Transarticular Screw Research Articles

Comparative analysis of clinical outcomes of surgically stabilised atlanto-axial instability with various surgical methods

Objectives: The atlanto-axial segment consists of the atlas and axis forming a complex transitional structure bridging the occiput and cervical spine. The functional result of the joint is to provide support for the occiput and greatest range of motion and flexibility possible while maintaining stability. The main objective of the study is to assess clinical changes post surgery of atlanto-axial instability fixation comparing impact of various surgical methods.Materials and Methods: Single centred prospective study with sample size of 50. Demographic data, detailed history of symptoms and other co-morbidities were recorded. The anatomic characteristics of cervicovertebral junction, presence of compression and atlantoaxial instability evaluated. Operative details, types of approach, method of fixation chosen-transarticular screws, screw and rod fixation (SRF), occipitocervical plating and combination of transarticular screws on one side and SRF other side noted. Comparison was done based on demographic data, clinical features and neurological status pre and post operatively.Results: Mean age was 30.22 years, ranging from 7 to 71 years with majority belonged to 11-20 years age-group (17/50, 34%). Majority of the patients had a congenital cause for instability (22/50, 44%), 17 of the 50 patients (34%) had co-morbidities with Down’s syndrome being most common. Most common symptom being quadriparesis followed by neck pain. Most common procedure done was C1-C2 Screw plus rod fixation followed by trans-articular screw. Mean Nuricks grading was 3.32±1.09 pre-operatively with significant change was noted at 3 months post-op follow-up 2.84±1.21 (p

Clinical Comparison of Combined Cortical Bone Trajectory and Transarticular Surface Screw Versus Standard Pedicle Screw Insertion by Wiltse Approach for L5 Isthmic Spondylolisthesis.

This was a retrospective cohort study. The objective of this study was to assess the effectiveness and invasiveness of a combined screw insertion technique [using cortical bone trajectory (CBT) screw and transarticular surface screw (TASS)] for patients with L5 isthmic spondylolisthesis. Lumbosacral posterior fixation using TASS is safe, with high biomechanical strength. However, data regarding its clinical outcomes, effectiveness, and invasiveness, are lacking. This study included 111 patients who underwent single-level L5-S1 posterior lumbar interbody fusion (PLIF) for L5 isthmic spondylolisthesis. The cohort was stratified into 2 groups: the Wiltse group included patients who underwent PLIF between 2008 and 2013 with standard pedicle screw fixation via Wiltse approach and the CBT/TASS group included those who underwent PLIF from 2014 onward with CBT/TASS fixation. After propensity score matching of the CBT/TASS and Wiltse groups, the surgical times, estimated blood loss (EBL), length of in-hospital stays, clinical scores, serum creatine kinase concentration, radiographic parameters, and bone union rate were compared using the χ2 test or Mann-Whitney U test. In addition, multivariate linear regression analyses, with surgical time and EBL as objective variables applied after Box-Cox transformation, were performed. The matched CBT/TASS group showed significantly shorter surgical times (P<0.001), lower EBL (P=0.032), shorter in-hospital stays (P=0.005), and lower 3-day postoperative serum creatine kinase concentrations (P=0.014) than the matched Wiltse group. However, neither the postoperative grade of spondylolisthesis, the L5-S1 lordotic angle, nor the clinical scores were significantly different between matched groups. The bone union rates were 94.7% and 96.2% in the matched CBT/TASS and Wiltse groups, respectively (P=1.000). Regression analysis showed that CBT/TASS was an independent factor significantly related to shorter surgical times and lower EBL (P<0.001 and P=0.001, respectively). Compared with Wiltse approach, CBT/TASS is a less invasive technique, with a shorter surgical time and sufficient clinical outcomes for patients with L5 isthmic spondylolisthesis. Level III-treatment benefits.

