Screw System Research Articles

Biomechanical assessment of anterior plate system, bilateral pedicle screw and transdiscal screw system for high-grade spondylolisthesis: a finite element study

Biomechanical assessment of anterior plate system, bilateral pedicle screw and transdiscal screw system for high-grade spondylolisthesis: a finite element study

Comparison of dynamic hip screw with anti-rotation screw and femoral neck system internal fixation for the treatment of garden II-IV type femoral neck fractures.

Femoral neck fractures, which are fractures occurring from the femoral head to the base of the femoral neck, are prevalent in the elderly population. With the progression of societal aging, the incidence of femoral neck fractures has been steadily increasing, making it a significant global issue that urgently needs to be addressed. To compare the efficacy and safety of dynamic hip screw (DHS) with anti-rotation screw and femoral neck system (FNS) internal fixation for the treatment of Garden II-IV type femoral neck fractures. A total of 90 patients with Garden II-IV type femoral neck fractures were randomly assigned to either the control group (n= 45) treated with DHS and anti-rotation screw or the experimental group (n= 45) treated with FNS. Surgical outcomes, including incision size, blood loss, operation time, fluoroscopy frequency, and fracture healing time, were compared. Postoperative complication rates, reoperation rates, Harris scores, and visual analogue scale (VAS) scores were also assessed. The experimental group demonstrated significantly reduced incision length, blood loss, operation time, and fluoroscopy frequency compared to the control group (P< 0.01). No significant differences were observed in fracture healing time, Garden classification, or fracture reduction outcomes between the two groups (P> 0.05). At 6 months post-treatment, both groups showed significant improvements in Harris scores and VAS scores compared to pre-treatment (P< 0.05), with no significant differences between the groups (P> 0.05). The rates of internal fixation failure, nonunion, and avascular necrosis of the femoral head, as well as overall incidence of postoperative complications and reoperation rates, showed no significant differences between the two groups (P> 0.05). Both DHS with anti-rotation screw and FNS internal fixation demonstrated comparable efficacy and safety profiles in the treatment of Garden II-IV type femoral neck fractures. The experimental group showed advantages in terms of reduced incision length, blood loss, operation time, and fluoroscopy frequency, while maintaining similar clinical outcomes and complication rates.

Open reduction and internal fixation of mandibular condyle fractures using AUTOFIX 2.0® cannulated compression screw system: A technical innovation with intraoperative CT-scan

Condylar process fractures remain a matter of ongoing controversy in maxillofacial surgery because of variety of opinions and proposed treatment modalities offered in the literature. The trend is toward open reduction and internal fixation (ORIF) whenever there is displacement or dislocation combined with unstable occlusal conditions. The fundamental treatment goals are anatomical fixation and early return to function. However, ORIF of a fractured condyle carries significant risks, including facial nerve damage, and presents challenges in reducing and stabilizing the fractured segment in an area of limited access. We present here an innovative technique for ORIF of condylar head fractures. It consists in fracture reduction and stabilization with two Kirschner wires followed by osteosynthesis with two cannulated headless compression screws using the AUTOFIX 2.0® system (Stryker, Kalamazoo, USA). This new technique, combined with intraoperative CT scan, ensures satisfactory reduction and stabilization of the dislocated joint segment, thereby restoring the condyle to its physiologically normal position.

Biportal Endoscopic Transforaminal Lumbar Interbody Fusion: The Double-Cage Technique

Biportal endoscopic transforaminal lumbar interbody fusion (BETLIF) is a novel spinal fusion procedure using the unilateral biportal endoscopic technique. The hydrostatic pressure of saline irrigation suppresses bleeding, enabling us to perform delicate surgery in a crystal-clear and magnified surgical field with almost no bleeding. Adequate neural decompression, disc space preparation, and bony endplate preservation can be achieved safely. The sturdy endplate reduces the incidence of cage subsidence and provides good initial stability. We use 2 interbody fusion cages and a large amount of bone graft to promote fusion. Reduction of the spondylolisthesis can also be achieved using a modern pedicle screw system. This article presents a step-by-step demonstration of the BETLIF technique in a 68-year-old patient with degenerative scoliosis and spondylolisthesis at L4-5, including his clinical presentation and treatment results. BETLIF is a safe, effective, and revolutionary minimally invasive solution for spinal fusion. Its advantages include a magnificent surgical field, direct decompression, minimum blood loss, radical discectomy, meticulous endplate preparation, cage insertion under direct visual control, and excellent treatment results with a high fusion rate and few complications.

