per 100,000 beneficiaries in each Hospital Referral Region (HRR). For THA in aggregate, a positive correlation was found between number of THA performed per 1,000 beneficiaries and increasing TJA surgeon density. Positive correlations were also noted when HRRs were stratified by size from 50,000 to 250,000 beneficiaries. The number of THA performed per 1,000 beneficiaries in regions with AAHKS members was greater than in regions without (4.03 vs 3.29; p=0.008). In contrast, there was no correlation between the rate of TKA utilization and HRR surgeon density, and no consistent relationship between TKA rate and HRRs stratified by size. Likewise, there was no difference in the rate of TKA between HRRs with and without AAHKS members (8.48 vs 8.84; p=0.18). The frequency of THA positively correlates with AAHKS surgeon density in all but the largest HRRs and was greater in regions with AAHKS members than in those without. Such relationships were not apparent for TKA utilization. These data may have important implications for more cost-effective utilization of THA

The unparalleled events of the year 2020 continue to evolve and challenge the worldwide community on a daily basis. The COVID-19 pandemic has had a major impact on all aspects of our lives, and has caused major morbidity and mortality around the globe. The impact of COVID-19 on the practice of orthopedic surgery has been substantial with practice shutdowns, elective surgery restrictions, heightened utilization of telemedicine platforms and implementation of precautionary measures for in-person clinic visits. During this transition period the scholarly and educational pursuits of academic surgeons have been de-emphasized as the more immediate demands of clinical practice survivorship have been the priority. This unavoidable focus on clinical practice has heightened the importance of orthopedic subspecialty societies in maintaining an appropriate level of attention on research and educational activities. Under the outstanding presidential leadership of Robert Barrack, MD, The Hip Society adapted to the profound challenges of 2020, and maintained strong leadership in the realms of education and research. The recent 2020 summer meeting of the Hip Society was a testimonial to the resilience and dedication of the Society members to ongoing innovation in research and education. Due to travel and social distancing restrictions the 2020 summer meeting was transitioned from an in-person to a virtual meeting format. Dr Barrack and Program Chair Dr John Clohisy assisted with oversight of the meeting, while Olga Foley and Cynthia Garcia ensured the success of the meeting with remarkable planning and organization. These collaborative efforts resulted in an organized, well-attended, high level scientific meeting with engaging discussion and a remarkable virtual conference environment. The Bone & Joint Journal is very pleased to partner with The Hip Society to publish the proceedings of this very unique virtual meeting. The Hip Society is based in the United States and membership is granted to select individuals for leadership accomplishments in education and research related to hip disease. The Society is focused on the mission of advancing the knowledge and treatment of hip disorders to improve the lives of patients. The vision of the Hip Society is to lead in the discovery and dissemination of knowledge related to disorders of the hip. The annual closed meeting is one of the most important events of the society as this gathering highlights timely, controversial and novel research contributions from the membership. The top research papers from The Hip Society meeting will be published and made available to the wider orthopedic community in The Bone & Joint Journal. This partnership with The Bone & Joint Journal enhances the mission and vision of The Hip Society by international dissemination of the meeting proceedings. Given the far-reaching circulation of The Bone & Joint Journal the highest quality work is available to an expanding body of surgeons, associated healthcare providers and patients. Ultimately, this facilitates the overarching Hip Society goal of improving the lives of our patients. The 2020 virtual Hip Society meeting was characterized by outstanding member attendance, high quality paper presentations and robust discussion sessions. The meeting was held over two days and encompassed 58 open paper presentations divided into ten sessions with moderated discussions after each session. All papers will be presented in this issue in abstract form, while selected full papers passing our rigorous peer review process will be available online and in The Bone & Joint Journal in a dedicated supplement in 2021. The first session of the meeting focused on issues related to complex primary THA and osteonecrosis of the femoral head. Dr Gross presented on the conversion of hip fusion to THA in 28 patents at a mean 7 years. He reported a high clinical success rate, yet complications of heterotopic ossification and neurologic injury were relatively common. Consideration of heterotopic ossification prophylaxis and the selective use of a constrained liner