The application of C2 transpedicular screw, C1 laminar hook fixation and bone graft in the atlantoaxial instability

Traumatic atlantoaxial instability usually results from a motor vehicle accident, falls and motorcycle accidents. Atlantoaxial instability can lead to spinal cord compression and neck pain, but, spasticity and radicular symptoms as well. The purpose of surgery is to remove the compression and stabilize the joint permanently. To date, several surgical techniques have been described to remedy C1-C2 instability. In this study, the clinical and radiological outcomes of patients who operated with the C1 (Atlas bone) laminar hooks fixation and bilateral C2 (Axis bone) trans-pedicular screw technique were shown. Also, the advantages and disadvantages of this technique are discussed. From March 2010 to December 2017, 12 patients who have atlantoaxial instability were surgically treated by modified fixation technique which consists C1 laminar hooks fixation and bilateral C2 transpedicular screw. Twelve patients were operated with this procedure from March 2010 to December 2017. All the patients were checked with flexion-extension x-rays at the end of the twelfth week. The posterior bony fusion formation was observed on imaging in all patients. C2 bilateral pedicle screw combined with C1 laminar hook system is a good method for atlantoaxial instability in the conditions which is not convenient for insertion of C1 lateral mass and C2 trans-articular screw. However, this method may not be available in some cases such as traumatic, infection, neoplastic or degenerative pathologies in which the posterior arch of the atlas is damaged.

A Clinical Study to Assess the Efficacy of Anterior Transarticular C1-C2 Screw Fixation for Stabilization of AtlantoAxial Instability

Introduction: The upper cervical spine includes the atlas (C1) and Axis (C2). The anatomy of upper twovertebrae is unique from each other. Atlanto-axial articulation is the most unique, mobile segment of spine,which largely depends on ligamentous supports based on integrity of odontoid for its stability. Historically,atlanto-axial subluxation was treated by reduction and fusion of C1-C2 joint. However, High riding vertebralartery precludes the placement of posterior trans-articular screw, which is liable to injury during screwplacement. Socomputed tomography scans can be used to evaluate the risk of “high riding” vertebral arteryduring the management of atlanto-axial subluxation. Hence, anterior trans-articular screw fixation techniqueavoids the course of high riding vertebral artery.Material and Method: Nine patients underwent NCCT cervical spine with 3-D reconstruction and clinicalevaluation of pain was done by recording the VAS score done pre operatively and after surgery.Results: All surgical cohorts underwent anterior C1-C2 fixation with an average follow up for 24 months.All patients were assessed as per fixed protocol of our local hospital guidelines of orthopaedics department.Pain score was clinically evaluated by VAS score before and after surgery yielding 90% excellent result.Conclusion: Anterior Trans-articular C1-C2 screw fixation isa minimally invasive technique with less bloodloss, shorter skins car and faster post-operative recovery. It is an appropriate technique for stabilization ofAtlanto-Axial instabilities.

Prevalence of high-riding vertebral arteries and narrow C2 pedicles among Central-European population: a computed tomography-based study

High-riding vertebral artery (HRVA) and narrow C2 pedicles (C2P) pose a great risk of injuring the vessel during C2 pedicle or transarticular screw placement. Recent meta-analysis revealed a paucity of European studies regarding measurements and prevalence of these anatomical variants. Three hundred eighty-three consecutive cervical spine CT scans with 766 potential screw insertion sites were analyzed independently by two trained observers. C2 internal height (C2InH), C2 isthmus height (C2IsH), and C2P width were measured. Kappa statistics for inter- and intraobserver reliability as well as for inter-software agreement were calculated. HRVA was defined as C2IsH of ≤ 5 mm and/or C2InH of ≤ 2 mm. Narrow C2P was defined as C2P width ≤ 4 mm. STROBE checklist was followed. At least 1 HRVA was found in 25,3% (95% CI 21,1–29,8) of patients (16,7% of potential sites). At least 1 narrow C2P was seen in 36,8% (95% CI 32,1–41,7) of patients (23,8% of potential sites). Among those with HRVA, unilateral HRVA was present in 68,0% (95% CI 58,4–77,0), whereas bilateral HRVA in 32,0% (95% CI 23,0–41,6). No difference in terms of laterality (right or left) was seen neither for HRVA nor narrow C2P. Significant differences were found between females and males for all measurements. Each parameter showed either good or excellent inter- or intraobserver, and inter-software agreement coefficients. HRVA and narrow C2P are common findings in Central-European population and should be appreciated at the planning stage before craniocervical instrumentation. Measurements can be consistently reproduced by various observers at varying intervals using different software.

