Screw Head Research Articles

Prospective evaluation of ultrasound features of magnesium-based bioabsorbable screw resorption in pediatric fractures.

Bioabsorbable magnesium-based alloy screws release gas upon resorption. The resulting findings in the adjacent soft tissues and joints may mimic infection. The aim of the study was to evaluate the ultrasound (US) findings in soft tissues and joints during screw resorption. Prospectively acquired US studies from pediatric patients treated with magnesium screws were evaluated for screw head visibility, posterior acoustic shadowing, twinkling artifact, foreign body granuloma, gas (soft tissue, intra-articular), alterations of the skin and subcutaneous fat, perifascial fluid, localized fluid collections, hypervascularization, and joint effusion. Sixty-six US studies of 28 pediatric patients (nfemale = 9, nmale = 19) were included. The mean age of the patients at the time of surgery was 10.84years; the mean time between surgery and ultrasound was 128.3days (range = 6-468days). The screw head and posterior acoustic shadowing were visible in 100% of the studies, twinkling artifact in 6.1%, foreign body granuloma in 92.4%, gas locules in soft tissue in 100% and intra-articular in 18.2%, hyperechogenicity of the subcutaneous fat in 90.9%, cobblestoning of the subcutaneous fat in 24.2%, loss of normal differentiation between the epidermis/dermis and the subcutaneous fat in 57.6%, localized fluid collection in 9.9%, perifascial fluid in 12.1%, hypervascularization in 27.3%, and joint effusion in 18.2%. US findings in pediatric patients treated with magnesium screws strongly resemble infection, but are normal findings in the setting of screw resorption. Bioabsorbable magnesium-based alloy screws release gas during resorption. The resulting US findings in the adjacent soft tissues and joints in pediatric patients may mimic infection, but are normal findings. • Bioabsorbable magnesium-based alloy screws release gas upon resorption. • The resulting ultrasound findings in children's soft tissues and joints closely resemble those of soft tissue infection or osteosynthesis-associated infection. • Be familiar with these ultrasound findings in order to avoid inadvertently misdiagnosing a soft tissue infection or osteosynthesis-associated infection.

Automatic 3D Postoperative Evaluation of Complex Orthopaedic Interventions.

In clinical practice, image-based postoperative evaluation is still performed without state-of-the-art computer methods, as these are not sufficiently automated. In this study we propose a fully automatic 3D postoperative outcome quantification method for the relevant steps of orthopaedic interventions on the example of Periacetabular Osteotomy of Ganz (PAO). A typical orthopaedic intervention involves cutting bone, anatomy manipulation and repositioning as well as implant placement. Our method includes a segmentation based deep learning approach for detection and quantification of the cuts. Furthermore, anatomy repositioning was quantified through a multi-step registration method, which entailed a coarse alignment of the pre- and postoperative CT images followed by a fine fragment alignment of the repositioned anatomy. Implant (i.e., screw) position was identified by 3D Hough transform for line detection combined with fast voxel traversal based on ray tracing. The feasibility of our approach was investigated on 27 interventions and compared against manually performed 3D outcome evaluations. The results show that our method can accurately assess the quality and accuracy of the surgery. Our evaluation of the fragment repositioning showed a cumulative error for the coarse and fine alignment of 2.1 mm. Our evaluation of screw placement accuracy resulted in a distance error of 1.32 mm for screw head location and an angular deviation of 1.1° for screw axis. As a next step we will explore generalisation capabilities by applying the method to different interventions.

