Pin Insertion Research Articles

Dynamic Analysis of Continuous Pin Insertion Machines and Their Application in Precision Connector Manufacturing

Dynamic Analysis of Continuous Pin Insertion Machines and Their Application in Precision Connector Manufacturing

Is bicortical femoral pin insertion safe for Image-based Robotic Knee Arthroplasty Surgery ? A comparative complications analysis in 970 Consecutive Cases

ObjectivesLimited data exists on complications associated with robotic image-based system in knee arthroplasty. This study aims to document complications in robotic arm-assisted knee arthroplasties, and evaluate the system’s safety by comparing two femoral pin insertion methods: bicortical diaphyseal with additional stab wounds, and unicortical metaphyseal placement through the main incision. MethodsAll patients undergoing primary knee arthroplasty with the image-based robotic system (Mako, Stryker, Mako Surgical Corp., Fort Lauderdale, FL, USA) from 1st March 2021 to 31st January 2024 with a minimum follow-up of 2 months were included. Demographics, system and non-system-related complications, as well as outcomes were recorded. Complications were categorized as either major (requiring a second surgical intervention) or minor. ResultsA total of 970 consecutive cases (median age 69.3 years) were analyzed. The unicortical group comprised 651 cases, while the bicortical group 319. The incidence of non-system-related complications was 2.37%, with the most common being joint stiffness (10 cases; 1.03%), followed by lateral femoral condyle fracture (4;0.41%). The overall incidence of system-specific complications was 1.03%. Pin-related femoral fractures occurred in 0.2% of cases, all postoperatively and in the unicortical group. There was no statistically significant difference between the femoral pin insertion-related complication rates among the two groups (0.3% in the unicortical, compared to 0% in the bicortical group; p-value= 0.3). Complications included tibia fracture (0.1%), delayed wound healing (0.2%), superficial wound infection (0.1%), tibia osteomyelitis (0.1%), and “exostosis” (0.2%). The major complications rate was 0.3% and minor 0.7%. ConclusionsMinimal system-specific overall complications indicate that robotic arm-assisted surgery is safe. The bicortical diaphyseal femoral pin insertion method does not increase the complication rates compared to the unicortical metaphyseal method. Level of evidenceIII

Comparative Efficacy and Safety of Robot-Assisted vs. Freehand Screw Placement in Femoral Neck Fractures: An Updated Systematic Review and Meta-Analysis.

Background: Femoral neck fractures pose significant surgical challenges with high morbidity and mortality. Traditional freehand screw placement often yields variable outcomes. Recent robotic advancements offer a promising alternative with enhanced precision. Methods: This systematic review compares the efficacy and safety of robot-assisted versus freehand techniques. A comprehensive literature search across multiple databases up to July 2024 included studies comparing both techniques. Primary outcomes were the union rate and time, functional outcomes, operative time, intraoperative parameters, and complication rates. Meta-regression analyses identified treatment response determinants. Results: Twenty-four studies (1437 patients) were included. Robot-assisted screw placement significantly improved the union rate, reduced the union time, and showed superior functional outcomes. Additionally, it resulted in shorter operative times, less intraoperative blood loss, and fewer instances of fluoroscopy and guide pin insertion. The risk of femoral neck necrosis was notably lower with robotic assistance. Meta-regression highlighted the robot type, patient age, and sample size as significant factors. Conclusions: Despite the promise of robot-assisted screw placement, limitations exist. The evidence being mainly from China raises concerns about generalizability. The lack of long-term follow-up data hinders assessment of technique durability. Unreported surgeon expertise levels and learning curves affect result validity. High initial costs and steep learning curves of robotic systems also present barriers to widespread adoption.

Ultrasound-guided techniques for managing length- unstable femoral shaft fractures in children