An interval prediction approach for quantifying the thermal error uncertainty of ball screw system

The ball screw system is one of the most core components of CNC machine tool, and its thermal positioning error directly affects the machining accuracy of parts. Establishing a data-based thermal error model is currently a popular method to predict this thermal error. Uncertain disturbances are unavoidable in reality. However, most of the existing thermal error models are deterministic, which cannot consider the uncertainty and generally can only provide the predictive value. To quantify the uncertainty of thermal error from the ball screw system, this paper proposes an interval prediction method, in which gated recurrent unit (GRU) neural network is embedded into the model and prediction interval (PI) evaluation indexes are used to determine the model parameters. Both the temporal and spatial characteristics of thermal error in the ball screw system are taken into account by the proposed method. The experimental data has verified that the proposed method can effectively generate PIs for the thermal error of ball screw system.

A biomechanical investigation comparing a novel bone cement bridging screw system with conventional treatment methods for Kummell’s disease

Based on the characteristics of Kummell’s disease (KD) and related anatomical structures of the thoracolumbar spine, a novel bone cement screw system has been designed to effectively avoid the cement loosening and displacement. This experiment aimed to assess the biological effects of the novel bone cement screw system in KD on fresh cadaveric thoracolumbar spine specimens, thereby discussing its potential application value and providing a foundation for clinical implementation. This study employed a total of 50 fresh female adult cadaver specimens. Each specimen underwent extraction of the T12 to L2 segment followed by the creation of an artificial KD model at the L1 segment and subsequent establishment of five distinct types of bone cement repair models. Model A represents the percutaneous vertebroplasty (PVP) model, Model B combines PVP with unilateral percutaneous pediculoplasty (PPP), Model C combines PVP with bilateral PPP, Model D introduces the novel bone cement screw combined with unilateral PVP, and Model E combines the novel screw with bilateral PVP, each group consists of 10 specimens. Subsequently, the six-axis spine robot was employed to execute cement three-dimensional biomechanical strength tests in six directions, including anterior flexion and posterior extension, left and right lateral bending, as well as left and right rotation. The novel bone cement screw, whether used unilaterally or bilaterally in combination with the PVP model, exhibits significantly reduced bone cement mobility and superior biomechanical stability during anterior flexion, posterior extension, left lateral bending, and right lateral bending (P<0.05).No significant differences were observed among the five models under both left and right rotation (P > 0.05).When comparing the novel bone cement screw combined with PVP unilaterally and bilaterally, no statistically significant difference was observed in the stability of bone cement across all six directions of motion (P>0.05). To conclude, this novel bone cement bridging screw system exhibits superior biomechanical stability compared to commonly used treatments. Furthermore, both unilateral and bilateral implementations of the novel bone cement screw system yield without significant differences observed. These findings present a reliable and innovative approach for clinical management of KD.

Destabilization of Pedicle Screws and Migration of Connecting Rod into the Posterior Cranial Fossa in a Patient After Posterior Spondylosynthesis with a Screw System

When performing osteosynthesis for spinal instability after traumatic injury, diagnostic difficulties arise due to the migration of metal structure components to distant “atypical” anatomical areas, which is associated with the risk of neurological deficit and life-threatening conditions. This article presents a casuistic case of migration of a metal structure component through an iatrogenic opening in the occipital bone into the posterior cranial fossa in a patient who had previously undergone instrumental correction for comminuted fractures of the cervical vertebrae. It should be noted that there are no data on “spontaneous” perforation of the occipital bone by metal osteosynthesis elements in the domestic literature.