Effects of the internal contact surfaces of dental implants on screw loosening: A 3-dimensional finite element analysis

Statement of problemThe effects of the internal contact surfaces of dental implants on screw loosening have yet to be investigated. PurposeThe purpose of this 3-dimensional finite element analysis (FEA) study was to evaluate and compare the mechanical effects of the abutment implant angle (θ), the abutment screw head diameter (D), and the abutment screw length (L) on screw loosening. Material and methodsA total of 27 models presenting various mechanical scenarios were built by using combinations of 3 different θ (30 degrees, 45 degrees, and 60 degrees), D (2.65 mm, 2.75 mm, and 2.85 mm), and L (4 mm, 5 mm, and 6 mm). In FEA, a static test with a 200-N force inclined 30 degrees in the implant axial direction was applied to the upper surface of the abutment to evaluate and compare the maximum von Mises stresses of the implant components and the maximum total deformation in all models. In addition, modal analysis was applied to identify the natural frequencies in all models under free (unforced) vibration, and a Kruskal-Wallis statistical test (α=.05) was performed, followed by multiple pairwise comparisons by using the Dunn test. ResultsThe Kruskal-Wallis test found a significant influence of the θ on implant stress, total deformation, and natural frequency (P<.001). For example, increasing the θ from 30 degrees to 45 degrees and 60 degrees can considerably reduce the model’s natural frequencies to 18% and 26%, respectively. Similarly, the test underscored the significant impact of the D on both abutment screw stress and abutment stress (P=.010 and P=.002, respectively). However, the L appeared to have no significant effect on any of the dependent variables (P>.05). ConclusionsThe θ and the D significantly influenced the stresses of dental implant components, total deformation, and natural frequency of the model, which may impact the mechanical stability of the screw joint. However, the L does not appear to affect these values significantly.

Biomechanical Investigation of Bone Screw Head Design for Extracting Stripped Screw Heads: Integration of Mechanical Tests and Finite Element Analyses.

Enhancing the design of bone screw head sockets to prevent stripping and improve the torque required for smooth unscrewing is a significant challenge in orthopedic applications. This research aims to establish a quantitative methodology by integrating mechanical testing with finite element (FE) simulations to determine a safe limitation depth for the screwdriver when engaging with the hexagonal socket, thus avoiding stripped screw heads. A FE model was developed to investigate the biomechanical responses of the screw head design. Five custom-made hexagonal sockets were manufactured, and single load torsional tests were conducted to assess the mechanical performance of the screws and drivers. The results from the mechanical tests were compared with the FE simulations, demonstrating a close agreement and confirming the model's validity. Furthermore, additional FE models were created to study the impact of manufacturing tolerances on the socket width and screwdriver width. The findings revealed that the maximum torque to failure for the four designs was lower than the margins specified in ISO 6475. Additionally, increasing the depth of the screwdriver led to higher maximum torque values. This research suggests that the technique of screw insertion, specifically the depth of the driver tool within the screw socket, holds greater importance in preventing stripped screw heads than the design and manufacturing width of the bone screw's hexagonal socket and screwdriver. This confirms the importance of screwdriver engagement inside the bone screw socket to prevent stripped screw heads and sheds light on the added value of maximum torque prediction for future design modifications.

Experimental investigation and design consideration on pull-through capacity of a C-shaped purlin section

A small-scale experimental study was carried out to investigate the pull-through failure of the C-shaped Cold-Formed Steel (CFS) roof purlin sections subjected to wind uplift force. The parameters investigated to comprehend the pull-through behavior of roof purlin are thickness, web depth, flange width of the CFS purlin section, and size of the screw head diameter. The test specimens experienced two different modes of pull-through failure (rupture and bearing) along with the prying effect. It was observed that the pull-through failure mode transitions from rupture of the purlin section around the screw fastener in 1 mm thickness to bearing type in 2 mm and 3 mm thicknesses. The test results were compared with existing design limits and previous studies from the literature which concluded that the existing elastic design approach for the service limit state is unconservative. Hence, a suitable design limit to predict the critical pull-through capacity of C-shaped roof purlins under high wind load is proposed. Additionally, reliability studies were carried out to determine the resistance and safety factors for the proposed design equations. The suggested design specifications are applicable and conservative for the material strength in the range of 350 MPa.

A Novel Technique for Pars Defect Direct Repair with a Modified Smiley Face Rod for Spondylolysis and Isthmic Spondylolisthesis.

