Publications by authors named "Michael Hofstaetter"

Introduction: There are conflicting data regarding the safety of the direct anterior approach (DAA) for primary total hip arthroplasty (THA) during the learning process. The aim of this study was to evaluate the intra- and postoperative complication rates of DAA THA performed by supervised trainees compared with senior surgeons.

Material And Methods: A retrospective cohort study was conducted using a prospectively maintained arthroplasty database of patients who underwent primary THA via the DAA between 01/08/2013 and 31/12/2022.

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Background: The aim of this study was to assess the prevalence, microbiological spectrum, risk factors, and clinical outcomes of unexpected-positive-intraoperative-cultures (UPIC) in presumed aseptic and unclear revision-total-hip-/knee-arthroplasties (rTHA and rTKA) compared to culture-negative (CN) revisions.

Methods: This study reviewed all International-consensus-meeting-2018 (ICM 2018) negative or inconclusive rTHA (n = 751) and rTKA (n = 679) performed at our institution from 2011 to 2020 with a minimum follow-up of two years. A Kaplan-Meier-analysis was performed to determine the septic and aseptic-free implant survival in cases with UPIC's and matched culture-negative cases.

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Background: Ceramic femoral heads with titanium sleeves are commonly used in revision total hip arthroplasty (rTHA). Companies advise against combination with a retained femoral component from another manufacturer. However, no data are available.

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Background: There is only sparse knowledge on the psychological burden of patients who have periprosthetic joint infections. The aim of our study was to assess the need for psychological support following total joint arthroplasty of the hip and knee. A special focus was set on patients who had aseptic and septic complications.

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Aims: This study aimed to evaluate the BioFire Joint Infection (JI) Panel in cases of hip and knee periprosthetic joint infection (PJI) where conventional microbiology is unclear, and to assess its role as a complementary intraoperative diagnostic tool.

Methods: Five groups representing common microbiological scenarios in hip and knee revision arthroplasty were selected from our arthroplasty registry, prospectively maintained PJI databases, and biobank: 1) unexpected-negative cultures (UNCs), 2) unexpected-positive cultures (UPCs), 3) single-positive intraoperative cultures (SPCs), and 4) clearly septic and 5) aseptic cases. In total, 268 archived synovial fluid samples from 195 patients who underwent acute/chronic revision total hip or knee arthroplasty were included.

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Background: Osseointegration is essential for the long-term survival of cementless femoral stems and is dependent on periprosthetic bone quality and correct implantation technique. The aim of this study was to evaluate the 3-dimensional long-term fixation patterns of, and bone microarchitecture around, cementless hip stems.

Methods: Four specimens with varying degrees of bone quality and fixation characteristics from body donors who had received Alloclassic Zweymüller hip stems during their lifetime (mean time in situ at the time of death: 12.

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Introduction: The assessment of the knee alignment on long leg radiographs (LLR) postoperative to corrective knee osteotomies (CKOs) is highly dependent on the reader's expertise. Artificial Intelligence (AI) algorithms may help automate and standardise this process. The study aimed to analyse the reliability of an AI-algorithm for the evaluation of LLRs following CKOs.

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Background: Data regarding the diagnostic value of ultrasound (US)-determined fluid film and joint aspiration prior to revision total hip arthroplasty for suspected periprosthetic joint infections (PJIs) are limited. This study aimed to analyze the value of US-determined fluid film, characterized the preoperative and intraoperative microbiological spectrum and resistance patterns, and compared the concordance between preoperative synovial fluid and intraoperative culture results.

Methods: We analyzed 366 US examinations from 324 patients prior to revision total hip arthroplasty.

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The use of robotic-assisted surgery (RAS) in total knee arthroplasty (TKA) is becoming increasingly popular due to better precision, potentially superior outcomes and the ability to achieve alternative alignment strategies. The most commonly used alignment strategy with RAS is a modification of mechanical alignment (MA), labeled adjusted MA (aMA). This strategy allows slight joint line obliquity of the tibial component to achieve superior balancing.

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Article Synopsis
  • The study aimed to determine if patients with an isolated positive sonication fluid culture (SFC) after revision surgery for prosthetic joints have a higher infection rate compared to those with a negative SFC.
  • It analyzed data from 95 patients with positive SFC and 201 controls with negative SFC, finding infection rates of 12.6% and 7.0%, respectively, though the difference wasn't statistically significant.
  • The findings suggest infections are more common in positive SFC patients, highlighting the need for larger trials to better understand the impact of antibiotic treatment in these cases.
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Purpose: Osteoarthritis of the knee is commonly associated with malalignment of the lower limb. Recent classifications, as the Coronal Plane Alignment of the Knee (CPAK) and Functional Phenotype classification, describe the bony knee morphology in addition to the overall limb alignment. Data on distribution of these classifications is not sufficient in large populations.