were recommended. Dr Pagnano summarized the use of various contemporary porous acetabular components in 38 hips in the setting of prior pelvic radiation. The mean follow-up was 5 years and 10 year survivorship was 100% with all implants radiographically fixed. Dr Bolognesi's study demonstrated that THA in solid organ transplant patients is associated with higher risk for facility placement, transfusions and readmissions. This patient population also has increased mortality risk (4.3% risk at 1 year) especially lung transplant patients. The second group of papers focused on femoral head osteonecrosis. Dr Iorio presented single center data demonstrating that CT scan was a useful adjunct for diagnosis in the staging work-up for cancer, yet was not useful for ARCO staging and treatment decision-making. On the basic science side, Dr Goodman utilized a rabbit model of steroid-induced femoral head osteonecrosis to determine that immunomodulation with IL-4 has the potential to improve bone healing after core decompression. The session was concluded by Dr Nelson's study of ceramic-on-ceramic THA in 108 osteonecrosis patients. The median 12 year results were outstanding with marked increases in PROs, maintenance of high activity levels, and a 3.7% revision rate. In the second session attention was directed to THA instability and spinopelvic mobility. Dr Sierra presented a machine learning algorithm for THA dislocation risk. Two modifiable variables (anterior/lateral approach, elevated liner) were most influential in minimizing dislocation risk. Dr Taunton's study demonstrated a deep learning artificial intelligence model derived from postoperative radiographs to predict THA dislocation risk. High sensitivity and negative predictive value suggest that this model may be helpful in assessing postoperative dislocation risk. In reviewing a large single-center, multiple surgeon cohort of 2,831 DAA procedures, Dr Moskal noted a very low dislocation rate (0.45%) at minimum 2 years. Importantly, spinopelvic pathology or prior spinal instrumentation was not associated with an increased dislocation risk (0.30%). Dr Huo and colleagues analyzed pelvic tilt during functional gait in patients with acetabular dysplasia. They detected variable pelvic tilt on different surfaces with the data suggesting that patients with more anterior pelvic tilt while standing tend to have greater compensatory posterior pelvic tilt during gait. Dr Lamontagne reported on the sagittal and axial spinomobility in patients with hip OA, and highlighted reductions in pelvic tilt, pelvic-femoral-angle, lumbar lordosis and seated maximal trunk rotation when compared to controls. Dr Dennis showed that differences in spinopelvic mobility may explain the variable accuracy of acetabular version measurements on the cross-table lateral radiographs. Dr Gwo-Chin presented on a comprehensive functional analysis of 1,592 patients undergoing THA and observed that spinopelvic abnormalities are not infrequent (14%) in THA patients. Consistent with these findings Dr Murphy and collaborators identified a low prevalence of previous spinal instrumentation (1.5%), yet a high prevalence of spine stiffness (27.6%) in 149 patients undergoing THA. Session three highlighted various aspects of treating hip disease in young patients. Dr Peters investigated the need for subsequent hip arthroscopy in 272 patients treated with an isolated PAO. Only 4.8% of these patients required subsequent arthroscopy calling into question the routine use of combined arthroscopy and PAO. Three papers addressed questions related to THA in young patients. Dr Berend's study of 2532 hips demonstrated that high activity level was not associated with an increased risk of midterm aseptic or all cause failure. Dr Nunley presented on 43 young patients with an average age of 52 years treated with a cementless stem and modular dual mobility articulation. Stress shielding was minimal and no concerning metal ion release detected. Dr Garvin summarized minimum 15 year data of THA with highly cross-linked polyethylene in patient less than 50 years. These hips performed exceptionally well with no mechanical loosening or radiographic osteolysis. Dr Engh examined 10 year results of the Birmingham Hip Resurfacing implant and reported a 92.9 % overall survivorship, with males less than 55 years achieving a 98.3% survivorship. The session was concluded by long-term data on the Conserve Plus hip resurfacing arthroplasty. Dr Amstutz presented an impressive dataset depicting an 83.1% 20 year survivorship for this early resurfacing cohort. Direct anterior approach total hip arthroplasty was the focus of session four. Dr Meneghini reported on the anesthesia and surgical times of direct anterior and posterior approaches from a large healthcare system database. These data suggested longer OR and surgical times for the DAA both in the inpatient and ASC environments. Dr Clohisy introduced the technique and early outcomes of lateral decubitus position DAA. In a learning curve experience of 257 hips. 96% of acetabular components were in the Lewinneck safe zone, the aseptic revision rate was 0.9% and there were no