Feasibility of a novel type of complex anterior cervical fixation by using Mimics software / 中国骨伤

OBJECTIVE@#To investigate the feasibility of mimics software in analyzing a new type of complex anterior cervical fixation -- anterior transpedicular screw fixation+zero notch internal fixation.@*METHODS@#From January 2021 to September 2022, 50 normal pedestrians who underwent cervical spine CT scanning were selected for C1-C7 segment scanning, including 27 males and 23 females, aged from 25 to 65 years old with an average of (46.0 ± 9.0) years old. The dicom format is exported and engraved into the CD, and use the mimics software to perform 3D reconstruction of each segment. A simulated screw is placed on the image according to the critical value of zero notch screw (head and tail angle 44°, internal angle 29°). The position of zero notch screw in each segment is observed to determine the feasibility of anterior transpedicular screw fixation plus zero notch internal fixation.@*RESULTS@#For the upper zero notch screws the three-dimensional images of the cervical spine across all 50 subjects within the C3-C7 segments demonstrated safe position, with no instances of intersection with ATPS. For the lower zero notch screw, in C3-C4 and C4-C5, 4 out of 50 subjects are in the safe position in the three-dimensional images of cervical vertebrae, and 46 cases could achieve secure screw placement when the maximum caudal angle is(32.3±1.9) ° and (36.1±2.2) °, respectively. In C5-C6 and C6-C7 segments, no lower zero notch screws intersected with ATPS, and all screws are in safe positions.@*CONCLUSION@#Lower cervical anterior pedicle screw fixation plus zero notch internal fixation can achieve successful nail placement through the selected entry point and position.

Finite element analysis of the stability of Mason type Ⅲ radial head fracture fixed with three cross-bridge headless compression screw and locking plate / 中国骨伤

OBJECTIVE@#To compare the biomechanical stability of three cross-bridge headless compression screws and locking plates in the fixation of Mason type Ⅲ radial head fractures by finite element method.@*METHODS@#Using reverse modeling technology, the radial CT data and internal fixation data of a healthy 25-year-old male were imported into the relevant software. Three-dimensional finite element model of 3 cross-bridge headless compression screws and locking plates for MasonⅢ radial head fractures were established, and the radial head was loaded with 100 N axial loading. The maximum displacement, maximum Von Mises stress and stress distribution of the two groups were compared.@*RESULTS@#The maximum displacements of the three cross-bridge screws group and locking plate group were 0.069 mm and 0.087 mm respectively, and the Von Mises stress peaks were 18.59 MPa and 31.85 MPa respectively. The stress distribution of the three screws group was more uniform.@*CONCLUSION@#Both internal fixation methods can provide good fixation effect. CoMPared with the locking plate fixation method, the 3 cross-bridge headless compression screws fixation is more stable and the stress distribution is more uniform.

Single Kocher-Langenbeck approach combined with anterograde channel screw technique in treatment of acetabular transverse and posterior wall fractures / 中国修复重建外科杂志

OBJECTIVE@#To assess the effectiveness of the single Kocher-Langenbeck approach combined with anterograde channel screw technique for the treatment of acetabular transverse and posterior wall fractures.@*METHODS@#Between March 2020 and October 2022, 17 cases of acetabular transverse and posterior wall fractures were treated with the single Kocher-Langenbeck approach combined with anterograde channel screw technique. There were 11 males and 6 females, with an average age of 53.6 years (range, 42-64 years). Causes of injury included traffic accident in 12 cases, and falling from height in 5 cases. The time from injury to operation ranged from 4 to 16 days with an average of 8.8 days. The operation time, intraoperative blood loss, and fluoroscopy frequency were recorded; X-ray films were reviewed regularly after operation to observe the fracture healing, and postoperative complications were recorded. At last follow-up, Matta score was used to evaluate the reduction of fracture, Harris score and modified Merle D'Aubigné-Postel scores system were used to evaluate the hip joint function.@*RESULTS@#The operation time was 150-230 minutes (mean, 185.9 minutes), the intraoperative blood loss was 385-520 mL (mean, 446.2 mL), and the fluoroscopy frequency was 18-34 times (mean, 27.5 times). Postoperative fat liquefaction occurred in 1 case and the other incisions healed by first intention; 3 cases had limb numbness after operation, and the symptoms disappeared after active symptomatic treatment; no urogenital system and intestinal injury occurred. All patients were followed up 12-28 months (mean, 19.9 months). Bone union was achieved in all cases with an average healing time of 10.8 weeks (range, 8-14 weeks). There was no complication such as loosening and breakage of internal fixators. At last follow-up, according to Matta score, 12 cases achieved anatomic reduction, 3 satisfactory reduction, and 2 fair reduction, the satisfactory rate was 88.2%; according to Harris hip function score, 12 cases were excellent, 3 good, and 2 fair, the excellent and good rate was 88.2%; according to the modified Merle D'Aubign Aubigné-Postel scoring system, the results were excellent in 11 cases, good in 3 cases, and fair in 3 cases, with an excellent and good rate of 82.4%.@*CONCLUSION@#The single Kocher-Langenbeck approach combined with anterograde channel screw technique is a minimally invasive method for the treatment of acetabular transverse and posterior wall fractures with less complications, simple operation, and satisfactory effectiveness.

