载距突螺钉导向器在跟骨载距突螺钉置钉中的应用

背景：跟骨关节内骨折手术治疗时准确置入载距突螺钉可获得最佳固定效果。但由于跟骨复杂的解剖特点和术中有限的X线透视效果,完成载距突螺钉的准确置钉工作难度极大。而准确置入载距突螺钉的方法仍存较大争议。目的：探讨跟骨关节内骨折手术治疗时使用跟骨载距突螺钉导向器辅助载距突螺钉的准确置钉效果。方法方法：回顾性分析2010年7月至2013年12月手术治疗的42例（48足）跟骨关节内骨折病例,男35例,女7例;年龄15-67岁,平均38.9岁。根据Sanders分型：Ⅱ型22足,Ⅲ型19足,Ⅳ型7足。所有手术均采用跟骨外侧入路,术中使用跟骨载距突螺钉导向器辅助置入跟骨载距突螺钉。术后复查X线与CT,验证螺钉置入载距突的准确性。结果：42例患者术后随访7-28个月,平均17.4个月。按美国足踝外科协会Maryland足部功能评分标准进行功能评定：优21足,良19足,可8足,差0足;术后Maryland足部评分平均为87.8分,优良率83.3%。共置入53枚载距突螺钉。1枚螺钉从跟骨后关节面内下方露出部分螺纹,1枚螺钉从载距突前方穿出,1枚螺钉穿出载距突关节面进入距跟中关节,1枚螺钉远端一半螺纹在载距突下方露出,余49枚螺钉位于载距突内;螺钉置入精确率为92.5%（49/53）。结论：跟骨载距突螺钉导向器能辅助术者从跟骨外侧入路准确完成载距突螺钉置钉。     

载距突螺钉内固定治疗SandersⅡ型跟骨骨折的生物力学研究

 目的 探讨载距突螺钉内固定在SandersⅡ型跟骨骨折治疗中的作用及必要性。方法 将跟骨CT扫描后的Dicom数据输入Mimics 12.0软件及Ansys 13.0软件中构建跟骨三维有限元数字模型。而后,将此模型导入Solidworks 2010软件中,根据Sanders分型切割跟骨,建立SandersⅡ型跟骨骨折模型。将AO跟骨钢板及螺钉的几何参数输入Solidworks 2010软件中,在跟骨模型的基础上建立两种内固定模拟,一种为钢板放于跟骨外侧面,在钢板后关节面下方2枚螺钉孔、钢板后方2枚螺钉孔、钢板下方1枚螺钉孔、钢板前方2枚螺钉孔分别垂直跟骨打入松质骨螺钉;另一种为在前一种固定方式的基础上再在钢板后关节面最下方螺钉孔向载距突打入1枚皮质骨螺钉。在相同条件下分别对两种内固定模型加载,行非线性有限元分析,分别计算两种内固定模型的应力分布情况。结果 在相同条件的加载下两种内固定跟骨模型的最大主应力均集中于载距突皮质骨,载距突螺钉内固定模型在骨缝间位移值、跟骨最大主应力值、钢板螺钉内固定系统的最大主应力值方面均较无载距突螺钉内固定模型小,且应力更分散。结论 载距突螺钉内固定治疗跟骨骨折符合生物力学稳定性,可很好地用于临床。     

Sanders Ⅱ型跟骨骨折螺钉微创治疗的有限元优化分析

目的:探讨Sanders Ⅱ型跟骨骨折微创治疗时螺钉不同固定方式后的生物力学特点.方法:将CT 扫描后的跟骨Dicom 数据输入Mimics 21.0 软件及Ansys 15.0 软件中构建跟骨三维有限元数字模型;将此模型导入UG NX 10.0 软件中,根据Sanders 分型切割跟骨,建立后关节面塌陷的Sander...     