ObjectiveThe management of length-unstable femoral shaft fractures(LUFSFs) in pediatric patients is still controversial. This study aims to explore the clinical efficacy of ultrasound-guided closed reduction combined with external fixation for treating LUFSFs in children.MethodsWe conducted a retrospective analysis of clinical data from 19 pediatric patients with LUFSFs who underwent ultrasound-guided closed reduction and external fixation between January 2018 and January 2023. Ultrasound was employed not only to facilitate closed reduction of the fracture but also to guide real-time insertion of Schanz pins and monitor pin length as it traversed the opposite cortex. Surgical time, intraoperative fluoroscopy count, hospital stay length, fracture fixation duration, complication incidence, fracture reduction quality at the final follow-up were recorded.ResultsThe patients’ average age was 7.5 years( range: 5 to 11 years). The mean surgical duration was 70.4 min (range: 48–105 min), and the average intraoperative fluoroscopy count was 6.5 (range: 2–16). Fracture fixation lasted an average of 10.9 weeks (range: 7–20 weeks). All patients were followed up for more than one year. 6 cases of superficial pin tract infection occurred, which resolved with oral antibiotics and enhanced needle tract care. No deep infections were observed. Temporary stiffness of the knee joint was observed in 2 patients. According to Flynn’s efficacy evaluation system, fracture reduction quality at the final follow-up was rated as excellent in 11 cases and satisfactory in 8 cases, yielding a combined success rate of 100% (19/19).ConclusionsThe technique of ultrasound-guided closed reduction combined with external fixation offers favorable outcomes for children aged 5 to 11 years with LUFSFs, reducing reliance on fluoroscopic guidance.

Comparison of analgesia nociception index, surgical pleth index and hemodynamic parameters between patients receiving fentanyl versus dexmedetomidine analgesia for supratentorial craniotomy - an open label active-controlled randomized trial.

Dexmedetomidine decreases heart rate (HR) and increases high frequency (HF) component of HR variability (HRV). Analgesia Nociception Index (ANI) measures nociception by analyzing the influence of respiration on HF component of HRV while surgical pleth index (SPI) derives this information from photoplethymographic signals of finger arterioles. Therefore, during administration of dexmedetomidine, reliability of ANI may vary. This study compared the changes in ANI, SPI and hemodynamics (HR and mean arterial pressure [MAP]) during various noxious stimuli with fentanyl and dexmedetomidine intraoperative analgesia. In this trial, patients undergoing elective supratentorial surgery under general anesthesia were randomized to receive either fentanyl or dexmedetomidine infusion for intraoperative analgesia. ANI (instantaneous and mean), SPI, HR and MAP were compared before and after noxious stimuli (intubation, skull pin insertion, skin incision and craniotomy) with respect to magnitude of maximum change in the variable and the time taken for the maximal change (defined as response time) between the groups. A total of 58 patients, 29 in each group were recruited into the study. At intubation, SPI changed significantly more in the fentanyl group compared to dexmedetomidine group (37 versus 20 units, p = 0.007). At skull pinning, ANI values (both instantaneous and mean) changed more in dexmedetomidine group (p = 0.024 and 0.009) with significantly longer response time (p = 0.039). There was no difference between the groups with respect to any of the variables at skin incision and craniotomy. ANI during use of dexmedetomidine and SPI while using fentanyl, might be the better choices as intraoperative nociception monitors.

An in vitro comparison of mixed-reality navigation to traditional freehand and patient-specific instrumentation techniques for glenoid guide pin insertion during shoulder arthroplasty

BackgroundAccurate insertion of the glenoid guide pin in shoulder arthroplasty (RSA) is important for obtaining optimized glenoid component position and orientation. The objective of this study was to evaluate and compare the accuracy of three glenoid guide pin insertion techniques: 1) traditional software planning using freehand guide pin insertion (freehand), 2) guide pin insertion utilizing patient-specific instrumentation (PSI), and 3) using a mixed reality navigation (MR-NAV) system. MethodsTwenty (20) computer tomography (CT) scans were obtained from patients exhibiting glenoid erosion patterns according to the Walch and Favard classifications. Cases were planned using validated three-dimensional (3D) preoperative planning software. The CT data was then used to 3D print triplicate plastic models of each glenoid to evaluate the three guide pin insertion techniques. The first technique employed traditional software planning with freehand guide pin insertion. The second method used preoperatively planned PSI guides, while the third utilized a MR-NAV system, which provided real-time holographic guidance during guide pin insertion. Once all guide pins had been inserted into the models, an independent optical tracking system and custom digitization device was used to quantify the position and orientation of each guide pin relative to the glenoid. The outcomes for this study included the absolute mean error in guide pin inclination, version, and entry point relative to the preoperative plan. The absolute Total Global Error was also assessed, which was defined as the sum of the absolute guide pin orientation and position error relative to the preoperative plan. ResultsNo statistically significant differences between MR-NAV and PSI were found for the inclination error (2±1° versus 2±1°; P=0.056), version error (1±1° versus 1±1°; P=1.000), and Total Global Error (5±1 [mm+deg] versus 5±1 [mm+deg], P=1.000), respectively. The freehand technique produced significantly greater error than MR-NAV and PSI for inclination (5±3°, P≤0.017), version (4±3°, P≤0.032) and Total Global Error (8±3 [mm+deg], P<0.001). No statistically significant differences in the entry point error were observed between all guide pin insertion methods (P≥0.058). DiscussionThese results demonstrate that the precision and accuracy of MR-NAV is comparable to PSI and superior to a freehand technique for glenoid guide pin insertion in-vitro. Further study is needed to compare the accuracy of these techniques intra-operatively, in addition to assessing a potential learning curve between surgeons of varying experience with the MR-NAV system.