O-arm navigation versus C-arm navigation for guiding percutaneous long sacroiliac screws placement in treatment of Denis type Ⅱ sacral fractures / 中国修复重建外科杂志

OBJECTIVE@#To compare the effectiveness of O-arm navigation and C-arm navigation for guiding percutaneous long sacroiliac screws in treatment of Denis type Ⅱ sacral fractures.@*METHODS@#A retrospective study was conducted on clinical data of the 46 patients with Denis type Ⅱ sacral fractures between April 2021 and October 2022. Among them, 19 patients underwent O-arm navigation assisted percutaneous long sacroiliac screw fixation (O-arm navigation group), and 27 patients underwent C-arm navigation assisted percutaneous long sacroiliac screw fixation (C-arm navigation group). There was no significant difference in gender, age, causes of injuries, Tile classification of pelvic fractures, combined injury, the interval from injury to operation between the two groups ( P>0.05). The intraoperative preparation time, the placement time of each screw, the fluoroscopy time of each screw during placement, screw position accuracy, the quality of fracture reduction, and fracture healing time were recorded and compared, postoperative complications were observed. Pelvic function was evaluated by Majeed score at last follow-up.@*RESULTS@#All operations were completed successfully, and all incisions healed by first intention. Compared to the C-arm navigation group, the O-arm navigation group had shorter intraoperative preparation time, placement time of each screw, and fluoroscopy time, with significant differences ( P<0.05). There was no significant difference in screw position accuracy and the quality of fracture reduction ( P>0.05). There was no nerve or vascular injury during screw placed in the two groups. All patients in both groups were followed up, with the follow-up time of 6-21 months (mean, 12.0 months). Imaging re-examination showed that both groups achieved bony healing, and there was no significant difference in fracture healing time between the two groups ( P>0.05). During follow-up, there was no postoperative complications, such as screw loosening and breaking or loss of fracture reduction. At last follow-up, there was no significant difference in pelvic function between the two groups ( P>0.05).@*CONCLUSION@#Compared with the C-arm navigation, the O-arm navigation assisted percutaneous long sacroiliac screws for the treatment of Denis typeⅡsacral fractures can significantly shorten the intraoperative preparation time, screw placement time, and fluoroscopy time, improve the accuracy of screw placement, and obtain clearer navigation images.

Morphometric study and anatomical variation with its incidence of foramina transversaria on the lower cervical vertebrae / Estudio morfométrico y variación anatómica con la incidencia de forámenes transversos en las vértebras cervicales inferiores

SUMMARY: Anatomical variation of the foramina transversaria (FT) is associated with vertebral neurovascular symptoms and can cause complications after lower spine surgery, especially cervical pedicle screw (CPS) insertion. FT variation has been documented and classified in various populations, as this information can help increase cervical stability in subaxial vertebral surgery. Although the morphometry of the upper cervical spine in Thai populations has been reported, there have yet been no studies examining the features of FT. The FT of dried cervical spines (C3-C7; left and right side; n = 107, male = 53 and female = 54) were examined for morphological variation, and their anteroposterior (AP) and transverse (T) diameters were measured using a digital vernier caliper. Morphometric data and variations were compared by sex and lateral side. It was that the C3-C6 FT in both sexes were round, and the C7 FT was elliptical with an oblique right side. FT diameters did not differ significantly by sex except for the AP diameters of C6-C7 and for T diameters of C4 and C7. The left AP diameters of C3-C6 were significantly longer than the right, as were the T diameters of C4 and C7 FT. Additionally, T diameter was significantly longer than that of the AP, except that of the left C6 in male spines, which did not differ from the AP. Most FT examined were round. These findings should be considered in the provisional diagnosis of vertebral neurovascular symptoms caused by FT variation as well as that of neurovascular damage after cervical pedicle screw placement.

La variación anatómica del foramen transverso (FT) se asocia con síntomas neurovasculares vertebrales y puede causar complicaciones después de la cirugía de columna cervical inferior, especialmente la inserción de tornillos pediculares cervicales (TPC). La variación del FT se ha documentado y clasificado en varias poblaciones, ya que esta información puede ayudar a aumentar la estabilidad cervical en la cirugía vertebral subaxial. Aunque se ha informado sobre la morfometría de la columna cervical superior en poblaciones tailandesas, aún no se han realizado estudios que examinen las características de FT. Se examinó la variación morfológica del FT de vértebras cervicales secas (C3-C7; lado izquierdo y derecho; n = 107, hombres = 53 y mujeres = 54), y se midieron sus diámetros anteroposterior (AP) y transverso (T) usando un pie de metro digital. Se compararon datos morfométricos y variaciones por sexo y lado. Los FT de C3-a C6 en ambos sexos eran redondos, y el FT C7 era elíptico con el lado derecho oblicuo. Los diámetros del FT no difirieron significativamente por sexo excepto para los diámetros AP de C6- C7 y para los diámetros transversos de C4 y C7. Los diámetros AP izquierdos de C3-C6 eran significativamente más largos que los del lado derecho, al igual que los diámetros transversos de C4 y C7. Además, el diámetro transverso fue significativamente mayor que el AP, excepto el C6 izquierdo en las vértebras de hombres, que no difirió del AP. La mayoría de los FT examinados eran redondos. Estos hallazgos deben ser considerados en el diagnóstico provisional de síntomas neurovasculares vertebrales causados por la variación del FT, así como en el de daño neurovascular tras la colocación de tornillos pediculares cervicales.

