Search Results (52)

In the field of orthopedic surgery, particularly distraction osteogenesis (DO), the mechanical environment plays a decisive role in the quality of bone regeneration and the safety of the soft tissue envelope. The continuous monitoring and accurate prediction of distraction resisting forces (DRF) are critical for preventing soft tissue complications such as nerve ischemia, joint contractures, and mechanical failure of the lengthening device. However, current clinical practice relies heavily on subjective assessment or passive monitoring tools that lack predictive capabilities. To address this gap, this study proposes a comprehensive solution combining a custom mechanical acquisition system with a high-fidelity finite element (FE) prediction method. The system design features a novel “double-ring” sensor interface specifically engineered to decouple axial distraction forces from parasitic bending moments generated by asymmetric muscle tension. Furthermore, a patient-specific FE model utilizing the Ogden hyperelastic constitutive law was derived, explicitly based on the patient’s muscle volume from preoperative CT imaging, to predict the non-linear force evolution. The feasibility and accuracy of the system were validated in a pilot in vivo study using a single ovine model ($N=1$). To isolate the soft tissue resistance from callus formation, distraction was performed immediately postoperatively up to a total length of 4 cm. Experimental results demonstrated the system’s high linearity ($R^2>0.999$) and its ability to capture the characteristic viscoelastic relaxation of living tissues. The FE model successfully predicted the peak distraction forces, showing improved agreement with experimental data at larger distraction magnitudes. By integrating mechanical sensing with predictive modeling, this framework lays the foundation for future closed-loop, patient-specific control in distraction osteogenesis. Full article

In the present qualitative study, we first synthesize research to clarify the concept of error in science as developed by epistemologists, philosophers, and historians. We also examine the concept of error in educational science, drawing from studies on science learning and teaching. To do this, we analyzed references found through a systematic review of books and journals. We also selected published articles on the history of physics and chemistry and consulted documents authored by scientists in English or in official translations. We guided our selection by choosing sources relevant to conceptualizing error in scientific and educational contexts. Our key findings show two categories of scientific error: those that have contributed to scientific progress and those that have hindered it. Some renowned scientists, such as Aristotle and Buridan, put forward theories of force and movement that were later shown to be false. However, these errors did not always impede scientific advancement. This research highlights how scientific errors have shaped the evolution of science and reveals insights into the scientific process and the resilience of the scientific community. In science education, researchers use various terms such as “student naïve reasoning,” “students’ alternative conceptions,” “students’ alternative theory,” and “misconceptions.” Students’ errors, like scientific errors, can be classified into two categories. The first type involves errors from distractions, misunderstandings, or unintentional mistakes. The second type results from students’ interactions with many natural and man-made phenomena, the common language used in society (which differs from scientific language), and errors passed down by teachers or found in textbooks. Finally, we note that identifying errors among scientists and students supports the development of strategy-based teaching for meaningful science learning. From this perspective, students will be pleased to know that some of their conceptions of force and motion are “similar” to those developed by Aristotle and Buridan, even if these conceptions are false relative to those developed by Galileo and Newton. Recognizing both scientists’ and students’ errors is essential for creating teaching strategies that promote deeper science learning. Full article

According to Sigmund Freud, the unconscious is full of contradictions (wild emotional impulses, baseless fears, and repressive forces) but it is also a control mechanism. It is no wonder that digital platforms—requiring uniformity, reliable protocols, secure transmissions and proprietary algorithms as well as an enormous database about human desire and impulses—would gravitate toward a model of control, or more specifically, the ideal of automating impulsive actions and reactions. Similar to the Freudian unconscious, digital platforms and networks are infamously black-boxed, meaning their operations (inner workings) are made invisible to the average user, including information about them. Yet, the digital unconscious also seems to perfect and promote this as an automatic destructive force (a death drive fed by extraction, consumption and a will to endless profit) that is incommensurate with life on the planet. Using the recent pleas by the Tuvaluan Minister of Justice, Communication, and Foreign Affairs (Simon Kofe) to the United Nations Convention on Climate Change, this article will argue that denial has replaced repression as the key mechanism of the digital unconscious, allowing twenty-first century media to offer itself as pharmakon (both poison and a remedy or at least a distraction) to those twenty-first century crises that nineteenth-, twentieth-, and twenty-first-century media continue to advance. Full article

