Screw Length Research Articles

Pedicle Morphology Analysis in Adolescents with Lenke Type 5 Idiopathic Scoliosis in Thai Population

Abstract Background The surgical management of adolescent idiopathic scoliosis (AIS) often incorporates the utilization of pedicle screws, which are three-column construct devices. A comprehensive understanding of the pedicle morphology is essential for determining the appropriate pedicle screw diameter. While previous studies have examined pedicle morphology in Lenke type 1 AIS, there is a scarcity of information about the pedicle morphology in Lenke type 5 AIS, especially in the Thai population. Objective The aim of this study is to analyze the morphology of the thoracolumbar pedicle, specifically the pedicle width and trajectory length on both the concave and convex sides within a sample of the Thai population diagnosed with Lenke type 5 AIS. Materials and Methods In this study, we used computed tomography (CT) measurements to examine the thoracolumbar pedicle morphology in Lenke type 5 AIS patients in the Thai population. We also analyzed the pedicle width and trajectory length on both concave and convex sides in 112 AIS patients with Lenke type 5 curvature. Results A total of 3,808 pedicles from 112 consecutive AIS patients of Lenke type 5 were enrolled in the study. It was observed that the transverse pedicle width was notably smaller on the concave side compared with the convex side in the apical region of the thoracolumbar spine (T12 to L2). Additionally, the pedicle width of T3 was also found to be significantly smaller on the concave side. Moreover, it was noted that the pedicle trajectory length is significantly longer on the concave side, indicating that the concave side in the apical region may have the capacity to accommodate a slightly longer pedicle screw at T3, T6, L2, L3, and L4. Conclusion Our analysis of measurements indicates that the thoracolumbar pedicle morphology in Lenke type 5 AIS among the Thai population typically shows smaller widths and longer trajectory lengths on the concave side. This information enhances our understanding of the appropriate selection of pedicle screw diameter and length for treating Lenke type 5 AIS in the Thai population.

Clinical Application of 3D-Assisted Surgery Techniques in Treatment of Intra-Articular Distal Radius Fractures: A Systematic Review in 718 Patients.

Objectives: Three-dimensional (3D) technology is increasingly applied in the surgical treatment of distal radial fractures and may optimize surgical planning, improve fracture reduction, facilitate implant and screw positioning, and thus prevent surgical complications. The main research questions of this review were as follows: (1) "How do 3D-assisted versus 2D-assisted distal radius fracture surgery compare in terms of intraoperative metrics (i.e., operation time and fluoroscopy frequency)?", and (2) "What are the effects of 3D-assisted versus 2D-assisted surgery on postoperative outcomes (patient-reported outcome measures (PROMs), range of motion (ROM), fracture reduction, complication rate, and screw placement accuracy)?" Methods: This review was performed according to the Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines. In total, 873 articles were found between 1 January 2010 and 1 April 2024, of which 12 (718 patients) were suitable for inclusion. The quality of the studies, assessed using the McMaster quality assessment, ranged from moderate to excellent, although the surgical techniques and outcome measures varied widely. Articles comparing a 3D group to a 2D group (conventional imaging) and reporting on primary or secondary outcomes were included in the analysis, for which weighted means and ranges were calculated. Results: Three different concepts of 3D-assisted surgery techniques were identified: (1) 3D virtual surgical planning (VSP), (2) 3D-printed handheld models, and (3) 3D intraoperative guides. Differences between 3D-assisted and conventional 2D-assisted surgery were evaluated. Regarding intraoperative metrics, 3D-assisted surgery significantly reduced operation time by 6 min (weighted mean 66.9 versus 73.2 min) and reduced the fluoroscopy frequency by 1.1 images (5.8 versus 4.7 times). Regarding postoperative outcomes, the weighted mean of the DASH score differed between the 3D- and 2D-assisted groups (17.8 versus 23.9 points), and no differences in PRWE or VAS score were found. Furthermore, our results showed no significant differences in the ROM and fracture reduction parameters. In terms of complications, the application of 3D-assisted surgery decreased the complication rate from 10.7% to 3.6%, and the use of screws with appropriate lengths improved from 75% to 86%. Conclusions: Applications of 3D-assisted surgery in distal radial fracture surgery can slightly reduce the operation time and fluoroscopy frequency. Evidence for the improvement of fracture reduction and functional outcomes is still lacking, although it likely reduces the complication rate and improves the use of appropriate screw lengths.