Lumbar spondylolysis is a common fatigue fracture of the pars interarticularis of the lamina of the lumbar spine in adolescent athletes presenting with pars clefts. Some pseudarthrotic lumbar spondylolysis causes low back pain or radiculopathy. This study presents a case of pseudarthrotic lumbar spondylolysis that was successfully treated using a modified smiley face rod technique. We developed a modified smiley face rod technique, which places pedicle screws in the lateral edge of the pedicle to preserve the erector spinae muscles and inserts a U-shaped rod between the spinous processes to preserve the supraspinous ligament. When a U-shaped rod penetrates the interspinous ligament subcutaneously, the resection of the supraspinous ligaments can be avoided. When the screw head is positioned more anterolaterally, a compression force is applied perpendicular to the surface of the pars cleft by rod clamping. This intrasegmental fusion technique preserves the mobile segment and simultaneously repairs the pars cleft. It is less invasive and more appropriate than interbody fusion for young athletes to avoid the possibility of future adjacent segment disorders. This is a minimally invasive procedure that can easily achieve bone fusion and should be introduced for patients who are suffering from the symptoms of pseudarthrotic lumbar spondylolysis.

INFORMATION SYSTEM FOR MAKING PC WIRE HEADS WITH PNEUMATIC SYSTEMS IN HEADING MACHINE

Pc wire or Prestressed concrete wire is iron thread with a round cross section and has indentations on its surface. Pc wire is widely used in the construction of buildings or buildings, railway sleepers and piles. This paper discusses the process of making pc wire heads and pneumatic systems that function as driving hammer dies in making pc wire. The aim of the research is to know the work process of making pc wire head (screw iron), calculating the pneumatic system for making pc wire head (screw iron). The data needed in the preparation of this report was obtained by collecting data, namely field studies which are direct data collection. data obtained through direct observation in the field accompanied by a field supervisor then Literature Study where literature study is data collection through literature books, journals, making pc wire heads by cutting pc wire with a diameter of 7.1 mm along 152 mm using a cutting grinder and then clamping it in a vise so that the screw iron does not shift when getting pressure from the die, the die will press the pc wire so that it is formed with a circular diameter of 13 mm and 7 mm thick. From the calculation of the density of dry air, the result is = 87.08 Pa, the result of the hydrostatic calculation is 609.78 Pa, and from the calculation of the Double Acting Cylinder, the result is 254.34 N.

Augmented Reality-Supported Rod Bending in Multilevel Spinal Fusion Using the ADVISE Software

One of the most common reasons for poor patient outcomes and revision surgery in spinal fusion is hardware failure. Screw loosening or pullout occurs in up to one-quarter of all cases. It is known that even small screw-rod misalignments can cause significant mechanical overloads during rod fixation, which can result in hardware failure. To address this crucial surgical step, a novel augmented reality-assisted software was developed to generate custom rod templates that are precisely adapted to the individual patient. The novel software, which runs on a tablet, is used in spinal fusion surgery and is based on the use of a specific pedicle screw system, in which the polyaxial screw heads are connected to detachable guides. These guides can be recognized by the tablet camera and a light detection and ranging scanner. This image information is processed to determine the spatial positions of the screw heads and to calculate an ideally fitting rod template. The calculated rod template is displayed in a 1-to-1 scale on the tablet screen. This template is used to cut and bend the rods of the pedicle screw system. Finally, the custom bent rod can be inserted into the screw heads without tension. The augmented reality-assisted software is intended to give surgeons access to patient-specific intraoperative real-time data, helping them in bending rods that are more precisely adapted to the individual patient compared with the freehand technique.

The Feasibility of Multiple Fixation Points in C2.

