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Background Highly crosslinked polyethylene (HXLPE) was introduced to reduce wear and osteolysis in total joint arthroplasty. While many studies report wear and osteolysis associated with HXLPE, analytical techniques, clinical study design and followup, HXLPE formulation and implant design characteristics, and patient populations differ substantially among investigations, complicating a unified perspective. Questions/purposes Literature on first-generation HXLPE was summarized. We systematically reviewed the radiographic wear data and incidence of osteolysis for HXLPE in hip and knee arthroplasty. Methods PubMed identified 391 studies; 28 met inclusion criteria for a weighted-averages analysis of two-dimensional femoral head penetration rates. To determine the incidence of osteolysis, we estimated a pooled odds ratio using a random-effects model. Results Weighted-averages analyses of femoral head penetration rates in HXLPE liners and conventional UHMWPE liners resulted, respectively, in a mean two-dimensional linear penetration rate of 0.042 mm/year based on 28 studies (n = 1503 hips) and 0.137 mm/year based on 18 studies (n = 695 hips). The pooled odds ratio for the risk of osteolysis in HXLPE versus conventional liners was 0.13 (95% confidence interval, 0.06–0.27) among studies with minimum 5-year followup. We identified two clinical studies of HXLPE in TKA, preventing systematic analysis of outcomes. Conclusions HXLPE liner studies consistently report lower femoral head penetration and an 87% lower risk of osteolysis. Reduction in femoral head penetration or osteolysis risk is not established for large-diameter (> 32 mm) metallic femoral heads or ceramic femoral heads of any size. Few studies document the clinical performance of HXLPE in knees.

Previous projections of total joint replacement (TJR) volume have not quantified demand for TJR surgery in young patients (< 65 years old). We developed projections for demand of TJR for the young patient population in the United States. The Nationwide Inpatient Sample was used to identify primary and revision TJRs between 1993 and 2006, as a function of age, gender, race, and census region. Surgery prevalence was modeled using Poisson regression, allowing for different rates for each population subgroup over time. If the historical growth trajectory of joint replacement surgeries continues, demand for primary THA and TKA among patients less than 65 years old was projected to exceed 50% of THA and TKA patients of all ages by 2011 and 2016, respectively. Patients less than 65 years old were projected to exceed 50% of the revision TKA patient population by 2011. This study underscores the major contribution that young patients may play in the future demand for primary and revision TJR surgery. Level of Evidence: Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

The current risk of infection in contemporary total knee arthroplasty (TKA) as well as the relative importance of risk factors remains under debate as a result of the rarity of the complication and temporal changes in the treatment and prevention of infection. We therefore determined infection incidence and risk factors after TKA in the Medicare population. The Medicare 5% national sample administrative data set was used to identify and longitudinally follow patients undergoing TKA for deep infections and revision surgery between 1997 and 2006. Cox regression was used to evaluate patient and hospital characteristics. In 69,663 patients undergoing elective TKA, 1400 TKA infections were identified. Infection incidence within 2 years was 1.55%. The incidence between 2 and up to 10 years was 0.46%. Women had a lower risk of infection than men. Comorbidities also increased TKA infection risk. Patients receiving public assistance for Medicare premiums were at increased risk for periprosthetic joint infection (PJI). Hospital factors did not predict an increased risk of infection. PJI occurs at a relatively high rate in Medicare patients with the greatest risk of PJI within the first 2 years after surgery; however, approximately one-fourth of all PJIs occur after 2 years. Level of Evidence: Level II, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.

Understanding the cause of failure and type of revision total knee arthroplasty (TKA) procedures performed in the United States is essential in guiding research, implant design, and clinical decision making in TKA. We assessed the causes of failure and specific types of revision TKA procedures performed in the United States using newly implemented ICD-9-CM diagnosis and procedure codes related to revision TKA data from the Nationwide Inpatient Sample (NIS) database. Clinical, demographic, and economic data were reviewed and analyzed from 60,355 revision TKA procedures performed in the United States between October 1, 2005 and December 31, 2006. The most common causes of revision TKA were infection (25.2%) and implant loosening (16.1%), and the most common type of revision TKA procedure reported was all component revision (35.2%). Revision TKA procedures were most commonly performed in large, urban, nonteaching hospitals in Medicare patients ages 65 to 74. The average length of hospital stay (LOS) for all revision TKA procedures was 5.1 days, and the average total charges were $49,360. However, average LOS, average charges, and procedure frequencies varied considerably by census region, hospital type, and procedure performed. Level of Evidence: Level II, economic and decision analysis. See Guidelines for Authors for a complete description of levels of evidence.