Transarticular Fixation Following Mobilization of "High-Riding" Vertebral Artery.

The article identifies the feasibility of transarticular screw fixation after mobilizing the vertebral artery in cases where it is in a "high-riding" location. A 42-yr-old male patient had a 4-yr history of progressive quadriparesis. Investigations revealed severe basilar invagination. There was assimilation of atlas and C2-3 fusion. The vertebral artery was "high-riding" into the pedicle-facet of C2 vertebra on both sides. Vertebral artery loop was exposed and mobilized inferiorly on both sides after careful drilling of pedicular bone on the posterior aspect of the dome of the artery. C2 facetal bone on the anterior face of the vertebral artery dome was now available for screw insertion. The C1-2 facets and the articulation were directly in line, making transarticular screw fixation relatively straightforward. The wide bone space available permitted insertion of 2 screws in a transarticular fashion on both sides. The patient had satisfactory clinical improvement. Imaging after 22 mo showed bone fusion across the facets. Mobilization of the high-riding vertebral artery loop can help salvage the surgical procedure of lateral mass stabilization.

Anthropometric evaluation for surgical feasibility of C1-C2 transarticular screw stabilization in Indian population.

Study Design:This study was a radiographic observational study for C1–C2 anthropometry.Purpose:The purpose of the study was to understand the anatomic relationship of C1–C2 in view of transarticular screw (TAS) fixation, to overcome the difficulties related with TAS placement, and to minimize the technique-related complications.Materials and Methods:It was an anthropometric observational study with retrospectively obtained anatomical data of randomly selected 116 patients from a single center. The anatomical measurements such as pars width, pars height, screw trajectory, and length were evaluated on the axial, sagittal, and three-dimensional reconstructed cervical CT scan using the radiant DICOM viewer software by the two fellowship trained spine surgeons which were blind to the study group details. The intra- and interobserver reliability with regard to the measured parameters was statistically analyzed.Results:The mean age of male and female was 28 and 29 years. The average BMI was calculated to be 23.5 and 25 for males and females, respectively. The mean right pars width in males was 5.78 ± 0.93 (range: 3.1–6.5 mm), while in female, it was 5.84 ± 0.95 (range: 3.1–6.5). The mean left pars width in males was 5.95 ± 1.13 (range: 3.8–8.1 mm), while in females, it was 5.70 ± 1.18 (range: 3.7–8.1 mm). Right side mean pars height in males was 5.90 ± 1.2 (range: 3.7–9.4 mm), and in females, it was 6.11 ± 1.04 (range: 3.8–9.3 mm). Left-sided mean pars height in males was 6.0 ± 1.1 (range: 3.2–9.4 mm) as compared to females, in which it was 5.77 ± 1.23 (range: 4.1–9.3 mm). The mean lateral angulation angle in males was 9.99° ± 1.70° (8.1°–15°), while in females, it was 10.15° ± 1.73° (8.1°–15°). The mean sagittal angulation in males was 26.33° ± 3.32° (21.0°–32.80°), while in females, it was 27.18 ± 3.05 (21.0°–32.10°). The average screw length in males was 41.74 ± 5.63 (34–54.8 mm), whereas in females, it was 41.35 ± 4.77 (34–54.8 mm).Conclusion:This study provides a morphometric database which is characteristic of the C1–C2 vertebrae in the normal Indian population with regard to the anatomic feasibility of the TAS fixation for various C1–C2 pathologies. The C2 pars width and height measured in the current study can guide the selection of TAS screws in the Indian population. This study could serve in providing the baseline anatomic parameters assessed in the healthy individuals to design and develop customized screws and related implant assembly which might provide wider clinical applicability.