Efficacy analysis of 3D printing prefixed nail path model assisted lumbar and sacral hemivertebra orthopaedic surgery

To analyze the safety and effectiveness of 3D printing prefabricated nail path model assisted lumbosacral hemivertebra orthopaedic surgery. A retrospective analysis was performed on 8 patients with lumbosacral hemivertebra deformity admitted from January 2016 to July 2021, including 3 males and 5 females, aged 6 to 15 at the time of surgery. The hemivertebra of 4 cases located on the left side and 4 cases on the right side. The hemivertebra of 1 case located at L2,3, 2 cases at L3,4, 2 cases at L4,5, and 3 cases at L5S1. Four cases were fully segmented hemivertebra and 4 cases were incomplete segmented hemivertebra. The patient CT data was imported into Mimics 21.0 software for modeling, and then the model data was imported into 3-Matic software. The vertebra requiring screw placement was selected to simulate the optimal screw placement angle and length, and the model was printed for preoperative planning and intraoperative guidance. All patients underwent orthopedic surgery with the aid of 3D printing preset nail path model. The safety and effectiveness of the 3D printing prefabricated nail tunnel model assisted lumbosacral hemivertebra orthopaedic surgery was evaluated by comparing the imaging parameters of the patients. The main outcome measures were the Cobb angle of the main curve, the Cobb angle of the proximal compensatory curve, the coronal balance index C7 plumb line-center sacral vertical line(C7PL-CSVL), the accuracy of nail placement, and the correction rate of scoliosis before surgery, 1 week and 1 year after surgery. All of 8 patients were followed up for 13 to 31 months. A total of 98 pedicle screws were placed in 8 patients. The number of pedicle screw grades A, B, C, D, E was 38, 46, 10, 4, 0 screws. The screws of grade A and B were defined as good position, the accuracy rate of screw placement was 85.7%. The Cobb angle of the main curve were 21° to 38° before operation, 5° to 11° at 1 week after operation, 7°to 12° at 1 year after operation. The Cobb angle of the proximal compensatory curve were 16° to 39° befoer operation, 7° to 12 °at 1 week after operation, 7° to 14° at 1 year after operation, the correction effect remained good with no correction loss. The coronal balance index C7PL-CSVL were 20 to 35 mm before operation, 11 to 18 mm at 1 week after operation, 10 to 16 mm at 1 year after operation, the coronal imbalance improved. The scoliosis correction rate was 65.6% to 84.2% 1 week after surgery, and 61.9% to 81.6% 1 year after surgery. The use of 3D printing prefixed nail tunnel model in lumbosacral hemivertebra osteotomy is safe and effective, and can significantly improve patients' local deformities. It is a reliable method to assist lumbar sacral hemivertebra osteotomy.

Exploring cortical trajectory of the lumbar vertebrae: a morphometric study in dry skeletons: a retrospective study in Thailand.

Retrospective cohort study. This study aimed to explore the morphometry of the Thai lumbar vertebrae. The cortical bone trajectory (CBT) is a novel approach for vertebral screw fixation aimed at addressing spinal instability associated with spinal disorders. The morphometry of the lumbar vertebrae is crucial in tailoring screw design for each CBT application, given the significant variations in optimal screw sizes, lengths, and angles among populations. A total of 300 dried lumbar columns were used to measure the pedicle height (PH) and width (PW), length for cortical bone trajectory (LCT), cephalad screw angle (CSA), axial cortical bone trajectory angle (ACA), and possible cortical zones for the CBT. The following average values were calculated: PH in L1, 15.09±1.44 mm; PW in L5, 16.96±2.42 mm; LCT in L3, 35.75±2.61 mm; CSA in L1, 20.85°±2.30°; and ACA in L5, 21.83°±2.49°. Women generally had shorter PH and PW than men, with significant differences across lumbar levels. The LCT was significantly shorter in women and was notably different between the left and right sides. The CSA and ACA varied significantly between sexes and sides, with specific lumbar levels showing wider angles in one sex over the other. The most common cortical zones for screw tips were Z3 and Z10, with high incidences across all lumbar levels. This study presents detailed lumbar vertebral morphometry data specific to the Thai population. The results are essential for CBT application in screw fixation procedures. This information will contribute to the production of optimally designed screws for Thai patients in the future.

Anatomy of Lister's Tubercle: Implications for Volar Locked Plating of the Distal Radius.