Proximal femoral fractures are a serious complication, especially for elderly patients. Detailed epidemiological analyzes provide a valuable resource for stakeholders in the health care system in order to foresee future development possibly influenceable by adaption of therapeutic procedures and prevention strategies. This work aimed at answering the following research questions: (1) What are the incidence rates of proximal femoral fractures in the elderly U.S. population? (2) What is the preferred treatment procedure for these fractures? Proximal femoral fractures occurred between January 1, 2009 and December 31, 2019 in patients ≥ 65 years were identified from the Medicare Physician Service Records Data Base. The 5% sample of Medicare beneficiaries, equivalent to the records from approximately 2.5 million enrollees formed the basis of this study. Fractures were grouped into head/neck, intertrochanteric, and subtrochanteric fractures. The overall incidence rate, age and sex specific incidence rates as well as incidence rate ratios were calculated. Common Procedural Terminology (CPT) codes were used to identify procedures and operations. In 2019, a total number of 7982 femoral head/neck fractures was recorded. In comparison to 9588 cases in 2009, the incidence substantially decreased by 26.6% from 666.7/100,000 inhabitants to 489.3/100,000 inhabitants (z =  − 5.197, p < 0.001). Also, in intertrochanteric fractures, a significant decline in the incidence by 17.3% was evident over the years from 367.7/100,000 inhabitants in 2009 to 304.0 cases per 100,000 inhabitants in 2019 (z =  − 2.454, p = 0.014). A similar picture was observable for subtrochanteric fractures, which decreased by 29.6% (51.0 cases per 100,000 to 35.9 cases per 100,000) over the time period (z =  − 1.612, p = 0.107). Head/neck fractures were mainly treated with an arthroplasty (n = 36,301, 40.0%). The majority of intertrochanteric fractures and subtrochanteric fractures received treatment with an intramedullary device (n = 34,630, 65.5% and n = 5870, 77.1%, respectively). The analysis indicated that the incidence of all types of proximal femoral neck fractures decreased for the population of elderly patients in the U.S. within the last decade. Treatment of head and neck fractures was mainly conducted through arthroplasty, while intertrochanteric and subtrochanteric fractures predominantly received an intramedullary nailing.

Although efficacious psychological treatments for internalizing disorders are now well established for school-aged children, until recently there have regrettably been limited empirical efforts to clarify indicated psychological intervention methods for the treatment of mood and anxiety disorders presenting in early childhood. Young children lack many of the developmental capacities required to effectively participate in established treatments for mood and anxiety problems presenting in older children, making simple downward extensions of these treatments for the management of preschool internalizing problems misguided. In recent years, a number of research groups have successfully adapted and modified parent–child interaction therapy (PCIT), originally developed to treat externalizing problems in young children, to treat various early internalizing problems with a set of neighboring protocols. As in traditional PCIT, these extensions target child symptoms by directly reshaping parent–child interaction patterns associated with the maintenance of symptoms. The present review outlines this emerging set of novel PCIT adaptations and modifications for mood and anxiety problems in young children and reviews preliminary evidence supporting their use. Specifically, we cover (a) PCIT for early separation anxiety disorder; (b) the PCIT-CALM (Coaching Approach behavior and Leading by Modeling) Program for the full range of early anxiety disorders; (c) the group Turtle Program for behavioral inhibition; and (d) the PCIT-ED (Emotional Development) Program for preschool depression. In addition, emerging PCIT-related protocols in need of empirical attention—such as the PCIT-SM (selective mutism) Program for young children with SM—are also considered. Implications of these protocols are discussed with regard to their unique potential to address the clinical needs of young children with internalizing problems. Obstacles to broad dissemination are addressed, and we consider potential solutions, including modular treatment formats and innovative applications of technology.

We aimed to answer the following questions: (1) How did numbers of revision knee arthroplasty procedures develop in Germany over the last decade compared to primary TKA? (2) How high was the percentage of septic interventions in knee prosthesis revisions? (3) Which treatment strategy was chosen for surgical treatment of knee PJI? Revision arthroplasty rates as a function of age, gender, infection and type of prosthesis were quantified based on Operation and Procedure Classification System codes using r evision knee arthroplasty data from 2008 to 2018, provided by the Federal Statistical Office of Germany (Destatis). In 2018, a total number 23,812 revision knee arthroplasties were performed in Germany, yielding an overall increase of 20.76% between 2008 and 2018. In comparison, primary TKA procedures increased by 23.8% from 152,551 performed procedures in 2008 to 188,866 procedures in 2018. Hence, 12.6% of knee arthroplasties required a revision in 2018. Septic interventions increased by 51.7% for all revisions . A trend towards higher numbers in younger patients was observed. Compared to 2008, 17.41% less DAIR procedures were performed, whereby single-stage and two- or multi-stage change increased by 38.76% and 42.76% in 2018, respectively. The increasing number of revision knee arthroplasty in Germany, especially in younger patients and due to infection, underlines the need for future efforts to improve treatment strategies to delay primary arthroplasty and avoid periprosthetic joint infection.