Biomechanical study of the stability of posterior cervical expansive open-door laminoplasty combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation: a finite element analysis

BackgroundPosterior cervical expansive open-door laminoplasty (EODL) may cause postoperative C5 palsy, and it can be avoided by EODL with bilateral C4/5 foraminotomy. However, prophylactic C4/5 foraminotomy can compromise cervical spine stability. To prevent postoperative C5 palsy and boost cervical stability, We propose a new operation method: EODL combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation. However, there are no studies on the biomechanical properties of this surgery.PurposeEvaluating the biomechanical characteristics of EODL combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation and other three classic surgery.MethodsAn original model (A) and four surgical models (B-E) of the C2-T1 vertebrae of a female patient were constructed. (B) EODL; (C) EODL combined with bilateral C4/5 foraminotomy; (D) C3-6 expansive open-door laminoplasty combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation; (E) C3-6 expansive open-door laminoplasty combined with bilateral C4/5 foraminotomy and C3-6 lateral mass screw system. To compare the biomechanical properties of cervical posterior internal fixation; (E) C3-6 expansive open-door laminoplasty combined with bilateral C4/5 foraminotomy and C3-6 lateral mass screw system. To compare the biomechanical properties of cervical posterior internal fixation methods, six physiological motion states were simulated for the five models using a 100N load force and 1.5Nm torque. The biomechanical advantages of the four internal fixation systems were evaluated by comparing the ranges of motion (ROMs) and maximum stresses.Results The overall ROM of Model C outperformed the other four models, reaching a maximum ROM in the extension state of 10.59°±0.04°. Model C showed a significantly higher ROMs of C4/5 segment than other four models. Model D showed a significantly lower ROM of C4/5 segment than both Model B and Model C. Model E showed a significantly lower ROM of C4/5 segment than Model D. The stress in the four surgical models were mainly concentrated on the internal fixation systems.ConclusionEODL combined with bilateral C4/5 foraminotomy and short-segment lateral mass screw fixation can maintain the stability of the spine and has minimal effects on the patient’s cervical spine ROMs in the extension and flexion state. As a result, it may be a promising treatment option for cervical spondylotic myelopathy (CSM) to prevention of postoperative C5 palsy.

PROSES PEMBUATAN THUMB SCREW DENGAN MENGGUNAKAN MESIN CNC BUBUT SERTA PEMBUATAN ULIR SECARA KONVENSIONAL DI PT. AMANAH JAYA PERSADA

Thumb Screws are multi-purpose fasteners designed to be tightened and loosened by hand. They are primarily used to secure cable panel covers, safety covers, battery compartments, and other parts or components that may need to be removed and reinstalled frequently. The screw system is known and has been used by humans for several centuries. The aim of creating this screw system is basically to find an easy way to combine or connect two components so that this combination becomes a single unit that is useful in accordance with its function. The Thumb Screw manufacturing process uses a CNC lathe and conventional tapping. A CNC lathe is used to make the Thumb Screw using Alumunion copper alloy series 2000 material in the form of a long pipe with a length of 26.50 mm and a diameter of 15.20 mm and a tap is used to make the thread hole. Then measure the material dimensions again as the final finishing stage

Elderly trochanteric fracture outcomes: Unveiling the risks of excessive postoperative sliding - A retrospective multicenter (TRON group) investigation