Determining accurate intraoperative screw length in complex distal radius fractures may pose difficulties. With volar plate fixation, excessive screw length may result in extensor pollicis longus injury and this can be challenging to determine via intraoperative imaging. This study aims to identify the precise anatomic location and parameters of Lister's tubercle on the dorsal aspect of the radius. The anatomy and location of Lister's tubercle was evaluated in 26 cadaveric arms, of which 27% were female, with a mean age of 73.6 years. Additionally, Lister's tubercle was evaluated on 198 computed tomography (CT) scans using a quantitative distal radius surface map. Median age was 28 years, and 28% of the patients were female. As measured in cadaveric arms, the mean Lister's tubercle length was 12.6 mm, and width was 5.4 mm. The distance from the radial styloid to the distal and proximal border of Lister's tubercle averaged 23.0 and 10.4 mm, respectively. Of the total distal radial width, Lister's tubercle begins 43% from the radial border and spans to 42% of the ulnar border, encompassing 16% of the entire width of the dorsal distal radius. On CT mapping, the distance between the peak of Lister's tubercle and the ulnar and radial border of the radius was 46% and 54%, respectively. Female sex was associated with a smaller distal radius width, but not with a smaller Lister's tubercle. Knowledge of Lister's tubercle anatomy may assist in more precise screw placement in volar locked plating of distal radius fractures. IV-Therapeutic.

Applying 3D-Printed Porous Ti6Al4V Prostheses to Repair Osteomyelitis-Induced Partial Bone Defects of Lower Limbs: Finite Element Analysis and Clinical Outcomes.

The clinical management of partial bone defects in lower limbs, particularly those resulting from osteomyelitis, remains a significant challenge. This study aimed to systematically evaluate the effectiveness of 3D-printed porous Ti6Al4V prostheses in addressing osteomyelitis-induced partial bone defects. We established a comprehensive protocol for utilizing 3D-printed prostheses for bone defect repair, encompassing 3D simulation of prosthesis implantation and internal fixation, finite element analysis (FEA), and clinical implementation. Mimics software facilitated simulation of fixation patterns and screw lengths. FEA modeled bone defects in the distal metaphyseal femur and distal diaphyseal tibia to assess changes in stress conduction pre- and post-prosthesis implantation. The clinical study involved eight patients (average age: 56.3 years) with an average defect length of 14.9 cm. Postoperative outcomes were evaluated using X-rays and the Lower Extremity Functional Scale (LEFS). FEA demonstrated that the implanted prostheses effectively shared stress and reduced the load on residual bone in both models, thus lowering the risk of fractures under external forces. The average follow-up period was 24.5 months, with patients initiating weight-bearing activities on average 7.8 days post-surgery. Serial postoperative X-rays demonstrated long-term stability of the prostheses, with progressive bone regeneration around and integration with the prostheses. While two patients experienced infection recurrence requiring prosthesis removal and debridement, the remaining six showed significant improvement in LEFS scores, increasing from 31.5 preoperatively to 61.0 at the last follow-up. 3D-printed porous Ti6Al4V prostheses effectively restore anatomical integrity and optimize stress conduction in lower limbs, resulting in substantial functional recovery. This innovative approach shows promise for wider clinical adoption and warrants further investigation in medical practice.

Vertebral Body Morphology in Neuromuscular Scoliosis with Spastic Quadriplegic Cerebral Palsy

Background/Objectives: The distorted vertebral body has been studied in scoliosis; however, there is little knowledge about the difference between neuromuscular and idiopathic scoliosis. This study aimed to investigate the vertebral body morphology in patients with spastic quadriplegic cerebral palsy and scoliosis (CP scoliosis) and compare them with those of apex- and Cobb angle-matched patients with adolescent idiopathic scoliosis (AIS). Methods: Thirty-four patients with CP scoliosis and thirty-two patients with AIS were included. The pedicle diameter, chord length, and vertebral body rotation were evaluated at one level above the apex, one level below the apex, and at the apex using a reconstructed computed tomography scan. The apex of the curve and Cobb angle were too diverse between patients with CP scoliosis or AIS. Eighteen patients were matched in each group according to the apex and Cobb angle (within 5-degree differences) of the major curve, and compared between matched groups (mCPscoliosis vs. mAIS). Results: In the comparison of the apex and Cobb angle-matched groups, there was no statistical difference in the Cobb angle between mCPscoliosis (80.7 ± 13.8 degrees) and mAIS (78.6 ± 13.6 degrees, p = 0.426), and the vertebral body rotation (25.4 ± 15.4° in mCPscoliosis vs. 24.4 ± 6.5° in mAIS, p = 0.594). There was no difference in the pedicle diameters of either the convex (3.6 ± 1.1 mm in mCPscoliosis vs. 3.3 ± 1.2 mm in mAIS, p = 0.24) or concave side (3.1 ± 1.2 mm in mCPscoliosis vs. 2.7 ± 1.6 mm in mAIS, p = 0.127). However, the patients in the mCPscoliosis group were younger (12.7 ± 2.5 years vs. 14.6 ± 2.4 years, p = 0.001), and the chord length was shorter on the convex (38.0 ± 5.0 mm vs. 40.4 ± 4.9 mm, p = 0.025) and concave (37.7 ± 5.2 mm vs. 40.3 ± 4.7 mm, p = 0.014) sides compared with those of the mAIS group. Conclusions: With a similar apex and Cobb angle, the vertebral body rotation and pedicle diameter in patients with CP scoliosis were comparable to those with AIS; however, the chord length was shorter in CP scoliosis. For the selection of the pedicle screw in CP scoliosis, the length of the pedicle screw should be more considered than the diameter.