dislocations. Dr Beaule analyzed femoral stem cement mantle with the DAA and posterior approaches by comparing two matched cohorts. Stem alignment and cement mantle quality were equivalent with both approaches. Similarly, Dr Emerson demonstrated technical feasibility and fewer cemented femoral stem failures when compared to cementless stems in a series of 360 DAAs THAs. The final paper of the session presented by Dr Hamilton examined the impact of surgical approach on dislocation after isolated head and liner exchange. Neither the posterior nor the anterior approach was superior in reducing the dislocation rate for these high dislocation risk procedures. The fifth session explored contemporary topics related to anesthesia and pain management. Dr Byrd opened the session with a comparative study evaluating general versus spinal anesthesia for hip arthroscopy. This preliminary study was provoked by the desire to minimize aerosolized exposure early in the COVID-19 pandemic by transitioning to spinal anesthesia. Both anesthetic methods were effective. Dr Austin presented a randomized, double-blind controlled trial comparing spinal anesthetic with mepivacaine, hyperbaric bupivacaine and isobaric bupivacaine. Mepivacaine patients ambulated earlier and were more likely to be discharged the same day. Dr Mont provided a very timely study on the effects of “cannabis use disorder” and THA outcomes. This administrative database study of 44,154 patients revealed this disorder to be associated with longer hospital stays, increased complications rates and higher costs. Dr Bedair investigated whether a highly porous acetabular component submerged in an analgesic solution could enhance perioperative pain management. Interestingly, this novel strategy was associated with a reduction of postoperative pain scores and opioid consumption in 100 experimental patients compared to 100 controls. The concluding paper of the session by Dr Della Valle examined whether decreased discharge opioids led to increased postoperative opioid refills. A large single-center study of 19,428 patients detected a slight increase (5%) in opioid refills but a reduction in total refill morphine milligram equivalents. The final, sixth session of day one considered various challenging aspects of revision hip arthroplasty. Dr Nam started the session with review of preliminary results from a randomized control trial comparing closed incision negative-pressure therapy with a silver-impregnated dressing for wound management in 113 hips undergoing revision arthroplasty. Unlike previous reports, the negative pressure therapy was associated with a higher reoperation rate for wound-related complications. Dr Bostrom highlighted the potential clinical impact of basic biological interventions by establishing the presence of Neutrophil Extracellular Traps (NETS) in fibrotic tissue from human aseptic loosening specimens and in a murine model of unstable tibial implantation. NET inhibition in the murine model prevented the expected tibial implant osseointegration failure. Dr Lombardi presented early 3.3 year clinical results of a highly porous Ti6al4v acetabular component in complex primary and revision arthroplasty. Survivorship for aseptic loosening was 96.6 % and 95.3% for the primary and revision cases, respectively. Dr Schwarzkopf and colleagues explored the impact of time to revision arthroplasty on clinical outcomes. Analysis of 188 revision cases revealed early revisions (less than 2 years from primary) were associated with worse outcomes, longer hospitalizations and higher reoperation rates. Mid-term results for modular dual mobility implants in revision arthroplasty were reviewed by Dr Lachiewicz who reported on 126 hips at a mean 5.5 years. 11% of hips dislocated and the 6 year survival was 91%. An outer head diameter of 48mm or greater was associated with a lower risk of dislocation. Dr Berry concluded the session by discussing the outcomes of treating the challenging problem of interprosthetic femur fractures. A single-center study of 77 cases treated over 32 years demonstrated a 79% success rate free of reoperation at 2 years with 95% of patients being ambulatory. The second day commenced with the seventh session evaluating recent strategies to improve short-term THA outcomes. Dr Bozic and colleagues investigated the association of quality measure public reporting with hip/knee replacement outcomes. Annual trend data from 2010–2011 and 2016–2017 indicate that hospital-level complication and readmission rates decease after the start of public reporting, yet it is difficult to prove a direct effect. Dr Slover reviewed his institutions experience with the Comprehensive Care for Joint Replacement (CJR) model and emphasized that lower CJR target prices make it increasingly difficult for programs to meet target price thresholds. Cost saving strategies including same day discharge and reduction of home health services may result in smaller losses of positive margins. Dr Barsoum reported on the influence of patient and procedure-related risk factors of length of stay after THA. Patient-related risk factors provided substantial predictive value yet