载距突的解剖学研究及其在跟骨关节内移位骨折手术中的应用

目的 通过研究跟骨载距突本身及其与周围组织的解剖学关系来设计内固定的最佳位置和角度. 方法①测量正常跟骨的以下指标:载距突的前倾角、跟骨后关节面前部的前倾角、跟骨中部最大宽度、载距突基底部厚度,②观察跟骨内部结构,⑧研究载距突及其周围结构解剖学,④观察跟骨中部螺钉模拟内固定及测量相关角度,⑤随访观察27例经外侧入路切开复位内固定治疗的跟骨关节内移位骨折患者的效果. 结果载距突的前倾角、跟骨后关节面前部的前倾角、跟骨中部最大宽度、载距突基底部最大及最小厚度分别是50°±5°、69°±5°、(41.75±1.76)mm、(12.14±1.60)mm、(4.81±1.07)mm;载距突中关节面下方的骨小梁结构致密,并且与跟骨后关节面下方的致密骨小梁相连续;载距突与走行于其内侧的肌腱血管关系密切;在冠状面上测量自后关节面到载距突的三个进针点打入克氏针的最佳进针方向分别是:最低点向上25°±5°、最高点向下3°±3°、中点向上13°±3°;根据以上测量值进行手术,无患者出现复位或内固定失败的情况,疗效按照美国足踝外科协会后足评分系统评分,优良率为88.9%. 结论载距突是跟骨关节内移位骨折手术时螺钉置入的理想位置,应根据跟骨中部的横径选择螺钉的长度,根据载距突基底部的最小径选择螺钉的直径,根据载距突与后关节面的相互关系决定螺钉的进钉方向,可以获得满意的临床疗效.     

Preliminary experience with a novel facet-based lateral mass drill guide for the placement of lateral mass screws compared to freehand technique: a cadaveric study

BACKGROUND CONTEXTLateral mass screw fixation is the standard for posterior subaxial cervical fixation. Several freehand surgical techniques for placing lateral mass screws have been described which rely on anatomical landmarks and surgeon mastery of the technique to safely place screws. The accuracy of these freehand techniques is inherently variable and can be influenced by a surgeon's level of clinical experience. A novel technique was developed that utilizes the plane of the facet joint to create lateral mass screw pilot holes parallel with the joint line to improve the safety and accuracy of lateral mass screw placement regardless of experience.PURPOSETo assess the safety and accuracy of lateral mass screw placement using a novel lateral mass drill guide instrument (LM Guide), compared to standard freehand technique.STUDY DESIGNRandomized cadaveric study utilizing multiple surgeon evaluators to compare the safety and accuracy of guided cervical lateral mass placement compared to traditional freehand techniques.MATERIALS AND METHODSLateral mass screws were placed from C3 to C7 in 20 cadaver specimens by 8 spine surgeons of varying levels of clinical experience (4 attendings, 4 fellows). Screws were placed bilaterally using standard anatomic landmarks (“freehand”) randomly allocated on one side and using the LM Guide on the other. Cadaveric specimens were imaged with high-resolution CT to assess screw placement. Zone grading for safety was conducted based on screw tip position and clinical severity of screw breach was based on proximity to surrounding neurovascular anatomy. Screws were graded as safe, at-risk, or critical, with at-risk and critical screws considered malpositioned. To assess the accuracy of screw trajectory placed using the LM Guide compared to freehand, sagittal screw angle was measured and compared to an “ideal” screw path parallel to the facet joint line. Freehand and LM Guide groups were compared using Pearson's chi-square correlation.RESULTSScrew placement using the LM guide yielded a significantly lower rate of screw malpositioning, with 7 of 91 (7.7%) compared with 18 of 99 (18.2%) screws placed in the At-Risk or Critical Zones, p<.05. Of the 91 screws inserted using the LM Guide, 84 (92.3%) were in the Safe Zone, 7 (7.7%) were At-Risk, and 0 were in Critical zones. There was no incidence of neural or transverse foramen breaches with the LM Guide. In comparison, for the 99 screws inserted freehand, 81 (81.8%) were Safe, 14 (14.1%) were At-Risk, and 4 (4.1%) were in Critical zones. The 4 Critical zone freehand screw breaches included 1 neural foramen breach, 2 transverse foramen breaches, and 1 facet breach. The LM Guide also resulted in higher accuracy of screw trajectory, as indicated by a significant reduction in sagittal screw angle compared with freehand, p<.01. Notably, in the less-experienced surgeon cohort, the LM Guide significantly reduced the sagittal screw angle and resulted in no critical screw breaches compared to 3 critical breaches with freehand technique suggesting there might be a benefit in decreasing the learning curve associated with lateral mass screw placement.CONCLUSIONSLateral mass screw placement with a novel LM Guide that uses the facet joint to control screw trajectory improved the accuracy and reproducibility of screw placement with a significant reduction in screw breach rate and sagittal screw angle compared to freehand techniques regardless of surgeon experience level.CLINICAL SIGNIFICANCEThe inherent variability of freehand lateral mass screw placement can increase the risk of clinical complications associated with screw malpositioning. The technique presented in this cadaveric study may be a viable alternative to standard freehand technique that can improve the overall safety of lateral mass screw placement.     

