Aristeidis Hristos Zibis

This article presents the design, construction, and validation of an open-source apparatus for biomechanical testing of hip implants. The device enables controlled axial loading of implant constructs, addressing common limitations in terms of cost, complexity, and adaptability. The design emphasizes reproducibility, using widely available components and specimen-specific 3D-printed alignment tools, while ensuring high accuracy in load application and displacement measurement. The apparatus replicates physiological stance-phase loading (1.00× body weight (BW) axial, ~1.55× BW abductor, ~2.47× BW joint compression forces). The displacement values obtained by the validated finite element model and the Digital Image Correlation (DIC) technique on cadaveric specimens were compared and a mean displacement difference of 0.17 mm ± 0.09 mm was observed. Detailed build instructions and step-by-step operating protocols are provided, along with access to open-source CAD files. This work aims to facilitate broader access to customized biomechanical testing solutions for orthopedic research and education.

Objective: To quantify and map bone mineral density (BMD) at the bases of human finger phalanges using computed tomography (CT) with a calibration phantom and to compare BMD both between and within digits. Methods: Ten cadaveric hands (H1 to H10) were CT scanned with a Model 3 CT Calibration Phantom (Mindways). All data were processed in the Horos software (Version 4.0.0) and the regions of interest (ROIs) at each phalangeal base were delineated. Hounsfield Units (HU) were converted to BMD (mg/cm³) per the phantom framework. Descriptive statistics and repeated-measures ANOVA analyses were performed for each digit and corresponding phalangeal level (proximal, middle, distal). Inter-digital comparisons were performed at corresponding phalanx levels and intra-digital variations were analyzed within digits across phalangeal levels. Results: Mean BMD varied across digits and phalangeal levels. At the proximal phalanx base, the thumb and index fingers exhibited the highest values, whereas at the middle phalanx base the middle and ring fingers demonstrated the highest mean BMD values. At the distal phalanx base, the little finger demonstrated the highest BMD value, while the lowest value was observed at the distal phalanx of the index finger. Intra-digital analysis revealed distinct distribution patterns: BMD decreased distally in the thumb and index fingers, peaked at the middle phalanx in the middle and ring fingers, and was highest distally in the little finger. Repeated-measures ANOVA demonstrated statistically significant intra-digital differences in the thumb and index fingers, whereas no statistically significant inter-digital differences were observed across corresponding phalangeal levels. Conclusions: CT-based, phantom-calibrated BMD mapping at the bases of the phalanges demonstrates substantial intra-digital variability and descriptive inter-digital differences. These site-specific findings may provide additional information relevant to implant selection and preoperative planning for fixation in phalangeal fractures and tendon- or ligament-to-bone insertion injuries in hand surgery.

Background/Objectives: Artificial intelligence (AI) and its subfield deep learning (DL) have rapidly evolved into a central tool in modern medicine. The purpose of this work was to examine if DL neural networks can discriminate efficiently the microvessel network of post-COVID-19 patients from healthy individuals from. Methods: A non-contact, digital slit-lamp video capillaroscopy system was used to record high magnification images form the bulbar conjunctival microcirculation of 12 COVID-19 survivors (named “COVID-19 Group”) and 12 healthy volunteers (named “Control Group”). Four pretrained convolutional neural networks (CNNs) were fine-tuned by transfer learning and their performance was assessed by standard binary classification evaluation criteria. Results: A scene-centric CNN named GoogLeNet-Places365 excelled on all evaluation criteria with an average testing accuracy, sensitivity, specificity and AUC (area under the curve) of 92%, 92%, 91%, and 0.971, respectively. Conclusions: Post-COVID effects on the eye microcirculation can be detected by deep CNNs, and there is now evidence for the first time, that AI could provide a risk-free, painless, contactless, fast, and accurate detection method of viral effects that does not depend on the optical clarity of the eye.

Purpose: Total hip arthroplasty is among the most successful orthopedic procedures; however, approximately 10%–20% of patients require revision surgery within 15–20 years. Potential failure mechanisms at the bone–implant interface include stress shielding and excessive micromotion. This experimental work aims at examining the optimal ratio of femur length and stem length with respect to primary stability and stress shielding effect, employing a validated finite element analysis. Methods: One hundred human femora were reconstructed from computed tomography (CT) scans, and for each femur, 13 personalized cementless stems were designed with varying lengths (70–130 mm, in 5 mm increments), resulting in 1300 finite element models. Each model was analyzed under standardized joint and muscle loading conditions. The model was validated experimentally after cadaveric implantation with digital image correlation (DIC) under static loading. Primary outcomes included micromotion at the bone–implant interface and proximal stress shielding. Optimal stem length was determined as the ratio of stem‐to‐femur length that minimized the combined normalized scores of micromotion and stress shielding. The effect of stem‐to‐femur length ratio was analysed with linear regression. Results: The analysis revealed a correlation between femoral length and stem length. Longer stems provided better initial stability and reduced micromotion. On the other hand, shorter stems demonstrated less proximal stress shielding and a better stress distribution resembling that of the intact femur. The optimal stem length was found to be 18.5% ± 2.7% (mean ± SD) of the femur length in terms of the mean of calculated micromotions and stress shielding, indicating that personalized stem length selection can enhance the bone–implant osseointegration. Conclusion: The selection of a stem length that corresponds proportionally to femoral length can improve primary stability and stress shielding upon implantation, highlighting the importance of enhancing initial fixation in order to extend the lifespan of hip replacements. Level of Evidence: N/A.

