The aim of this study was to gain information on the prevalence and manifestation of hallux valgus and associated foot pathology in ancient Egyptian mummies. Additionally, we investigated possible indicators of postmortem deformation of the feet during mummification. For this study, 34 mummies that had undergone whole body computed tomography (CT) were selected. For qualitative assessment, the body position of the mummies as well as of the feet and the type of wrapping of the feet were documented. At the first metatarsophalangeal joint, the preservation of the flexor hallucis longus tendon, the preservation of the joint capsule/ligaments, and the presence of the medial and lateral sesamoid were documented. Additionally, osteophytes were analyzed. Toe deformities were assessed for all toes. For quantitative assessment, the hallux valgus angle, the intermetatarsal angle D I/II, D I/V, and D IV/V, and the distal metatarsal articular angle (DMAA) were measured. Additionally, sesamoid grading was performed. All 63 evaluable feet showed claw toes in one or more toes. Measurements of hallux valgus angle ranged from -19 degrees to 23 degrees (mean 4.6 degrees). A pathological hallux valgus angle was found in 4 out of 34 mummies (11.8%), unilateral in one, and bilateral in three. In two of the mummies with bilateral pathological hallux valgus angle, pathological DMAA and subluxation of the medial sesamoids were also present, supporting the diagnosis of hallux valgus. A negative intermetatarsal angle was present in both feet of three mummies. In this study, we found a high prevalence of feet changes that indicated postmortem deformities rather than intravital pathologies. This finding raises questions regarding the validity of measurements of the hallux valgus angle postmortem. For further paleopathological studies of hallux valgus, we recommend an approach using a combination of qualitative and quantitative characteristics of hallux valgus and associated feet pathologies.

The prevalence of hip osteoarthritis is increasing and frequently requires total hip arthroplasty (THA). However, a standardized rehabilitation protocol to ensure sustainable functional recovery from THA has yet to be established. Therefore, this study compared the effects of real-time feedback-assisted home-exercise versus standard written instructions on the functional performance of patients following unilateral THA. This study was designed as a cluster-randomized controlled pilot trial with two parallel groups. Data from three-dimensional movement analysis, clinical examination, body-composition, activity monitoring and questionnaires were collected at baseline four weeks post-surgery, and follow-ups at three- and six-months post-surgery. Baseline measurements were followed by an eight-week supervised group exercise therapy. For home-exercise the control-group received printed instructions, whereas the intervention-group was provided a real-time feedback prototype. A total of 22 patients, aged 52 to 73 years (mean 62.9), participated in the study, 21 completed the intervention and thereof, 19 could be assessed at six-months post-surgery. No statistically significant differences were found for the primary outcomes frontal knee, pelvis and trunk range-of-motion during level walking, nor the secondary outcomes Harris Hip Score (HHS), SF-12 and IPAQ short form. Both groups improved their mean walking speed, cadence, step length, isometric knee flexion force of operated limb, SF-12 physical domain and HHS. Real-time feedback assisted home-exercise after THA did not differ when compared to commonly used written instructions in improving function and quality of life. However, patients in the real-time feedback group reported greater motivation and self-confidence regarding exercise performance, which was not reflected in the recorded numbers of home-exercise sessions. The study was prospectively registered on 7th December 2023 at ClinicalTrials.gov NCT06161194.

The biomechanical performance of intramedullary nails in metaphyseal regions strongly depends on distal locking configuration. This study aimed to evaluate screw–bone interface stability under combined axial and torsional cyclic loading for different distal locking configurations of intramedullary nails, focusing on the effects of screw number, spatial distribution, interscrew distance, and multiplanar versus coplanar fixation using a standardized synthetic bone model. Six distal locking configurations (n = 5 per group) were tested under stepwise cyclic axial compression, superimposed with a constant torsional moment (± 2 Nm, 2 Hz). Primary endpoints were cycles to failure, cycles to 1 mm axial displacement, and cycles to 0.5° rotation. All constructs failed by progressive screw cut-through within the synthetic bone. The three-screw multiplanar configuration exhibited the highest endurance (≈ 36,000 cycles to failure) and lowest micromotion (≈ 34,000 cycles to 1 mm displacement), significantly outperforming the two-screw configurations overall (p = 0.002). Increasing interscrew distance from 10 mm to 34 mm improved migration resistance by approximately 25

Tibial plateau fractures are complex injuries requiring anatomical reduction and stable fixation to restore joint congruency and function. Digital tools, including CT reconstructions, computer-assisted implant planning, and finite element (FE) modeling, have the potential to improve fixation strategies. This experimental study investigated whether FE-based preoperative planning enhances the stability of tibial plateau fracture fixation compared with conventional planning, assessing construct stiffness, load to failure, and fracture stability under physiologic loading. Twelve human cadaveric lower limbs (78 ± 10 years) with induced Schatzker IV fractures were randomized to conventional (n = 6) or FE-based planning (n = 6). In the FE group, fragment reduction, screw trajectories, and implant positioning were optimized via computational modeling and guided intraoperatively by individual targeting guides. Conventional planning used standard CT visualization. All specimens were fixed using a medial locking plate and tested under axial loading, including stiffness measurement and progressively increasing cyclic loading until failure. Plate and screw positioning did not clearly differ between approaches, however FE-based planning promoted more consistent locking screw utilization and more frequent individual screw usage. FE-based planning yielded higher load to failure (1050 ± 535 N vs. 442 ± 226 N, p = 0.041), more cycles to failure (10,100 ± 5400 vs. 4100 ± 2400; p = 0.046), and more symmetrical construct stiffness. After adjustment for anatomical variations, differences in failure load were no longer statistically significant. Tibial plateau widening during loading was comparable between groups. These findings suggest that FE-based planning can enhance construct stability and reduce fixation asymmetry. Further clinical validation is needed to determine whether these benefits translate into improved outcomes.