空心钉内固定治疗累及中距关节面的载距突骨折

目的:探讨空心钉内固定治疗跟骨单纯载距突骨折的临床疗效。方法:自2012年8月至2017年6月,采用空心钉内固定治疗累及中距关节面的载距突骨折患者13例,男10例,女3例,年龄26～58岁。测量并比较术前、术后1年CT冠状面上跟骨宽度及中距、后距关节间隙距离以评估距下关节面平整度,术后1年采用美国足踝外科协会(American Orthopaedic Foot and Ankle Society,AOFAS)踝与后足评分标准对其临床疗效进行评估。结果:13例患者获得随访,时间9～70个月。骨折均骨性愈合,愈合时间8～16周。术后未出现距下关节炎、腱鞘炎等并发症。跟骨宽度由术前的46.2～52.7 mm降至术后的35.2～39.2 mm,中距关节间隙由术前的4.5～4.8 mm降至术后的1.9～2.2 mm,后距关节间隙由术前的2.4～2.8 mm降至术后的1.9～2.3 mm。术后1年AOFAS评分为77～94,其中优1例,良12例。结论:采用2枚空心钉交叉内固定治疗累及中距关节面的载距突骨折疗效满意,载距突骨折块可以得到良好复位,中距关节面恢复平整,足部功能改善明显。     

Isolierte Fraktur des Sustentaculum tali: ein Fallbericht

Case reportA 32 years old male patient slipped while going downhill and injured his right foot. The next day X-rays were taken in which no bony injury was seen. Because of persistent complaints additional diagnostic by MRI and CT were performed. These showed a displaced fracture of the sustentaculum tali. The sustentaculum tali was fixed with screws. The fracture healed with a congruent articular surface and good functional outcome.ConclusionFractures of the sustentaculum tali are rare and are overseen frequently because of overlapping structures on X-rays. Even low energy trauma can cause these fractures in young patients. In patients with persistent complaints of the foot an additional cross-sectional diagnostic is strongly recommended.     

The sustentaculum tali: anatomic, radiographic, and surgical considerations

Three purposes of this study were to: 1) describe the sustentaculum tali in relation to surrounding structures, 2) identify its radiographic projection onto the lateral calca neus, and 3) determine optimal angles for screw placement. Twelve cadaver specimens were used. The length a width of the sustentaculum was measured. Its midpoint was measured from surrounding anatomic landmarks. A point on the lateral calcaneal wall "point A" was chosen. This marks the intersection of two lines bisecting the midpoint of the posterior facet and the lateral calcaneal height. The angles required to pass a pin from point A into the sustentaculum were determined. The sustentaculum projected as a triangular/elliptical structure on the lateral radiograph. It was superimposed on the anterior portion of the posterior facet.     

Morphology of sustentaculum tali: Biomechanical importance and correlation with angular dimensions of the talus

Summary of background data

The talus and the calcaneus share the bulk of load transmitted from the leg to the skeleton of the foot. The present study analyses the inter-relationship between the superior articular surface and the angular dimensions of the talus with the morphology of the sustentaculum tali.

Objective

Identification of possible relationships between different angular parameters of the talus morphology and the sustentaculum tali in context of load transmission through the foot.

