Pedicle Axis Research Articles

Does the Iliac Wing Influence L5 Pedicle Screw Fixation?

To explore whether the iliac wing influences L5 pedicle screw (PS) fixation and to propose methods to reduce such influence. A total of 100 computed tomography scans (from 50 male and 50 female patients) of the lower lumbar region and pelvis were obtained and 3-dimensionally reconstructed. Cylinders with 6.5-mm diameters were drawn to simulate the different trajectories of L5 PS. The maximum lengths and lateral angles of trajectories, and the vertical distances from the inner edge of the iliac wing to these trajectories, were measured. The maximum lengths and lateral angles differed significantly among trajectories; the maximum length, but not the lateral angle, differed significantly between male and female subjects. The influence of the iliac wing was more significant in male than in female subjects. The iliac wing had a greater effect on screws implanted along the pedicle axis than on screws for which the trajectories commenced at Du's entry point and passed through the center of the pedicle. This study elucidates the influence of the iliac wing on L5 PS fixation. Careful attention is required when implanting PSs, especially in male patients. The combined use of Du's technique and a percutaneous method for PS implantation effectively reduces the influence of the iliac wing. To minimize the complications of PS fixation further, preoperative simulation of fixation for each patient is very important.

Clinical significance of superior articular process as a reference point for free-hand pedicle screw insertion in thoracic spine.

The trajectory of the pedicle screw perpendicular to the SAP (superior articular process) is consistent with the universal trajectory presented in the previous study of the entry point using computed tomography. The ideal entry point and trajectory of pedicle screw insertion have been a matter of considerable debate. We attempted to find the relationship between SAP and entry point and trajectory of the pedicle screw.Thoracic spine CT (computed tomography) scans of 9 volunteers were studied. A safe zone for the trajectory of the screw in the axial (MarginAx) and sagittal (MarginSag) was defined as the zone between lines perpendicular to the SAP along the medial and lateral cortex of the pedicle in the axial section, and the superior and inferior cortex in the sagittal section without violation of the pedicle walls. The midline of MarginAx and MarginSag was defined as the safe entry point of the trajectory in the axial and sagittal planes (TrajectoryAx and TrajectorySag), respectively.MarginAx and MarginSag were 4.14 ± 0.99 and 9.03 ± 2.01 mm, respectively. There was a statistically significant difference in TrajectoryAx between the upper and middle, and between the upper and lower (P = .0076 in both cases), but not between the middle and lower thoracic spine (P = .066). TrajectorySag was within 1 mm at the levels of T4, T8, T11 vertebrae and at 0 mm at the other levels. Thus, the midpoint of MarginSag was within 1 mm from the SAP base.There was a constant angular relationship with the SAP and the pedicle axis; the line perpendicular to the SAP can act as a trajectory. Therefore, we suggest that the SAP might be the only accurate and safe reference for pedicle screw insertion in the thoracic spine perpendicular to the SAP using freehand technique.

Computerized Tomography-Based Morphometric Analysis of Subaxial Cervical Spine Pedicle in Asymptomatic Indian Population.

The purpose of this study was to analyze morphometry of the subaxial cervical spine pedicles in an Indian population based on computed tomography (CT), and thus assess the safety and feasibility of cervical pedicle screw in the subaxial cervical spine. CT scans of 500 subaxial cervical spine vertebrae were analyzed from 100 patients presenting to our institution and undergoing cervical spine CT scan for an unrelated cause as part of ATLS protocol. Pedicle width (PW), pedicle axis length (PAL), pedicle transverse angulation (PTA), and lateral pedicle distance (LPD) were calculated on axial CT scans, and pedicle height (PH), pedicle length (PL), superior pedicle distance (SPD), and pedicle sagittal angulation (PSA) were calculated on sagittal CT scans. The mean PW ranged from 4.3 mm at C3 to 5.7 mm at C7. Mean PH ranged from 5.5 mm at C3 to 6.1 mm at C7. Mean PTA ranged from 44.5° at C3 to 37.1° at C7. PSA ranged from 16.65° at C3 to 3.29° at C7. Mean LPD ranged from 1.6 mm at C3 to 3.4 mm at C6. Mean SPD ranged from 3.5 mm at C3 to 1.15 mm at C7. Mean PAL ranged from 29.6 mm at C3 to 33.04 mm at C7. Mean PL ranged from 5.2 mm at C3 to 5.78 mm at C7. Our CT-based morphometric study confirms that cervical pedicle screw placement is possible in most of the Indian population except at C3 in females. A thorough understanding of pedicle anatomy with proper CT-based preoperative planning can mitigate the risk associated with pedicle screw placement in subaxial cervical spine.