The Pin Structure Design of LaVAi-1.5-1400 Microwave Vertical Tubular Furnace Based on COMSOL

The microwave heating process will involve a variety of physical phenomena, including the distribution of the electromagnetic field in the heating cavity, the heat generated by electromagnetic loss, and the transfer of heat inside the material during heating. In this paper, the simulation software COMSOL Multiphysics 5.6 based on the finite element analysis method is used to establish the microwave heating model of Al2O3/SiC composites and design the pinning structure of the experimental furnace for multi-mode microwave heating. From the uniformity of microwave heating of the sample and the coupling with microwave, the heating characteristics of the sample with different pin spacing, pin radius, and pin insertion depth were simulated and analyzed. This pin structure design can be used to control the heating conditions of Al2O3/SiC composites in microwave heating ovens to meet industrial requirements.

Assessment of verbal (conventional) training versus models training for head frame fixation in neurosurgery

Cranial immobilization is an essential first step in cranial surgeries. Complications related to head fixation frames are under-reported and given less importance during training. Authors report their experience of using verbal (Conventional) training and training by models of “head fixation frame” and “wooden head” for head frame application for cranial surgeries. Models of the “Head Fixation Frame” (Mayfield clamp) and “wooden human head” were made using metal (iron) and wood, respectively. Major craniometric landmarks and dural venous sinuses were marked on the head model. A total of 15 trainee residents of &gt;18 months (Group A, n = 4), &lt; 18 months (Group B, n = 5), and without neurosurgical training (Group C, n = 6) were assessed for head frame application on human cadaver heads after verbal (conventional) training (n = 8) and training on models (n = 7). Various parameters, such as time taken for pin application, selection of pin site, and quadrants, were evaluated for adequacy of pin placements and position of head. Both methods were compared for assessment of better training method. Model training for head frame fixation was found better with regard to all aspects out of which time for positioning the head and for pin application, selection of quadrants of the head, site for pin insertions, and need of intervention by faculty were significant. Training on models of “head fixation frame” and “head” is better than conventional training. It is simple and safe and will prevent pin-related complications.

Comparison of the Efficacy of Sterile Silicone Studs Versus Lidocaine for the Attenuation of the Hemodynamic Response to Skull Pin Insertion: A Randomized Controlled Trial

BackgroundSkull pin insertion causes hypertension and tachycardia that adversely affects cerebral hemodynamics. We compared the efficacy of sterile silicone studs (SS) and pin site infiltration with lidocaine in attenuation of the sympathetic response to skull pin insertion. MethodsOne hundred and twenty adult patients undergoing supratentorial craniotomy under general anesthesia were randomized to receive either medical-grade sterile SS (Group SS) or 2 ml of 2% plain lidocaine infiltration at each pin site (Group LO). The primary objective was the comparison of the hemodynamic (heart rate [HR] and mean arterial pressure [MAP]) response to skull pin insertion at baseline and 0, 1, 2, 3 and 5 minutes of skull pin insertion. The secondary objectives were to assess the requirement of rescue analgesia (fentanyl), complications like pin-site bleeding, and the surgeon satisfaction score. ResultsThe HR in Group LO was significantly greater at 0, 1, 2, 3 and 5 mins post pin insertion as compared to Group SS (P <0.05). The MAP was also significantly higher in Group LO at 0, 1, 2, and 3 mins post pin insertion (P = 0.001, 0.01, 0.034 and 0.042 respectively) as compared to Group SS. The number of patients requiring fentanyl [17/60 (28.3%) v/s 40/60 (66%), P=0.001] was lower in Group SS. The incidence of pin site bleeding was also lower in Group SS along with a greater surgeon satisfaction score. ConclusionSterile SS appears to be more effective than lidocaine infiltration in attenuating the hemodynamic response to skull pin insertion with minimal adverse effects. Further multi-centre studies are necessary to conclusively establish the safety and efficacy of sterile SS.