Methods

One articular surface and three angular parameters at the junction of the head and the body were measured from dried human talar bones. Corresponding calcaneal samples were measured for four dimensions at the sustentaculum tali. Correlation and regression statistical values between parameters were worked out and analysed.

Results

Several parameters within the talus demonstrated significant correlations amongst themselves. The neck vertical angle showed a strong correlation with the articulating surface area below the head of the talus.

Conclusions

The inter-relationship between articular and angular parameters within the talus demonstrates strong correlation for certain parameters. Data presented in the study may be helpful to adjust calcaneal and talar screw placement techniques, prosthesis designing and bio-mechanical studies at this important region.     

Comparison of Initial Compression Force Across the Subtalar Joint by Two Different Screw Fixation Techniques

The purpose of this study was to compare the magnitude of compressive force across the posterior facet of the subtalar joint between 2 different screw orientations in a simulated subtalar fusion model fixated with cannulated 7.3-mm screws. Eight paired fresh, frozen cadaver feet were used. Before testing, the bone mineral density of the calcanei and tali was measured with dual energy x-ray absorptiometry to ensure comparable bone mineral density. The paired cadaver calcanei and tali were noted to have less than .05 g/cm(2) difference in bone mineral density. The paired specimens were each randomly assigned to 1 of 2 methods of fixation across the subtalar joint: a plantar approach, where the screw was oriented vertically from the plantar aspect of the calcaneus, distal to the tuberosity; and a posterior approach, where the screw was oriented obliquely from the posterior calcaneal tuberosity. A load-sensing washer was placed under the cancellous screw head before insertion of the screw to measure the magnitude of the compression force across the simulated fusion site. The mean compression force for the posterior-to-anterior approach was 581 N, with a standard deviation of 242 N. The mean force for the plantar-to-superior approach was 604 N, with a standard deviation of 276 N. The compression force obtained by the 2 approaches was not significantly different (P = .74). The plantar-to-superior fixation technique represents an alternative subtalar arthrodesis technique to the posterior-to-anterior approach, potentially allowing one to revise a previously failed arthrodesis when the standard fixation techniques cannot be applied.     

Clinical accuracy of cervical pedicle screw insertion using lateral fluoroscopy: a radiographic analysis of the learning curve

Abstract  

Cervical pedicle screw is thought to be the most stable instrumentation for reconstructive surgery of the cervical spine. However, because of the unresolved and inherent risk of neurovascular injuries due to screw perforation, it remains not widespread nowadays despite the excellent biomechanical property. Fifty-two consecutive cases having undergone spinal reconstruction using cervical pedicle screw were investigated. There were 24 females and 28 males. The mean follow-up period was 53 months. Those patients were stratified into three groups according to the period of screw insertion. A total of 280 screws were inserted. Ninety-two screws in 19 cases, 100 screws in 18 cases and 88 screws in 15 cases were inserted in the earlier, the middle and the later periods, respectively. Clinical results including complications were recorded in all cases. Screw perforations were evaluated in both plain X-ray and CT. Screw perforations occurred in 11 (12.0%), 7 (7.0%) and 1 (1.1%) screws in each period. There were no complications, such as infection, neurological deterioration and neurovascular injury directly related to screw insertion. The learning curve showed a significant improvement especially in the later period. However, the perforation rates in both the earlier and middle periods must not be underestimated. Surgeons with less experience must insert cervical pedicle screws with the assistance of a senior surgeon to avoid lethal complications.     

Outcome and safety analysis of 3D-printed patient-specific pedicle screw jigs for complex spinal deformities: a comparative study

Background Context

Spinal deformities are very challenging to treat and have a great risk of neurologic complications because of hardware placement during corrective surgery. Various techniques have been introduced to ensure safe and accurate placement of pedicle screws. Patient-specific screw guides with predrawn and prevalidated trajectory seem to be an attractive option.

Fractures of the sustentaculum tali

Objective

Anatomical reconstruction of displaced sustentaculum tali fractures via a direct medial approach.

Indications

Displaced fractures of the sustentaculum tali with incongruity or depression of the medial facet of the subtalar joint, entrapment of the flexor hallucis longus or flexor digitorum longus tendons, fracture line extending into the posterior facet of the subtalar joint.