The short-term outcomes of hip arthrodesis in children and adolescents with end-stage hip disease

ABSTRACT BACKGROUND: The management of end-stage hip disease in children and adolescents is a challenging clinical problem. While total hip replacement (THR) offers the benefit of improved mobility, this is offset by the risk of multiple revisions. Hip arthrodesis remains a salvage option to relieve pain and restore function at the cost of hip movement. This study aimed to determine the short- to medium-term outcome of hip arthrodesis in paediatric and adolescent patients in a developing world setting. METHODS: All children and adolescents under the age of 18 years who underwent hip arthrodesis between 2010 and 2014 were included in the study. Measurements included diagnosis, preoperative deformity, fusion position, fusion rate and functional outcomes. Our surgery involved transarticular compression screw fixation and subtrochanteric osteotomy. Postoperative skeletal traction maintained optimal limb position for two weeks, after which spica cast immobilisation was used. RESULTS: Nineteen patients (11 female) had hip fusions at a mean age of 12 years (range 5-18). The mean follow-up period was 5 years (range 1-8). Most cases were due to end-stage TB arthritis (12/19; 63%). Other causes were septic arthritis (3/19; 16%); neglected slipped capital femoral epiphysis (1/19; 5%); post-traumatic avascular necrosis (1/19; 5%); and idiopathic chondrolysis (2/19; 11%). Primary fusion was achieved in 68% (13/19) of cases. Six patients developed complications. Complications included adduction drift (3/19), failed fusion (3/19), screw malpositioning (1/19) and screw breakage (1/19). Eight reoperations were required in six patients. In two of these patients, one additional surgery had to be performed to achieve fusion or correct limb position. The mean fusion position was 31° (range 20 to 50) flexion, 2° (range 10 to -10) abduction, and 1° (range 10 to -10) external rotation. Mean leg length discrepancy was 1.8 cm (range 0 to 4.5) of shortening. All except one patient reported relief of hip pain and satisfaction with the procedure. CONCLUSION: While hip arthrodesis is a technically challenging procedure, high fusion rates and reliable pain relief may be expected in these patients. However, complications should be anticipated, and reoperation may be required to achieve fusion and an optimal limb position Level of evidence: Level 4 Keywords: end-stage hip arthritis, TB hip, hip arthrodesis, hip fusion, subtrochanteric osteotomy

Is there any parameter to predict the risk of screw breakage following transarticular screw fixation of Lisfranc injuries? A retrospective study on 61 patients

Is there any parameter to predict the risk of screw breakage following transarticular screw fixation of Lisfranc injuries? A retrospective study on 61 patients

Lumbar canal stenosis in "young" - How does it differ from that in "old" - An analysis of 116 surgically treated cases.

Objective:Patients treated for lumbar canal stenosis (LCS) were retrospectively analyzed to evaluate the differences in clinical management in those below (Group A) and those above (Group B) the age of 50 years. All patients were treated with the premise that instability is the nodal point of the pathogenesis of LCS and “only-stabilization” is the surgical treatment.Materials and Methods:During the period June 2014 to June 2020, 116 cases were diagnosed to have LCS and surgically treated by the Goel modification of Camille's transarticular screw fixation technique.Results:Twenty-four patients in Group A and six patients in Group B had a history of “significant” injury to the back at the onset of clinical symptoms. The indices suggested that the intensity of symptoms was relatively more severe in Group A than in Group B. Unilateral leg symptoms were more common in Group A (68%) than in Group B (31.8%). Neurological motor deficits were more common in Group A (28%) than in Group B (12%) patients. Spinal segments surgically treated in Group A ranged from 1 to 4 (average 2 levels) and in Group B it ranged from 2 to 5 (average 3 levels). During the follow-up period that ranged from 6 to 72 months (average 37 months), 100% of patients had varying degrees of relief from symptoms.Conclusions:LCS is confined to a lesser number of spinal segments in the Group A patients. The symptoms were radicular in nature and relatively severe in Group A than in Group B patients.