Short-term clinical and radiologic outcomes of reverse total shoulder arthroplasty with navigation system in the Asian population: a retrospective comparative stud

BackgroundIn reverse total arthroplasty (rTSA), glenoid component positioning is a critical factor for outcomes especially in Asian population with smaller glenoid. The purpose of this study was to compare the clinical and radiologic outcomes of rTSA with and without the navigation system with a minimum follow-up of two years in Asian population. MethodsThis was a retrospective comparative study of 33 rTSA with the navigation system (NAV group) and 40 conventional rTSA (CON group). Radiologic measurements regarding the position of the glenoid component, glenoid vault perforation by the central cage, and scapular notching, as well as clinical outcomes including range of motion (ROM), functional scores and complications were compared. Number, length, and angulation of screws were assessed. ResultsThe mean age was 73.9 ± 5.9 years with a mean follow-up of 30.1 ± 6.4 months. The NAV group more frequently utilized augmented baseplate (P < 0.001), showed less superior inclination (P = 0.030) and had lower incidence of glenoid vault perforation (P = 0.040). The length of superior (P = 0.001) and inferior screws (P = 0.045) was longer in the NAV group. In the NAV group compared to the CON group, more inferior orientation of superior screws (P < .001), more anterior orientation for inferior screws (P = 0.031), and anterior screws (P = 0.003) were observed. The NAV group showed significantly less penetration into the suprascapular fossa by a superior screw (P = 0.007). Final ROM, functional scores, and complications showed no significant differences between two groups. ConclusionIn short-term follow-up, the use of a navigation system in rTSA showed no significant difference in clinical outcomes and complications compared to conventional implantation. However, it enabled a lower superior inclination and a reduced glenoid vault perforation by the central cage, simultaneously allowing for the insertion of longer peripheral screws in a safer direction compared to conventional implantation.

Determining the Optimal Morphometry of Pedicle Screws in Lumbar and Thoracic Spine in the Iranian Population

Background: The improper length and direction of pedicle screw may also cause it to penetrate the adjacent organs. Unknowing the safe zone of dimensions and directions of the pedicles is essential to proper screw placement. Methods: The present study is a cross-sectional morphometric study on patients with spinal trauma referred to the neurosurgical department in 2021. The MARCO PACS software scale measured the CT scan images and included the vertebral left pedicle diameter, pedicle body distance, body aorta distance, pedicle diameter, height, and area. The entry point and direction of the pedicle screw were made with the “free-hand” method. Results: 301 patients were included, consisting of 113 females (37.5%) and 188 males (62.5%). The mean age of the participants was 42.87±12.3 years. “Among all T12 vertebra parameters, just body aorta distance was not significant between genders (p-value=0.311). The pedicle height and body aorta distance were lowest among 18-35 years patients (p-value=0.001) (p-value=0.003), respectively. Post-hoc analysis revealed a significant difference between 18-35 and 51-70 years for body aorta distance in the L1 vertebra (p-value=0.002). Conclusion: The present investigation has shown significant differences between genders for optimal left pedicle screw parameters, which should be considered before surgery.

