ACROMIOCLAVICULAR DISLOCATIONS—Open Reduction with Screw Fixation

Athletes with complete separation of the acromioclavicular joint were uniformly restored to full athletic competence by an operation consisting of direct repair of the involved ligamentous structures with temporary fixation by a metallic lag screw approximating the clavicle to the coracoid. The metallic fixation was left in place an average of eight weeks and the screw was then removed under local anesthesia. A number of professional and collegiate football players returned to the rigors of football with no discomfort or disability.     

Experimental and finite element comparison of various fixation designs in combined loads

The short- and long-term successes of tibial cementless implants depend on the initial fixation stability often provided by posts and screws. In this work, a metallic plate was fixed to a polyurethane block with either two bone screws, two smooth-surfaced posts, or two novel smooth-surfaced posts with adjustable inclinations. For this last case, inclinations of 0, 1.5, and 3 deg were considered following insertion. A load of 1031 N was eccentrically applied on the plate at an angle of approximately 14 deg, which resulted in a 1000 N axial compressive force and a 250 N shear force. The response was measured under static and repetitive loading up to 4000 cycles at 1 Hz. The measured results demonstrate subsidence under load, lift-off on the unloaded side, and horizontal translation of the plate specially at the loaded side. Fatigue loading increased the displacements, primarily during the first 100 cycles. Comparison of various fixation systems indicated that the plate with screw fixation was the stiffest with the least subsidence and liftoff. The increase in post inclination from 0 to 3 deg stiffened the plate by diminishing the liftoff. All fixation systems demonstrated deterioration under repetitive loads. In general, the finite element predictions of the experimental fixation systems were in agreement with measurements. The finite element analyses showed that porous coated posts (modeled with nonlinear interface friction with and without coupling) generated slightly less resistance to liftoff than smooth-surfaced posts. In the presence of porous coated posts, Coulomb friction greatly overestimated the rigidity by reducing the liftoff and subsidence to levels even smaller than those predicted for the design with screw fixation. The sequence of combined load application also influenced the predicted response. Finally, the finite element model incorporating measured interface friction and pull-out responses can be used for the analysis of cementless total joint replacement systems during the post-operation period.     

Resorbable PLLA-PGA plate and screw fixation in pediatric craniofacial surgery: clinical experience in 1883 patients

The need to provide rigid bony fixation in the surgical treatment of craniofacial deformities has inspired an on-going evolution of surgical innovations and implants. Because of the young age of many treated craniosynostosis patients and the unique pattern of cranial vault growth, the extensive implantation of metal devices is potentially problematic. The use of resorbable plate and screw devices offers all of the benefits of rigid fixation without many of their potential risks. Since the introduction of resorbable plate and screw devices in 1996, tens of thousands of craniofacial patients have received implants, but long-term results from a large series have yet to be reported. A combined prospective and retrospective analysis was done on 1883 craniosynostosis patients under 2 years of age treated by 12 surgeons from seven different geographic locations over a 5-year period who used the same type of resorbable bone fixation devices (poly-L-lacticpolyglycolic copolymer). Specifically, the incidence of postoperative infection, fixation device failure, occurrence of delayed foreign-body reactions, and the need for reoperation resulting from device-related problems were determined. Technical difficulties and trends in device use were also noted. From this series, significant infectious complications occurred in 0.2 percent, device instability primarily resulting from postoperative trauma occurred in 0.3 percent, and self-limiting local foreign-body reactions occurred in 0.7 percent of the treated patients. The overall reoperation rate attributable to identifiable device-related problems was 0.3 percent. Improved bony stability was gained by using the longest plate geometries/configurations possible and bone grafting any significant gaps across plated areas that were structurally important. The specific types of plates and screws used evolved over the study period from simple plates, meshes, and threaded screws to application-specific plates and threadless push screws whose use varied among the involved surgeons. This report documents the safety and long-term value of the use of resorbable (LactoSorb) plate and screw fixation in pediatric craniofacial surgery in the infant and young child. Device-related complications requiring reoperation occurred in less than 0.5 percent of the implanted patients, which is less frequent than is reported for metallic bone fixation. Resorbable bone fixation for the rapidly growing cranial vault has fewer potential complications than the traditional use of metal plates, screws, and wires.     