procedure-related risk factors (hospital site and surgical approach) remain the main drivers of predicting length of stay. Dr Hozack reviewed an impressive, single surgeon cohort of 3,977 DAA THAs and analyzed adverse events and 90 day perioperative outcomes. Simultaneous bilateral DAA THA was comparable with unilateral or staged bilateral procedures in regards to complications, readmission rate and home discharge rate but with an increased risk of transfusion. To examine the risk of complications with outpatient joint arthroplasty, Dr Della Valle performed a single-surgeon matched cohort analysis comparing outpatient and inpatient hip and knee arthroplasties. Outpatient procedures were not associated with an increased risk of any postoperative complications and actually experienced fewer emergency department visits. The eighth session covered various contemporary challenges in hip arthroplasty care. Dr Griffin began the session with an analysis of the timing of complications associated with two-stage exchange procedures for periprosthetic joint infection (PJI). Of the 189 hips included, 41.6% had a complication and the mortality was 14.1% at 2.5 years, highlighting the morbidity of this treatment method. Dr Fehring provided data assessing the fate of two-stage reimplantation after failed debridement, antibiotics and implant retention (DAIR) for a prosthetic hip infection. This analysis of 114 hips yielded concerning results demonstrating a 42.9% treatment failure of patients treated with a previous DAIR compared to a 12.3% failure rate in patients treated with an initial 2-stage procedure. Dr Jacobs reviewed the analysis of 106 femoral heads with severe corrosion and identified a chemically dominated etching process termed “column damage” to be a detrimental damage mode within CoCr femoral heads that is directly linked to banding within its microstructure. These data indicate that implant alloy microstructure must be optimized to minimize the release of fretting-corrosion products. Simon Mears presented retrospective data from 184 THAs with a dual modular femoral stem. A subgroup of hips with a modular, cobalt chromium femoral neck had a pseudotumor visualized in 15% with only 55% of these having elevated CoCr levels. These findings may support the use of routine follow-up MARS MRI for modular CoCr femoral neck prostheses. The final two studies explored timely issues related to viral illness and hip surgery. Dr Browne analyzed three large administrative databases to elucidate whether patients are at increased risk for viral illnesses following total joint replacement. The incidence of postoperative influenza after total joint replacement was not increased compared to patients not undergoing total joint replacement surgery suggesting that arthroplasty procedures may not heighten the risk of viral illness. In the final paper of the session Dr Haddad presented important data regarding perioperative complications in coronavirus positive patients undergoing surgical treatment of femoral neck fractures. In this multicenter cohort study from the United Kingdom 82 coronavirus positive patients were shown to have longer hospital stays, more critical care unit admissions, higher risk of perioperative complications and an increased mortality compared to 340 coronavirus negative patients. The eighth session had two papers on alternative femoral stem designs and three presentations more focused on femoral fracture treatments. Dr Mihalko focused on the European and US experiences with the Metha femoral neck retaining stem. The US experience mirrored the encouraging results from Europe with a 94% all cause femoral survivorship and a 99.1% femoral aseptic loosening survivorship at 5 years. Dr Kraay summarized dual energy x-ray absorptiometry (DEXA) evaluation of 16 low modulus composite femoral components at long-term follow-up of a mean 22 years. The bone mineral density associated with the implant increased in Gruen zones 2–6 and showed limited decreases in zones 1 and 7. These data support the concept that a low modulus femoral stem may more effectively load the proximal femur. Dr Springer provided data from the American Joint Replacement Registry (AJRR) and by evaluating outcomes of exact matched cohorts of 17,138 patients treated with cementless or cemented femoral implants for femoral neck fractures. Cemented implants were associated with marked reduction in early revision and periprosthetic fractures. However, cemented fixation was associated with an increased mortality at 90 days and 1 year. Additional data from the AJRR was presented by Dr Huddleston who investigated the risk factors for revision surgery after arthroplasty in a cohort of 75,333 femoral neck fractures. THA when compared to hemiarthroplasty was associated with higher early and overall revision rates. Cementless femoral fixation and increased age were also associated with higher rates of any revision. Both of these studies from the AJRR suggest that further consideration should be given to femoral fixation preferences in the femoral neck fracture population. Dr Vail summarized his institution's experience with an interdisciplinary hip fracture