Managing the Anomalous Vertebral Artery in C1-C2 Stabilization for Congenital Atlantoaxial Instability.

Objectives This study aimed to demonstrate the technique of handling the anomalous vertebral artery in congenital atlantoaxial instability. The vertebral artery course can be variable in congenital atlantoaxial instability, especially if there is assimilation of atlas. The surgical technique to stabilize the atlantoaxial joint should ensure the patency and safety of the vertebral artery and prevents devastating stroke. Computed tomography (CT) angiography of the vertebral artery is mandatory in planning the surgical strategies. The vertebral artery can be injured during dissection of soft tissues between atlas and axis and can be compromised during distraction and instrumentation. The vertebral artery needs to be mobilized based on the tortuosity in the course during instrumentation and prevents compression of the artery against bony structures or screw heads. The vertebral artery has to be identified earlier in the course of dissection and should protect it. It is also imperative to choose the surgical approach that can be performed under vision using operative microscope rather than adapting blind procedures like transarticular screw. Here, in our present case, we demonstrate the technique of mobilizing the vertebral artery which was coursing medially preventing the access for the instrumentation and perform stabilization of atlantoaxial joint using Goel–Harms technique, and prevent its compression after placement of screw by deroofing the bony ridges of axis ( Figs. 1 and 2 ). We also emphasize the various technical nuances during the stabilization with distraction of joint space of atlas and axis. The link to the video can be found at: https://youtu.be/pgURpF_jACc .

Outcome of Osteophytes After Only-Fixation as Treatment for Multilevel Cervical Spondylosis–A Minimum of 12 Months Follow-Up

This report analyzes the significance of osteophytes in the overall pathologic scheme in patients with single-level or multilevel cervical spinal degeneration. From January 2010 to December 2018, 249 patients with cervical spondylosis were surgically treated. The alterations in ventral compression caused by disc bulges, osteophytes, and ligament buckling (disc-osteophye-ligament [DOL] complex) at single or multiple levels were evaluated after surgical treatment that involved only spinal fixation and did not involve any kind of bone or soft tissue decompression. Delayed (≥1 year after surgery) postoperative imaging was available in 165 patients and these patients formed the study group. Forty-five patients underwent facet distraction arthrodesis (group A), 106 patients underwent only-fixation involving transarticular screw insertion (group B), and 14 patients underwent hybrid fixation that involved both intra-articular spacers and transarticular fixation techniques (group C) as the surgical treatment. The size of the DOL complex at the segments that underwent fixation was reduced in 136 patients. The size of the DOL complex or its related dural or neural compression did not increase in any of the cases evaluated. Reduction in the size of DOL was more pronounced in patients in group A in both immediate postoperative and delayed images and in patients in group C at spinal levels at which facet distraction was performed using facet distraction spacers. Spinal stabilization reduces the size of osteophytes. Facet distraction spacers are more effective in reduction of the size of DOL in both immediate and delayed postoperative periods.

Ankle Arthrodesis Through a Fibular-Sparing Anterior Approach.