Analysis using three-dimensional simulation software for spinal screw placement and computed tomographic scan images. To assess the feasibility of achieving multiple (three or four) screw fixation points in C2 vertebra by using a combination of pedicle and laminar screws. Secure C2 fixation using multiple screws is required or beneficial in some unique cases. However, to the best of our knowledge, there have been no reports analyzing the feasibility of multiple screw fixation in C2. We used 1.0-mm interval computed tomographic scan images of 100 patients (50 men and 50 women) and screw trajectory simulation software. The diameter of all screws was set at 3.5 mm, considering its common usage in real surgery. The anatomical feasibility of placing both pedicle and laminar screws on the same side was evaluated. For all feasible sides, the three-dimensional distance between the screw entry points was measured. In 85% of cases, both pedicle and laminar screws could be placed on both sides, allowing for the insertion of 4 screws. In 11% of cases, 2 screws could be placed on one side, while only 1 screw was feasible on the other side, resulting in the placement of 3 screws. In all 181 sides where both types of screws could be inserted, the distance between their entry points exceeded 16.1 mm, which was sufficient to prevent the collision between the screw heads. C2 vertebra can accommodate three (11%) or four (85%) screws in 96% of cases.

Incomplete Screw Thread Engagement of Proximal Fragment: A Possible Failure Risk After Internal Fixation for Femoral Neck Fractures.

Background For successful internal fixation for femoral neck fracture, the sliding mechanism of the screw is important because it can induce inter-fragmental compression. The thread should penetrate the fracture line and be located within the proximal fragment. If screw thread engagement is incomplete and a part of the thread remains within the distal fragment, the screw sliding can be disturbed, potentially leading to fixation failure. We hypothesized that screw threadin the fracture is a risk of fixation failure. Methods We studied 133 hips that underwent internal fixation for femoral neck fracture using dual sliding and compression screws (DSCS) with 20 mm threads. The existence of incomplete thread engagement and fixation failure (cut out, perforation, pseudoarthrosis, or femoral neck shortening) were evaluated on anteroposterior hip radiography postoperatively. The distances from the thread end to the fracture line, screw head to the femoral head cortex, and femoral head diameter were measured to analyze their relationships with any incomplete thread engagement and fixation failure. Differences in evaluation data were assessed using Fisher's exact test, Student's t-test, and receiver operating characteristic (ROC) analysis. Results Forty-six cases had at least one screw with incomplete thread engagement, and the other 87 hips had a complete engagement. The failure rate in the group of hips with incomplete thread engagement was significantly higher (7/46, 15.2%) than that in the group of hips with complete thread engagement (3/87, 3.4%) (P = 0.032). Incomplete thread engagement was found in 59 out of 266 screws (22.2%), and a femoral head ≤ 43.9 mm in diameter was associated with an increased risk of incomplete thread engagement. Most incomplete thread engagement screws (81.4%) had < 5 mm thread length within the distal fragment. Conclusion A partially threaded screw is a significant risk of fixation failure after internal fixation for a femoral neck fracture. The smaller femoral head diameter increases the possibility of incomplete thread engagement. Shortening the thread length by 5 mm may help to avoid incomplete thread engagement.

Functional outcome of type 4 Pipkin classification of femoral head fracture operated by open reduction internal fixation by ganz safe surgical dislocation approach management: a case report

Fracture of the femoral head is a severe, relatively uncommon injury; typically, it may have associated with traumatic posterior dislocation of the hip joint with or without acetabulum fracture. The Pipkin classification is the most commonly used classification system. Controversies include the preferred surgical approach (anterior versus posterior) versus ganz safe surgical dislocation approach and whether to perform femoral head fragment excision or internal fixation. Presenting a case report of 28 years old young male with a motor vehicle road traffic accident and suffered a head of femur fracture on right hip joint with posterior wall of right acetabulum fracture with Judet-Letournel type posterior wall and type 4 Pipkin’s classification of femoral head fracture. This patient was undergone for emergency surgical intervention of open reduction, internal fixation through Ganz approach and insertion of Herbert screws for femoral head and interfragmentary screw for trochanteric osteotomy. The patient was followed up for 1 year and have a complete range of motion at hip joint with painless daily lifestyle. Type 4 Pipkin classification of femoral head fracture managed timely and with surgical intervention by ganz safe surgical dislocation approach provides visualization to femoral head and whole acetabulum with internal fixation of femur head by herbert screw which preserves normal anatomic contour of femoral head shows appropriate reduction of fracture fragments and it may also avoid hemiarthroplasty surgeries. Fracture of the femoral head has been associated with a relatively poor functional outcome and requires timely management and surgical intervention. Specially type 4 Pipkin classification of femoral head fracture treated by ganz safe surgical dislocation approach with internal fixation of femur head by herbert screw shows better outcome and avoid risk of AVN of femoral head. Complications associated with fracture of the femoral head and subsequent treatment include osteonecrosis, post-traumatic osteoarthritis, heterotopic ossification and implant failure.