Imaging measurement and clinical significance of the angle between the axis of pedicle and the plane of lamina in lower cervical vertebra

To explore the imaging measurement and clinical significance of the angle between the axis of pedicle and the plane of lamina in lower cervical vertebra. Methods: Three dimensional reconstruction of CT scan was performed in 30 patients with cervical deformity, and the angle between the axis of pedicle and the plane of lamina was measured with the specific reconstructed CT image of C3-C7. Results: 1) The left and right transverse angle of C3-C7 between the axis of pedicle and the ipsilateral plane of lamina were 98.3°±6.3°, 98.0°±5.1°, 97.5°±6.9°, 95.1°±5.0°, 85.8°±5.4° and 96.7°±8.2°, 98.7°±7.1°, 97.8°±3.6°, 93.2°±6.2°, 86.8°±5.7°, respectively, which showed a gradual decreasing trend. Meanwhile the angle of C3-C6 was more than 90 degrees and C7 was less than 90 degrees. In addition to C6 with C3 and C7 with other segments, the rest of the differences between the sections was not statistically significant (all P>0.05). 2) The left and right transverse angle of C3-C7 between the axis of pedicle and the pedicle of vertebral arch of lamina were 0.2°±4.5°, 1.2°±7.2°, -0.8°±6.8°, -3.3°±5.4°, -14.7°±4.0° and -1.6°±5.4°, 1.9°±4.6°, -0.5°±6.0°, -4.6°±5.3°, -13.7°±3.4°, respectively, which showed a first increasing and then reducing trend. Meanwhile the angle of C4 was maximum angle. In addition to C6 with C3, C6 with C4, and C7 with other segments, the differences between the sections was not statistically significant (all P>0.05). 3) The left and right sagittal angle of C3-C7 between the axis of pedicle and the ipsilateral plane of lamina were 77.7°±7.6°, 77.0°±7.1°, 85.3°±8.4°, 94.1°±2.2°, 94.9°±3.8° and 78.5°±7.1°, 76.2°±6.2°, 86.4°±6.4°, 94.0°±2.7°, 95.6°±3.8°, respectively, which showed a gradual increasing trend. The angle of C3-C4 was less than 90 degrees. C5 showed large variation and C6-C7 was more than 90 degrees. In addition to C3 with C4 and C6 with C7, the differences between the sections was statistically significant (all P<0.05). There was no significant difference between the two sides of the above indexes (all P>0.05). Conclusion: In low cervical vertebra, there is a certain angle relationship between the axis of pedicle and the plane of lamina, which can provide reference for the clinical determination of angle of pedicle screw insertion.

Safe corridor for the implantation of thoracolumbar pedicle screws in growing pigs: A morphometric study.

The pig spine is widely used as a large animal model for preclinical research in human medicine to test new spinal implants and surgical procedures. Among them, pedicle screw is one of the most common method of fixation of those implants. However, the pedicle of the porcine vertebra is not as well defined and not as large as the pedicle of the human vertebra. Therefore, the position of the screw should be adapted to the pig and not merely transposed based on the literature on humans. The purpose of this study is to determine the characteristics of the optimum implantation corridors for pedicle screws in the thoracolumbar spine of piglets of different ages using computed tomography (CT) and to determine the size and length of these corridors in pigs of different ages. CT scans from five groups of age: 6, 10, 14, 18, and 26 weeks were reviewed. For each thoracolumbar vertebrae, the pedicle width, pedicle axis length, and the pedicle angle was measured for the left and right pedicle. A total of 326 thoracic vertebrae and 126 lumbar vertebrae were included in the study. Pedicles are statistically larger but not longer for the lumbar vertebrae. An important variation of the pedicle angle is observed along the spine. In all pigs, an abrupt modification of the pedicle angle between T10 and T11 was observed, which corresponds to the level of the anticlinal vertebra which is the vertebra for which the spinous process is nearly perpendicular to the vertebral body. In conclusion, this study provides a quantitative database of pedicle screw implantation corridors in pigs of different ages. When using pedicle screws in experimental studies in pigs, these results should be considered for selecting the most suitable implants for the study but also to ensure a correct and safer screw position. Improving study procedures may limit postoperative complications and pain, thereby limiting the use of live animals.