A novel total joint replacement (TJR) that treats lumbar spine degeneration was previously assessed under Mode I and Mode IV conditions. In this study, we relied on these previous wear tests to establish a relationship between finite element model (FEM)-based bearing stresses and in vitro wear penetration maps. Our modeling effort addressed the following question of interest: Under reasonably worst-case misaligned conditions, do the lumbar total joint replacement (L-TJR) polyethylene stresses and strains remain below values associated with Mode IV impingement wear tests? The FEM was first formally verified and validated using the risk-informed credibility assessment framework established by ASME V&V 40 and FDA guidance. Then, based on criteria for unreasonable misuse outlined in the surgical technique guide, a parametric analysis of reasonably worst-case misalignment using the validated L-TJR FEM was performed. Reasonable misalignment was created by altering device positioning from the baseline condition in three scenarios: Axial Plane Convergence (20–40°), Axial Plane A-P Offset (0–4 mm), and Coronal Plane Tilt (±20°). We found that, for the scenarios considered, the contact pressures, von Mises stresses, and effective strains of the L-TJR-bearing surfaces remained consistent with Mode I (clean) conditions. Specifically, the mechanical response values fell below those determined under Mode IV (worst-case) boundary conditions, which provided the upper-bound benchmarks for the study (peak contact pressure 83.3 MPa, peak von Mises stress 32.2 MPa, and peak effective strain 42%). The L-TJR was judged to be insensitive to axial and coronal misalignment under the in vitro boundary conditions imposed by the study.

Background Unicompartimental knee arthroplasty (UKA) is a promising and increasing application to treat unicompartimental knee osteoarthritis. However, revision arthroplasty numbers after UKA are unknown. Therefore, aim of this study was to determine the nationwide burden of revision after UKA by answering the following questions: (1) How did numbers of revision UKA procedures developed over the last decade as a function of age and gender? (2) How high is the percentage of revision UKA procedures due to infection? (3) Which therapy strategy was chosen for surgical treatment of aseptic revision UKA? Methods Revision arthroplasty rates as a function of age, gender, infection and type of prosthesis were quantified based on Operation and Procedure Classification System codes using revision knee arthroplasty data from 2008 to 2018, provided by the Federal Statistical Office of Germany (Destatis). Results Over the last decade, revision UKA increased by 46.3% up to 3105 procedures in 2018. A trend towards higher numbers in younger patients was observed. Septic interventions constituted 5.7% of all revisions, whereby total procedures increased by 67.1% from 2008 through 2018. The main treatment strategy was an exchange to a bicondylar surface replacement prosthesis, which was done in 63.70% of all cases, followed by exchange to a femoral and tibial shaft-anchored (16.2% of all revisions). Conclusion The increasing number of revision arthroplasty after UKA in Germany, especially in younger patients and due to infection, underlines the need for future efforts to improve treatment strategies beyond UKA to delay primary arthroplasty and avoid periprosthetic joint infection.

Ultra-high-molecular-weight polyethylene (UHMWPE) components for orthopedic implants have historically been integrated into metal backings by direct-compression molding (DCM). However, metal backings are costly, stiffer than cortical bone, and may be associated with medical imaging distortion and metal release. Hybrid-manufactured DCM UHMWPE overmolded additively manufactured polyetheretherketone (PEEK) structural components could offer an alternative solution, but are yet to be explored. In this study, five different porous topologies (grid, triangular, honeycomb, octahedral, and gyroid) and three surface feature sizes (low, medium, and high) were implemented into the top surface of digital cylindrical specimens prior to being 3D printed in PEEK and then overmolded with UHMWPE. Separation forces were recorded as 1.97–3.86 kN, therefore matching and bettering the historical industry values (2–3 kN) recorded for DCM UHMWPE metal components. Infill topology affected failure mechanism (Type 1 or 2) and obtained separation forces, with shapes having greater sidewall numbers (honeycomb-60%) and interconnectivity (gyroid-30%) through their builds, tolerating higher transmitted forces. Surface feature size also had an impact on applied load, whereby those with low infill-%s generally recorded lower levels of performance vs. medium and high infill strategies. These preliminary findings suggest that hybrid-manufactured structural composites could replace metal backings and produce orthopedic implants with high-performing polymer–polymer interfaces.