Background: In recent years, a variety of short stems have been introduced. To date, mid- and long-term results of calcar-guided short-stem designs have been rarely available. Materials and methods: Two hundred and sixteen calcar-guided short stems were included in combination with a cementless cup in a prospective study. Patients were allowed full weight-bearing on the first day postoperatively. Harris hip score (HHS) as well as pain and satisfaction on visual analogue scale (VAS) were assessed during a median follow-up of 61.7 months. Standardised radiographs were analysed at predefined time points regarding radiological alterations such as bone resorption and remodelling, radiolucency, osteolysis and cortical hypertrophy using modified Gruen zones. Results: At mid-term follow-up, no revision surgery of the stem had to be performed in the whole collective. At 5 years, HHS was 97.8 (SD 4.7), satisfaction on VAS was 9.7 (SD 0.7), rest pain on VAS was 0.1 (SD 0.5), and load pain on VAS was 0.6 (SD 1.2). Compared to the 2-year results, femoral bone resorption increased significantly at the 5-year follow-up (3.9% versus 42.3%). Rate of femoral cortical hypertrophy remained stable, occurring in a total of 9 hips (4.5%). At the 5-year follow-up, 2 stems (1.0%) showed non-progressive radiolucent lines with a maximum width of 2 mm. Signs of osteolysis were not observed. Compared to the 2-year follow-up, no further subsidence was observed. Conclusions: The rate of stem revision (0%) at the mid-term follow-up was remarkable and indicates the principle of using a calcar-guided short stem as being a safe procedure. However, signs of bone-remodelling, indicating some amount of stress-shielding, must be acknowledged at 5 years depending on stem alignment and type of anchorage. Level of evidence: IV, Prospective observational study Trial registration German Clinical Trials Register, DRKS00012634, 07/07/2017 (retrospectively registered)

Background: Comprehensive preoperative education is essential for optimizing outcomes and ensuring informed consent in patients undergoing total hip arthroplasty (THA). Emerging artificial intelligence (AI) tools, such as ChatGPT, offer scalable support for patient education, but their clinical application requires rigorous evaluation to ensure accuracy, safety, and trust. Objective: This study assessed patients’ preferences and satisfaction with AI-assisted informed consent in THA, comparing traditional physician consultations to those supported by native ChatGPT and a customized version enhanced with retrieval-augmented generation (RAG). It also examined how state anxiety and general attitudes toward AI affect preferences for AI-supported consent and whether RAG integration improves ChatGPT response quality. Methods: A total of 36 patients scheduled for elective THA were assigned to one of three groups (12 each): (1) standard physician-only consultations (control), (2) physician-assisted consultations supported by native ChatGPT, and (3) supported by ChatGPT enhanced through RAG. Data collection involved standardized Likert scale questionnaires assessing patient satisfaction with the consent process, perceived informedness, anxiety levels, and attitudes toward AI. The ChatGPT responses were independently evaluated by physicians for relevance, accuracy, clarity, completeness, adherence to evidence-based guidelines, and appropriate length. Instances of hallucinations, factually incorrect or misleading outputs, were identified and rated by severity. Statistical analyses compared outcomes across groups and explored associations. Results: Patients interacting with the ChatGPT+RAG model reported significantly higher satisfaction levels with information delivery (P=.01) and perceived level of informedness (P=.01) than those using the native ChatGPT model. The mean number of patient questions in the control group was 20, compared with 39 in the native ChatGPT group (P=.06) and 52 in the ChatGPT+RAG group (P=.002). The majority of participants across all groups preferred a human clinician providing less accurate information over a more accurate AI-only assistant. These preferences were not influenced by sociodemographic variables (age, gender, and education), health literacy, state anxiety, or general attitudes toward AI. The ChatGPT+RAG model outperformed the native ChatGPT model across all evaluated response quality dimensions (all P<.01) and exhibited a significantly lower hallucination rate (5/52, 10% versus 15/39, 38%; P=.002). Conclusions: Integrating RAG with ChatGPT significantly improves the quality, clarity, and reliability of preoperative information, enhancing patient satisfaction and engagement beyond native ChatGPT. However, patients maintain a strong preference for physician-led informed consent, underscoring the role of AI chatbots as complementary tools rather than replacements. These findings support the cautious adoption of customized AI assistants to augment, not substitute, human interaction in surgical consent processes.