The COVID-19 pandemic imposed unprecedented restrictions on movement and daily life, testing the resilience and adaptability of existing housing stock, as families worldwide were forced to adapt their homes into multifunctional environments. In New Zealand, where lockdowns were among the most stringent globally, homes rapidly transformed into workplaces, schools, gyms, and places of refuge. Little is known about how these adaptations affected the sustainability of homes and occupants’ well-being, particularly in the context of future crises. This study examined the economic, environmental, and psychosocial impact of the COVID-19 lockdown on New Zealand households. A questionnaire survey was conducted, and a quantitative analysis method was employed using survey data from 92 valid responses from New Zealand respondents who experienced lockdowns in various types of housing. To find important patterns and connections, descriptive and inferential statistical analyses were conducted. Findings revealed that economic factors had the strongest influence on respondents’ perceived experience during the COVID-19 lockdown, with households reporting increased electricity and water use but reduced fuel costs. Environmental factors were also significant, with respondents noting the importance of fresh air, sunlight, acoustic privacy, and more spacious rooms, alongside the critical need for a dedicated workspace. Psychosocial effects included higher distraction levels, monotony, and heightened concern for health. Group differences highlighted the influence of age and the number of bedrooms on the perceived experience of lockdown. This pilot work offers a New Zealand perspective on the intersection of the pandemic with the sustainability of homes. The practical implications of this study highlight the need for sustainable housing retrofits, hybrid work policies that support ergonomic and acoustically adequate home offices, and demographic-sensitive interventions to enhance resilience and occupant well-being in future crises. Full article

Magnetically controlled spinal growing rods, used for treating early-onset scoliosis (EOS), face a critical clinical limitation: insufficient distraction force. Compounding this issue is the inherent inability to directly monitor the mechanical output of such implants in vivo, which challenges their safety and efficacy. To overcome these limitations, optimizing the rotor’s maximum torque is essential. Furthermore, defining the “continuous rotation domain” establishes a vital safety boundary for stable operation, preventing loss of synchronization and loss of control, thus safeguarding the efficacy of future clinical control strategies. In this study, a transient finite element magnetic field simulation model of a circumferentially distributed permanent magnet–rotor system was established using ANSYS Maxwell (2024). The effects of the clamp angle between the driving magnets and the rotor, the number of pole pairs, the rotor’s outer diameter, and the rotational speed of the driving magnets on the rotor’s maximum torque were systematically analyzed, and the optimized continuous rotation domain of the rotor was determined. The results indicated that when the clamp angle was set at 120°, the number of pole pairs was one, the rotor outer diameter was 8 mm, the rotor achieved its maximum torque and exhibited the largest continuous rotation domain, while the rotational speed of the driving magnets had no effect on maximum torque. Following optimization, the maximum torque of the simulation increased by 201% compared with the pre-optimization condition, and the continuous rotation domain was significantly enlarged. To validate the simulation, a rotor torque measurement setup incorporating a torque sensor was constructed. Experimental results showed that the maximum torque improved from 30 N·mm before optimization to 90 N·mm after optimization, while the driving magnets maintained stable rotation throughout the process. Furthermore, a spinal growing rod test platform equipped with a pressure sensor was developed to evaluate actuator performance and measure the maximum distraction force. The optimized growing rod achieved a peak distraction force of 413 N, nearly double that of the commercial MAGEC system, which reached only 208 N. The simulation and experimental methodologies established in this study not only optimizes the device’s performance but also provides a viable pathway for in vivo performance prediction and monitoring, addressing a critical need in smart implantable technology. Full article

