Niels Hammer

Walking, posture and childbirth all depend on the pelvic ring, yet human pelvic dimorphism is usually interpreted from static birth-canal dimensions. We asked whether sex differences in pelvic function are explained by overall size and static pelvimetry or by available mechanical deformation pathways. We analysed 278 anatomically standardized lumbopelvic finite-element models built from clinical computed tomography scans. In each model, modal decomposition separated pelvic deformation into a shared, ranked set of pathways, allowing us to compare pathway stiffness, load recruitment and sensitivity to ligamentous and cartilaginous constraints. Overall pelvic size accounted for much of the baseline stiffness spectrum, confirming a strong size-dependent component. However, size- and age-adjusted sex differences remained: male pelves showed approximately 20% higher eigenvalues than female pelves in modes 2 and 9. Loading probes showed a common backbone in both sexes during habitual support, whereas inlet opening revealed a different response organization, with female pelves distributing deformation across a broader, coordinated set and a higher effective number of participating modes. The principal inlet-opening pathway was most sensitive to the pubic symphysis and anterior sacroiliac ligamentous constraints. Pelvic dimorphism, therefore, lies not only in canal shape, but in the organization of mechanical pathways that balance support with deformation.

Bone radiodensity is often reduced to global Hounsfield Unit (HU) summaries, although its spatial distribution may contain biologically relevant information. This study introduced a template-based framework for spatial radiodensity mapping of the adult human hyoid and tested whether spatial descriptors capture age- and sex-related variation better than whole-bone HU measures. Clinical head-and-neck CT scans from 300 adults, including 180 females and 120 males, were analyzed. Hyoids were segmented, normalized into a common anatomical template, and divided into 1500 supervoxels for spatial analysis. Scalar HU summaries were compared with PCA-based spatial descriptors, and regional effects were assessed using supervoxel-wise models with false-discovery-rate correction. The registered radiodensity maps showed spatial coherence, with neighboring supervoxels displaying more similar profiles than distant ones. In this cohort, spatial descriptors outperformed mean HU for age prediction, although performance remained limited (R² = 0.255). Sex classification was moderate (ROC AUC = 0.810; balanced accuracy = 0.725). After the spatial features were adjusted for native volume, sex-classification AUC fell to 0.671, and none of the 51 unadjusted regional sex associations survived volume adjustment. Age-related associations involved the hyoid body, the body–greater horn transition, and the proximal-to-mid greater horns. These findings demonstrate spatial coherence in the registered maps but show that the sex-related pattern is strongly size-dependent.

Purpose: Intraoperative three‐dimensional (3D) surface scanning is not routinely used in total knee arthroplasty (TKA) but may allow real‐time evaluation of the native joint surface anatomy, enabling intraoperative evaluation and potential adaptation of implant alignment. Methods: In this experimental study, four unembalmed knee joints from post‐mortem donors underwent computer tomography scanning to generate ground‐truth 3D bone models. A handheld structured‐light surface scanner was then used to capture the 3D structure of the distal femur and the patella at different stages during TKA. Fiducial markers were used to compare registration accuracy between a marker‐based and an anatomical landmark‐based approach. Conformity between the native anatomy and the femoral component was numerically quantified. Simulated variations of the implant positioning were compared with the initial position. Results: Scanning took 40–60 s per scan; the resulting point cloud was utilized to create a 3D model in 3 min on average, capturing anatomic details with an accuracy of ~0.2 mm. Aligning scans based on bony landmarks was more accurate compared to marker‐based registration. Surface conformity comparisons between the femoral component and the native anatomy demonstrated consistent agreement at the distal and posterior condyles, whereas greater deviations were observed in the trochlear region. Simulated sagittal and mediolateral adjustments of the implant orientation were associated with measurable changes in trochlea surface conformity. Conclusion: This study demonstrates the technical feasibility of intraoperative structured‐light 3D surface scanning for the analysis of femoral and patellar surface geometry, allowing for quantitative assessment of femoral component orientation relative to the native anatomy in a controlled experimental setting. The use of 3D scanning hardware may allow for faster acquisition of high‐resolution surface data, compared to conventional imaging techniques. The small sample size and absence of in vivo validation limit the scope of the findings, requiring further studies to evaluate clinical application. Level of Evidence: Level V, experimental feasibility study based on post‐mortem studies.

Over three decades since its introduction, the Thiel embalming method remains a widely used and praised technique in anatomical education and clinical training. This study compared for the first time the Thiel original protocol (TO) and a Modified version (TM) across user groups—undergraduate medical students, student demonstrators in anatomy, postgraduate trainees, and expert anatomists—to evaluate tissue quality and educational suitability. A total of 520 participants assessed both methods based on tissue preservation, color, pliability, and achievement of learning objectives. Undergraduate medical students and demonstrators rated TO significantly higher than TM in all domains ( p < 0.01), highlighting its lifelike appearance, clear anatomical definition, and superior dissection properties. Anatomists supported these findings, citing better tissue realism and structural integrity in TO specimens. Postgraduate users, mainly orthopedic surgeons, rated both methods similarly for musculoskeletal and nervous tissues, but preferred TO for the clarity of visceral organs ( p < 0.01). While TM offered improvements for musculoskeletal training, users reported challenges including overly soft viscera, liquefied fat, and reduced structural clarity, making it less suitable for beginners. Both TO and TM were rated superior to formaldehyde‐ or ethanol‐based techniques in terms of educational utility and realism. Qualitative feedback confirmed TO as better suited for undergraduate anatomy education, particularly for dissection. TM, though valuable in specialized postgraduate training, was seen as less appropriate for novice learners. The findings highlight the need to align embalming protocols with educational goals and experience levels, with TO remaining the preferred method for foundational anatomical training.