The effect of medial calcar screws on the treatment of Neer type Ⅲ proximal humeral fracture with Multiloc intramedullary nailing / 中华创伤骨科杂志

Objective:To investigate the effect of the use of medial calcar screws on the treatment of Neer type Ⅲ proximal humeral fracture with Multiloc intramedullary nailing.Methods:A retrospective study was conducted to analyze the data of 36 patients with Near type Ⅲ fracture of the proximal humerus who had received Multiloc intramedullary nailing at Department of Upper Limbs, Sichuan Orthopedic Hospital from January 2016 to December 2021. There were 6 males and 30 females with an age of (63.9±5.3) years. They were divided into 2 groups according to whether medial calcar screws had been used or not. There were 17 cases in the group without medial calcar screws and 19 cases in the group with medial calcar screws. The 2 groups were compared in terms of flexion and lifting, external rotation, internal rotation and back touch, visual analogue scale (VAS), American Shoulder and Elbow Surgeons (ASES) score, Constant-Murley score for shoulder function (Constant score), neck shaft angle, and incidence of complications at the last follow-up.Results:There were no statistically significant significances in the preoperative general data between the 2 groups, indicating comparability between the groups ( P>0.05). The 36 patients were followed up for 13.5(12.0,19.8) months after surgery. The flexion and lifting, external rotation, internal rotation and back touch, VAS, ASES score, Constant score, neck shaft angle at the last follow-up in the group without medial calcar screws were, respectively, 134.1°±8.4°, 32.1°±5.3°, 14.0 (13.0, 15.5) , 0.0 (0.0, 1.0), 78.2±5.2, 78.0±5.8, and 137.6°±8.1°, insignificantly different from those in the group with medial calcar screws [134.7°±6.1°, 35.0(30.0, 35.0)°, 14.0(13.0, 15.0), 1.0 (0.0, 1.0), 78.2±5.4, 76.7±4.5, and 136.9°±6.4°] ( P>0.05). Postoperative complications occurred in 6 patients in each group, showing no statistically significant difference between the 2 groups ( P=1.000). Conclusion:The use of medial calcar screws has no significant impact on the postoperative shoulder function and incidence of complications in the treatment of Neer type Ⅲ fractures of the proximal humerus with Multiloc intramedullary nailing.

Feasibility of using cortical bone trajectory screws in osteoporotic thoracolumbar fixation based on evaluation of bone CT values at bone-screw interface / 中华创伤骨科杂志

Objective:To evaluate the feasibility of using cortical bone trajectory (CBT) screws in the osteoporotic thoracolumbar fixation by comparing the bone CT values at the bone-screw interface between traditional trajectory (TT) screws and CBT screws in patients with different bone densities.Methods:The high-resolution CT imaging data of thoracolumbar segments following thoracic or lumbar spine fractures from April 2020 to October 2022 were collected at The Second Hospital Affiliated to Wenzhou Medical University for retrospective analysis. They were divided into 3 groups: a normal bone mass group, an osteopenia group and an osteoporosis group. From each group 30 cases were chosen (90 cases in total, 36 males and 54 females). All the data were imported into Mimics 18.0 for three-dimensional bone reconstruction in which placement of TT and CBT screws was simulated on the vertebrae from T10 to L2 (non-fractured vertebrae). Regions of interest (ROI) where each simulated screw intersected the bone were segmented to measure their CT bone values. For each vertebra in each group, the relative difference percentage in average CT value of ROI between TT and CBT screws was calculated. The CT values of ROI were compared in the same group between TT and CBT screws from T10 to L2; the CT values of ROI were compared in the same screws among the 3 groups from T10 to L2; the CT values of ROI were compared between the CBT screws in the osteopenia and osteoporosis groups and the TT screws in the normal bone mass group; the relative difference percentages in average CT value of ROI between CBT and TT screws were compared between the 3 groups from T10 to L2.Results:The average CT value of ROI for CBT screws was significantly higher than that for TT screws from T10 to L2 in every group ( P< 0.001); as for the CT values of ROI for CBT and TT screws from T10 to L2, the osteoporosis group<the osteopenia group<the normal bone mass group ( P<0.001); from T10 to L2, the CT value of ROI for CBT screws in the osteopenia group was significantly higher than that for TT screws in the normal bone mass group ( P<0.001); the CT value of ROI for CBT screws in the osteoporosis group was not significantly different from that for TT screws in the normal bone mass group ( P>0.05). At T10, T12, and L1, the relative difference percentage in average CT value of ROI between CBT and TT screws was significantly higher in the osteopenia and osteoporosis groups than that in the normal bone mass group ( P<0.05), but there was no such a difference between the osteopenia and the osteoporosis groups ( P>0.05). At T11 and L2, there was no significant difference between the 3 groups in the relative difference percentage in average CT value of ROI between CBT and TT screws ( P>0.05). Conclusions:As bone mass decreases, both CBT and TT screws lead to a significant decrease in the bone density at the bone-screw interface. In patients with osteoporosis, CBT screws can still lead to a higher bone density at the bone-screw interface than TT screws, thus providing a higher strength at the bone-screw interface.