数字化骨科理念辅助椎弓根置钉在寰枢椎不稳中的临床应用

目的:探讨3D打印辅助置钉技术用于寰枢椎不稳椎弓根置钉的安全性及准确性。方法:收集2013年1月到2015年1月西安交通大学第一附属医院收治的寰枢椎不稳病例,术前采用3D打印技术构建个体化3D打印模型,在模型上模拟置钉,获取最佳置钉点、置钉角度等个体化置钉数据,并于术中辅助椎弓根螺钉置入。通过CT扫描评价置钉准确性,测量术前、术后患者寰齿间隙判断寰枢椎复位情况,测量颈延角评价脊髓压迫改善情况,并采用日本骨科学会(JOA)评分判断患者脊髓功能改善情况。术后定期随访观察固定效果、稳定性、神经损伤等手术并发症的发生情况。结果:13例患者均采用3D打印辅助置钉技术进行内固定治疗,手术顺利,术中及术后无血管、神经损伤等并发症,复位及内固定效果满意。共置入椎弓根螺钉31枚,其中29枚完全在椎弓根内,置钉准确率为93.5%。寰枢椎较术前明显复位,术后寰齿间隙、颈延角和JOA评分较术前明显改善,差异具有统计学意义(P0.05)。结论:3D打印技术辅助上颈椎椎弓根置钉的准确性及安全性均较高。     

Injectable calcium phosphate cement for augmentation around cancellous bone screws. In vivo biomechanical studies

In lower cancellous apparent bone density, it can be difficult to achieve adequate screw fixation and hence stable fracture fixation. Different strategies have been proposed, one of them is through augmentation using calcium phosphate cement in the region at or close to the screw thread itself. To support the hypothesis of an improved screw fixation technique by augmentation of the bone surrounding the implanted screw, in vivo biomechanical and densitometric studies are performed on rabbit specimen where normal and simulated weak bone quality are considered. In particular, the evolution of screw stability till 12 weeks following the implantation is quantified. A statistical significance in the pull out force for augmented versus non-augmented screws was found for the shorter time periods tested of ≤ 5 days whilst the pull out force was found to increase with time for both augmented and non-augmented screws during the 12 week course of the study. The results of the study demonstrate that the use of an injectable calcium phosphate cement which sets in vivo can significantly improve screw pull out strength at and after implantation for normal and simulated weak bone quality.     

Bold螺钉治疗内踝骨折的疗效分析

目的：对比Bold螺钉和普通空心螺钉内固定治疗单纯内踝骨折的疗效。方法：空心螺钉治疗单纯内踝撕脱骨折57例,分为A组Bold螺钉内固定治疗内踝骨折25例,B组使用普通空心螺钉内固定32例。结果：两组57例均获得随访,两组病例远期均能得到较坚强的固定和良好的功能恢复,但Bold螺钉组相对普通螺钉组愈合时间更快（P〈0.05）,下床活动时间更早（P〈0.05）,早期踝关节功能评分高（P〈0.05）,但六个月后没有明显差异。结论：Bold螺钉内固定有助于内踝骨折早期愈合和早期功能锻炼,是一种比较好的内固定材料,值得推广。     

Bold 螺钉治疗内踝骨折的疗效分析

目的:对比Bold螺钉和普通空心螺钉内固定治疗单纯内踝骨折的疗效。方法:空心螺钉治疗单纯内踝撕脱骨折57例,分为A组Bold螺钉内固定治疗内踝骨折25例,B组使用普通空心螺钉内固定32例。结果:两组57例均获得随访,两组病例远期均能得到较坚强的固定和良好的功能恢复,但Bold螺钉组相对普通螺钉组愈合时间更快(P<0.05),下床活动时间更早(P<0.05),早期踝关节功能评分高(P<0.05),但六个月后没有明显差异。结论:Bold螺钉内固定有助于内踝骨折早期愈合和早期功能锻炼,是一种比较好的内固定材料,值得推广。     