Contraindications

Infected or grossly contaminated soft tissue, severely restricted vascular supply to the foot, high perioperative risk.

Surgical technique

Direct medial approach over the sustentaculum tali, retraction of the tendons, joint exploration, fracture reduction using the medial facet and cortical outline as guidelines, fracture fixation with two small fragment screws from medial to lateral directed slightly plantarly and posteriorly. Fractures with depression of the medial facet as a whole can alternatively be reduced and fixed percutaneously.

Postoperative management

Lower leg splint for 5–7 days, partial weight-bearing with 20 kg for 6–8 weeks (until radiographic signs of consolidation) in the patient’s own shoewear, early range of motion exercises of the ankle, subtalar and mid-tarsal joints.

Results

Over a course of 15 years, 31 patients were treated operatively for sustentacular fractures. In all, 27 patients (87?%) had additional fractures to the same foot and ankle. Eighteen patients with a mean age of 41 years treated at our institution with screw fixation for a unilateral fracture of the sustentaculum tali could be followed for a mean of 80 months (range 15–151 months). No wound healing problems or infections were seen with the medial approach. At the time of follow-up, 15 sustentaculum tali fractures had an average Foot Function Index of 21.6 and an average AOFAS Ankle–Hindfoot Score of 83.6. Patients with isolated fractures of the sustentaculum tali had significantly better scores than those with additional injuries. In 1 patient, an additional lateral process fracture of the talus required subtalar fusion due to persistent pain. Care must be taken not to overlook these atypical calcaneal fractures and accompanying injuries to the mid-tarsal joint and the lateral talar process as seen in 45% and 23%, respectively, in the present series.     

Radiographic and clinical assessment of a freehand lateral mass screw fixation technique: is it always safe in subaxial cervical spine?

Background contextMany spine surgeons use the freehand technique for lateral mass (LM) screw fixation. However, issues about its safety still exist.PurposeTo examine the safety of the freehand technique after LM screw insertion.Study designRetrospective case series.Patient sampleA total of 26 patients (21 men and five women) who underwent LM screw fixation via the freehand technique were included.Outcome measuresPostoperative computed tomography images and medical records were analyzed.MethodsDuring surgery, the lateral trajectory of screws was set using the adjacent spinous process (SP) after the cranial trajectory was set by palpating the joint surface. Computed tomography analyses were performed for the measurement of screw angles, and axial images were evaluated to determine the SP length that would be long enough to not involve the transverse foramen. The medical records were evaluated for the investigation of surgery-related complications.ResultsEach axial and sagittal angle of the screws showed a significant difference. A total of 18 screws (13.5%) involved the transverse foramen, and the mean axial angle of the screws was significantly smaller than the group not involving the foramen (p=.0078). A total of eight screws (6.0%) violated the facet, and the mean sagittal angle was significantly smaller than the group not violating the facet. The average difference in angles between the screw and the actual joint surface was largest at C6 (p=.0472). The mean maximum length of the SP, long enough to not involve the transverse foramen was significantly short at C3 and C6 (p=.0015). The actual SP length in one patient was longer than the maximum SP length determined through analysis in the case of C6. If the SP of C7 was used in C6, the SP length would not be safe in six patients.ConclusionsExcellent outcomes were observed with the use of the freehand technique for the insertion of LM screw at the subaxial C spine. However, this technique using the SP may pose a relative risk at C6.     