Clinical outcomes of primary Latarjet technique in recurrent shoulder dislocation using BioLatarjet® LCS cannulated flat head screws

Background: The Latarjet technique is an effective procedure that reconstructs and augments the glenohumeral joint instability. It improves stability by increasing the glenoid width and using the sling effect. The aim of the study was to assess the functional outcomes of the primary Latarjet treatment with BioLatarjet® LCS cannulated flat head screws in cases of recurrent shoulder dislocation. Methods: In this retrospective study, 30 patients were treated with the primary Latarjet technique. Rowe score, visual analog scale (VAS), Quebec back pain disability scale (QDS), and, American shoulder and elbow surgeon score (ASES), and range of motion (ROM) were evaluated in the selected population at the time point of 6-week, 3-month, and 6-month after surgery for the determination of the functional outcomes in them. Results: The results showed that all patients had excellent or good functional outcomes with significant improvements in Rowe score, VAS score, QDS, and ASES scores (p&lt;0.0001). The ROM in patients for forward elevation, cross body adduction, external rotation by side of body/neutral, and internal rotation by side of body/neutral were related to better clinical outcome and less movement of recurrent instability with optimal graft placement. Conclusions: These findings have clinical significance in that they demonstrate the effectiveness of the Latarjet technique in improving stability without significantly increasing the risk of complications. The BioLatarjet® LCS cannulated flat head screws were found to be safe and efficient for primary Latarjet surgeries, providing appropriate graft healing and a low recurrence of instability, with a good return-to-sports rate.

Experimental and finite element analysis of flexural performance of steel-timber composite beams connected by hybrid-anchored screws

The shear connection between the steel and the timber slab is one of the keys to designing steel-timber composite (STC) beams. By three groups of four-point bending tests and finite element simulations, the effects of hybrid anchorage and filling materials on the flexural performance of STC beams were investigated. Firstly, compared with the STC beam connected by ordinary screws, when epoxy resin and mortar were respectively used as the filling material in the STC beams connected by hybrid-anchored screws, the slip stiffness values were increased by 18.79% and 48.40%, the capacity values were increased by 10.13% and 15.15%, and the maximum end slip values were reduced by 8.77% and 8.97%, respectively, indicating that mortar was more effective. Secondly, due to the strong restraint provided by the filling material and the H-steel flange for the screw tip and head, respectively, double plastic hinges were generated in the screw, and the development of double plastic hinges at both ends of the simply supported STC beam is more significant. Thirdly, finite element analysis showed that the mortar strength (greater than 30 MPa) had little effect on the flexural performance of STC beams connected by hybrid-anchored screws; increasing the number of hybrid-anchored screws can significantly improve the slip stiffness of the connection interface of STC beams and reduce the slip.

Are modular pedicle screws associated with a high complication rate following posterior spinal fixation?