Stress analysis of a centrally fractured rib fixated by an intramedullary screw

The stress on an intramedullary screw rib fixation device holding together a centrally fractured human rib under in vivo force loadings was studied using finite element analysis (FEA). Validation of the FEA modelling using pullout from porcine ribs proved FEA to be suitable for assessing the structural integrity of screw/bone systems such as rib fixated by a screw. In the human rib fixation investigation, it was found that intramedullary bioresorbable Bioretec screws can fixate centrally fractured human ribs under normal breathing conditions. However, under coughing conditions, simulation showed Bioretec fixating screws to bend substantially. High stresses in the screw are mainly the result of flexion induced by the force loading, and are restricted to thin regions on the outside of the screw shaft. Stiffer screws result in less locally intense stress concentrations in bone, indicating that bone failure in the bone/screw contact regions can be averted with improvements in screw stiffness.     

Biomechanical effects of posterior pedicle fixation techniques on the adjacent segment for the treatment of thoracolumbar burst fractures: a biomechanical analysis

Abstract

Posterior pedicle fixation technique is a common method for treating thoracolumbar burst fractures, but the effect of different fixation techniques on the postoperative spinal mechanical properties has not been clearly defined, especially on adjacent segments. A finite element model of T10-L2 with moderate T12 vertebra burst fracture was constructed to investigate biomechanical behavior of three posterior pedicle screw fixation techniques. Compared with traditional short-segment 4 pedicle screw fixation (TS-4) and intermediate long-segment 6 pedicle screw fixation (IL-6), mono-segment 4 pedicle screw fixation (MS-4) provides a safer surgical selection to prevent the secondary degeneration of adjacent segments in the long-term.     

An approximate model for cancellous bone screw fixation

This paper presents a finite element (FE) model to identify parameters that affect the performance of an improved cancellous bone screw fixation technique, and hence potentially improve fracture treatment. In cancellous bone of low apparent density, it can be difficult to achieve adequate screw fixation and hence provide stable fracture fixation that enables bone healing. Data from predictive FE models indicate that cements can have a significant potential to improve screw holding power in cancellous bone. These FE models are used to demonstrate the key parameters that determine pull-out strength in a variety of screw, bone and cement set-ups, and to compare the effectiveness of different configurations. The paper concludes that significant advantages, up to an order of magnitude, in screw pull-out strength in cancellous bone might be gained by the appropriate use of a currently approved calcium phosphate cement.     

齿状突几何参数、骨密度与生物力学性质的相关性研究

目的:齿状突骨折是颈椎的严重损伤,其中大部分需要行前路螺钉内固定术治疗,齿状突的几何参数对螺钉的选择起决定性作用,其骨密度则影响螺钉对骨质的把持力,齿状突固有的生物力学性质对齿状突骨折固定效果进而对骨折愈合有较大影响,基于以上考虑,本课题分析并比较了几何参数、骨密度与生物力学性质的相关性,评价其指导临床应用的意义。方法:将15例经福尔马林浸泡的国人枢椎标本剔除周围软组织,分别测量并分析各个标本的几何参数、骨密度以及扭转刚度、剪切刚度、拉伸刚度等生物力学性质的特点,并比较它们之间的相关性。结果:齿状突为一椭球形结构,难以容纳两枚内固定螺钉,齿状突的几何参数、骨密度和生物力学性质之间没有相关性。结论:临床上在对齿状突骨折采用螺钉内固定前需要了解齿状突的解剖结构并据此选取适当尺寸的螺钉,应根据齿状突基底部的横径选择螺钉的直径,根据基底部到前唇的距离选择螺钉光滑段的长度,根据枢椎高度选择螺钉长度,齿状突的几何参数、骨密度和齿状突的生物力学性质之间并无相关性,并不能根据齿状突几何参数、骨密度来预测其生物力学强度进而预测内固定的初始稳定性。     