Differential diagnosis between avascular necrosis (AVN) and transient osteoporosis of the hip (TOH) can be complicated even for experienced MSK radiologists. Our study attempted to use MR images in order to develop a deep learning methodology with the use of transfer learning and a convolutional neural network (CNN) ensemble, for the accurate differentiation between the two diseases. An augmented dataset of 210 hips with TOH and 210 hips with AVN was used to finetune three ImageNet-trained CNNs (VGG-16, InceptionResNetV2, and InceptionV3). An ensemble decision was reached in a hard-voting manner by selecting the outcome voted by at least two of the CNNs. Inception-ResNet-V2 achieved the highest AUC (97.62%) similar to the model ensemble, followed by InceptionV3 (AUC of 96.82%) and VGG-16 (AUC 96.03%). Precision for the diagnosis of AVN and recall for the detection of TOH were higher in the model ensemble compared to Inception-ResNet-V2. Ensemble performance was significantly higher than that of an MSK radiologist and a fellow (P < 0.001). Deep learning was highly successful in distinguishing TOH from AVN, with a potential to aid treatment decisions and lead to the avoidance of unnecessary surgery.

Proprioception is a specialized sensory modality encompassing the movement of the joint and its position in space, and it involves the conversion of mechanical deformation of tissues into neural signals. Mechanoreceptors are specialized nerve structures able to transmit mechanical deformation through electrical signals to dorsal root ganglion sensory neurons and are abundant in the muscles, tendons and ligaments of the knee joint. They are believed to play an important role in knee proprioception and dynamic knee stability. Proprioception should always be taken into consideration for successful reconstruction of the cruciate-deficient knee and for pain and function management in the arthritic knee. Advances in histological methods of detection are numerous and continue to highlight the presence and role of mechanoreceptors after ligament reconstruction, depending on choice of graft. In this review, we present the current knowledge of anterior and posterior cruciate ligaments and grafts mechanoreceptors, and their role in proprioception of knee joint, focusing on each type of mechanoreceptors.

The purpose of this study was to compare the measurement of several anatomical features of the medial patellofemoral ligament (MPFL) between magnetic resonance imaging (MRI) and by direct fashion during dissection. We hypothesized that the measurements between these two techniques would agree. MRI of 30 fresh-frozen cadaveric knees was followed by dissection. MPFL patella and femoral attachment were evaluated; their shape, length, and width were measured; and measurements were compared. MRI was deemed unreliable for the determination of several of the aforementioned anatomical features. Important findings include: (a) observations on MPFL attachment at medial patella side and attachment to quadriceps were identical between dissection and MRI; (b) average width at patella insertion was significantly different between the two methods (p = 0.002); and (c) an attachment to the quadriceps tendon was present in 20/30 specimens and d. detailed measurements of a thin, non-linear, and three-dimensional structure, such as the MPFL, cannot be performed on MRI, due to technical difficulties. This anatomical radiological study highlights the shape, anatomical measurements (length and width), and attachment of the MPFL using a relatively large cadaveric sample and suggests that MRI is not reliable for detailed imaging of its three-dimensional anatomy.

Purpose: Clinically-oriented anatomy education has been proposed as an effective strategy in anatomy curricula. We aimed to explore the level of extent the literature supports the fact that case-based learning (CBL) can play a significant role in anatomy education. Materials and methods: We searched PubMed, Scopus, Education Resources Information Center (ERIC), and Cochrane database to find articles with the purpose to explore the educational outcomes of case-based anatomy learning. We extracted from each paper authors, type of study (comparative or not), number of participants, level of outcome according to the Kirkpatrick hierarchy, outcomes of CBL concerning the acquisition of anatomical knowledge, and the participants’ perceived enjoyment, motivation, and aid to anatomy learning. Results: Nine articles were included. Three of them evaluated the acquisition of anatomical knowledge, while six papers evaluated the participants’ perceptions. All studies showed positive outcomes regarding the students’ anatomy examination performances, reported confidence, enjoyment, motivation, and ability of CBL to facilitate anatomy learning. Conclusion: Although the existing research has mainly evaluated students’ perceptions, the outcomes of CBL in anatomy education encourage more extensive use of this method in anatomy curricula. Further research is expected to shed more light on the role that CBL can play in modern anatomy education and to clarify if it can replace or supplement didactic teaching.