Influence of Screw Length and Cement Position Within the Injured Vertebra on Fixation Strength in Short-Segment Fixation of Osteoporotic Thoracolumbar Burst Fractures

The prevalence of osteoporotic vertebral fractures has increased with aging populations, necessitating effective treatments such as percutaneous kyphoplasty combined with posterior screw fixation. However, biomechanical research on the effects of using short screws on fixation stability and bone stress or on the impact of bone cement bonding to screws on structural strength is lacking. This study aimed to optimize short-segment fixation strategies for osteoporotic thoracolumbar burst fractures by analyzing the biomechanical effects of pedicle screw length and bone-cement augmentation. Four models of the thoracolumbar spine were established using computed tomography data of a female volunteer: 1) short screws in the injured vertebra without contact with the bone cement, 2) long screws without contact with the bone cement, 3) long screws in contact with the bone cement, and 4) long screws without the bone cement. The 4 fixation models were simulated under physiological loads. The range of motion, implant stress, and segmental stability were assessed. The 3 groups containing the bone cement exhibited similar performances in terms of stability and stress distribution, whereas the group without the bone cement exhibited a poorer biomechanical performance. Incorporation of the bone cement enhanced the biomechanical properties of the structure, and short screws in the injured vertebra without contact with the bone cement did not significantly compromise the biomechanical performance. Short screws in injured vertebrae without contact with the bone cement can achieve satisfactory stability and stress distribution. It is feasible to implant short screws in the injured vertebrae, reduce the number of bilaterally injured vertebrae, and inject bone cement through the non-pedicle approach during the surgical procedure, which simplifies the surgical process.

Computer modeling and validation testing for glenoid component rotation and optimal glenoid screw angles for reverse shoulder arthroplasty in an Asian population

PurposeGood initial fixation of glenoid component for reverse total shoulder arthroplasty (RTSA) relies on component placement and screw purchase in the scapula bone. This is especially difficult in an Asian population with small glenoid geometry. Optimal glenoid component roll angle and screw angulation to achieve the longest screws for best fixation has not been defined in the current literature.MethodsComputer 3D modelling of 133 scapulas with RTSA performed were analyzed to determine patient specific optimal glenoid roll angle (GRA) for the longest bi-cortical screws attainable. The cranial-caudal angle (CCA), anterior-posterior angle (APA) and lengths for the superior and inferior screws were measured. Validation testing using calculated average (CA) angles and rounded average (RA) angles to the nearest 5 degree were recomputed for each case to determine the bi-cortical screw lengths achievable. The CA and RA screw lengths were compared against patient specific modelling using paired-sample t-tests.ResultsAverage GRA was − 1.6°, almost perpendicular to the long axis of the glenoid and achieves an average bi-cortical screw length of 51.3 mm and 45.5 mm for the superior and inferior screws respectively. The CCA and APA were 9.1° cranial and 6.5° posterior for the superior screw and screw angulation of 11.2° caudal and 0.7° anterior for the inferior screw. Validation testing shows statistically shorter screw lengths in the CA and RA models compared to patient specific modelling (p < 0.01).ConclusionValidation testing with average angles for GRA, CCA and APA demonstrates strong patient heterogeneity and anatomical variation. Despite this, screw lengths attainable in the RA group were > 38 mm with good safety profile. Surgeons may consider the additional use of navigation-assisted, or 3D printed patient specific instrumentation to optimize baseplate and screw configuration for RTSA.

Validation of the Lift-Off Screw Technique in Patients Undergoing Corrective Osteotomy for Malunited Distal Radius Fractures

The purpose of this study was to validate the clinical accuracy of the lift-off screw (LOS) technique for volar tilt correction (VTC) in patients undergoing corrective osteotomy for dorsally angulated distal radius fracture malunions. We conducted a retrospective review of 23 patients with dorsally angulated distal radius fracture malunions treated with corrective osteotomy using the LOS technique. The LOS equation Ls= [tan(Tc) ∗ Lp+ C]/[cos(⍬s)] and standardized intraoperative fluoroscopic images were used to determine and compare the calculated and clinical VTC and final volar tilt. Correlations between the LOS length and the clinical VTC were calculated, as well as between the desired VTC and the correction accuracy. Preoperative volar tilt ranged from-6° to-50° (mean=-22.9° ± 10.6°). The calculated VTC was 32.7° ± 9.4°, and the clinical VTC achieved was 25.8° ± 9.3°. The difference between the clinical and calculated correction was-6.9°, with an average postoperative clinical volar tilt of 2.8° ± 5.7°, compared with a calculated volar tilt of 9.7° ± 4.4°. There was a moderately strong positive correlation between LOS screw length and clinical VTC achieved, and a moderately weak negative correlation between the desired amount of correction and the accuracy of the correction. The LOS technique is a reproducible method to plan the amount of sagittal plane correction during corrective osteotomy surgery for dorsally angulated distal radius fracture malunions. We demonstrate that this technique underestimates the clinical correction achieved by an average of 7°, with larger deformities experiencing greater undercorrection. Undercorrection of volar tilt during corrective osteotomy should be anticipated by surgeons and considered in future implant and cutting guide designs. Therapeutic IV.