采用载距突螺钉固定技术治疗膝关节内骨折的疗效分析

目的:探讨载距突螺钉固定术治疗膝关节内骨折的疗效。方法:选取我院骨科收治的膝关节内骨折的患者80例,根据患者骨折固定方法而分为实验组(40例)与对照组(40例)。实验组采用载距突螺钉固定技术进行治疗,对照组采用开口后观察骨折程度,并对关节周围平整性进行修复,如需固定可借助克氏针,部分可运用牵引手法等进行修复。两组患者术后均予以常规抗炎治疗。比较两组患者膝关节功能恢复情况、疗效及并发症情况。结果:与对照组相比,实验组总有效率较高,并发症发生率较低(P0.05);HSS评分比较,实验组HSS评分明显高于对照组(P0.05)。结论:载距突螺钉固定技术能够提高膝关节内骨折患者的临床疗效,降低并发症的发生率,改善膝关节的功能活动。     

Biomechanical differences of Coflex-F and pedicle screw fixation combined with TLIF or ALIF--a finite element study

Lumbar interbody fusion is a common procedure for treating lower back pain related to degenerative disc diseases. The Coflex-F is a recently developed interspinous spacer, the makers of which claim that it can provide stabilisation similar to pedicle screw fixation. Therefore, this study compares the biomechanical behaviour of the Coflex-F device and pedicle screw fixation with transforaminal lumbar interbody fusion (TLIF) or anterior lumbar interbody fusion (ALIF) surgeries by using finite element analysis. The results show that the Coflex-F device combined with ALIF surgery can provide stability similar to the pedicle screw fixation combined with TLIF or ALIF surgery. Also, the posterior instrumentations (Coflex-F and pedicle screw fixation) combined with TLIF surgery had lower stability than when combined with ALIF surgery.     

Biomechanical differences of Coflex-F and pedicle screw fixation combined with TLIF or ALIF – a finite element study

Lumbar interbody fusion is a common procedure for treating lower back pain related to degenerative disc diseases. The Coflex-F is a recently developed interspinous spacer, the makers of which claim that it can provide stabilisation similar to pedicle screw fixation. Therefore, this study compares the biomechanical behaviour of the Coflex-F device and pedicle screw fixation with transforaminal lumbar interbody fusion (TLIF) or anterior lumbar interbody fusion (ALIF) surgeries by using finite element analysis. The results show that the Coflex-F device combined with ALIF surgery can provide stability similar to the pedicle screw fixation combined with TLIF or ALIF surgery. Also, the posterior instrumentations (Coflex-F and pedicle screw fixation) combined with TLIF surgery had lower stability than when combined with ALIF surgery.     

Computational biomechanical analysis of postoperative inferior tibiofibular syndesmosis: a modified modeling method

To analyze the biomechanical effect of syndesmotic screw through three and four cortices, a total of 12 finite element models simulating healthy ankles, tibiofibular syndesmosis injured ankles, and post-operative ankles by screw fixations through three or four cortices were built. A set of biomechanical data were obtained to find that screw fixation methods for inferior tibiofibular syndesmosis can help recover most of the biomechanical relations of the ankle especially the tricortical fixation, while the screw of quadricortical fixation bear more stress than the tricortical fixation. The modeling method for finite element models was also modified for saving more time and realizing personalized modeling for clinical application.     