Background: Temporary internal distraction is a safe surgical technique that has been shown to improve correction of severe scoliosis. The traditional surgical adjunct for scoliosis treatment in the perioperative period is halo gravity traction, but there are several known disadvantages of this technique. We describe the technical nuances of temporary internal distraction using the construct-to-construct technique, a surgical adjunct that utilizes two rods joined by lateral domino connectors to enact powerful internal distraction or compression forces on the spine for achieving spinal deformity correction. Methods: This study was designed as a retrospective review and illustrative surgical technique report. The primary aim was to describe the construct-to-construct internal distraction and compression technique for scoliosis correction, with illustrative models and representative clinical cases. Results: Internal distraction using the construct-to-construct configuration is performed early in the surgery to take advantage of the viscoelastic properties of the spine as gradually increasing distraction forces are applied. The surgical technique for applying internal distraction and compression using the construct-to-construct configuration is discussed in detail. Conclusions: Construct-to-construct internal distraction and compression techniques are powerful methods to correct severe scoliosis curves, serially distract traditional growing rod constructs, and close three-column osteotomies. Full article

Background/Objectives: This review analyzes the effects of invasive and non-invasive methods of knee joint unloading on knee loading, employing a biomechanical model to evaluate their impact. Methods: PubMed, Web of Science, Cochrane, and Scopus were searched up to 15 May 2024 to identify eligible clinical studies evaluating Joint Space Width, Cartilage Thickness, the Western Ontario and McMaster Universities Osteoarthritis Index, the Knee Injury and Osteoarthritis Outcome Score system, Gait velocity, Peak Knee Adduction Moment, time to return to sports and to work, ground reaction force, and the visual analogue scale pain score. A second search was conducted to select a biomechanical model that could be parametrized, including the modifications that each treatment would impose on the knee joint and was capable of estimate joint loading to compare the effectiveness of each method. Results: Analyzing 28 studies (1652 participants), including 16 randomized clinical trials, revealed significant improvements mainly when performing knee joint distraction surgery, increasing Joint Space Width even after removal, and high tibial osteotomy, which realigns the knee but does not reduce loading. Implantable shock absorbers are also an attractive option as they partially unload the knee but require further investigation. Non-invasive methods improve biomechanical indicators of knee joint loading; however, they lack quantitative analysis of cartilage volume or Joint Space Width. Conclusions: Current evidence indicates a clear advantage in knee joint unloading methods, emphasizing the importance of adapted therapy. However, more extensive research, particularly using non-invasive approaches, is required to further understand the underlying knee joint loading mechanisms and advance the state of the art. Full article

Background and Objectives: This study compares the biomechanical performance of a new-generation implant designed for patella fracture fixation with the traditional tension band method. Its goal is to assess fracture fixation’s stability and the new implant’s potential advantages in reducing complications such as skin irritation, pain, and implant failure. Materials and Methods: In this experimental study, 20 calf patellae were divided into two groups. The first group was treated with the traditional tension band method, while the second group received the new-generation implant, designed using finite element analysis (FEA) for optimization. Both groups underwent biomechanical testing with axial forces at a 45° flexion angle to simulate real-life load conditions. The maximum forces at which mechanical insufficiency occurred were recorded. Data were analyzed using SPSS for statistical comparison. Results: Finite element analysis revealed that the new-generation implant provided better fracture line stability than the tension band method under applied forces. In the biomechanical tests, the maximum force at which mechanical insufficiency occurred was significantly higher in the new-generation implant group (1130 ± 222 N) compared to the tension band method group (680.5 ± 185.4 N), with a statistically significant difference (p = 0.008). The new implant demonstrated superior fixation, with better resistance to distraction forces. Conclusions: The new-generation implant offers enhanced biomechanical stability compared to the traditional tension band method, particularly regarding fixation strength under applied forces. This study supports the potential of the new implant to improve fixation stability and reduce common complications associated with patella fracture surgeries. Further testing in more extensive human cadaver studies is recommended to confirm these findings and assess long-term clinical outcomes. Full article