Background: Despite the general success of total knee arthroplasty (TKA), addressing periprosthetic joint infection (PJI) and the resulting long-term complications is a growing medical need given the aging population and the increasing demand for arthroplasty. A larger proportion of patients face revision surgery because of the long-term complication of aseptic loosening despite clearance of the infection. The pathomechanisms leading to prosthetic loosening are not understood as it has been widely assumed that the bone stock recovers after explantation revision surgery. While clinical observations suggest a reduced osteogenic potential in patients with PJI, knowledge regarding the relevant biology is sparse. In the present study, we investigated the inflammatory impact of PJI on the bone and bone marrow in the vicinity of the joint. Additionally, we evaluated changes in the local inflammatory environment in a 2-stage exchange at both explantation and reimplantation. Methods: In this study, we analyzed 75 human bone and bone-marrow specimens (obtained from 65 patients undergoing revision arthroplasty with cement for the treatment of PJI) for markers of inflammation. Samples were analyzed using hematoxylin and eosin overview staining, fluorescent immunohistochemical staining, flow cytometry, and polymerase chain reaction (PCR). Results: Leukocyte prevalence was significantly elevated at explantation (femur, +218.9%; tibia, +134.2%). While leukocyte prevalence decreased at reimplantation (femur, −49.5%; tibia, −34.2%), the number of cells remained significantly higher compared with the control group (femur, +61.2%; tibia, +54.2%). Expression of inflammatory markers interleukin (IL)-1α (femur, +2,748.7%; tibia, +1,605.9%), IL-6 (femur, +2,062.5%; tibia, +2,385.7%), IL-10 (femur, +913.7%; tibia, +897.5%), IL-12 (femur, +386.1%; tibia, +52.5%), IL-18 (femur, +805.3%; tibia, +547.7%), and tumor necrosis factor (TNF)-α (femur, +296.9%; tibia, +220.9%) was significantly elevated at prosthesis explantation in both femoral and tibial specimens. Expression remained significantly elevated at reimplantation for all inflammatory markers except IL-12 compared with the control group. Conversely, there were only limited inflammatory changes in the bone marrow environment. Conclusions: The present study demonstrated a strong and lasting upregulation of the proinflammatory environment in the joint-surrounding osseous scaffold in patients with PJI. Our data suggest that modulating the inflammatory environment has substantial potential to improve the clinical outcome in affected patients.

We developed a human Bone‐on‐a‐Chip (BOAC) model that integrates autologous primary immune and bone cells on native human bone substrates within a xeno‐free, perfused environment. In contrast to existing models, which focus primarily on hematopoietic or stromal compartments, our system recapitulates key aspects of functional bone remodeling and enables the maintenance of mature immune cells (up to 42 days), with preserved functional responsiveness at defined time points during culture. Dynamic flow and sequential cell seeding facilitated osteoclast‐mediated resorption, osteoblast‐driven matrix formation, and the maintenance of donor‐specific immune profiles over extended culture periods. The balance between bone cell activity and immune cell persistence was further optimized by controlled temperature modulation. The BOAC model preserves key features of bone and bone marrow physiology, including extracellular matrix formation, soluble factor signaling, and cellular heterogeneity. The bone scaffold provides a physiologically relevant 3D architecture derived from decellularized human trabecular bone. Single‐nucleus RNA sequencing confirmed the presence of major donor‐specific immune and bone cell populations. This 3D human in vitro system provides a robust platform for translational research and personalized medicine.

Background: Periprosthetic joint infection (PJI) following knee arthroplasty can significantly compromise patient mobility and quality of life. The newly proposed TNM classification system, adapted from oncology, categorizes PJI severity but has not yet been correlated with both subjective and objective outcomes post PJI treatment. Objective: This study evaluates the applicability of the TNM classification system for predicting outcomes in knee PJI revision surgeries. Methods: We conducted a retrospective analysis of 108 patients who underwent revision surgeries for knee PJI at our institution from January 2012 to January 2023. We assessed the correlation between the TNM classification and postoperative outcomes using the Knee Society Score (KSS) function and knee score, as well as the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Results: The TNM classification demonstrated that higher ‘T’ stages were significantly associated with worse functional and subjective outcomes. The ‘N’ classification had limited predictive value, likely due to treatment adjustments based on pathogen type. The ‘M’ classification correlated with functional outcomes but not with subjective scores, suggesting that patients with more severe preoperative comorbidities might adjust their expectations. Conclusions: While the TNM classification shows potential, its current form as a prognostic tool in PJI management is limited. Enhancing the ‘T’ component, coupled with the integration of a validated morbidity score such as the CCI could improve its prognostic value. Despite its shortcomings, the TNM system may still provide valuable prognostic insights for both patients and surgeons in tackling complex PJI.