Morphometric analysis of typical cervical vertebral pedicle - An osteological study

Background: Successful placement of cervical pedicle screws requires accurate identification of entry point, trajectory and appropriate size of implant. Studies and guidelines regarding the direction of pedicle screw insertion and pedicle dimensions in Indian population are very limited and hence the objective of our study was to do Morphometric analysis of Typical Cervical Vertebral pedicle (C3 to C6) Materials and Methods: Osteological study of the pedicle was performed in 100 typical (C3-C6) dry bone specimens. The vertebral pedicles were evaluated by measuring its height, width, length, lateral mass + pedicle length, total pedicle axis length and transverse pedicle angle. Results: In our study, the mean pedicle length of C3, C4, C5, C6 was 6.04, 5.48, 5.30, and 5.92 respectively. The mean pedicle height in our study ranged from 5.05 mm (C3) to 5.86 mm (C6). The Range of Mean pedicle width was from 4.79 to 5.16 mm. The mean lateral mass + pedilce length ranged from 11.17 to 13.18 mm while the mean total pedicle axis length ranged from 27.05 to 30.04 mm. Conclusions: We found that there were high individual variations. The pedicle dimensions were relatively smaller in Indians compared to previous studies in other population. This mandates preoperative CT evaluation of pedicle and smaller size pedicle screws customized according to pedicle dimensions of Indians.

Morphometric analysis of the lumbar vertebrae in the Turkish population using three-dimensional computed tomography: correlation with sex, age, and height

Morphometric measurements of lumbar vertebrae are different in European and Asian populations. Transpedicular screws are candidates for the ideal method to treat instability of lumbar vertebrae and provide very strong stabilisation. Our study reflects the variation of morphometric measurements of lumbar vertebrae in the Turkish population according to sex, age, and height. The aim of our study was to measure the transverse pedicle diameter (TPD), vertical pedicle diameter (VPD), pedicle axis length (PAL), and transverse pedicle angle (TPA) of the lumbar vertebrae, using three-dimensional computed tomography (3D-CT), and assess variations according to sex, age, and height. Prospective cohort, Therapeutic Level III, Urban Level III Trauma Centre. The study design adopted a morphometric analysis using 3D-CT of the lumbar vertebrae in the Turkish population, with variation in terms of sex, age, and height and comparison with previous studies. In 240 cases, measurements of TPC, VPD, PAL, and TPA with 3D-CT were performed on a total of 1200 lumbar vertebrae. The values at each lumbar level were compared in groups based on sex, age, and height. The results of our study determined the normal values of TPD, VPD, PAL, and TPA of lumbar vertebrae in the Turkish population using 3D-CT. Additionally there were variations in TPD, VPD, and PAL according to sex, age, and height. TPA varied according to age, while no difference was found in terms of sex or height. The morphometric measurements of lumbar vertebrae in the Turkish population are similar to western populations. Sex, age, and height are factors affecting reliable screw choice.

Evaluation of Correction of Radiologic Parameters (Angulation and Displacement) and Accuracy of C2 Pedicle Screw Placement in Unstable Hangman's Fracture with Intraoperative Computed Tomography-Based Navigation.