The mechanical behavior of the growth plate plays a central role in longitudinal bone growth, yet constitutive material descriptions suitable for finite element modeling remain poorly defined. In particular, hyperelastic material parameters for growth plate tissue have not previously been reported.In this study, unconfined compression tests were performed on porcine growth plate samples from the proximal femur, distal femur, and proximal tibia using a force-driven, stepwise termination point protocol. Full-field digital image correlation was employed to measure deformation directly at the growth plate throughout loading and relaxation. Equilibrium responses were characterized using a three-term Yeoh hyperelastic model, while time-dependent behavior was described by a two-term Prony series.The applied loading protocol covered physiologically relevant joint force magnitudes and resulted in compressive strains ranging from 5.6% to 35%. Significant differences in hyperelastic material response were observed between growth plate types (p < 0.05), whereas no consistent effects of medial–lateral location or individual specimens were detected. Viscoelastic parameters showed limited variability across anatomical location. Correlation analyses revealed significant associations between relaxation-related energy dissipation and histological features such as growth plate thickness and chondrocyte column orientation (p < 0.05).These results provide the first experimentally derived hyperelastic and viscoelastic material parameters for growth plate tissue and establish a computationally efficient constitutive framework for finite element modeling of growth plate mechanics.

Anatomical museum collections represent an important resource for medical education, research, and the preservation of scientific heritage. However, many historical collections remain insufficiently cataloged, which limits their accessibility and long-term usability. This study reports on a phase of a bilateral project aimed at the systematic cataloging of anatomical specimens from the Anatomical Museum of Danylo Halytsky Lviv National Medical University, conducted in collaboration with the Division of Macroscopic and Clinical Anatomy at the Medical University of Graz. A structured inventory and documentation process was implemented, including the collection, verification, and standardization of archival and specimen-level data. The collection comprises mummified specimens (158), wet preparations (198), paraffined specimens (15), and skeletal materials (233 macerated bones, skulls, and complete skeletons). A unified cataloging framework was developed to integrate historical and current inventory data into a centralized digital database. A total of 604 specimens were cataloged in the present phase of the project. The process enabled the organization of heterogeneous material into a standardized system and revealed gaps in historical documentation, particularly for older specimens. The study demonstrates the feasibility of implementing a systematic cataloging approach for complex anatomical collections. It highlights the potential of structured digital documentation to improve collection management and supports the value of international collaboration in advancing anatomical curation and education.

Implantation of a femoral stem in total hip arthroplasty alters physiological load transfer within the proximal femur. Short-stem designs aim to preserve bone stock and maintain proximal load sharing, yet the influence of femoral neck resection height and its interaction with femoral morphology on primary stability remain insufficiently understood. This in vitro biomechanical study investigated these effects using 33 human femora classified as Dorr B or C. In a paired design, a cemented calcar-guided short stem was implanted with either a low (standard) or +5 mm higher femoral neck resection. Specimens underwent cyclic fatigue loading to assess reversible and irreversible micromotion and interface strain, followed by ultimate compression to quantify global fixation strength. Primary stability was assessed by reversible and irreversible translation of the prosthetic head center of rotation and by cortical interface strain measurements using digital image correlation. Overall fixation strength and irreversible deformation remained comparable across resection heights and Dorr types. In contrast, resection height and femoral morphology influenced reversible micromotion and interface strain, with higher resection reducing reversible micromotion, particularly in Dorr C femora and shifting lateral interface strain toward compression. These findings suggest that surgical technique and femoral morphology mainly affect local, reversible bone–cement–implant mechanics rather than global fixation strength.

Objective: The aim of this review was to summarize the available evidence concerning the innervation of the sinus tarsi with regard to partial ankle denervation. Methods: A systematic literature search according to the PRISMA guidelines was conducted using the databases PubMed and Embase. The following search algorithm was used: “(innervation ankle joint)” OR “(denervation ankle joint)” OR “(sinus tarsi syndrome)” OR “(innervation sinus tarsi)” OR “(denervation sinus tarsi)” OR “(articular branches)”. Anatomical and clinical studies that provided information on the innervation of the sinus tarsi were included. Exclusion criteria comprised former systematic reviews. Results: Only 4 studies met the review criteria. The number of specimens included averaged 18 (range: 5-28). Nerves involved in the innervation of the sinus tarsi were the deep peroneal nerve (DPN), the sural nerve (SN), and the superficial peroneal nerve (SPN). For the DPN, articular branches were reported to arise either from its main trunk or from one of its terminal branches, with the number of articular branches ranging from 2 to 4 (mean: 2.9). The SN was reported to contribute in up to 24% of cases, with an articular branch originating from the medial aspect of the SN. As a variation, the SPN may contribute 1 small branch arising from the intermediate dorsal cutaneous nerve at the level of the anterior border of the trochlea tali. Conclusion: The summarized data may inform surgical planning, pending validation in larger studies. Cite this article as: Hohenberger G, Wittig U, Pretterklieber M, Hammer N, Pretterklieber B. The sensory innervation pattern of the sinus tarsi regarding partial ankle denervation: A systematic review. Acta Orthop Traumatol Turc., 2026; 60(3), 0564, doi: 10.5152/j.aott.2026.25564.