Comparison of efficacy of O-arm assisted and free-hand pedicle screw placement in the treatment of AO type C thoracolumbar fracture / 中华创伤杂志

Objective:To compare the effect of O-arm assisted and free-hand pedicle screw placement in the treatment of AO type C thoracolumbar fracture.Methods:A retrospective cohort study was used to analyze the clinical data of 34 patients with type C thoracolumbar fracture admitted to Henan Provincial People′s Hospital from January 2018 to June 2021, including 23 males and 11 females; aged 42-63 years [(50.4±7.4)years]. The fracture was located at T 11 in 4 patients, T 12 in 10, L 1 in 12, L 2 in 6, T 11~12/L 1 in 1 and T 12/L 1 in 1. Posterior reduction and internal fixation was carried out for all patients, of whom 18 were treated with O-arm assisted pedicle screw placement (navigation group) and 16 with free-hand pedicle screw placement (free-hand group). The operation time, single screw placement time, intraoperative bleeding volume, operation mode and screw placement accuracy were compared between the two groups. The kyphotic Cobb angle, visual analogue score (VAS) and American Spinal Injury Association (ASIA) score were compared between the two groups before operation, at 1 week after operation, at 3 months after operation and at the last follow-up. Postoperative complications were observed. Results:All patients were followed up for 12-29 months [(16.8±6.1)months]. There was no significant difference between the two groups in the operation time, intraoperative bleeding volume and operation mode (all P>0.05). The single screw placement time was (9.4±1.6)minutes in navigation group, but was (10.8±1.5)minutes in free-hand group ( P<0.05). The screw placement accuracy was 97.4% in navigation group, but was 81.5% in free-hand group ( P<0.01). The kyphotic Cobb angle and VAS had no significant differences between the two groups before operation (all P>0.05). The kyphotic Cobb angle in navigation group and free-hand group was (4.3±1.1)° and (5.9±1.1)° at 1 week after operation, (4.4±1.2)° and (5.7±1.3)° at 3 months after operation, and (4.4±1.2)° and (6.8±0.9)° at the last follow-up, decreased significantly from that before operation [(21.8±3.1)°, (22.2±3.2)°] (all P<0.01). The kyphotic Cobb angle in navigation group was significantly lower than that in free-hand group at 1 week, 3 months after operation and at the last follow-up (all P<0.01). The VAS in navigation group and free-hand group was (3.2±0.7)points and (4.1±0.7)points at 1 week after operation, (2.4±0.6)points and (3.0±0.8)points at 3 months after operation, and (1.8±0.9)points and (2.6±0.7)points at the last follow-up, decreased significantly from that before operation [(8.4±0.8)points, (8.3±0.9)points] (all P<0.01). The VAS in navigation group was significantly lower than that in free-hand group at 1 week, 3 months after operation and at the last follow-up (all P<0.01). The ASIA score showed no significant difference within and between the two groups before operation, at 1 week, 3 months after operation and at the last follow-up (all P>0.05). Postoperative incision infection occurred in 1 patient in both groups ( P>0.05). Implant failure such as loosening or displacement was not observed in navigation group, and only occurred in 2 patients in free-hand group ( P>0.05). Conclusion:Compared with free-hand pedicle screw placement, O-arm assisted pedicle screw placement in the treatment of AO type C thoracolumbar fracture has advantages of rapid and accurate screw placement, good reduction and notable pain relief.

Dynamic Fixation versus Static Screw Fixation for Syndesmosis Injuries in Pronation External Rotation Ankle Fractures: A Retrospective Case Control Study

@#Introduction: The current standard treatment for ankle syndesmosis injury is static screw fixation. Dynamic fixation was developed to restore the dynamic function of the syndesmosis. The purpose of this study was to determine that which of static screw fixation and dynamic fixation is better for treatment of ankle syndesmosis injury in pronationexternal rotation fractures. Materials and methods: Thirty patients were treated with dynamic fixation (DF group) and 28 patients with static screw fixation (SF group). The primary outcome was Olerud–Molander Ankle Outcome Score. The secondary outcome were Visual Analogue Scale score and American Orthopedic Foot and Ankle Society score, radiographic outcomes, complications and cost effectiveness. To evaluate the radiographic outcome, the tibiofibular clear space, tibiofibular overlap, and medial clear space were compared using the pre-operative and last follow-up plain radiographs. To evaluate the cost effectiveness, the total hospital cost was compared between the two groups Results: There was no significant difference in primary outcome. Moreover, there were no significant difference in secondary outcome including Visual Analogue Scale score and American Orthopedic Foot and Ankle Society score and radiographic outcome. Two cases of reduction loss and four cases of screw breakage were observed in the SF group. No complication in the DF group was observed. Dynamic fixation was more cost effective than static screw fixation with respect to the total hospital cost. Conclusion: Although dynamic fixation provided similar clinical and radiologic outcome, dynamic fixation is more cost effective with fewer complications than static screw fixation in ankle syndesmosis injury of pronation-external rotation fractures.