Background and Objectives: To investigate the natural metatasophalangeal (MTP) joint distance, we studied the appropriate degree of distraction for arthroscopy and the associated factors, including age, gender, and body mass index (BMI). Materials and Methods: Sixty-seven patients who underwent MTP joint arthroscopy or foot and ankle surgery from April 2013 to June 2020 were enrolled. Foot plain radiographs were taken using a mini-fluoroscan with no traction, manual traction, and traction of 5 pounds, 10 pounds, and 15 pounds to measure the MTP joint distance. Age, gender, and BMI were compared as associated factors. The minimum joint distance of MTP joint arthroscopy was defined as 2.8 mm, which was the sheath size of a 1.9 mm, 30° high-definition arthroscope. Results: Regarding natural MTP joint space sizes, the MTP-2 joint had the largest joint size (2.39 ± 0.37 mm). The MTP-5 joint had the smallest joint size (1.59 ± 0.34 mm). Traction of 10 lb was an appropriate distraction force for the MTP-1 joint (3.09 ± 0.03 mm) and MTP-4 joint (3.07± 0.47 mm) in arthroscopy. Traction of 5lb was an appropriate distraction force for the MTP-2 (3.32 ± 0.60 mm), MTP-3 (2.89 ± 0.50 mm), and MTP-5 (2.97 ± 0.49 mm) joints. For the MTP-1 and MTP-4 joints, males had significantly greater joint space sizes than females for no traction (p = 0.039), manual traction (p = 0.002), and traction of 5 pounds (p = 0.004), 10 pounds, (p = 0.013), and 15 pounds (p = 0.024). There was no statistically significant difference in joint space size according to age or BMI for any MTP joints (p > 0.05). Conclusions: Among natural joint spaces without traction, the MTP-2 joint had the largest joint size while the MTP-5 joint had the smallest joint size. In MTP joint arthroscopy, a traction power of 10 lb is sufficient for appropriate distraction of all MTP joints. Less distraction power is required for males than for females, especially for the MTP-1 and MTP-4 joints. Full article

Distraction Osteogenesis (DO) revolutionizes bone lengthening without donor sites, which is crucial in maxillofacial reconstruction (MRA). Manual DO devices are standard, but continuous DO devices promise faster treatments and better outcomes. Current continuous distractors lack ideal MRA due to size, force generation, and power source limitations. This study introduces a passive distractor system for continuous DO in MRA, aiming to bridge existing gaps and provide an ideal solution for human MRA use. It utilizes a miniaturized mechanism powered by a passive energy source, eliminating the need for active power. Advanced manufacturing methods enable the reduction of device size while hydraulic systems ensure controlled and smooth movement. The system includes a proximal bone fixture, movable distractor components, and passive drive means for distraction force application. Results show promising potential to address existing limitations. By utilizing passive energy for continuous force generation, the device size is reduced, and the need for force transition mechanisms is minimized. This innovative system and method offer an ideal treatment environment for MRA in humans. Further research and clinical evaluation are essential to validate its efficacy and safety in clinical practice. Full article

Background: Surgeons often encounter patients with intestinal failure due to inadequate intestinal length (“short bowel syndrome”/SBS). Treatment in these patients remains challenging and the process of physiologic adaptation may take years to complete, which frequently requires parenteral nutrition. We propose a proof-of-concept mechanical bowel elongation approach using a self-expanding prototype of an intestinal expansion sleeve (IES) for use in SBS to accelerate the adaptation process. Methods: IESs were deployed in the small intestines of Sprague Dawley rats. Mechanical characterization of these prototypes was performed. IES length–tension relationships and post-implant bowel expansion were measured ex vivo. Bowel histology before and after implantation was evaluated. Results: IES mechanical studies demonstrated decreasing expansive force with elongation. The deployment of IES devices produced an immediate 21 ± 8% increase in bowel length (p < 0.001, n = 11). Mechanical load testing data showed that the IESs expressed maximum expansive forces at 50% compression of the initial pre-contracted length. The small-intestine failure load in the rats was 1.88 ± 21 N. Intestinal histology post deployment of the IES showed significant expansive changes compared to unstretched bowel tissue. Conclusions: IES devices were scalable to the rat intestinal model in our study. The failure load of the rat small intestine was many times higher than the force exerted by the contraction of the IES. Histology demonstrated preservation of intestinal structure with some mucosal erosion. Future in vivo rat studies on distraction enterogenesis with this IES should help to define this organogenesis phenomenon. Full article