Opinions vary regarding optimal treatment of unstable hangman's fractures, including rigid orthosis and internal fixation. The anatomy of upper cervical spine is complex. The advent of intraoperative 3-dimensional navigation systems facilitates safe and accurateinstrumentation. To evaluate radiologic parameters of fracture morphology in unstable hangman's fracture in preoperative and postoperative period and accuracy of inserting axis pedicle screws by using intraoperative computed tomography-based navigation. Fifteen patients with unstable hangman's fractures with age ranging from 17 years to 81 years were operated using computed tomography-based navigation from September 2011 to march 2016. Patient's age, sex, mechanism of injury, associated injuries, and neurologic status were noted. Clinical outcome, accuracy of screw insertion, preoperative and postoperative displacement, and angulation of C2 over C3 and bony fusion were assessed. Overall, 76 screws were inserted including 30 screws in C2 pedicle with 2 (2/60; 6.7%) malplaced screws in C2 pedicle. Mean follow-up period was 34 ± 18 months (range 7-80 months). Mean hospital stay was 12.8 ± 2.4 days. Mean preoperative and postoperative displacements were 4.09 mm ± 1.78 mm and 1.82 mm ± 1.14 mm respectively with a mean reduction of 2.27 mm ± 1.49 mm. Mean preoperative angulation was 7.23° ± 11.96° and postoperative angulation was 2.32° ± 4.77° with a mean reduction of 5.11° ± 11.96°. Bony fusion was achieved and rotation was preserved at C1-C2 joint in all cases. Intraoperative O-arm-based navigation is a safe, accurate, and effective tool for screw placement in patients with unstable hangman fracture and achieves good anatomical reduction.

A quantitative anatomical study of ideal insertion pathway of anterior axis pedicle screw fixation

Objective To explore an ideal screw insertion point and optimal trajectory for anterior axis pedicle screw (AAPS) so as to provide an anatomical basis for AAPS placement. Methods CT scan of the cervical spine was performed for 40 healthy Chinese adults. Then, the CT data were imported into the Mimics software to reconstruct the three-dimensional images of the axes. The data were divided into two groups according to the gender. The following data were measured: pedicle centerline minimal diameter on both left and right sides, pedicle axial length, the distance between entrance point and upper endplate, the distance between entrance point and median sagittal plane, the distance between entrance point and peak of crista lambdoidalis of C2 vertebral body, extraversion angle and sagittal angle. The screw fixation parameters for AAPS were measured using the Mimics software. Results There was no statistical difference between the left and right sides as well as between the genders(P>0.05). The entrance point for insertion of AAPS was recommended to be on (4.39±0.67)mm from the upper endplate, and on (3.95±0.44)mm from the median sagittal plane. The ideal pedicle axial length was (34.15±2.93)mm, and the pedicle centerline minimal diameter was (7.04±0.87)mm. The distance between the entrance point and the peak of crista lambdoidalis of C2 vertebral body was (1.45±0.19)mm. The ideal extraversion angle was (30.80±2.79)°, and the ideal sagittal angle was (36.35±3.26)°. Conclusion The ideal insertion pathway of AAPS placement can avoid spinal canal, foramen intervertebrale and other important anatomical structure, which is feasible in regard of anatomy. The insertion point can refer to the peak of crista lambdoidalis of C2 vertebral body. However, AAPS placement should be individualized in term of its anatomy variability. Key words: Axis; Pedicle screws; Anatomy

Anterior pedicle spreader reduction for unilateral cervical facet dislocation

ObjectiveThe anterior only surgical procedure including discectomy, open reduction and fusion is used as a recommended approach in the treatment of unilateral cervical facet dislocations, but is difficult to achieve satisfactory anterior open reduction by vertebra distractor to spread the facet joints, especially for delayed management of unilateral cervical facet dislocation (7–21days). The goal of this study was to report an anterior pedicle spreader technique to distract directly the facet joint for anterior reduction and the results of 4 patients with successful application and describe safety. MethodsFour patients with unilateral cervical facet dislocation who failed to open anterior reduction by vertebra spreader procedure were surgically treated by the anterior pedicle spreader reduction. In these 4 patients (3 males and 1 female), the distribution of spine level was from C4/5 to C6/7; the neurological status was comprised 2 patients with ASIA E, 1 with D and 1 with A; the surgical management was ranged from 7 to 18days. After discectomy, if failed to open anterior reduction procedure, the anterior pedicle spreader was inserted along the pedicle axis with the fluoroscope-assisted view imaging. The spreader was distracted directly to the facet joint and pushed in a caudad direction to achieve posterior translation of the upper segment. ResultsPostoperatively, all patients had obtained successful reduction and satisfactory anatomic sagittal alignment. There was no complication owing to the use of this technique. The ASIA A showed no neurological improvement; the patient with ASIA D was improved neurologically to ASIA E; no ASIA E patients showed neurological deterioration. ConclusionsAnterior pedicle spreader reduction represents an efficacious but technically challenging option for the delayed treatment of unilateral cervical facet dislocation.