Combined anterior and posterior ring fixation versus posterior ring fixation alone in the management of unstable Tile B and C pelvic ring injuries: A randomized controlled trial / 中华创伤杂志(英文版)

PURPOSE@#Combined anterior and posterior ring (APR) fixation is classically performed in Tile B2 and C1 injuries to achieve superior biomechanical stability. However, the posterior ring (PR) is the main weight bearing portion that is responsible for weight transmission from the upper parts of the body to the lower limbs through the sacrum and the linea terminalis. It is hypothesized that isolated PR fixation can achieve comparable radiological and clinical outcomes to APR fixation. Therefore, we conducted this study to compare the two fixation principles in managing Tile B2 and C1 injuries.@*METHODS@#Our study included 20 patients with Tile B2 injuries and 20 patients with Tile C1 injuries. This study was a randomized control single-blinded study via computerized random numbers with a 1:1 allocation by using random block method. The study was performed at a level one trauma center. A total of 40 patients with Tile B2 and C1 injuries underwent combined APR or isolated PR fixation (Group A and B, respectively). Matta & Tornetta radiological principles and Majeed pelvic scoring system were used for the assessment of primary outcomes and postoperative complications. Secondary outcomes included operative time, amount of blood loss, intraoperative assessment of reduction, need of another operation, length of hospital stay, ability to weight bear postoperatively and pain control metrics. We used student t-test to compare the difference in means between two groups, and Chi-square test to compare proportions between two qualitative parameters. We set the confidence interval to 95% and the margin of error accepted to 5%. So, p ≤ 0.05 was considered statistically significant.@*RESULTS@#The mean follow-up duration was 18 months. The operative time (mean difference 0.575 h) and the intraoperative blood loss (mean difference 97.5 mL) were lower in Group B. Also, despite the higher frequency of rami displacement before union in the same group, there were no significant differences in terms of radiological outcome (excellent outcome with OR = 2.357), clinical outcome (excellent outcome with OR = 2.852) and postoperative complications assessment (OR = 1.556) at last follow-up.@*CONCLUSION@#The authors concluded that isolated PR fixation could favorably manage Tile B2 and C1 pelvic ring injuries with Nakatani zone II pubic rami fractures and intact inguinal ligament. Its final radiological and clinical outcomes and postoperative complications were comparable to combined APR fixation, but with less morbidity (shorter operation time, lower amount of blood, and no records of postoperative wound infection).

Feasibility analysis and nail planning ofS2 iliac crest screw placement in children / 中国骨伤

OBJECTIVE@#To evaluate the feasibility of S2 alar iliac screw insertion in Chinese children using computerized three-dimension reconstruction and simulated screw placement technique, and to optimize the measurement of screw parameters.@*METHODS@#A total of 83 pelvic CT data of children who underwent pelvic CT scan December 2018 to December 2020 were retrospectively analyzed, excluding fractures, deformities, and tumors. There were 44 boys and 39 girls, with an average age of (10.66±3.52) years, and were divided into 4 groups based on age (group A:5 to 7 years old;group B:8 to 10 years old;group C:11-13 years old;group D:14 to 16 years old). The original CT data obtained were imported into Mimics software, and the bony structure of the pelvis was reconstructed, and the maximum and minimum cranial angles of the screws were simulated in the three-dimensional view with the placement of 6.5 mm diameter S2 alar iliac screws. Subsequently, the coronal angle, sagittal angle, transverse angle, total length of the screw, length of the screw in the sacrum, width of the iliac, and distance of the entry point from the skin were measured in 3-Matic software at the maximum and minimum head tilt angles, respectively. The differences among the screw parameters of S2 alar iliac screws in children of different ages and the differences between gender and side were compared and analyzed.@*RESULTS@#In all 83 children, 6.5 mm diameter S2 iliac screws could be placed. There was no significant difference between the side of each screw placement parameter. The 5 to 7 years old children had a significantly smaller screw coronal angle than other age groups, but in the screw sagittal angle, the difference was more mixed. The 5 to 7 years old children could obtain a larger angle at the maximum head tilt angle of the screw, but at the minimum cranial angle, the larger angle was obtained in the age group of 11 to 13 years old. There were no significant differences among the age groups. The coronal angle and sagittal angle under maximum cephalic angle and minimum cranial angle of 5 to 7 years old male were (40.91±2.91)° and (51.85±3.75)° respectively, which were significantly greater than in female. The coronal angle under minimum cranial angle was significantly greater in girls aged 8-10 years old than in boys. For the remaining screw placement angle parameters, there were no significant differences between gender. The differences in the minimum iliac width, the screw length, and the length of the sacral screws showed an increasing trend with age in all age groups. The distance from the screw entry point to the skin in boys were significantly smaller than that of girls. The minimum width of the iliac in boys at 14 to 16 years of age were significantly wider than that in girls at the same stage. In contrast, in girls aged 5 to 7 years and 11 to 13 years, the screw length was significantly longer than that of boys at the same stage.@*CONCLUSION@#The pelvis of children aged 5 to 16 years can safely accommodate the placement of 6.5 mm diameter S2 alar iliac screws, but the bony structures of the pelvis are developing and growing in children, precise assessment is needed to plan a reasonable screw trajectory and select the appropriate screw length.