Locked plate osteosynthesis functions as an internal fixator, yet load-induced plate–bone and fragment–fragment contacts – key transitions from load-bearing to load-sharing – remain poorly characterized. This study quantified their effects on construct stiffness, plate strain, and interfragmentary motion under axial loading. Twenty-seven configurations were tested using epoxy-glass surrogate bone fixed with titanium LCP plates, varying fracture gap (3–9 mm), working length (49–121 mm), and plate–bone distance (0–3 mm). Digital image correlation measured strain and motion. Contact events were identified manually from characteristic transitions in the force–displacement response, supported by corresponding changes in plate-surface strain progression. Geometric parameters dominated initial stiffness (125–442 N/mm), decreasing with plate elevation and working length in elevated setups. Within the investigated load range up to 600 N, 16/27 configurations showed non-linear transitions associated with contact events: fragment–fragment contact caused pronounced stiffness increases and strain stagnation at the fracture gap, whereas plate–bone contact was associated with local plate-surface strain stagnation at the location overlying the contact while strain at the fracture gap continued to increase. Interfragmentary motion stagnated after contact, confirming contact-dependent shifts in load transfer. Response surface regression explained 81.9

Complex tibial plateau fractures continue to pose a significant challenge for surgeons. In recent years, the widespread use of CT imaging has led to new insights leading to novel classifications that facilitate 360° stabilization techniques. Visualization in 3D has improved both fracture reduction and surgical outcomes. This study investigated whether preoperative planning of complex tibial plateau fracture fixation via finite element modeling (FEM) could enhance the fixation performance achieved by experienced surgeons and potentially improve outcomes for less experienced surgeons. In twelve left cadaveric fresh-frozen human knees with intact soft tissue reproducible Schatzker type IV fractures with lateral depression were created. The samples were paired on the basis of bone mineral density and then randomly allocated into two groups. Six senior surgeons with extensive experience in the operative treatment of tibial plateau fractures performed two procedures: one using standard preoperative planning and one using FEM-optimized fixation planning. All fractures were stabilized with a medial locking plate and supplemental single screws when needed. The operation time, radiation dose and implant usage were documented. Surgeon mental workload was measured by the NASA task load index. Finally, the samples were biomechanically tested over four quasistatic load ramps from 10 to 200 N, followed by a cyclic sinusoidal load with increasing load level until failure. Failure was defined as either ≥ 5° varus/valgus malalignment or a vertical impression of the condyles ≥ 3 mm. The initial stiffness and load to failure were assessed via a 3D motion tracking system. Statistical analysis was conducted using Student’s t-tests. No significant differences were observed in terms of operative time or intraoperative radiation exposure. However, the NASA-TLX mental demand test revealed a statistically significant advantage for the FEM-planned group (33 ± 12.4 vs. 49 ± 8.6 (p = 0.043)), indicating a reduced cognitive load. Additionally, the FEM group exhibited superior biomechanical performance, with a higher load to failure of 1050 ± 535 N vs. 442 ± 226 N (p = 0.041). This biomechanical feasibility study demonstrated that FEM-based preoperative planning is feasible and easy to implement for complex tibial plateau fractures. This planning supports specialized surgeons in challenging operations and can improve the stability of osteosynthesis.

OBJECTIVES:This study evaluates liquid-rubber-coating to prevent moisture loss in bone during long-term biomechanical testing and digital image correlation (DIC) measurements. Can liquid-rubber-coating preserve bone mechanical properties and enhance DIC measurements? METHODS:Two experimental series used porcine femora in a 4-point-bending setup (n=6). Series 1 compared dehydration with and without rubber-coating during a 21-h drying period, focusing on bending stiffness and weight loss. Series 2 compared liquid-rubber-coating to acrylic-paint for DIC measurements across 50-2,000 µε principal strain. RESULTS:After 21 h, weight loss of the uncoated samples was almost three times higher (7.9 ± 0.4 % vs. 2.9 ± 0.6 %, p<0.001). Bare samples increased bending stiffness by 16.3 ± 4.7 % (p=0.003) vs. 5.8 ± 4.0 % (p=0.155) with coating. DIC noise was 174 ± 121 µε with acrylic-coating and 158 ± 113 µε with liquid-rubber (p=0.700). Bland-Altman analysis showed no significant differences between the groups (p≥0.128). CONCLUSIONS:The liquid-rubber-coating substantially reduced moisture loss and maintained bone mechanical properties over 21 h, without significant alteration to mechanical properties. DIC performance showed no consistent coating-related differences, indicating the coating as a time-stable, water-impermeable alternative to acrylics. Notably, coated samples exhibited reduced odour. Future work should test liquid-rubber-coatings under physiological loading in human bone to improve DIC accuracy for finite element validation and digital twin precision.