Radiographic anatomical relationship between spinous process and pedicle in thoracolumbar and lumbar spine.

Pedicle screws are widely used in spinal surgeries, but it remains technically demanding to place. There are numerous studies on the anatomy of pedicle; however, there is very little insight on the relationship between the pedicle and the spinous process, which is an important part of the spinal posterior column.The aim of the study was to investigate the radiographic anatomical relationship between spinous processes and pedicles in the thoracolumbar and lumbar spine, in order to reveal a novel entrance point for pedicle screw insertion.Sixty candidates were enrolled in this study; cases were excluded with degenerative disorders and other disorders as osteoporosis, deformity, and tumor. Radiographs and computer tomography scans between T10 and L5 were obtained on each case. The distance was measured that between the superior margin of spinous process root and the superior border, the inferior border and the axis of pedicle. In laboratory, 5 fresh cadavers were used to imitate the pedicle screw insertion.The basic reference point was supposed as the intersection between the horizontal line of superior margin of spinous process root and the central vertical line of the superior facet. For T10 to T12, the pedicle axis was 5 mm beyond the reference point. For L1 to L4, the pedicle axis was at the reference point. At L5, the pedicle axis was 5 mm beneath the reference point. In laboratory, 80 screws were all inserted into pedicles successfully according to the newly referred entrance point.The study reveals the radiographic anatomical relationship between the pedicle and the spinous process. The pedicle axis is around the horizontal line of the superior margin of spinous process root. It provides a new anatomic mark of pedicle screw entrance point.

Pedicle Fractures of Axis

Cervical spinal column anatomically can be divided two part as upper and lower cervical spine. Upper cervical spine consists of the foramen magnum, paired occipital condyles, atlas and axis. C2 is the largest structure with its unique shape and function in this segment. The pars interarticularis and the pedicle are differently located in axis in comparison with other vertebrae. These two parts can be confused in the axis because of their unique anatomical localization. The pedicle of axis is the portion beneath the superior facet and anteromedial to the transverse foramen. In the other hand, the pars interarticularis or isthmus of axis is the narrower portion between the superior and inferior articulating facets. Fracture located at the pedicle of axis is extremely rare. The publications in this subject are still at the case presentation level. The presumed mechanism of injury is axial compression occurring in association with an asymmetrical lateral or rotatory component of the atlas on axis. Computerized tomography images with bone window and three-dimensional reconstruction of images of axis are the gold standard in the neuroradiological imaging of fracture. There is no specific clinical symptom and finding in the clinical diagnosing of the pedicle fracture. The neck pain may probably be present and the only symptom in the patient with unilateral pedicle fracture of axis. In the management of axis pedicle fracture, it is important that the patient’s age, presence of neurological deficit, additional fracture, ligament damage, and instability of the fracture. Isolated single-sided pedicle fractures are usually fractured in the form of unfragmented fissures. Such kinds of fractures are stabile fractures of C2. There is no need for surgical treatment in such patients.

Easy method to simplify “freehand” subaxial cervical pedicle screw insertion

Study Design:Technical note.Objectives:The objective of this study is to check out safety and rationality of standardized and fast tricks to select trajectory of subaxial cervical pedicle screw (SCPS) insertion, based on simple angles to bony landmarks.Materials and Methods:Stage 1 – Computed tomography (CT)-morphometric analysis of C3–C7 vertebrae of ten patients with cervical degenerative diseases. Stage 2 – SCPS insertion in 6 cadavers, according to the developed technique (59 pedicle screws). Stage 3 – SCPS insertion in 6 patients, according to the developed technique (32 pedicle screws).Results:CT-morphometric analysis showed that the average length of C3–C7 pedicle channels was 32 mm, the average angle between a pedicle axis and an axis of contralateral lamina - 180°, the average angle between a pedicle axis and plane of a posterior surface of a lateral mass amounted to 90° and the coordinates of an optimal entry point – 2 mm from a lateral edge and 2 mm from an upper edge of the lateral mass posterior surface. During the cadaveric study, 39 screws had a satisfactory position (66.1%), 7 screws permissible (11.9%), and 13 screws unacceptable (22%). During the clinical study, 26 screws (81.25%) had satisfactory position, 4 (12.5%) had permissible position, and 2 (6.25%) unacceptable position.Conclusion:Developed and clinically approved a method for simplicity SCPS insertion is relatively safe and cheap. No doubt, it requires further investigation, but the results of primary analysis allow us to recommend it to wide practical application.