Scaling-Up for the Counter-Rotating Twin Screw Extrusion of Polymers.

A novel and original computer scaling-up system for the counter-rotating twin screw extrusion of polymers was developed. In the system, each scaling parameter (scaling criterion) may be considered as an objective function to be minimized for the single parameters or the functional relationships along the length of the screw. Scaling was based on the process simulation, which was performed using the comprehensive (or global) counter-rotating twin screw extrusion program called TSEM (Twin Screw Extrusion Model). The extrusion process was scaled by applying GASESTWIN (Genetic Algorithms Screw Extrusion Scaling) software developed for this purpose using genetic algorithms. Scaling up the extrusion process was carried out to enhance extrusion process throughput according to the scaling criteria specified by the single quantities of polymer melt temperature at the die exit and relative melting length, and by distributions along the screw length of the extrusion parameters of the polymer melt temperature and polymer plasticating. The global objective function had the lowest value for the selected extrusion parameters, which means the minimal differences between the values of the scaled-up processes and extrusion throughput was significantly increased. The solution to the problem of scaling the counter-rotating process presented in this paper complements the existing solutions for optimizing and scaling basic variants of the extrusion process, i.e., flood-fed and starve (metered)-fed single-screw extrusion, as well as co-rotating and counter-rotating twin-screw extrusion.

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.

Experiences with the infra-acetabular screw placement technique in acetabular fracture surgery

To investigate the application experiences and effectiveness of the infra-acetabular screw (IAS) placement technique in acetabular fracture surgery. A clinical data of 34 patients with complex acetabular fractures with anterior and posterior columns separation, who were admitted between January 2019 and October 2023 and treated with IAS fixation, was retrospectively analyzed. There were 23 males and 11 females with an average age of 55.3 years (range, 18-78 years). The acetabular fractures caused by traffic accident in 20 cases, falling from height in 12 cases, crushing injury in 1 case, and bruising with a heavy object in 1 case. According to the Letournel-Judet classification, there were 7 cases of anterior column fracture, 8 cases of anterior wall/column plus posterior hemi-transverse fracture, 2 cases of T-shaped fracture, and 17 cases of both-column fracture. The time from injury to surgery was 4-21 days (mean, 8.6 days). The time of IAS placement and the intraoperative blood loss were recorded. After surgery, the X-ray film and CT scan were re-examined, and the modified Matta score was used to assess the quality of fracture reduction. The trajectory of IAS in the channel was analyzed based on CT scan, and the screw length was measured. During follow-up, the fracture healing was observed and the hip function was assessed according to the modified Merle d'Aubigné-Postel scoring system at last follow-up. The IAS was successfully implanted in all 34 patients. The length of IAS ranged from 70 to 100 mm (mean, 86.2 mm). The time of IAS placement ranged from 10 to 40 minutes (mean, 20.7 minutes). The intraoperative blood loss ranged from 520 to 820 mL (mean, 716.8 mL). All patients were followed up 8-62 months (mean, 21.8 months). After surgery, 4 patients developed lateral femoral cutaneous nerve injury, 2 developed popliteal vein thrombosis of the lower extremity, 3 developed incision infection, and no surgical complication such as arteriovenous injury or obturator nerve palsy occurred. At last follow-up, the hip function was rated as excellent in 14 cases, good in 13 cases, fair in 4 cases, and poor in 3 cases according to the Merle d'Aubigné-Postel scoring system, with an excellent and good rate of 79.41%. Imaging re-examined showed that the quality of fracture reduction was rated as excellent in 9 cases, good in 19 cases, and poor in 6 cases according to the modified Matta score, with an excellent and good rate of 82.35%; and 25 (73.53%) IAS trajectories were located in the channel. All fractures obtained bony union, and the healing time was 12-24 weeks (mean, 18 weeks). During follow-up, there was no loosening or fracture of the plate and screws. IAS placement technique can effectively strengthen internal fixation and prevent fracture re-displacement, making it a useful adjunct for treating complex acetabular fractures with anterior and posterior columns separation.