Optical motion capture (OMC) is the clinical gold standard for instrumented gait analysis. Inertial measurement units (IMU) offer a faster and more scalable alternative. A key prerequisite for its clinical application is a comparable potential for pathology detection. This prospective, two-center study compared the classification performance of IMU based 2-Segment Foot Model kinematics data with OMC based Oxford Foot Model data. Included were healthy controls (IMU: n = 30; OMC: n = 20), patients after tibiotalar (IMU: n = 15; OMC: n = 19), and subtalar arthrodesis (IMU: n = 15; OMC: n = 21), assessed via both IMU and OMC. Kinematic waveforms were converted into scalar features using functional principal component analysis (FPCA), which preserves the temporal structure of the full gait cycle while yielding scalar scores suitable for machine learning classification Three different machine learning classification approaches were used. All approaches achieved high discriminative performance for both modalities, with consistently higher performance for OMC. Mean accuracies for the different modalities and ML models ranged between 0.67 and 0.81 for the IMU data and were consistently greater for OMC data (0.83 - 0.91). Mean AUC values remained high (IMU 0.920-0.926; OMC 0.944-0.965). Feature patterns indicated that group separation was primarily driven by FPCA-derived features of hindfoot/tibia kinematics, while differentiation between tibiotalar and subtalar arthrodesis required FPCA-derived features spanning hindfoot/tibia and forefoot/tibia across multiple planes. IMU derived 2-Segment Foot Model kinematics enable clinically meaningful classification of arthrodesis related gait patterns and separation from healthy controls, supporting clinical applicability. However, OMC using a multi segment foot model remained superior with respect to maximal classification accuracy.

BACKGROUND: Freezing of Gait (FOG) is a severe symptom of Parkinson’s Disease (PD) that affects mobility and quality of life. The ‘Characterizing Freezing of Gait Questionnaire’ (C-FOG) is an assessment tool for screening and determining subtypes of FOG. However, it currently only exists in the English language. This study aimed to translate the C-FOG from English to German METHODOLOGY: This project was conducted from September 2024 to February 2025 at a University of Applied Sciences in Krems, Austria and applied the Translation, Review, Adjudication, Pretest, and Documentation (TRAPD) process. This included professional translations, 1 review-workshop with 4 participants, adjudication, pre-testing in 2 workshops with 11 participants, including 8 healthcare workers and 3 people with Parkinson’s disease, and parallel detailed documentation of all changes and decisions. RESULTS: In the first translation stage of the C-FOG two professional translators provided two different preliminary German translations. The original questionnaire was divided into 62 translation units to provide a detailed descriptive analysis of the adaptations made in each step of the translation process. During the review stage, 31 units (50%) of the preliminary translations required adaptation. During the pre-test stage, the participants discussed the German translation of the C-FOG that had been adjudicated in the previous stage. This resulted in the need for further adaptations of 25 translation units (40%), while 37 units (60%) required no additional changes. Following back-translation by a professional translator and feedback from the first author of the original questionnaire, the German version of the C-FOG, the C-FOG-D, was finalized. CONCLUSION: This study provides a systematically conducted German translation of the Characterizing Freezing of Gait Questionnaire using the TRAPD process to ensure understandability and equivalence to the original questionnaire. A full consensus was reached among the participants involved in the final translation stage. For future validation studies and potential modifications to the questionnaire, it is necessary to include more people with PD experiencing FOG. A larger sample size could offer a more comprehensive perspective on how individuals differ in their perceptions of FOG, and to what extent the language used in the questionnaire effectively captures these experiences.

Motion reconstruction provides essential inputs for analyzing human movement through musculoskeletal simulations. To reconstruct joint angles from motion capture data, several multibody kinematic optimization methods have been developed. However, a computationally efficient method yet simple to implement while ensuring consistent kinematics at all levels is lacking. Here, we propose a potential field method generated by virtual spring-dampers connecting measured-derived skin markers to segment-fixed model points to reconstruct motion in a forward dynamic manner by solving the equations of motion. The virtual spring-damper forces move the mechanical system to minimize the elastic potential and the distance between markers during the motion. Several evaluation strategies are performed which demonstrate that the potential field method is computationally fast (2.5ms per frame) with comparable accuracy to the well-established least squares method in terms of reconstructed marker trajectories and joint angles (RMSE < 0.37 mm, 1.87°) and with low marker residuals (< 18.7 ± 12.6 mm) in line with reported ranges. Furthermore, soft tissue artifacts are compensated well compared to the simulated true values (RMSE < 1.66 mm, 3.69°). Sternoclavicular, scapulothoracic and glenohumeral rotations were reconstructed well the major trends and magnitudes of experimental measurements. We anticipate our method will pave the way for complex applications that demand reliable and rapid large-scale biomechanical analysis of human movement.