BackgroundIntramedullary nailing (IMN) for femoral trochanteric fractures (FTF) is the primary surgical intervention. Excessive lag screw sliding (ES) of the femoral neck screw sometimes occurs. This multicenter investigation sought to 1) determine the prevalence of ES, 2) evaluate the relationship between ES and postoperative complications, and 3) identify the factors of ES in elderly patients with FTF undergoing IMN. MethodsFrom 2016 to 2020, 1448 patients with FTF were treated using a short IMN across 11 institutions (TRON group). Upon applying exclusion criteria, 519 patients (127 men, 392 women; mean age, 84.4 years) were included. The postoperative sliding distance was measured immediately after surgery and at final follow-up. A sliding distance of ≥8 mm categorized patients as having ES. We identify the factors contributing to ES using the logistic regression analysis, with a p < 0.05 as statistical significance. ResultsES was observed in 116 patients (22.4 %). Patients with ES had a higher incidence of postoperative cut-out and peri-implant fracture. Logistic regression analysis showed that achieving optimal reduction in both AP and lateral views (odds ratio (OR) 0.48, p = 0.0012) and the use of a double screw system or twin screws with integrated locking mechanism significantly reduced the risk of ES (OR 0.27, 0.17; p = 0.0027, <0.001). ConclusionsThe incidence rate of ES was 22.4 %. ES was associated with a higher risk of postoperative complications. The surgeons should aim for optimal reduction and use a double screw or twin screws with an integrated interlocking mechanism as the implant of choice.

Comparison of Clinical and Radiographic Outcomes Between Solid Headless and Headed Screws in the Treatment of Zone II and III Fifth Metatarsal Fractures in Elite Athletes

Background: Zone II and III fifth metatarsal (5-MT) fractures among athletes are typically managed with percutaneous fixation following anatomic reduction. However, screw head discomfort and refracture after bone union can occur because of the loads placed on the foot during play. Several hardware systems that use a smaller screw head compared to traditional hardware systems have been developed to minimize the rate of postoperative hardware complications. This study compares clinical and radiographic outcomes of 5-MT fractures in elite athletes treated with a solid headless screw vs a solid headed screw. We hypothesized that the headless screw would be associated with faster union rates, faster clearance times, and lower incidence of symptomatic hardware compared to the headed screw. Methods: Athletes competing at a collegiate level or higher treated for a zone II or III 5-MT fracture between 2016 and 2022 by 2 surgeons fellowship-trained in foot and ankle orthopaedics were screened. Operative notes were reviewed to determine the hardware system used. Subjects were divided based on the hardware system used during operation: headed screw and headless screw. Time to radiographic union, time to full clearance, and return to competition were determined. Postoperative complications, including nonunions, need for revision, need for hardware removal, and refractures were also noted. Results: Forty eligible patients (44 feet) were identified. The solid headed screw group included 20 patients (21 fractures), and the solid headless screw group included 20 patients (23 fractures). Average time to union for the headed screw group was 11.78 (range, 5.86-19.00) weeks; average time to union for the headless screw group was 11.65 (range, 6.00-22.57) weeks ( P = .93). Nineteen out of twenty (95%) patients were able to return to competition in both groups. Average time to return to competition for the headed screw group was 26.9 (range, 10.00-47.86) weeks, while average time for the headless screw group was 21.2 (range, 6.86-55.00) weeks ( P = .55). The overall complication rate for the headed screw was 23.8%, which was not statistically different from the overall complication rate for the headless screw of 13.0% ( P = .35). Conclusion: In this relatively small sample of elite athletes undergoing operative fixation of a 5-MT fracture, fixation using either a headless or headed screw system had similar good outcomes in regard to times to union, return to competition, and complication rate regardless of solid screw head type used. Level of Evidence: Level III, retrospective cohort study.

Robust feature design for early detection of ball screw preload loss

The ball screw is a critical device for precision linear motion control that has widespread applications in industrial robots, computer numerical control (CNC) machines, and high-precision leveling systems, among others. Because high-precision positioning is ensured by the addition of a preload to the ball screw system, it is crucial to detect and monitor the loss of preload at the earliest possible stage of degradation. The degradation process of the ball screw can be characterized in two stages: the initial reduction of preload without backlash, followed by a loss of preload with an emergence of backlash. To explore the change of the ball screw dynamics caused by degradation, a novel fixed cycle feature test (FCFT) is implemented in combination with multi-level mass experiments and a run-to-failure (RTF) test. The relationships of the ball screw dynamics with preload, worktable mass, and axis position are investigated, with a focus on the axial natural frequency as an indicator of preload loss. Experimental results validate the axial natural frequency’s role as a reliable early detector of preload loss for interventive use in a prognostic system.