椎旁肌退变与短节段腰椎融合内固定术后螺钉松动的相关性分析

摘要 目的：分析椎旁肌退变与短节段腰椎融合内固定术后螺钉松动的相关性。方法：回顾性分析2018年6月至2020年6月广州市番禺区中医院行短节段腰椎融合内固定术治疗的251例腰椎退行性疾病患者的临床资料，根据术后螺钉松动情况分为松动组（n=47）和对照组（n=204）。收集患者的临床资料，对比两组椎间植骨融合情况、螺钉直径、螺钉长度、螺钉椎内长度、椎旁肌的肌肉相对总横截面积（rtCSA）和脂肪浸润程度（FI）。应用多因素logistic回归分析短节段腰椎融合内固定术后螺钉松动发生的危险因素，并描绘受试者工作特征（ROC）曲线检验危险因素预测短节段腰椎融合内固定术后螺钉松动的效能。结果：251例患者平均随访时间（24.16±7.28）个月，其中47例患者在最终随访时发生螺钉松动，总体松动率18.73%。两组性别、骨密度比较差异有统计学意义（P＜0.05）。与对照组相比，松动组的多裂肌FI增高（P＜0.05）。与对照组相比，松动组的竖脊肌rtCSA减少，竖脊肌FI增高（P＜0.05）。多因素logistic回归分析显示竖脊肌FI较高是短节段腰椎融合内固定术后螺钉松动发生的独立危险因素，而竖脊肌rtCSA较高、骨密度较高则是保护因素（P＜0.05）。ROC曲线分析显示：骨密度、竖脊肌rtCSA、竖脊肌FI等3指标单独及联合应用时：ROC-AUC（0.95CI）分别为0.708（0.446～0.971）、0.736（0.495～0.951）、0.648（0.335～0.965）、0.842（0.719～0.957）。联合应用预测效能较高。结论：竖脊肌的退变是短节段腰椎融合内固定术后螺钉松动的危险因素。当骨密度＜-3.00 g/cm²、竖脊肌rtCSA＜1.45%及FI＞35.00%时，提示术后发生螺钉松动的可能性大，可作为短节段腰椎融合内固定术后评价螺钉松动风险的参考指标。     

Effect of screw position on load transfer in lumbar pedicle screws: a non-idealized finite element analysis

Angled screw insertion has been advocated to enhance fixation strength during posterior spine fixation. Stresses on a pedicle screw and surrounding vertebral bone with different screw angles were studied by finite element analysis during simulated multidirectional loading. Correlations between screw-specific vertebral geometric parameters and stresses were studied. Angulations in both the sagittal and axial planes affected stresses on the cortical and cancellous bones and the screw. Pedicle screws pointing laterally (vs. straight or medially) in the axial plane during superior screw angulation may be advantageous in terms of reducing the risk of both screw loosening and screw breakage.     

不同后路术式治疗胸腰椎爆裂骨折的临床效果比较

目的：探讨不同后路术式治疗胸腰椎爆裂骨折的临床效果。方法：将我院骨科收治的96例胸腰椎爆裂骨折患者随机分为两组,分别使用经伤椎椎弓根六钉固定法（六钉组,65例）和跨伤椎短节段四钉固定法（四钉组,31例）进行复位固定,测量并比较术后6个月两组矢状面Cobb角、冠状面Cobb角和伤椎椎体前缘压缩比及术后并发症情况的差异。结果：两组患者术前矢状面和冠状面Cobb角、伤椎椎体前缘压缩比的差异无统计学意义（P〉0．05）。术后6个月,六钉组矢状面Cobb角、伤椎椎体前缘压缩比、术后并发症发生率均显著低于四钉组（P〈0．05）,两组冠状面Cobb角均为0°。四钉组术后并发痘的发生率为22．6％,而六钉组术后并发症的发生率为4．6％,显著低于四钉组（P〈0．05）。结论：经伤椎椎弓根六钉固定法治疗胸腰椎爆裂骨折疗效优于跨伤椎短节段四钉固定法．且不良反应较少．具有较高的临床应用价值。     

空心钉固定治疗骶骨骨折的临床疗效分析

目的:探讨空心钉固定治疗骶骨骨折的临床疗效及其安全性。方法:回顾性分析2010年1月至2013年1月骶骨骨折患者50例,其中男36例,女14例。按照Denis分类法,Ⅰ型22例,Ⅱ型14例,Ⅲ型14例,36例采用空心钉固定治疗,14例采用非手术保守治疗。结果:治疗后,根据Majeed评分标准进行评定,其中空心钉组优10例,良18例,可8例;非手术组优1例,良7例,可6例。全部患者经手术治疗后骨折均愈合,未出现断钉现象。结论:空心钉固定治疗骶骨骨折较保守治疗有更好的功能恢复及生活质量,空心钉固定具有术后恢复快,避免神经损伤,患者可尽早行功能锻炼,促进骨质愈合,改善患者预后,具有良好的临床疗效。