External Fixation Before Planned Conversion to Internal Fixation in Orthopaedic Trauma: Controversies and Current Trends.

External fixation is a widely used technique for a myriad of bone fractures and pathologies in all extremities. Despite its widespread use, controversies and unknowns still exist. This review article seeks to discuss current literature surrounding pin insertion technique, pin-site care, intraoperative use during conversion to definitive fixation, the relationship of pin sites to definitive fixation, and pin-site management after removal for temporary external fixation.

Audio Distraction for Traction Pin Insertion: A Prospective Randomized Controlled Study.

Insertion of a skeletal traction pin in the distal femur or proximal tibia can be a painful and unpleasant experience for patients with a lower-extremity fracture. The purpose of this study was to determine whether providing patients with audio distraction (AD) during traction pin insertion can help to improve the patient-reported and the physician-reported experience and decrease pain and/or anxiety during the procedure. A prospective randomized controlled trial was conducted at 2 level-I trauma centers. Patients ≥18 years of age who were conscious and oriented and had a medical need for skeletal traction were included. Patients were randomized to receive AD or not receive AD during the procedure. All other procedure protocols were standardized and were the same for both groups. Surveys were completed by the patient and the physician immediately following the procedure. Patients rated their overall experience, pain, and anxiety during the procedure, and physicians rated the difficulty of the procedure, both on a 1-to-10 Likert scale. A total of 54 patients met the inclusion criteria. Twenty-eight received AD and 26 did not. Femoral fractures were the most common injury (33 of 55, 60.0%). Baseline demographic characteristics did not differ between the 2 groups. The overall patient-reported procedure experience was similar between the AD and no-AD groups (3.9 ± 2.9 [95% confidence interval (CI), 3.1 to 4.7] versus 3.5 ± 2.2 [95% CI, 2.9 to 4.1], respectively; p = 0.55), as was pain (5.3 ± 3.2 [95% CI, 4.4 to 6.2] versus 6.1 ± 2.4 [95% CI, 5.4 to 6.8]; p = 0.28). However, anxiety levels were lower in the AD group (4.8 ± 3.3 [95% CI, 3.9 to 5.7] versus 7.1 ± 2.8 [95% CI, 6.3 to 7.9]; p = 0.007). Physician-reported procedure difficulty was similar between the groups (2.6 ± 2.0 [95% CI, 2.1 to 3.1] versus 2.8 ± 1.7 [95% CI, 2.3 to 3.3]; p = 0.69). AD is a practical, low-cost intervention that may reduce patient anxiety during lower-extremity skeletal traction pin insertion. Therapeutic Level I . See Instructions for Authors for a complete description of levels of evidence.

A study on the high power microwave effects of PIN diode limiter based on deep learning algorithm.

PIN diodes, due to their simple structure and variable resistance characteristics under high-frequency high-power excitation, are often used in radar front-end as limiters to filter high power microwaves (HPM) to prevent its power from entering the internal circuit and causing damage. This paper carries out theoretical derivation and research on the HPM effects of PIN diodes, and then uses an optimized neural network algorithm to replace traditional physical modeling to calculate and predict two types of HPM limiting indicators of PIN diode limiters. We proposes a neural network model for each of the following two prediction scenarios: in the scenario of time-junction temperature curves under different HPM irradiation, the weighted mean squared error (MSE) between the predicted values from the test dataset and the simulated values is below 0.004. While in predicting PIN limiter's power limitation threshold, insertion loss, and maximum isolation under different HPM irradiation, the MSE of the test set prediction values and simulation values are all less than 0.03. The method proposed in this research, which applies an optimized neural network algorithm to replace traditional physical modeling algorithms for studying the high-power microwave effects of PIN diode limiters, significantly improves the computational and simulation speed, reduces the calculation cost, and provides a new method for studying the high-power microwave effects of PIN diode limiters.