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Artificial-intelligence (AI) allows large-scale analyses of long-leg-radiographs (LLRs). We used this technology to derive an update for the classical regression formulae by Trotter and Gleser, which are frequently used to infer stature based on long-bone measurements. We analyzed calibrated, standing LLRs from 4200 participants taken between 2015 and 2020.

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Background: Scapulothoracic orientation, especially scapular internal rotation (SIR) may influence range of motion in reverse total shoulder arthroplasty (RTSA) and is subjected to body posture. Clinical measurements of SIR rely on apical bony landmarks, which depend on changes in scapulothoracic orientation, while radiographic measurements are often limited by the restricted field of view (FOV) in CT scans. Therefore, the goal of this study was (1) to determine whether the use of CT scans with a limited FOV to measure SIR is reliable and (2) if a clinical measurement could be a valuable alternative.

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Article Synopsis
  • Metal artifacts from hip implants affect CT scans' ability to diagnose fractures and implant issues, prompting a study on scan parameters and artifact reduction algorithms.
  • The study analyzed nine hip stems using various CT protocols, including single-energy and dual-energy scans, with and without a metal artifact reduction algorithm (iMAR).
  • Results showed that iMAR significantly decreased metal streak artifacts, with the best image quality coming from a single-energy protocol using a tin filter, highlighting its potential for clinical use.
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Purpose: Despite advances of three-dimensional imaging pelvic radiographs remain the cornerstone in the evaluation of the hip joint. However, large inter- and intra-rater variabilities were reported due to subjective landmark setting. Artificial intelligence (AI)-powered software applications could improve the reproducibility of pelvic radiograph evaluation by providing standardized measurements.

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Introduction: Patients who require a spacer exchange as part of a two-stage procedure for the treatment of periprosthetic hip and knee joint infections (PJI) have high failure rates. Little is known about the clinical impact of microbiological results and changes in the microbiological spectrum and resistance pattern in these patients.

Material And Methods: Between 01/2011 and 12/2019, 312 patients underwent a total of 327 two-stage revision arthroplasties at our institution.

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Purpose: Unexpected-positive-intraoperative-cultures (UPIC) are common in presumed aseptic revision-total-knee-arthroplasties (rTKA). However, the clinical significance is not entirely clear. In contrast, in some presumably septic rTKA, identification of an underlying pathogen was not possible, so-called unexpected-negative-intraoperative-cultures (UNIC).

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Background: Periprosthetic joint infections (PJI) are a major concern in shoulder arthroplasty, which in some cases require two-stage exchange. While it was shown that low-virulence bacteria are the most isolated pathogens in shoulder PJI, little is known about changes in microbiological spectrum and resistance patterns during two-stage revision.

Methods: This retrospective study included all patients (n = 25) who received a two-stage revision from January 2011 to December 2020 for shoulder PJI in one institution.

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Background Context: In severe cases of postoperative spinal implant infections (PSII) multiple revision surgeries may be needed. Little is known if changes in the microbiological spectrum and antibiotic resistance pattern occur between revision surgeries.

Purpose: Analysis of the microbiological spectrum and antibiotic resistance pattern in patients with multiple revision surgeries for the treatment of PSII STUDY DESIGN: Retrospective database analysis.

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Purpose: The purpose of this study was to evaluate the reliability of a newly developed AI-algorithm for the evaluation of long leg radiographs (LLR) after total knee arthroplasties (TKA).

Methods: In the validation cohort 200 calibrated LLRs of eight different common unconstrained and constrained knee systems were analysed. Accuracy and reproducibility of the AI-algorithm were compared to manual reads regarding the hip-knee-ankle (HKA) as well as femoral (FCA) and tibial component (TCA) angles.

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Objectives: The unique properties of dalbavancin (DAL) emphasize the need to explore its clinical benefits to treat periprosthetic joint infections (PJIs). The present study aimed to compare the treatment outcome of dalbavancin with Standard of Care (SoC) in hip and knee PJIs.

Methods: Eighty-nine patients were selected for each group of this study based on our prospectively maintained PJI database.

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Article Synopsis
  • - Osteopetrosis is a rare hereditary disorder with increased but poor-quality bone mass, with two main types: ADOII caused by CLCN7 gene mutations and a more severe ARO form associated with additional health issues.
  • - A report on an adult male with ADOII showed a lack of typical mutations but revealed low levels of CLCN7 mRNA and potentially recessive gene variations, hinting at complex genetic factors.
  • - Analysis of the patient's bone structure indicated abnormal mineralization and poor remodeling, with high bone density but brittleness, likely due to reduced CLCN7 expression affecting bone repair mechanisms.
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