Effect of Screw Length in Volar Plating for Intra-Articular Distal Radius Fractures: A Biomechanical Study

PurposeThe purpose of this study was to compare the effect of varying screw lengths on load to failure and retention of the dorsal ulnar corner fragment after fixation of comminuted intra-articular distal radius fractures in a cadaveric model. MethodsTwenty-four fresh frozen cadaveric forearms were subjected to a standardized distal radius osteotomy to mimic an intra-articular fracture pattern. Dual X-ray absorptiometry scans were performed to ensure minimal variability in bone density. All fractures were fixed with a volar locking plate and distal locking screws. Three different lengths of distal locking screws were used in each group of eight specimens to simulate the clinical decision of different distal screw lengths. The screw lengths tested were bicortical, 100% of the width of the bone but unicortical, and 75% of the width of the bone and unicortical. All specimens were preconditioned with cyclic axial loading and then axially loaded using matching acrylic resin molds to clinical failure and fragment displacement as detected by a motion analysis system. Retention or loss of the dorsal ulnar corner fragment during loading was recorded as a binary variable. ResultsBetween the three groups, there were no statistically significant differences in precycling stiffness, postcycling stiffness, load at 2 mm displacement of the dorsal ulnar corner, or force at failure. The group with 75% length screws had a significantly higher loss of reduction of the dorsal ulnar corner (86%) compared with the other groups (0%). ConclusionsVarying screw lengths did not affect the stiffness or overall loads to failure of axially loaded specimens. However, the 75% length screws did not reliably secure the dorsal ulnar corner fragments. Although this did not significantly affect the overall load to failure of the construct, displacement of this fragment may have implications for rotation of the forearm through the distal radioulnar joint. Clinical relevanceSurgeons should consider the utilization of full-length unicortical locking screws to ensure adequate fixation of the dorsal ulnar corner.

A Screw Length of 14 mm Is Sufficient to Avoid the Physis During Juvenile Osteochondritis Dissecans Lesion Repair but This Can Vary Based on Age and Region of the Distal Femur

A Screw Length of 14 mm Is Sufficient to Avoid the Physis During Juvenile Osteochondritis Dissecans Lesion Repair but This Can Vary Based on Age and Region of the Distal Femur

Are different screw lengths associated with osteosynthesis quality in the region of the mental foramen?

AbstractIntroductionThe use of two monocortical malleable 04‐hole miniplates, placed above and below the mental foramen, has been indicated to prevent the adverse effects of tension and torsion forces on fracture healing. To obtain good fixation in the mandible's outer cortex screws, 5–8 mm long have been recommended. However, studies have shown thicknesses in the mental foramen region of up to 3 mm, meaning the length of the screw could be a risk to nerve or tooth root damage. The purpose of this study is to identify the influence of screw length on osteosynthesis quality in the region of the mental foramen.Materials and Methods10 synthetic polyurethane human lower jaw replicas were subjected to a linear loading test to evaluate fixation techniques with 5 and 10 mm of displacement. In the photoelastic analysis, 02 lower jaw models were made of photoelastic resin and subjected to linear loading in the fixation technique with 10 mm of displacement. Two 04‐hole miniplates in the region of the mental foramen either fixed completely with 4 mm screws (group 1) or with 5 mm screws in the tension zone and 8 mm screws in the compression zone (group 2). The variables were registered for peak load and peak displacement, and final load and final displacement. One‐way analysis of variance (ANOVA) was applied, followed by the Tukey test, with a significance of 5% (p = 0.05) for the comparisons between the means.ResultsConsidering 95% confidence intervals, the mechanical test showed no statistical differences in peak load between the fixations groups. In the photoelastic analysis, the fringes were concentrated on the distal segment of the fracture in both groups.ConclusionDue to the lack of statistical difference in the biomechanical and photoelastic tests, considering the methodologic limitation, our study indicates a tendency of advantage toward the treatment of fractures with two 04‐hole plates, fixed with 4 mm screws, to minimize complications like tooth or nerve damage. In vivo studies are needed to verify the convergence of the results of in vitro studies to evaluate the resistance and stability in real masticatory forces.

A 3D-CT Study of the Cortical Bone Trajectory Screw Placement Parameters Based on Lumbar CT.