Background: Severe and rigid scoliosis represents a type of spinal deformity characterized by a Cobb angle exceeding 90° and a flexibility of less than 30%. Halo spinal traction remains the established standard for managing severe scoliosis, although alternative approaches such as temporary internal distraction rods and staged surgical correction exist. The primary objective of this investigation was to compare two cohorts of patients treated using these distinct methods to ascertain any divergences in terms of surgical and radiological outcomes, pulmonary function (PF), and quality of life (QoL). Methods: This study encompassed a total of 62 pediatric patients meeting the specified criteria, which included severe idiopathic scoliosis (major Cobb curve >90) and flexibility <30%. Group 1 (G1) underwent surgical intervention involving preoperative Halo gravity traction (HGT) succeeded by posterior spinal fusion (PSF). On the other hand, Group 2 (G2) underwent a two-stage procedure starting with a less invasive temporary internal distraction technique (LITID) prior to PSF. The radiological outcomes, PF, and QoL were documented and assessed over a monitoring period ranging from 2 to 5 years. Results: The average preoperative major curves (MCs) measured 124° and 122° in G1 and G2, respectively (p < 0.426). Initial flexibility, as observed in preoperative bending films, ranged from 18% in G1 to 21% in G2 (p < 0.001). Following the ultimate surgical intervention, the MCs were corrected to 45° and 37.4° in G1 and G2, respectively (p < 0.001). The percentage correction of the MCs was higher in G2 (63% vs. 70% in G1 and G2, respectively), with significant between-group disparities (p < 0.001). The mean preoperative thoracic kyphoses (TKs) were 96.5° in G1 and 92° in G2 (p = 0.782), which were rectified to 45.8° in G1 and 36.2° in G2 (p < 0.001), equating to correction rates of 55% and 60% in the respective groups. Initially, G2 exhibited lower values for the percentage of predicted lung volume (FVC) and predicted FEV1 compared with G1 (49% and 58% vs. 54.5% and 60.8%; N.S.). Nonetheless, both groups demonstrated enhancements in their FVC and FEV1 values over the follow-up period. Conclusions: The surgical management of severe and untreated spinal curvatures in the pediatric and adolescent population can be considered safe, with a tolerable incidence of minor complications. LITID emerges as a method offering improved QoL and pulmonary function, achieving notably substantial average corrections in deformity by 70% in the coronal plane and 60% in the sagittal plane, alongside a mean increase in trunk height of 10.8 cm. Furthermore, a typical reduction of 76% in rib humps and enhancements in respiratory function, as indicated by improvements in 1 s predicted forced expiratory volume (by 25–56%) and forced vital capacity (by 35–65%), were achieved, leading to a clinically and statistically significant enhancement in QoL when evaluated using SRS-22r, without resorting to more radical, high-risk procedures. Full article

This comprehensive study presents a pioneering approach to limb lengthening, leveraging the advancements in wireless technology to enhance orthopedic healthcare. Historically, limb lengthening has been a response to discrepancies caused by fractures, diseases, or congenital defects, utilizing the body’s innate ability to regenerate bone and surrounding tissues. Traditionally, this involved external or internal fixation devices, such as the Ilizarov and Taylor Spatial frames or the Precice nail and Fitbone. The focal point of this research is the development and testing of a wireless intramedullary nail implant prototype, controlled remotely via a mobile application. This implant comprises a microcontroller, Bluetooth Low Energy module, a brushed DC motor controlled through an H-bridge, and a force sensor, all powered by medical-grade batteries. The integration of wireless technology facilitates patient autonomy in managing limb lengthening, reducing the need for frequent clinical visits. The methodology involves a detailed block diagram for our proposed work, outlining the process from treatment planning to the initiation of limb lengthening via the mobile application. Osteogenesis, the formation of new bone tissue, plays a crucial role in this procedure, which includes pre-surgery assessment, osteotomy, latency, distraction, consolidation, and removal phases. Key challenges addressed include custom battery design for efficient operation, size constraints, and overcoming signal interference due to the Faraday cage effect. Attenuation testing, simulating human tissue interaction, validates the implant’s connectivity. In conclusion, this research marks a significant stride in orthopedic care, demonstrating the feasibility of a wireless implant for limb lengthening. It highlights the potential benefits of reduced clinical visits, cost efficiency, and patient convenience. Despite limitations such as battery requirements and signal interference, this study opens avenues for future enhancements in patient-centered orthopedic treatments, signaling a transformative shift in managing limb length discrepancies. Full article