CT Evaluations for C2 Pedicle Screw Fixation: Multiplanar Computerized Tomography Measurements in 100 Moroccan Patients

Abstract Background: Transpedicular screw fixation in the Axis is difficult due to its relation with adjacent anatomic features. Successful placement requires a sufficient understanding of axis pedicle. Objective: The aim was to assess length and width of the C2 pedicle in Moroccan population in order to evaluate the safety of pedicle screw fixation. Patients and methods: We evaluated the C2 pedicle morphology using computed tomography (CT) imaging in 100 patients (30 females and 70 males; age range, 18–70; mean, 36,2 ± 11,9 years). Axial CT cutting was made at 1.25 mm intervals. The measurements of C2 pedicles were performed on CT images using its measurement tools. The pedicle transverse width was defined as the mediolateral diameter of the pedicle isthmus. Pedicle length (distance from the posterior cortex of the lateral mass to the middle of the vertebral body). Results: The overall mean pedicle transverse widths (PTW) were 5.3 mm (4.1 to 7.1 mm), in males were 5.2 ± 0.5 mm and 5 ± 0.4 mm in females. The overall mean pedicle lengths (PL) were ranged from 19,7 to 26.7 mm with average 22.5 mm. The mean PL in female was 21.8 ± 1.4 mm and 22.8 ± 1.7 mm in male. The mean PTW and PL were greater in males than in females at both sides, and this difference was statistically significant. On the other hand, they were not correlated to age in our adult patients. Conclusion: Our findings suggest that there were significant differences between individuals and ethnics. The preoperative CT scans undergoing cervical transpedicular fixation should be thoroughly analyzed for successful pedicle screws placement.

Cervical pedicle morphometry in a Latin American population: A Brazilian study.

The goal of this study was to conduct a detailed computed tomography (CT) assessment in the Brazilian population of the screw starting point, trajectory, and dimensions of pedicle in the cervical spine.Two hundred consecutive patients were retrospectively evaluated using cervical spine CT, with imaging reconstruction of each cervical vertebrae in the axial plane with 2 mm, and in sagittal reconstructions with 3 mm. Parameters in axial plane included the pedicle width (PW), pedicle axis length (PAL), pedicle transverse angle (PTA), and the distance from the entry point to the point between the lamina and spinous process (DEP). Measurements in the sagittal plane involved the pedicle height (PH) and the pedicle sagittal angle (PSA).The mean PW and PH were smaller in females than in males in all cervical vertebrae, but there were no significant differences of PTA among genders. PSA ranged from 15.2° to 23.7°. Mean values of PAL and DEP had a tendency to decrease from the proximal to distal cervical vertebrae. PW was <4 mm in 7.5% of men (C3) and 25% of women (C3), and <4.5 mm in 20% (C3 male) and 66% (C3 female). The intra- and inter-observer reliability were very good for the tomographic measurement of PW, and good for PH. For PAL, the intraobserver reliability was good, but the interobserver reliability varied from moderate to good. Considering PTA and PSA, the intraobserver reliability was good, but the interobserver reliability moderate for PTA and poor or fair for PSA. DEP measurements showed poor intraobserver reliability, and poor or moderate interobserver reliability.Our results presented similar trend of previous studies, but the frequency of patients with PW <4.5 mm in our population is higher, suggesting an increased risk during the attempting of transpedicular screw technique.

Subcutaneous pedicle propeller flap: An old technique revisited and modified!