protocol for patients undergoing arthroplasty for acute femoral neck fractures. His study compared 157 cases prior to protocol implementation with 114 patients treated after the protocol was established. The impact of the interdisciplinary protocol was impressive as evidenced by a reduced time to operative treatment, length of stay, complication rate and one-year mortality. All being achieved without an increase in readmissions or facility discharges. The final session of the meeting addressed innovations in perioperative care of THA patients. Dr Barrack started the session with an interesting study examining the feasibility and patient preferences regarding telemedicine. A cross-sectional telephone survey of 163 arthroplasty patients indicated that 88% of patients use the internet and 94% own a device capable of videoconferencing. Nevertheless, only 18% of patients preferred a video visit over an in-person clinic visit due to concerns of inferior care. Dr Barnes quantified preoperative optimization work in 100 arthroplasty patients by using EMR activity logs and determined the surgical team spends an average 75 minutes per case on preoperative work activities. Dr Duwelius reported the early outcomes of primary THA with a smartphone-based exercise and educational platform compared to standard of care controls. A randomized control trial design with 365 patients demonstrated similar outcomes and non-inferiority of the smartphone platform relative to complications, readmissions, emergency room/urgent care visits. The association of controlled substance use with THA outcomes was assessed by Dr Higuera Rueda. A quantitative assessment using the NarxCare score identified 300 and above as a score associated with adverse outcomes after THA. Dr Macaulay reviewed data from a large retrospective study of 1,825 THAs indicating that discontinuation of intermittent pneumatic compression devices does not increase the risk of venous thromboembolism in standard risk patients being treated with 81mg ASA BID as prophylaxis. Dr Antoniou presented the final paper of the meeting investigating potential changes in patient health status as an indication for surgery over time. Data from this large systematic review of the literature found patients undergoing THA at similar health status to the past with no influence form patient age, gender, year of enrollment or geographic region. As summarized above, the 2020 virtual Hip Society Summer Meeting was rich in scientific content, productive discussion and a collaborative spirit. This collective body of work will result in impactful scientific contributions and will serve as a foundation for future innovation and advancements in the treatment of hip disease

Aims

Our primary aim was to assess reoperation-free survival at one year after the index injury in patients aged ≥ 75 years treated with internal fixation (IF) or arthroplasty for undisplaced femoral neck fractures (uFNFs). Secondary outcomes were reoperations and mortality analyzed separately.

Introduction. PJI is a devastating complication following total joint arthroplasty. In this study, we explore the efficacy of a bacteriophage-derived lysin, PlySs2, against in-vitro biofilm on titanium implant surfaces and in an acute in-vivo murine debridement antibiotic implant retention (DAIR) model of PJI. Methods. In-vitro: Xen 36 S. aureus biofilm was grown on Ti-6Al-4V mouse tibial implants for 1 day or 5 days and subsequently exposed to growth media, 1000× minimal inhibitory concentration (MIC) Vancomycin, or 5× MIC PlySs2. Implants were sonicated and analyzed for Colony Forming Units (CFU). In-vivo: A Ti-6Al-4V implant was inserted into the proximal tibia of C57BL/6J mice (n=21). All mice received 10. 4. CFU inoculation of Xen 36 S. aureus to the knee joint capsule and the infection was permitted 5 days to progress. On day 5 the mice were separated into three groups (n=7/group): (1) no further surgical intervention (control group), (2) irrigation and debridement (I&D) with saline, (3) I&D with 2mg/mL PlySs2. No implant-exchange was performed to mimic a debridement, antibiotic, and implant retention (DAIR) therapeutic strategy. All mice were sacrificed at day 10. Results. CFU counts for 1-day and 5-day in-vitro grown biofilm on implants demonstrate a >3log-fold reduction with PlySs2 compared to Vancomycin (p=0.01) with no significant difference between Vancomycin and control. In-vivo the addition of PlySs2 to Vancomycin treated mice reduces bacterial load in the periposthetic tissue and implant (p<0.05) with 5 days of treatment. Conclusion. PlySs2 5× MIC exhibits superior anti-microbial effect compared to Vancomycin on implants with 1-day and 5–5day biofilm maturities. The addition of PlySs2 to Vancomycin treatment of an acute established PJI further reduces tissue CFU and implants CFU. For any tables or figures, please contact the authors directly

Aims

This study describes the variation in the annual volumes of revision hip arthroplasty (RHA) undertaken by consultant surgeons nationally, and the rate of accrual of RHA and corresponding primary hip arthroplasty (PHA) volume for new consultants entering practice.