Volar locking and angular stability plate for treatment of comminuted scaphoid fractures: a case series of 44 cases.

The primary method employed worldwide for the treatment of scaphoid fractures is screw fixation. However, in unstable and comminuted fractures, percutaneous fixation could produce complications due to technical challenges, such as improper axis positioning, inaccurate screw length measurement, intra-articular screw penetration, and impingement. Alternative open approaches for the surgical management of scaphoid fractures have been proposed, and in recent years, a new specific volar locking plate for the treatment of scaphoid fractures has been developed. This study aims to present the outcomes of this technique applied to 44 patients with unstable and comminuted fractures of the scaphoid. The purpose of the study is to verify the effectiveness of the volar plate in the treatment of comminuted scaphoid fractures and the necessity for plate removal when consolidation has occurred. Between January 2021 and March 2023, a specific volar locking plate for the treatment of scaphoid fractures was used in 44 patients. A retrospective study was conducted involving all patients, consisting of continuous clinical and radiographic assessments, functional evaluations (using QuickDASH and MHQ), and patient satisfaction surveys. All patients achieved clinical and radiographic recovery. However, the plate can impinge with nearby structures and should be removed once the fracture is consolidated. After plate removal, further improvement in range of motion was observed. The plate and screws system is a viable and appropriate method of osteosynthesis in the treatment of unstable and comminuted recent fractures occurring in the middle third of the carpal scaphoid.

Experimental and numerical study on a multilayer magnetic field rotary eddy current inertial damper

To improve the output damping force of the eddy current damper, a multilayer magnetic field rotary eddy current inertial damper (MMF-RECID) is proposed. The MMF-RECID is an inerter-based eddy current damper. A prototype device of the MMF-RECID is manufactured and tested, and its mechanical properties are systematically investigated. Firstly, the configuration of the MMF-RECID is described, and the calculation formulas of the axial force are derived. Secondly, an MMF-RECID prototype is designed and fabricated, and the apparent mass and energy dissipation performance under recycled axial loading are investigated. Three-dimensional transient numerical simulations of eddy current damping are conducted using the ANSYS Electronics Desktop. The results show that the eddy current damping force exhibits velocity nonlinearity, and the test results are consistent with the simulation results. Next, the study focuses on parameters influencing the maximum eddy current damping torque generated by the copper plate and the corresponding critical rotating speed. These parameters encompass the number and size of the magnets, the thickness of the copper plate, and the air gap. Finally, the earthquake-reduction effect of a six-degree-of-freedom structure equipped with MMF-RECID is analyzed. This study demonstrates that the ball screw system of MMF-RECID achieves a multiplicative effect of apparent mass and eddy current damping force, the eddy current damping force of a multi-layer magnetic field versus a single-layer magnetic field conforms to the law of linear superposition, and the hysteresis curves are stable. The eddy current damping torque can be improved by increasing the number and size of the magnets, and decreasing the air gap. The thickness of the copper plate significantly affects both the maximum damping torque and the critical speed, and the optimal thickness range is between 2 mm and 4 mm.

Reservas de carbono en tres sistemas silvopastoriles de la Amazonía peruana

Silvopastoral systems (SS) combine productivity with climate change mitigation and improve carbon (C) stocks. The objective of the research was to estimate C stocks in three silvopastoral systems of the high jungle. Three silvopastoral systems were selected for the study: Cedrelinga cateniformis (Tornillo), Eucalyptus spp. (Eucalyptus) and Inga edulis (Inga). Soil samples of 0-15 cm and 15-30 cm were collected and analyzed to determine their physical and chemical characteristics. The estimation of C reserves was carried out from biomass with allometric equations. Statistical analysis was performed using descriptive analysis (means and standard deviation) and ANOVA and use of the Scott Knott test. Soil properties did not show significant differences between SS, except for P, Al and CEC. Carbon reserves were higher in the screw system and lower in the inga system. In general, C reserves in the SS were greater in the soil and represented the main C reserve, surpassing the vegetation. The results highlight the importance of soil as a carbon sink and its role in mitigating climate change.