Anterior tooth (ANT) contacts induce a short-latency reflex inhibition of the human jaw-closing muscles. The jaw is a rigid class 1 lever for pinpoint targeting muscle force into a single bite point, the pivoting food particle. Seesaw reflex movements around the food particle fulcrum multiply the food-crushing force. Unpredictable jolts of reaction force caused by food crushing are subjected to the rostral ANT and caudally to the two articulate ends of the jaw triangle. The compression/distraction strains of food crushing must be monitored and inhibited by withdrawal reflexes. The mesencephalic ganglion (Vmes), neural myelin sheath, and muscle stretch receptors evolved subsequently to the advent of jaws to improve the velocity of proprioceptive and withdrawal reflexes. In mammalians, the spindles of the taut motor units, stretched by the food fulcrum, send excitatory monosynaptic feedback for the efferent neurons of the respective ipsilateral muscle units via the Vmes. In the Vmes, the spindle-input-mediating afferent neurons are coupled with another source of afferent feedback, which is also excitatory, from the back tooth (BAT) mechanoreceptors. The two sources of excitatory pulses are summated and targeted for the efferent neurons to boost the stretched and taut motor units. Likewise, the afferent feedback from the ANT mechanoreceptors is also coupled in the Vmes with concomitant feedback from spindles. The ANT output, however, is inhibitory to negate the excitatory feedback from the stretched jaw muscle units. The inhibitory feed from the anterior teeth temporarily blocks the excitatory potential of the masticatory motor efferent neurons to protect the anterior teeth and jaw joints from inadvertent strains. The inhibitory inputs from the anterior teeth alternate with the excitatory inputs from the BAT to determine which jaw-closing muscle units are activated or inhibited at any given instant of food crushing. The Vmes exists in all jawed vertebrates, and its evolution was probably motivated by demands for the control of bite force. The monosynaptic unilateral food-crushing excitatory and inhibitory reflexes (UFCRs) override the coexisting bilaterally executed feed for the jaw muscles from the central nervous system. The hypothesis proposed in this study is that the Vmes-mediated UFCRs combine neural inputs from tooth contacts with concomitant feedback from the muscle stretch receptors for the control of the mammalian food-crushing bite force. Full article

Introduction: Concomitant nerve injuries with musculoskeletal injuries present a challenging problem. The goals of nerve reconstruction for the shoulder include shoulder abduction and external rotation. When patients fail to achieve acceptable shoulder external rotation and shoulder abduction, tendon transfers such as trapezius transfer offer a reliable option in the subsequent stage. Case Presentation: A 32-year-old male presented with weak external rotation in his left shoulder, after previous axillary nerve reconstruction. He received the ipsilateral lower trapezius transfer with the aim of improving the external rotation. Discussion: The lower trapezius restores a better joint reaction force in both the compressive–distractive and anterior–posterior balancing and provides a centering force through the restoration of the anterior–posterior force couple. Conclusion: We believe that the ipsilateral lower trapezius transfer to the infraspinatus is a good outcome and is effective in improving overall shoulder stability and the shoulder external rotation moment arm or at least maintaining in neutral position with the arm fully adducted in patients with post axillary nerve injuries post unsatisfactory nerve reconstruction to increase the quality of life and activities of daily living. Full article