Modular pedicle screws have a separate head that can be intraoperatively assembled to the inserted shank. The aim of this study was to report associated intra- and post-operative complications and reoperation rates of posterior spinal fixations with modular pedicle screws at a single center. A retrospective, institutional chart review was performed on 285 patients who underwent posterior thoracolumbar spinal fusion with modular pedicle screw fixation between January 1, 2017, and December 31, 2019. The primary outcome was failure of the modular screw component. Other measures recorded were length of follow-up, other complications, and need for additional procedures. There were 1,872 modular pedicle screws (average 6.6 per case). There were no (0.0%) screw head dissociations at the rod screw junction. There was 20.8% overall complication rate (59/285) with 25 reoperations: 6 due to non-union and rod breakage, 5 for screw loosening, 7 for adjacent segment disease, 1 for acute postoperative radiculopathy, 1 for epidural hematoma, 2 for deep surgical-site infections, and 3 for superficial surgical-site infections. Other complications included superficial wound dehiscence [8], dural tears [6], non-unions not requiring reoperation [2], lumbar radiculopathies [3], and perioperative medical complications [5]. This study demonstrates that modular pedicle screw fixation has reoperation rates similar to those previously reported for standard pedicle screws. There was no failure at the screw-head junction, and no increases in other complications. Modular pedicle screws present an excellent option to allow surgeons to place pedicle screws without the risk of extra complications.

A Simple Technique to Prevent Screw Stripping During Hardware Removal Using Bone Wax.

Hardware removal is a common procedure in orthopedics, but it can be challenging and time-consuming. Difficulties in screw removal may arise due to bone growth or cement covering the screw heads, leading to screw damage, and increased surgical time. In this article, we describe a simple and inexpensive technique utilizing bone wax to protect screw heads from bone growth or cement, facilitating future implant removal. The application of bone wax over screw heads acts as a barrier, preventing bone growth or cement from engaging with the screw heads.

The Analysis of Screws Spacing Effect On The Flexural Strength Of Laminated Wood Beams From Pine Pallets Waste

Pine pallets are often used to design the interior of houses, as opposed to pine waste, which is underutilized due to its reduced strength and limited size. Therefore, this research aims to optimize the use of pine pallet waste by making laminated beams using screw joints and determining the effect of screw spacing on the strong bending of laminated beams. Flexural strength tests of laminated wood beams measuring 5 cm x 5 cm x 76 cm with varying screw spacing of 4 cm, 8 cm, 12 cm, and 16 were used to conduct this research. This is in addition to screw length, head, and body diameters of 5 cm, 8 mm, and 4 mm, respectively. Strong bending testing was carried out at the Structural Laboratory of the Department of Civil Engineering, Faculty of Engineering, Tidar University, Magelang. The test results of consecutive Modulus of Rupture (MOR) had average values of 20.996 MPa, 23.067 MPa, 20.207 MPa, 19.292 MPa. and Modulus of Elasticity (MOE) of 1,352.68 MPa, 1,449.35 MPa, 1,146.76 MPa, and 1,128.90 MPa. The result showed that the use of varying screw spacing has no significant effect on the flexural strength of laminated beams. Furthermore, the laminated pine pallet waste with screws can be used as an alternative to pure wood by paying attention to the proper joint spacing.

Pullout Strength of Pedicle Screws Inserted Using Three Different Techniques: A Biomechanical Study on Polyurethane Foam Block