Risk prevention and treatment of implant-supported central screw fracture / 口腔医学

@#In the complications of dental implant treatment, the mechanical complications, such as central screw breakage, are often complex and serious. This article analyzes factors that affect the loosening of the central screw. Understanding relevant risk factors can prompt doctors to take corresponding strategies to reduce the possibility of complications in clinical operations. After encountering broken cases, this paper also gives some ideas and methods of treatment, and finally summarizes clinical suggestions for preventing the central screw fracture.

Biomechanical Study on Different fixation Methods of Cannulated Screws for Posterior Malleolus Fracture / 医用生物力学

Objective To study biomechanical effects of cannulated screws at different fixation angles on posterior malleolus fracture based on finite element method, so as to determine the best fixation method of cannulatedscrew. Methods The finite element model of ankle joint, including tibia, fibula, astragalus, corresponding cartilage and ligaments was reconstructed using CT images, and 1 / 2 posterior malleolus fracture model was established on the basis of verifying its validity. The biomechanical effects of cannulated screw fixation on posterior malleolus fracture fixation model were analyzed. Results Compared with 0°,5°,10°,20° fixation model, the 15° fixation model had the smallest displacement. The screw stress of 15° fixation model was lower than that of 5°, 10°, 20° fixation model, and higher than that of 0° fixation model. But when the screw fixation angle was 0°, the peak contact pressure of ankle joint was much larger than that of normal ankle joint, which was easy to cause traumatic osteoarthritis. Conclusions Cannulated screw is safe and effective for treating posterior malleolus fracture which is less than 1 / 2 fragment size. The displacement and stress of the model are different at different fixation angles of screws. When the fixation angle of screw is 15°, the biomechanical stability is the best, which can be used to guide clinical operation.

Biomechanical Study on Atlantoaxial Dislocation Combined with Basilar Invagination by Different Posterior Internal Fixation Methods / 医用生物力学

Objective To investigate biomechanical differences of two posterior occipitocervical internal fixation techniques for treating basilar invagination with atlantoaxial dislocation (BI-AAD). Methods Intra-articular cage + posterior occipital plate+C2 pedicle screw (Cage+C2PS+OP), and intra-articular cage+C1 lateral mass screw+C2PS (Cage+C1LMS+C2PS) models were established based on occipitocervical CT data of the BI-AAD and clinical operation scheme, and the stability of atlantoaxial joint and stress distribution characteristics of C2 endplate and implanted instruments under different motion states were analyzed. Results Compared with the Cage+C1LMS+C2PS model, the atlantoaxial range of motion ( ROM) under flexion, extension, lateral bending and axial rotation in the Cage+C2PS+OP model were reduced by 5. 26% , 33. 33% , 43. 75% , -5. 56% , and stress peak of screw-rod fixation system were reduced by 47. 81% , 60. 90% , 48. 45% , 39. 14% , respectively. Under two internal fixation modes, stresses of C2 endplate and cage were mainly distributed on the compressive side during the motion, and both the screw-bone interface and the caudal side of screw subjected to large loading. Conclusions Two internal fixation methods could provide similar stability. However, the stress concentration of screw-rod system was more obvious and the possibility of screw loosening and fracture was greater under Cage+ C1LMS+C2PS fixation.

Biomechanical Comparison of Internal Fixation by Traditional and Cortical Bone Trajectory Pedicle Screw / 医用生物力学

Objective To compare the effects of cortical bone trajectory ( CBT) and traditional trajectory ( TT)pedicle screw internal fixation on the range of motion (ROM) and rod system stress of normal and osteoporotic(OP) spines. Methods The L3-S1 finite element models of normal and OP spines were established. The screwrod system with two kinds of trajectory was used for internal fixation of the L4-5 segment, so as to simulate sixphysiological loads, namely, flexion, extension, left / right bending, left / right rotation. The effects of two internalfixation methods on ROMs and maximum equivalent stress of screws in normal and OP spines were compared.Results For both bone conditions, CBT and TT significantly reduced ROM of the fixed segment (L4-5) and theentire segment of lower lumbar spine ( L3-S1). However, the ROM decline of CBT group was slightly smaller than that of TT group, and their ROMs were similar under flexion and extension, but the ROM differences were significant under lateral bending and axial rotation. In addition, for both the normal and OP spine models, themaximum equivalent stress of screws in CBT group was significantly higher than that in TT group. Compared withTT group, the screw stress of CBT group in normal spine model under flexion and extension, lateral bending,axial rotation was increased by 27% , 268% and 58% , respectively. However, when CBT technique was used atthe same time, the OP spine model had a smaller screw stress distribution than the normal spine model.Conclusions Compared with TT technique, CBT technique can achieve higher screw stress under OP conditionand reduce screw stress concentration under normal bone condition. In addition, CBT slightly increases ROMs of each segment, which is conducive to recovery of spinal physiological function after surgery. Lateral bending and axial rotation can produce negative mechanical effects, and these two physiological loads should be avoided.