The effect of pin angle on the microstructure of resin-infused pin-reinforced metal-composite hybrid joints

Metal-composite hybrid joints with through-thickness pins are high-performing, but a study is needed on manufacturing resin-infused composites with large pin angles. Single-pin metal-composite joints were investigated with pin angles of 0°, 20°, 45° and 80°. Microstructural characterisation revealed the pin insertion zone varied significantly with the pin angle and along the pin length. With increasing pin angle, the diamond-like resin-rich zone became triangular, asymmetric, and significantly reduced in size to effectively zero. Other asymmetric, complex and novel features were observed as well. Despite these features, the joints had suitably high quality and demonstrated the potential of resin-infused composites for high pin-angle joints.

An evaluation of large diameter through-thickness metallic pins in composites

There is increasing demand for functional through-thickness reinforcement (TTR) in composites using elements whose geometry exceeds limitations of existing TTR methods like tufting, stitching, and z-pinning. Recently, static insertion of large diameter TTR pins into heated prepreg stacks has proven a feasible and robust reinforcement process capable of providing accurate TTR element placement with low insertion forces and lower tow damage compared with existing methods for similar element sizes (>1mm diameter) like post-cure drilling. Local mechanical performance and failure mechanics of these pinned laminates are reported here. Laminates with a single statically inserted pins (1.2, 1.5, and 2.0 mm) can mostly retain their in-plane integrity alongside a local improvement in mode I delamination toughness in carbon fibre-benzoxazine laminates. Tensile strength is mostly unaffected by the pins resulting from delamination suppression, whereas there is up to a doubling of Young’s modulus. Compressive strength is significantly diminished (up to 42 %) in pinned laminates. Interlaminar toughness is improved, and peak toughness is pushed ahead of the crack as pin diameter increases. The lack of significant deterioration in in-plane tensile properties in pinned laminates produced using static insertion can expand the range and forms of materials that can be inserted compared to existing TTR.

Off-Label Use of an External Hand Fixator for Craniomaxillofacial Fractures-An Anatomical Feasibility Study.

The lack of resources limits the treatment of craniomaxillofacial fractures (CMF) in low-income countries (LIC). Therefore, Barton bandages and/or interdental wiring are considered in these regions. Fracture reduction is maintained by permanent occlusion for 6 weeks, which often leads to limited compliance and dissatisfying results. The aim of this cadaver-based study is to evaluate the feasibility of the use of an external face fixator (EFF) for the treatment of CMF, its biomechanical values and to define the optimal pin insertion points and angles. An AO hand fixator was used. CMF of types Le Fort 1-3 with split fractures of the hard palate were treated with EFF on 13 anatomical specimens. Fractures were created using a chisel, and pins were placed in specific anatomical regions. The maximal pull-out force [N] of pins was analysed by a tensile force gauge, and Fmax of the mandibular pins was evaluated. Computer tomography scans were performed on the healthy, fractured and EFF-treated skulls. The pull-out forces for the single pins were mandibular pins (n = 15, median 488.0 N), supraorbital pins (n = 15, median 455.0 N), zygomatic pins (n = 14, median 269.1 N), medial hard palate pins (n = 12, median 208.4 N) and lateral hard palate pins (n = 8, median 49.6 N). The results indicate that the operation technique is feasible, and the stability of the EFF is sufficient for maintaining the reduction. The required pins can safely be inserted into the described areas with good reduction results. Using EFF offers a feasible alternative to the non-surgical treatment of CMF in LIC.

Comparison of rehabilitation outcomes between robot-assisted and freehand screw placement in treatment of femoral neck fractures: a systematic review and meta-analysis