The cortical bone trajectory (CBT) technology is an effective substitute for traditional pedicle screw (PS) technology. However, there is still controversy about the CBT screw technology placement strategy. The objective of this study was to simulate cortical screw placement with the help of three-dimensional (3D) software, to discuss the differences in screws between genders and vertebral segments, and to explore a safer and more efficient strategy for cortical screw placement. Mimics Medical software was used to construct a 3D model of the lumbar spine, and the placement of CBT screws was simulated. The volume of each vertebral body from L1 to L5, the pedicle isthmus height (IH), the pedicle isthmus width (IW), and the sagittal vertebral distance (SAVD) were measured. The transverse distance (TD) and the longitudinal distance (LD) between the ideal starting point (SP) and the clinical SP (the intersection Q of the midline of the superior articular process and the horizontal line 1 mm below the transverse process) were measured. The cephalad angle (CA), lateral angle (LA), maximum screw diameter (MSD), maximum screw length (MSL) of each trajectory of the L1 to L5 vertebral bodies, and the percentage of the screw insertion depth (PSID) into the vertebral body were measured. Data were statistically analyzed using Student's t-test, one-way analysis of variance (ANOVA), and Tukey's test. Vertebral anatomical parameters and CBT screw parameters differed between males and females. Female patients had lower IH, IW, SAVD, CA, LA, MSD, and MSL than males. IH was greatest in L1 (male, 17.81 mm; female, 16.12 mm) and the smallest in L5 (male, 14.11 mm; female, 13.05 mm). IW was smallest in L1 (male, 8.89 mm; female, 7.37 mm) and greatest in L5 (male, 16.59 mm; female, 15.43 mm). The MSD of males was smallest in L1 (6.05 mm) and greatest in L3 (7.06 mm); the MSD of females was smallest in L1 (5.13 mm) and greatest in L4 (6.64 mm). MSL was greatest at L3 (male, 33.63 mm; female, 32.28 mm) and smallest at L5 (male, 31.25 mm; female, 29.97 mm). CA was smallest in L1 (male, 22.80°; female, 21.92°) and greatest in L3 (male, 25.29°; female, 24.33°). LA was smallest in L1 (male 12.37°, female 11.27°) and greatest in L5 (male 13.56°, female 12.96°). Among the males, TD was smallest at L1 (-0.51 mm) and greatest at L5 (1.37 mm), while LD was greatest at L2 (3.46 mm) and smallest at L5 (2.40 mm). In females, TD was greatest at L1 (0.12 mm) and smallest at L3 (-0.51 mm), while LD was greatest at L1 (3.69 mm) and smallest at L5 (2.08 mm). In the overall sample, the incidence of SAVD and PSID gradually increased from L1 to L5. The optimal screw placement strategy for CBT screws varies significantly according to sex and vertebral body segments, particularly noting the specificity of screw placement at L5. The optimal screw placement strategy should be selected based on the patient's sex and segment characteristics before surgery to maximize the safety and accuracy of CBT screw placement.

Risk Factors for Plate Infection, Exposure, and Removal in Mandibular Reconstruction.

Mandibular plate reconstruction (MPR) is often indicated after tumor ablation, osteoradionecrosis excision, and traumatic bone loss to restore oral functionality and facial cosmetics. There are limited analyses identifying risk factors that lead to plate infection (PIn), exposure, and removal ("plate complications"). Retrospective cohort study. Academic tertiary medical center. Patients who underwent MPR from 2013 to 2022 were identified. Risk factors for plate complications were analyzed based on demographic, clinical, intraoperative, and postoperative factors. Multivariable analysis was conducted with logistic regression. Survival analysis was conducted with a Cox model. Of the 188 patients analyzed, 48 (25.5%) had a plate complication [infection: 22 (11.7%); exposure: 23 (12.2%); removal: 35 (18.6%)]. Multivariate analysis revealed predictive associations between at least 1 plate complication and the following variables: smoking status, soft tissue defect size, number of plates, average screw length, and various postoperative complications. Other associations approached the threshold for significance. Prior and adjuvant radiation therapy, type of free flap, stock versus custom plates, and perioperative antibiotic prophylaxis regimens were not associated with plate complications. No plate complication was independently associated with lower overall survival. PIn (hazard ratio, HR: 7.99, confidence interval, CI [4.11, 15.54]) and exposure (HR: 3.56, CI [1.79, 7.08]) were independently associated with higher rates of plate removal. Plate complications are relatively common after MPR. Smoking history, specific disease characteristics, hardware used during surgery, and postoperative complications may help identify higher-risk patients, but additional larger-scale studies are needed to validate our findings and resolve discrepancies in the current literature.