Percutaneous pedicle screw fixation combined expandable tubular retractor in the treatment of spinal metastases / 北京大学学报(医学版)

OBJECTIVE@#To investigate the effectiveness of percutaneous pedicle screw fixation combined expandable tubular retractor in the treatment of patients with spinal metastases.@*METHODS@#In the study, 12 patients of spinal metastases treated with percutaneous pedicle screw fixation combined expandable tubular retractor in our hospital were retrospectively reviewed between June 2017 and October 2019. Among the 12 patients, 9 were males and 3 were females; the median age was 62.5 years [(65.1±2.9) years]. The decompression segment of 7 patients was located at the lower thoracic spine (including 1 patient with incomplete paraplegia) and the decompression segment of 5 patients was located at the lumbar spine; Tomita score was 6.0±0.6. Perioperative data of the patients were reviewed. Visual analog scale (VAS score), Karnofsky score, and Eastern Cooperative Oncology Group (ECOG) score were compared before and after surgery. The patient's survival, adjuvant treatment, and internal fixation failure were observed in the follow-up period.@*RESULTS@#All the 12 patients had a successful operation with percuta-neous pedicle screw fixation combined expandable tubular retractor. The average operative time, blood loss, and blood transfused of the patients were (247.0±14.6) min, (804.2±222.3) mL and (500.0±100.0) mL, respectively. The average amount of drainage was (240.8±79.3) mL. Drainage tubes were pulled out early postoperative [(3.2±0.3) d], allowing early mobilization. The patients discharged (7.8±0.8) d postoperative. All the patients were followed up for 6-30 months, and the average overall survival time was (13.6±2.4) months. During the follow-up period, 2 patients experienced screw displacement, the internal fixation was stable after conservative treatment and no revision surgery was performed. The VAS of the patients was 7.1±0.2 before surgery, which decreased to 2.3±0.1 and 2.8±0.4 at 3 and 6 months after surgery (P < 0.05). The Karnofsky score of the patients was 59.2±1.9 before surgery, which increased to 75.0±1.9 and 74.2±3.1 at 3 and 6 months after surgery (P < 0.05). The ECOG of the patients was 2.3±0.2 before surgery, which decreased to 1.7±0.1 and 1.7±0.2 at 3 and 6 months after surgery (P < 0.05).@*CONCLUSION@#For selected patients with spinal metastases, minimally invasive surgical treatment of spinal metastases (percutaneous pedicle screw internal fixation combined with expandable tubular retractor) can effectively relieve the clinical symptoms and improve the quality of life, with satisfactory clinical outcome.

Treatment of spinal burst fractures with pedicle screw fixation at high altitude area / 中国骨伤

OBJECTIVE@#According to the characteristics of spinal burst fractures in high-altitude areas and the local medical conditions, to explore the clinical efficacy of short-segment fixation with pedicle screws combined with screw placement in injured vertebrae in the treatment of thoracolumbar burst fractures.@*METHODS@#From August 2018 to December 2021, 12 patients with single-vertebral thoracolumbar burst fractures without neurological symptoms were treated with injured vertebral screw placement technique, including 7 males and 5 females;aged 29 to 54 years old, with an average of(42.50±7.95) years old;6 cases of traffic accident injury, 4 cases of high fall injury, 2 cases of heavy object injury;2 cases of T11, 4 cases of T12, 3 cases of L1, 2 cases of L2, and 1 case of L3. In the operation, screws were first placed in the upper and lower vertebrae of the fracture, pedicle screws were placed in the injured vertebra, and connecting rods were installed, and the fractured vertebral body was reset by positioning and distraction. Visual analogue scale (VAS) and Japanese Orthopedic Association (JOA) scoring were used to evaluate the changes in pain and quality of life of patients, and the kyphotic correction rate and correction loss rate of the injured segment were measured by X-ray.@*RESULTS@#All operations were successful without significant intraoperative complications. All 12 patients were followed up, the duration ranged from 9 to 27 months, with an mean of (17.75±5.79) months. VAS at 3 days after operation was significantly higher than that at admission (t=6.701, P=0.000). There was significant difference in JOA score between 9 months after operation and at admission (t=5.085, P=0.000). Three days after operation, Cobb angle was (4.42±1.16)°, and the correction rate was (82±5)% compared with (25.67±5.71)° at admission. Cobb angle was (5.08±1.24) °at 9 months after operation, with a corrected loss rate of (16±13)%. No loosening or breakage of internal fixation was found.@*CONCLUSION@#Under the high-altitude hypobaric and hypoxic environment, the effect of the operation should be ensured while reducing the trauma. The application of the technique of placing screws on the injured vertebra can effectively restore and maintain the height of the injured vertebra, with less bleeding and shorter fixed segments, which is an effective method.