PurposeTo compare the postoperative rehabilitation of femoral neck fractures treated with robot-assisted nailing and freehand nailing.MethodsWe systematically searched the PubMed, EMBASE, Cochrane, China National Knowledge Infrastructure(CNKI), WanFang database, China Science and Technology Journal Database (VIP) and Web of Science databases to identify potentially eligible articles. Indispensable data such as the year of publication, country, study type, robot type, age, number of patients, sex distribution, study design, and outcome indicators were extracted. The outcome indicators of interest included healing rate, length of healing time, Harris score, operation time, frequency of X-ray fluoroscopy, frequency of guide pin insertion, and intraoperative blood loss. RevMan 5.4.1 was used for the meta-analysis.ResultsFourteen studies with 908 participants were included in this meta-analysis. The results showed that in terms of healing rate (SMD = 2.75, 95% CI, 1.03 to 7.32, P = 0.04) and Harris score (SMD = 2.27, 95% CI, 0.79 to 3.75, P = 0.003), robot-assisted screw placement technique scores were higher than the traditional freehand technique. Additionally, operative time (SMD = -12.72, 95% CI, -19.74 to -5.70, P = 0.0004), healing time (SMD = -13.63, 95% CI, -20.18 to -7.08, P < 0.0001), frequency of X-ray fluoroscopy (SMD = − 13.64, 95% CI, − 18.32 to − 8.95, P < 0.00001), frequency of guide pin insertion (SMD = − 7.95, 95% CI, − 10.13 to − 5.76, P < 0.00001), and intraoperative blood loss (SMD = − 17.33, 95% CI, − 23.66 to − 11.00, P < 0.00001) were lower for patients who underwent robotic-assisted screw placement than those for patients who underwent the conventional freehand technique.ConclusionCompared to the freehand nailing technique, robot-assisted nailing helps improve postoperative healing rates in patients with femoral neck fractures; shortens healing times; better restores hip function; reduces the number of intraoperative fluoroscopies, guides pin placements; reduces intraoperative bleeding; and increases perioperative safety.

Efficacy and safety of dexmedetomidine in attenuating stress response to skull pin holder application in patients undergoing craniotomy

Background: Skull pin holder application during craniotomy can evoke stress response, which might lead to sudden rise in blood pressure (BP), causing intracranial hemorrhage, cerebral edema, and prolonged hospital stay. Dexmedetomidine has been shown to blunt the sympathoadrenal response to surgery. Aims and Objectives: The present study was undertaken to assess the efficacy and safety of dexmedetomidine in attenuating stress responses to skull pin holder application as compared to normal saline. Materials and Methods: After obtaining approval from the institutional ethics committee and written informed consent, patients of either sex undergoing elective craniotomy at the attached hospitals of Bangalore Medical College and Research Institute, Bengaluru, India, were randomized in a 1:1 ratio to receive normal saline or dexmedetomidine as premedication. Hemodynamic parameters, i.e., heart rate (HR), systolic BP (SBP), diastolic BP (DBP), and mean arterial pressure (MAP), were monitored at various time points until 30 min after skull pin application. Data were analyzed using the chi-squared test, repeated measure ANOVA, unpaired t-test, and Mann–Whitney U test, wherever applicable. Results: A total of 52 patients were included in the study, with 26 patients in each group. All the baseline parameters were matched. As a stress response, a significant increase in HR was seen after intubation (90.69 bpm) and skull pin insertion (87.92 bpm) in the normal saline group. However, there was no significant variation in HR in the dexmedetomidine group over 30 min (69.19 bpm–74.15 bpm). Dexmedetomidine reduced HR significantly as compared to normal saline after intubation (P = 0.03). Dexmedetomidine lowered SBP and DBP as compared to baseline throughout 30 min without any excursions during intubation and skull pin insertion. The SBP was significantly lower in the dexmedetomidine group after intubation as compared to saline (P = 0.02). Although a reduction in SBP was noted after skull pin insertion in the dexmedetomidine group, it was not statistically significant than saline. No significant difference was noted in DBP, MAP, or blood glucose between the two groups. No incidents of hypotension and bradycardia were noted. Conclusion: Dexmedetomidine maintained basal HR throughout 30 min without any variations in response to intubation and skull pin insertion. It also reduced SBP and DBP over 30 min. HR and SBP were significantly lower in the dexmedetomidine group as compared to saline after intubation. The same effect was noted in the dexmedetomidine group as compared to saline after skull pin insertion, but it was not statistically significant.

Risk of Skull Perforation with Halo Vest Skull Pins.

A halo vest is an immobilization device widely used to stabilize the cervical spine. Pain and infection at the skull pin insertion site are common complications, but skull perforation is rare, and most published studies are case reports. This study aimed to identify risk factors for skull perforation by comparing patients who did and did not develop perforation. Overall thickness and the thicknesses of the internal and external laminae of the skull at the skull pin insertion sites were measured on cranial computed tomography scans of 66 patients fitted with a halo vest. The results were compared between patients who did and did not develop perforation. Four patients developed perforations. All patients with perforation were older women, and their external and internal laminae were significantly thinner than those of patients who did not develop perforation. The reported causes of skull pin perforation include infection around the pin, osteoporosis, and an enlarged frontal sinus. However, most patients with perforation in the present study were older women, and the cause was the thinning of the external and external laminae.