Background:Post-burn axillary and elbow scar contracture is a challenging problem to the reconstructive surgeon owing to the wide range of abduction and extension that should be achieved, respectively, while treating either of the joint. The aim of this paper is to highlight the use of subcutaneous pedicle propeller flap for the management of post-burn axillary and elbow contractures.Methodology:This is a prospective case study of axillary and elbow contractures managed at a tertiary care hospital using propeller flap based on subcutaneous pedicle from 2009 to 2014. Surgical treatment comprised of subcutaneous-based pedicle propeller flap from the normal tissue within the contracture based on central axis pedicle. The flap was rotated axially to break the contracture. The technique further encompassed a modification, a Zig-Zag incision of the flap, which was seen to prevent hypertrophy along the incision line. There was a mean period of 12 months of follow-up.Results:Thirty-eight patients consisting of 22 males and 16 females were included in this study among which 23 patients had Type II axillary contractures and 15 had moderate flexion contractures at elbow joint. The post-operative abduction achieved at shoulder joint had a mean of 168° whereas extension achieved at elbow had a mean of 175°. The functional and aesthetic results were satisfactory.Conclusion:The choice of surgical procedure for reconstruction of post-burn upper extremity contractures should be made according to the pattern of scar contracture and the state of surrounding skin. The choice of subcutaneous pedicle propeller flap should be emphasised because of the superior functional results of flap as well as ease to learn it. Moreover, the modification of propeller flap described achieves better results in terms of scar healing. There is an inter-positioning of healthy skin in between the graft, so it prevents scar band formation all around the flap.

An RCT study on the feasibility of anterior transpedicular screw fixation in the cervicothoracic junction

We evaluated the trajectory and the entry points of anterior transpedicular screws (ATPS) in the cervicothoracic junction (CTJ). This study aimed at investigating the feasibility of ATPS fixation in the CTJ. Application of an ATPS in the lower cervical spine has been reported; however, there were no reports exploring the feasibility of anterior transpedicular screw fixation in the CTJ. CT scans were performed in 50 cases and multiplanar reformation was used to measure the related parameters on pedicle axis view at C6-T2. Transverse pedicle angle, outer pedicle width, pedicle axis length, distance transverse intersection point (DtIP), sagittal pedicle angle, anterior vertebral body height, outer pedicle height, and distance sagittal intersection point (DsIP) were measured. The prozone of CTJ was divided into three different regions, which were named as the "manubrium region", the region "above" and "below" the manubrium. The distribution of the trajectory of sagittal pedicle axes was recorded in the three regions and the related data were statistically analyzed. There was no statistical difference in gender (P>0.05). The transverse pedicle angle decreased from C6 (46.77°±2.72°) to T2 (20.62°±5.04°). DtIP increased from C6 to T2. DsIP was an average of 7.17mm. The sagittal pedicle axis lines of the C6 and C7 were located in the region above the manubrium. T1 was mainly in the manubrium region followed by the region above the manubrium. T2 was mainly located in the manubrium region followed by the region below the manubrium. Implantation of ATPS at C6, C7, and some T1 is feasible through the low anterior cervical approach, while it is almost impossible to approach T2 that way.

Medially-shifted rather than high-riding vertebral arteries preclude safe pedicle screw insertion

We enrolled 100 patients who underwent preoperative CT angiography before cervical spine instrumentation and investigated the morphology of the C2 pedicle from the perspective of pedicle screw (PS) trajectory using volume rendering and multiplanar reconstruction. The narrowest portion of the pedicle was identified as the pedicle isthmus. Safe C2 PS insertion was regarded to be not feasible when the height of the medullary cavity of the pedicle isthmus and/or width of the medullary cavity of the pedicle isthmus was ⩽4mm. Forty-five (22.5%) pedicles were ⩽4mm in width, and safe insertion of a PS was determined to be not feasible. Among these, seven pedicles were ⩽4mm in both height and width. The remaining 38 pedicles were ⩽4mm in width with heights >4mm. There was no pedicle with a width >4mm and height <4mm. In other words, short pedicles were always concomitantly narrow. Therefore, the seven pedicles ⩽4mm in both height and width were considered to be morphologically narrow. The heights of the pedicle isthmus were not limited by the vertebral artery groove (VAG) and safe C2 PS insertion can be considered feasible where the VAG is marginally cranial, whereas the widths of the pedicle isthmus are limited by the VAG. Therefore, safe C2 PS insertion is precluded only when the VAG courses cranially and medially. It is a medially-shifted, rather than a high-riding, vertebral artery that precludes safe C2 PS insertion. Therefore to avoid vertebral artery injury an axial CT scan, parallel to the pedicle axis, should be evaluated before C2 PS insertion.