Modified Ni-Nail and C-Nail systems for intra-articular fractures of the calcaneus: A biomechancial study

ObjectivesWe have proposed a novel intramedullary nail (Ni-Nail) by incorporating a sustentaculum tali screw to improve the fixation stability of minimally invasive treatment for calcaneal fractures. This study aimed to evaluate the biomechanical characters of the Ni-Nail system and compare it with traditional C-Nail system.MethodsA finite element model of a Sanders type-IIIAB calcaneal fracture was reconstructed and fixed using two intramedullary nail systems, which was validated by a cadaver study. A vertical loading of 700 N was applied to the subtalar joint surfaces, and 525 N Achilles tendon tension was applied to the superior border of the Achilles tuberosity. The von Mises stresses and fracture displacements of both fixation models were evaluated.ResultsThe maximum von Mises stress of the screws of Ni-Nail and C-Nail were 27.92 MPa and 57.42 MPa, respectively, while that of the main nail were 67.44 MPa and 53.01 MPa. In addition, the maximum fracture displacement of the Ni-Nail was larger than that of C-Nail by 15.6% (0.37 mm vs.0.32 mm).ConclusionsOur static simulation analysis showed that both Ni-Nail and C-Nail demonstrated similar biomechanical stability for calcaneal fixation. The Ni-Nail features a simple structure that is easier to operate and less traumatizing. Future studies may consider to further evaluate the clinical effectiveness by clinical trials and follow-ups.     

Primary pyomyositis of the paraspinal muscles: a case report and literature review

The objectives of this study were (1) to quantify the benefit of computer assisted orthopaedic surgery (CAOS) pedicle screw insertion in a porcine cadaver model evaluated by dissection and computed tomography (CT); (2) to compare the effect on performance of four surgeons with no experience of CAOS, and varying experience of pedicle screw insertion; (3) to see if CT with extended windows was an acceptable method to evaluate the position of the pedicle screws in the porcine cadaver model, compared to dissection. This was a prospective, randomised, controlled and blinded porcine cadaver study. Twelve 6-month-old porcine (white skinned Landrace) lumbar spines were scanned pre-operatively by spiral CT, as required for the CAOS computer data set. Computer randomisation allocated the specimens to one of four surgeons, all new to CAOS but with different levels of experience in spinal surgery. The usual anatomical landmarks for the freehand technique were known to all four surgeons. Two pedicles at each vertebral level were randomly allocated between conventional free hand insertion and an electromagnetic image guided surgery (NAVITRAK^®) and 6.5 mm cancellous AO screws inserted. Post-operatively, spiral CT was blindly evaluated by an independent radiologist and the spine fellow to assess the accuracy of pedicle screw placement, by each method. The inter- and intra-observer reliability of CT was evaluated compared to dissection. The pedicle screw placement was assessed as perfect if within the pedicle along its central axis, or acceptable (within < 2 mm from perfect), and measured in millimetres from perfect thereafter. One hundred and sixty-six of 168 pedicles in 12 porcine spines were operated on. Complete data were present for 163 pedicles (81 CAOS, 82 freehand). In the CAOS group 84% of screws were deemed acceptable or perfect, compared to 75.6% with the freehand technique. Screw misplacement was significantly reduced using CAOS (P = 0.049). Seventy-nine percent of CAOS screws were ideally placed compared with 64% with a conventional freehand technique (P = 0.05). A logistic linear regression model showed that the miss placed pedicle screw rate was significantly reduced using CAOS (P = 0.047). CAOS benefited the least experienced surgeons most (the research registrars acceptable rate increased from 70 to 90% and the spine fellow from 76 to 86%). CAOS did not have a statistically significant effect on the experienced consultant spine surgeon increasing from 70 to 79% (P = 0.39). The experienced general orthopaedic surgeon did not benefit from CAOS (P = 0.5). CT compared to dissection showed an intra-observer reliability of 99.4% and inter-observer reliability of 92.6%. The conclusions of this study were as follows: (1) an increased number of pedicle screws were ideally placed using the CAOS electromagnetic guidance system compared to the conventional freehand technique; (2) junior surgeons benefited most from CAOS; (3) we believe CAOS (Navitrak^®) with porcine lumbar spines evaluated by post operative CT, represents a useful model for training junior surgeons in pedicle screw placement; (4) experienced spine surgeons, who have never used CAOS, may find CAOS less helpful than previously reported.     