Pullout strength is an important indicator of the performance and longevity of pedicle screws and can be heavily influenced by the screw design, the insertion technique and the quality of surrounding bone. The purpose of this study was to investigate the pullout strength of three different pedicle screws inserted using three different strategies and with two different loading conditions. Three pedicle screws with different thread designs (single-lead-thread (SLT) screw, dual-lead-thread (DLT) screw and mixed-single-lead-thread (MSLT) screw) were inserted into a pre-drilled rigid polyurethane foam block using three strategies: (A) screw inserted to a depth of 33.5 mm; (B) screw inserted to a depth of 33.5 mm and then reversed by 3.5 mm to simulate an adjustment of the tulip height of the pedicle screw and (C) screw inserted to a depth of 30 mm. After insertion, each screw type was set up with and without a cyclic load being applied to the screw head prior to the pullout test. To ensure that the normality assumption is met, we applied the Shapiro–Wilk test to all datasets before conducting the non-parametric statistical test (Kruskal–Wallis test combined with pairwise Mann–Whitney-U tests). All screw types inserted using strategy A had a significantly greater pullout strength than those inserted using strategies B and C, regardless of if the screw was pre-loaded with a cyclic load prior to testing. Without the use of the cyclic pre-load, the MSLT screw had a greater pullout strength than the SLT and DLT screws for all three insertion strategies. However, the fixation strength of all screws was reduced when pre-loaded before testing, with the MSLT screw inserted using strategy B producing a significantly lower pullout strength than all other groups (p &lt; 0.05). In contrast, the MSLT screw using insertion strategies A and C had a greater pullout strength than the SLT and DLT screws both with and without pre-loading. In conclusion, the MSLT pedicle screw exhibited the greatest pullout strength of the screws tested under all insertion strategies and loading conditions, except for insertion strategy B with a cyclic pre-load. While all screw types showed a reduced pullout strength when using insertion strategy B (screw-out depth adjustment), the MSLT screw had the largest reduction in pullout strength when using a pre-load before testing. Based on these findings, during the initial screw insertion, it is recommended to not fully insert the screw thread into the bone and to leave a retention length for depth adjustment to avoid the need for screw-out adjustment, as with insertion strategy B.

Craniocaudal toggling increases the risk of screw loosening in osteoporotic vertebrae

Background and ObjectiveScrew loosening remains a prominent problem for osteoporotic patients undergoing pedicle screw fixation surgeries but its underlying mechanisms are not fully understood. This study sought to examine the interactive effect of craniocaudal or axial cyclic loading (toggling) and osteoporosis on screw fixation. MethodsQCT-based finite element models of normal (n = 7; vBMD = 156 ± 13 mg/cm3) and osteoporotic vertebrae (n = 7; vBMD = 72 ± 6 mg/cm3) were inserted with pedicle screws and loaded with or without craniocaudal toggling. Among them, a representative normal vertebra (age: 55; BMD: 140 mg/cm3) and an osteoporotic vertebra (age: 64; BMD: 79 mg/cm3) were also loaded with or without axial toggling. The individual and interactive effects of craniocaudal toggling and osteoporosis on screw fixation strength (the force when the pull-up displacement of the screw head reached 1 mm) and bone tissue failure (characterized by equivalent plastic strain) were examined by repeated measure ANOVA. ResultsA significant interactive effect between craniocaudal toggling and osteoporosis on screw fixation strength was detected (p = 0.008). Specifically, craniocaudal toggling led to a marked decrease in the fixation strength (68%, p < 0.05) and stiffness (83%, p < 0.05) only in the osteoporotic vertebrae but had no effect on screw fixation strength and stiffness of the normal vertebrae (p > 0.05). Likewise, most of the bone tissues around the screw in the osteoporotic vertebrae yielded following craniocaudal toggling whereas this result was not seen in the normal vertebrae. The axial toggling had no significant effect on bone tissue failure as well as pedicle screw fixation in normal or osteoporotic vertebrae. ConclusionsCraniocaudal toggling substantially reduces the screw fixation strength of the osteoporotic vertebrae by progressively increasing tissue failure around the screw, and therefore may contribute to the higher rates of screw loosening in osteoporotic compared to normal patients, whereas axial toggling is not a risk factor for pedicle screw loosening in normal or osteoporotic patients.

Evaluation of intraoperative coronal alignment using a computer-assisted rod bending system (CARBS) without intraoperative radiation exposure in adult spinal deformity surgery: a technical note and preliminary results.