High Accuracy of Three-Dimensional Navigated Kirschner-Wire-Less Single-Step Pedicle Screw System (SSPSS) in Lumbar Fusions: Comparison of Intraoperatively Planned versus Final Screw Position.

(1) Background: Our team has previously introduced the Single-Step Pedicle Screw System (SSPSS), which eliminates the need for K-wires, as a safe and effective method for percutaneous minimally invasive spine (MIS) pedicle screw placement. Despite this, there are ongoing concerns about the reliability and accuracy of screw placement in MIS procedures without traditional tools like K-wires and Jamshidi needles. To address these concerns, we evaluated the accuracy of the SSPSS workflow by comparing the planned intraoperative screw trajectories with the final screw positions. Traditionally, screw placement accuracy has been assessed by grading the final screw position using postoperative CT scans. (2) Methods: We conducted a retrospective review of patients who underwent lumbar interbody fusion, using intraoperative 3D navigation for screw placement. The planned screw trajectories were saved in the navigation system during each procedure, and postoperative CT scans were used to evaluate the implanted screws. Accuracy was assessed by comparing the Gertzbein and Robbins classification scores of the planned trajectories and the final screw positions. Accuracy was defined as a final screw position matching the classification of the planned trajectory. (3) Results: Out of 206 screws, 196 (95%) were accurately placed, with no recorded complications. (4) Conclusions: The SSPSS workflow, even without K-wires and other traditional instruments, facilitates accurate and reliable pedicle screw placement.

GeoExplainer: Interpreting Graph Convolutional Networks with geometric masking

For Graph Convolutional Network (GCN), the inherent geometric topology and relationships within spatio-temporal graphs are critical to factors affect its predictive performance. Understanding the decision-making process of GCN remains a challenging task. Existing perturbation-based explanation methods are primarily tailored for Graph Neural Network (GNN) models and focus on how the information of nodes or subgraphs in static graphs impacts GNN predictions. Due to the geometric properties of spatio-temporal graphs, screw theory serves as crucial mathematical tools for describing the geometric relationships and patterns of motion within the geometric space of spatio-temporal graphs. Therefore,we propose GeoExplainer, which utilizes screw theory to geometric masking for spatio-temporal graphs with strong geometric correlations, generating explanations for GCN. Our method perturbs spatio-temporal graphs using geometric masking, and ultimately generating explanations in the form of geometric masks serve as importance mappings for model prediction results. Firstly, we design a screw motion vector model with geometric constraints to describe the spatio-temporal graph in screw system. Then, we design a geometric screw perturbation to generate smooth geometric masks. Finally, we propose a geometric masking approach to optimize and update the geometric mixture mask. We utilize pointwise mutual information (PMI) to maximize the correlation between the model predictions after geometric perturbation and the original predictions, obtaining the optimal geometric mask as an explanation for GCN. The interpretable experiments of ST-GCN, HD-GCN, GCN and GIN models on four datasets with geometric relationships demonstrate that GeoExplainer outperforms eight competitive interpretation methods in quantitative and visualization analysis.