Fixation of calcaneal avulsion fractures using screws with and without suture anchors: a biomechanical investigation

BACKGROUND: Lag screw fixation commonly is used to treat avulsion fractures of the posterior calcaneal tuberosity, but this method may not offer reliable fixation. This study compared the strength to failure of lag screws compared to lag screw fixation augmented with suture anchors in these fractures. METHODS: The calcanei and Achilles tendons of 12 fresh lower extremity cadaver matched pairs were dissected and removed. An oblique osteotomy was created in the calcaneus, and two 4.0-mm lag screws were placed nearly perpendicular to the plane of the fracture in the dorsal aspect of the calcaneus with 30 degrees of divergence between them. In the contralateral specimen, the same procedure was done, but with two suture anchors placed 1.5 to 2 mm distal to the osteotomy. A zigzag suture technique through the Achilles tendon was used. The specimens were mounted and placed in a load frame for monotonic loading to failure. A paired Student t-test and a Pearson correlation were used to analyze the data (p 相似文献   

螺旋CT三维重建在髋膝关节骨折脱位中的应用

探讨用螺旋ＣＴ三维重建评价髋、膝关节骨折脱位的临床应用价值。方法：收集髋关节折脱位７例，胫骨平台骨折４例，采用螺旋ＣＴ三维重建检查，结果：１１例１５次检查均取得清晰立体图像，且可消除某一骨性结构，单独观察髋白骨折、股骨头骨折或胫骨折情况，还可消除术后扫描图像的金属放射状的伪影。     

Does 3D CT reconstruction help the surgeon to preoperatively assess calcaneal fractures?

BackgroundWith the advent of 3D volume rendered CT scans, more information is potentially available to aid the surgeon in complex calcaneal fractures. The primary aim was to determine if there is a difference in inter-observer and intra-observer reliability of 3D CT reconstructions compared to 2D CTs of calcaneus fractures based on classification, identification of specific fracture characteristics and proposed treatment. It is hypothesized that the correlation will be greater between experienced surgeons and trainees when using 3D CT. As a secondary aim, the authors wished to investigate the surgeons’ satisfaction with 3D CT.Patients and methodsThere were six raters, split into 2 groups: high and low surgical experience. Both 2D and 3D scans (10 patients) were reviewed by each rater by filling out a validated questionnaire. This sitting was over a period of six months and all scans were sent separately and randomly by our research coordinator. This process was repeated after a four-week break.ResultsThe overall evaluation and satisfaction of CT scans of calcaneal fractures was improved by the additional use of volume rendered 3D images. Inexperienced surgeons benefited more than experienced surgeons in terms of reliabilities with fracture configuration. 3D CTs were more likely to change the surgeons’ operative strategy. The consistency of deciding on the fracture classification and satisfaction was more uniform between all the raters when 3D CT was used.ConclusionInter-observer and intra-observer reliability of 3D CT reconstructions compared to 2D CTs of calcaneus fractures was greater based on classification, identification of specific fracture characteristics and proposed treatment. Inexperienced surgeons were more consistent when interpreting the scans using 3D CTs (improved inter-observer reliability) and were always more satisfied using the 3D CTs. As there is no extra cost or radiation exposure, we propose that 3D CTs may be valuable with preoperative teaching and planning.     

Pedicle screw insertion: robotic assistance versus conventional C-arm fluoroscopy

Bone-mounted robotic guidance for pedicle screw placement has been recently introduced, aiming at increasing accuracy. The aim of this prospective study was to compare this novel approach with the conventional fluoroscopy assisted freehand technique (not the two- or three-dimensional fluoroscopy-based navigation). Two groups were compared: 11 patients, constituting the robotical group, were instrumented with 64 pedicle screws; 23 other patients, constituting the fluoroscopic group, were also instrumented with 64 pedicle screws. Screw position was assessed by two independent observers on postoperative CT-scans using the Rampersaud A to D classification. No neurological complications were noted. Grade A (totally within pedicle margins) accounted for 79% of the screws in the robotically assisted and for 83% of the screws in the fluoroscopic group respectively (p = 0.8). Grade C and D screws, considered as misplacements, accounted for 4.7% of all robotically inserted screws and 7.8% of the fluoroscopically inserted screws (p = 0.71). The current study did not allow to state that robotically assisted screw placement supersedes the conventional fluoroscopy assisted technique, although the literature is more optimistic about the former.