Finite element analysis of PMMA bone cement reinforced screw plate fixation for osteoporotic proximal humeral fracture / 中国骨伤

OBJECTIVE@#With the help of finite element analysis, to explore the effect of proximal humeral bone cement enhanced screw plate fixation on the stability of internal fixation of osteoporotic proximal humeral fracture.@*METHODS@#The digital model of unstable proximal humeral fracture with metaphyseal bone defect was made, and the finite element models of proximal humeral fracture bone cement enhanced screw plate fixation and common screw plate fixation were established respectively. The stress of cancellous bone around the screw, the overall stiffness, the maximum stress of the plate and the maximum stress of the screw were analyzed.@*RESULTS@#The maximum stresses of cancellous bone around 6 screws at the head of proximal humeral with bone cement enhanced screw plate fixation were 1.07 MPa for No.1 nail, 0.43 MPa for No.2 nail, 1.16 MPa for No.3 nail, 0.34 MPa for No.4 nail, 1.99 MPa for No.5 nail and 1.57 MPa for No.6 nail. These with common screw plate fixation were:2.68 MPa for No.1 nail, 0.67 MPa for No.2 nail, 4.37 MPa for No.3 nail, 0.75 MPa for No.4 nail, 3.30 MPa for No.5 nail and 2.47 MPa for No.6 nail. Overall stiffness of the two models is 448 N/mm for bone cement structure and 434 N/mm for common structure. The maximum stress of plate appears in the joint hole:701MPa for bone cement structure and 42 0MPa for common structure. The maximum stress of screws appeared at the tail end of No.4 nail:284 MPa for bone cement structure and 240.8 MPa for common structure.@*CONCLUSION@#Through finite element analysis, it is proved that the proximal humerus bone cement enhanced screw plate fixation of osteoporotic proximal humeral fracture can effectively reduce the stress of cancellous bone around the screw and enhance the initial stability after fracture operation, thus preventing from penetrating out and humeral head collapsing.

Comparison of curative effect between percutaneous compression plate and cannulated compression screw in the treatment of displaced femoral neck fractures in young and middle-aged patients / 中国骨伤

OBJECTIVE@#To compare the efficacy of percutaneous compression plate and cannulated compression screw in the treatment of displaced femoral neck fractures in young and middle-aged patients.@*METHODS@#From January 2015 to July 2020, 68 young and middle-aged patients with displaced femoral neck fracture were retrospectively analyzed. Among them, 31 cases were fixed by percutaneous compression plate (PCCP), and 37 cases were fixed by cannulated compression screw (CCS). General data such as gender, age, cause of injury, comorbidities, fracture classification and cause of injury of two groups were collected. The operation time, intraoperative blood loss, hospital stay, full weight bearing time, fracture healing time, visual analogue scale(VAS), Harris hip score and complications were compared between two groups.@*RESULTS@#Patients in both groups were followed up for more than 2 years. There were no significant differences in operation time, intraoperative blood loss, fracture reduction quality, hospital stay and VAS between two groups. The fracture healing time in PCCP group was significantly shorter than that in CCS group (t=-4.404, P=0.000). The complete weight bearing time of PCCP group was significantly shorter than that of CCS group (t=-9.011, P=0.000). Harris score of hip joint in PCCP group was better than that in CCS group 2 years after operation (P=0.002). Complications occurred in 3 cases (9.68%) in PCCP group, while 11 cases (29.72%) in CCS group, with a statistically significant difference (P=0.042).@*CONCLUSION@#Both PCCP and CCS can be used for the treatment of displaced femoral neck fractures in young and middle-aged people. Compared with CCS, PCCP fixation can achieve shorter fracture healing time and create conditions for early full weight bearing. PCCP results in higher hip score and lower complications.

Comparison of curative effect between Tianji robot assisted screw placement and traditional cannulated screw internal fixation for femoral neck fracture / 中国骨伤

OBJECTIVE@#To investigate the clinical efficacy and advantages of Tianji orthopedic robot assisted cannulated screw internal fixation for femoral neck fracture.@*METHODS@#The clinical data of 41 patients with femoral neck fracture who underwent internal fixation with cannulated screws from January 2019 to January 2022 were retrospectively analyzed. According to different surgical methods, they were divided into Tianji robot group and traditional cannulated screw fixation group (traditional operation group). Among them, there were 18 patients in Tianji robot group including 8 males and 10 females with age of (56.00±4.22) years old, Garden typeⅠ (4 cases), type Ⅱ (11 cases), type Ⅲ (2 cases), and type Ⅳ (1 case). There were 23 patients in the traditional operation group, including 10 males and 13 females, aged (54.87±4.81) years old;there were 5 cases of Garden typeⅠ, 14 cases of type Ⅱ, 3 cases of type Ⅲ and 1 case of type Ⅳ. The operation time, intraoperative blood loss, fluoroscopy times, guide needle placement times, operation costs and other indicators were observed and compared between two groups. Harris score was used to evaluate hip joint function 12 months after operation.@*RESULTS@#The wounds of all patients healed in Grade A without complications. There were significant differences between two groups in terms of operation time, times of intraoperative fluoroscopy, times of guide needle placement, amount of intraoperative bleeding, and operation cost (P<0.05). All 41 patients were followed up for at least 12 months. The fractures of both groups were healed. There was no infection, screw loosening, fracture displacement and femoral head necrosis in Tianji robot group during follow-up;Screw loosening occurred in 2 patients in the traditional operation group during follow-up. At 12 months after operation, Harris hip joint function score of Tianji robot group was higher than that of traditional operation group in daily activity, lameness, joint activity score and total score (P<0.05).@*CONCLUSION@#Tianji robot assisted nail placement is a better method for the treatment of femoral neck fracture, which improves the surgical efficiency, is more accurate, has higher success rate of one-time nail placement, shorter operation time, less radiation, and has better hip joint function recovery after surgery.