Percutaneous treatment of type C distal radius fractures using dual-external fixator

BackgroundThis study aimed to introduce a potential alternative percutaneous treatment for AO types C1, C2, and C3 distal radius fractures using dual-external fixator (a no-bridging cemented-pin frame and a conventional wrist-bridging external fixator). Materials and methodsFrom January 2018 to January 2021, 52 patients (52 distal radius fractures) were treated with dual-external fixator. For comparison, 61 patients (61 distal radius fractures) were treated with a plate and screw system. Wrist function was assessed using the Mayo Wrist Score. Patient satisfaction was assessed using the Short Assessment of Patient Satisfaction. A P < 0.05 was considered statistically significant. ResultsFracture healing was achieved in all patients. At the final follow-up of 29 months (range, 24–34 months) vs 36 months (range, 26–39 months) (P > 0.05), the patients treated with dual-external fixator and a plate and screw system achieved mean ulnar deviations of 31° vs 29° (P < 0.05), mean Mayo Wrist Scores of 91.12 ± 5.98 vs 88.12 ± 7.54 (P < 0.05), and mean patient satisfaction scores of 23.42 ± 2.47 vs 23.04 ± 2.32 (P > 0.05). ConclusionsAO types C1, C2, and C3 distal radius fractures can be treated successfully using dual-external fixator. The technique is a potential alternative in addition to the conventional treatments. Level of evidenceLevel IIa.

Experimental study on the biomechanical stability of complex acetabular fractures in the quadrilateral area: application of a dynamic anterior titanium-plate screw system

Background and objectiveComplex acetabular fractures involving quadrilateral areas are more challenging to treat during surgery. To date, there has been no ideal internal fixation for these acetabular fractures. The purpose of this study was to evaluate the biomechanical stability of complex acetabular fractures using a dynamic anterior titanium-plate screw system of the quadrilateral area (DAPSQ) by simulating the standing and sitting positions of pelvic specimens.Materials and methodsEight formal in-preserved cadaveric pelvises aged 30–50 years were selected as the research objects. First, one hip of the normal pelvises was randomly used as the control model (group B) for measurement, and then one hip of the pelvises was randomly selected to make the fracture model in the 8 intact pelvises as the experimental model (group A) for measurement. In group A, acetabular both-column fractures in the quadrilateral area were established, and the fractures were fixed by DAPSQ. The biomechanical testing machine was used to load (simulated physiological load) from 400 N to 700 N at a 1 mm/min speed for 30 s in the vertical direction when the specimens were measured at random in simulated standing or sitting positions in groups. The horizontal displacement and longitudinal displacement of the acetabular fractures in the quadrilateral area were measured in both the standing and sitting simulations.ResultsAs the load increased, no dislocation or internal fixation breakage occurred during the measurements. In the standing position, the horizontal displacement of the quadrilateral area fractures in group A and group B appeared to be less than 1 mm with loads ranging from 400 N to 700 N, and there was no significant difference between group A and group B (p > 0.05). The longitudinal displacement appeared to be greater than 1 mm with a load of 700 mm in group A (700 N, 2 cases), and the difference was significant between group A and group B (p < 0.05). In the sitting position, the horizontal and longitudinal displacements of the quadrilateral areas were within 0.5 mm in group A and group B, and there was no significant difference between group A and group B (p > 0.05).ConclusionFor complex acetabular fractures in the quadrilateral area, DAPSQ fixation may provide early sitting stability, but it is inappropriate for patients to stand too early.

Effects of adaptive backlash minimization in worm gear for precision positioning

The paper introduces innovative solutions for worm gears, aiming at adaptive reduction of side clearance to improve accuracy. It addresses manufacturing challenges affecting tooth dimensions and deviations in shape, examining the impact of adjustment settings on clearance components. The document outlines patented solutions and identifies the causes of inaccuracies in worm gears, with a specific focus on the efficiency of a compliant worm in reducing side clearance. Comprehensive analyses were conducted using Matlab, CAD, and empirical data to investigate the impact of adjustments on clearance statistics, correlation, and spectral analyses before and after corrections. It establishes correlations between clearance parameters and assesses positioning accuracy using a rolling screw system. By demonstrating significant improvements in accuracy without the need for gear disassembly during operation, the developed gear compensates for manufacturing deviations. The paper also suggests assembly procedures for precision worm gears in small-scale production, taking into account various criteria for accuracy assessment.