Enhanced transverse strength of 3D printed acrylonitrile butadiene styrene parts by carbon fiber/epoxy pin insertion

Thermoplastic parts fabricated by material extrusion (MEX) 3D printing usually possess weak inter-layer bonding, leading to low mechanical performance in the Z-direction. Here, we develop a simple but effective post-treatment method to improve the Z-strength of MEX-printed acrylonitrile butadiene styrene (ABS) parts. In this method, commercial carbon fiber (CF) tows and epoxy were embedded into internal channels in MEX-printed structures to form high-strength CF/epoxy pins. Due to the mechanical interlock between the CF/epoxy pins and the printed ABS, the Z-strength of the printed parts improved significantly. Specifically, the Z-pinned ABS samples exhibit a strength of up to 71.74 MPa and a Young’s modulus of up to 5.93 GPa in the transverse direction, which were 335 % and 266 % higher than those of the printed neat counterparts, respectively. We find that the mechanical performance of the Z-pinned samples follows a simple rule of mixtures which is able to capture the Z-dependent mechanical strength and Young’s modulus. Also, curved CF/epoxy pins were successfully formed within printed thin-walled curved structures, offering the capability to strengthen MEX printed structures with complex shapes. This work demonstrates that the Z-pin embedding process can be an effective approach to improve the transverse strength of the MEX printed parts for load-bearing structural applications.

Early effectiveness of Ti-Robot assisted femoral neck system for minimally invasive treatment of elderly Garden type Ⅱ and Ⅲ femoral neck fractures

To investigate the early effectiveness of the Ti-Robot assisted femoral neck system (FNS) in the treatment of elderly Garden type Ⅱ and Ⅲ femoral neck fractures. A retrospective analysis was conducted on the clinical data of 41 elderly patients with Garden type Ⅱ and Ⅲ femoral neck fractures who were admitted between December 2019 and August 2022 and met the selection criteria. Among them, 21 cases were treated with Ti-Robot assisted FNS internal fixation (study group), and 20 cases were treated solely with FNS internal fixation (control group). There was no significant difference in baseline data, including gender, age, side, cause of injury, time from injury to surgery, fracture Garden classification, and fracture line classification, between the two groups ( P>0.05). Surgical effectiveness was evaluated based on parameters such as operation time (including incision time and total operation time), reduction level, number of dominant pin insertions, intraoperative fluoroscopy frequency, incision length, whether to extend the incision, need for assisted reduction, postoperative hospital stay, fracture healing time, incidence of osteonecrosis of the femoral head, postoperative visual analogue scale (VAS) score at 1 day, and Harris hip score at last follow-up. The study group showed significantly shorter incision time, fewer dominant pin insertions, fewer instances of extended incisions, fewer intraoperative fluoroscopy frequency, and smaller incisions than the control group ( P<0.05). There was no significant difference in total operation time, reduction level, and assisted reduction frequency between the two groups ( P>0.05). Both groups achieved primary wound healing postoperatively, with no complications such as incision leakage or skin infection. All patients were followed up 12-24 months with an average of 14.6 months. Fractures healed in both groups, with no significant difference in healing time ( P>0.05). There was no significant difference in postoperative hospital stay between the two groups ( P>0.05). The study group showed significantly better VAS score at 1 day after operation and Harris hip score at last follow-up when compared to the control group ( P<0.05). No complication such as internal fixation failure, fracture displacement, or hip joint varus occurred in both groups during the follow-up. Osteonecrosis of the femoral head occurred in 1 patient of the control group, while no was observed in the study group, and the difference in the incidence of osteonecrosis of the femoral head between the two groups was not significant ( P=0.488). Compared to sole FNS internal fixation treatment, Ti-Robot assisted FNS internal fixation for elderly Garden typeⅡ and Ⅲ femoral neck fractures can reduce incision time, achieve minimally invasive and accurate nail implantation, and decrease intraoperative fluoroscopy frequency, leading to improved postoperative hip joint function recovery.