Individualized transoral anterior surgery for complex craniocervical junction disorder with assistance of 3D printing technology

Objective To evaluate the value of 3D printing technology in transoral anterior surgery for complex craniocervical junction disorder. Methods From December 2009 to December 2013, 48 cases of atlantoaxial dislocation associated with complex craniocervical malformation were operated with the assistance of 3D printing technology. There were 19 males and 29 females, with mean 35 years of age (range, 6 to 59 years). Preoperative complications included 28 cases of atlas assimilation, 19 cases of os odontoideum, 17 cases of C2-3 fusion, 1 case of C2-5 fusion, 1 case of C1 posterior arch disconnection, and 1 case of C1 posterior arch aplasia. All cases had symptoms of spinal compression such as numbness and weakness of the extremity, standing or walking unsteady, etc. Preopoerative cervical MRI examinations showed the enlargement of anterior atlas-dens interval (ADI) or atlantoaxial dislocation. All cases' CT data in Dicom form were input into the Simpleware software to reconstruct 3D image, and then the image in STL form was imported to the 3D printer to make a fast prototyping model for the operation with same size as the cases' cervical spine. Based on above works, all cases underwent transoral anterior reduction plate (TARP) fixation in the craniocervical junction zone, including combined anterior-posterior surgery in 1 case. ADI was measured to evaluate the reduction of atlantoaxial dislocation, cervical-medullary angle (CMA) was measured to evaluate the improvement of compression on the medulla, and Japanese Orthopedic Association (JOA) scoring system was used to evaluate the improvement of spinal function. Results All cases went through successful surgery. Mean operation time was (145±45)min and mean blood loss was (53±15)ml. A total of 96 atlas lateral mass screws, 62 reverse axis pedicle screws and 36 axis vertebral body screws, 1 posterior axis pedicle screw and 1 axis translaminar screw were used. Postoperative CT scans showed all screw trajectories were good except that 4 reverse axis pedicle screws violated into the vertebrae artery foramen due to large outward inclination angle. No neurologic defect was found in all cases. Excellent rate of screw placement was 98%. Postoperative CT reconstruction images showed significant atlantoaxial reduction. ADI improved from (8.7±4.9)mm preoperatively to (2.7±1.9)mm postoperatively (P<0.05). CMA changed from preoperative (123±17)° to postoperative (159±18)° (P<0.05). All cases had obvious improvement of spinal compression symptoms. JOA scores improved from (9.5±1.7)points preoperatively to (15.7±0.9)points at 3 months postoperatively (P<0.05). All cases achieved bone union at a follow-up of 10-58 months. Conclusion 3D printing technology is helpful to the operation plan and manipulation for atlantoaxial dislocation associated with complex craniocervical deformities, which may improve the accuracy and safety during the procedure. Key words: Atlanto-axial joint; Dislocations; Imaging, three-dimensional; Computer-assisted design

Feasibility Study of Free-Hand Technique for Pedicle Screw Insertion at C7 without Fluoroscopy-Guidance.

Study DesignRetrospective interventional study.PurposeTo introduce a free-hand pedicle screw (PS) insertion technique without fluoroscopic guidance in the C7 vertebra and evaluate the procedure's feasibility and radiologic outcomes.Overview of LiteratureAlthough PS insertion at C7 has been recognized as a critical procedure in posterior cervical fusion surgery, conventional techniques for C7 PS have several limitations.MethodsThirty two patients (64 screws) who underwent PS insertion in C7 with the novel technique were included in this study. Postoperative clinical and radiological outcomes were evaluated. Special attention was paid to the presence of any problems in the screw position including cortical breaches of the PS and encroachment of the PS into the spinal canal or the vertebral foramen. This novel technique for PS insertion in C7 without fluoroscopy guidance had three key elements. First, the ideal PS entry point was chosen near the C6–7 facet joint using preoperative images. Second, the convergent angle distance was measured at axial computed tomography (CT) imaging, which defined the distance between the tip of C7 spinous process and the extended line passing through the pedicle axis from the ideal entry point. Third, the cranial-caudal angle distance was measured in sagittal CT images, which defined the distance between the tip of the C7 spinous process and the extended line passing through the pedicle axis.ResultsCortical breach on postoperative CT images was observed in three screws. All violated only the lateral wall of the affected pedicle. The breached screws occurred in the initial five cases. Postoperative neurologic deterioration was not observed in any patient, regardless of cortical breaching.ConclusionsThe novel technique successfully allows for C7 PS to be placed and is associated with a low rate of cortical breach.