Intraoperative radiographs and fluoroscopy are used in adult spinal deformity (ASD) surgery to prevent postoperative coronal malalignment but with limited accuracy. Therefore, we applied a computer-assisted rod bending system (CARBS: Bendini®) for an intraoperative coronal alignment evaluation. The purpose of this study is to introduce this novel technique and validate its accuracy. Fifteen ASD patients were included in the study. The heads of the bilateral S1 pedicle screws (S1), the S1 spinous process, and the bilateral greater trochanter (GT) and the C7 spinous process were recorded with CARBS for an intraoperative coronal alignment evaluation. The lines which connect the bilateral S1 and GT were used as references. The C7-center sacral vertical line (C7-CSVL) on the CARBS monitor was checked, and the C7-CSVL from the intraoperative CARBS recording and postoperative standing whole spine radiograph were compared. Intraoperative C7-CSVL with CARBS was 35.1 ± 31.6mm when the S1 pedicle screws were used as the reference line and was 16.6 ± 17.8mm when the GTs were used. Postoperative C7-CSVL by radiograph was 15.1 ± 16.5mm. In addition, the intraoperative C7-CSVL with CARBS and the postoperative C7-CSVL showed a strong positive correlation in both GT (R = 0.86, p < 0.01) and in S1(R = 0.79, p < 0.01), with a better correlation found in GT than in S1. Intraoperative C7-CSVL with CARBS was found to be highly accurate in ASD surgery. Our results suggest that this novel technique can be useful as an alternative to intraoperative radiography and fluoroscopy and may reduce radiation exposure.

How proximal femur fracture patients aged 65 and older fare in survival and cause of death 5+ years after surgery: A long-term follow-up.

Although the incidence of proximal femur fractures (PFFs) is increasing, few detailed reports on associated long-term outcomes and causes of death exist. We aimed to evaluate long-term outcomes and causes of death ≥5 years after surgical treatment of PFFs. This retrospective study included 123 patients (18 males, 105 females) with PFFs treated at our hospital between January 2014 and December 2016. Cases (median age: 90 [range, 65-106] years) comprised 38 femoral neck fractures (FNFs) and 85 intertrochanteric fractures (IFs). Surgical procedures included bipolar head arthroplasty (n = 35), screw fixation (n = 3), and internal fixation with nails (n = 85). The mean post-surgical follow-up time was 58.9 (range, 1-106) months. Surveyed items included survival (1 vs 5 years; sex; age, >90 vs <90 years; IF vs FNF), comorbidities, waiting time after the injury (died vs survived), operative time (proximal femoral nail antirotations [PFNA] vs FNF, died vs Survived), blood loss (PFNA vs FNF; died vs survived), and cause of death (IF vs FNF; <1 vs >1 year). Among all patients, 83.7% had comorbidities (IF, 90.5%; FNF, 81.5%). Among patients who died and survived, 89.1% and 80.5% had comorbidities, respectively. The most common comorbidities were cardiac (n = 22), renal (n = 10), brain (n = 8), and pulmonary (n = 4) diseases. Overall survival (OS) rates at 1 and 5 years were 88.9% and 66.7%, respectively. Male/female OS rates were 88.8%/88.3% and 66.6%/66.6% (P = .89) at 1 and 5 years, respectively. OS rates for the <90/≥90 age groups were 90.1%/76.7% and 75.3%/53.4 (P < .01) at 1 and 5 years, respectively. The 1- and 5-year OS (IF/FNF) rates were 85.7%/88.8% and 60%/81.5%, respectively; patients with IFs had significantly lower OS than those with FNFs at both timepoints (P = .015). There was a marked difference in the operative time between died (43.5 ± 24.0: mean ± S.D.) and survived (60 ± 24.4: mean ± S.D.) patients. The main causes of death were senility (n = 10), aspiration pneumonia (n = 9), bronchopneumonia (n = 6), worsening heart failure (n = 5), acute myocardial infarction (n = 4), and abdominal aortic aneurysm (n = 4). Overall, 30.4% of the cases were related to comorbidities and related causes (e.g., hypertension-related ruptured large abdominal aneurysm). Managing comorbidities may improve long-term postoperative outcomes of PFF treatment.