The open anterior approach to ankle arthrodesis offers a technique that provides several advantages for surgeons, such as easier visualization of the joint for deformity correction and preservation of the malleoli for potential future conversion to total ankle arthroplasty. The purpose of this study was to evaluate clinical, radiographic, and functional outcomes in a large series of patients undergoing open ankle arthrodesis via a fibular-sparing anterior approach. A retrospective review was performed of patients undergoing primary ankle arthrodesis with a single fellowship-trained foot and ankle orthopedic surgeon between 2009 and 2017. Patients were excluded if an approach other than anterior was performed. Patient-reported outcome measures (Foot and Ankle Ability Measure-Activities of Daily Living [FAAM-ADL], Short-Form 12 [SF-12], and visual analog scale [VAS] pain) were subsequently collected at a minimum of 24 months (2 years) following index surgery, along with outcome satisfaction and likelihood to repeat surgery. Fusion of the tibiotalar joint at the time of last radiographic follow-up was also assessed. Paired t tests were performed to assess change in pre- to postoperative outcomes, while linear regression analysis was performed to identify any patient factors associated with outcomes. Eighty-one patients, including 31 women and 50 men, with a mean age of 51.5 years and a mean follow-up of 58.9 (range, 24-104) months, were included. Sixty-two patients reported significant improvement in mean FAAM-ADL (P < .0001), SF-12 Physical Composite Scale (P < .0001), and VAS pain (P < .0001), while the SF-12 Mental Composite Scale also improved, though not significantly (P = .2854). Twelve patients (14.8%) experienced complications following their arthrodesis procedure. Seventy-nine patients (97.5%) achieved fusion at their last radiographic follow-up. Multiple linear regression analysis revealed age (B = 0.071 [0.004, 0.128]; P = .0373) to have a positive association with postoperative VAS pain. Ankle arthrodesis utilizing a fibular-sparing anterior approach combined with the transarticular screw fixation technique offers surgeons several advantages, along with a low postoperative complication rate, high rate of radiographic evidence of joint fusion, and substantially large improvement in pain and functional levels. Level IV, retrospective case series.

Prevalence of High-Riding Vertebral Artery: A Meta-Analysis of the Anatomical Variant Affecting Choice of Craniocervical Fusion Method and Its Outcome

A high-riding vertebral artery (HRVA) has been defined as a C2 isthmus height of ≤5 mm and/or internal height of ≤2 mm measured 3 mm lateral to the border of the spinal canal. Its reported prevalence has varied widely. If overlooked during the approach for craniocervical fusion, injury to the vertebral arteries can occur, affecting the outcome. The present meta-analysis aimed to provide the pooled prevalence of HRVAs. A comprehensive database search was conducted by 3 of us. Peer-reviewed studies that had followed the strict definition for HRVAs and had reported its prevalence were included. The risk of bias was assessed using the anatomical quality assessment tool. The PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines were followed. The pooled prevalence was calculated using a random effects model. The data from 20 studies with 3126 subjects (7496 sides) were analyzed. The overall pooled prevalence of ≥1 HRVA was 25.3% (95% confidence interval [CI], 19.6%-31.5%). The prevalence in those without the most important confounding factor, rheumatoid arthritis (RA), was 20.9% (95% CI, 16.5%-25.8%). Patients with RA had a prevalence of 42.9% (95% CI, 23.8%-63.1%). The difference between the non-RA and RA groups was statistically significant (P < 0.001, test of homogeneity, χ2). No geographical differences were noted (P= 0.20, test of homogeneity, χ2). Among those with HRVA, unilateral HRVA was present in 70.3% (95% CI, 65.2%-75.2%) and bilateral in 29.7% (95% CI, 24.8%-34.8%). No left or right side predilection was found (left, 50.8%; 95% CI, 33.8%-67.6%; right, 49.2%; 95% CI, 32.4%-66.2%). Craniocervical fusion should be preceded by examination of the vertebral arteries at the level of C2 because the presence of HRVAs is common and might preclude the safe insertion of transarticular or transpedicular screws.

Technical outcome of atlantoaxial transarticular screw fixation without supplementary posterior construct for rheumatoid arthritis.

Background: transarticular screw (TAS) fixation without a supplementary posterior construct, even in rheumatoid arthritis (RA) patients, provides sufficient stability with acceptable clinical results. Here, we present our experience with 15 RA patients who underwent atlantoaxial (AA) TAS fixation without utilizing a supplementary posterior fusion.Methods: To treat AA instability, all 15 RA patients underwent C1–C2 TAS fixation without a supplementary posterior construct. Patients were followed for at least 24 months. Pre- and postoperative sagittal measures of C1– C2, C2–C7, and C1–C7 angles, atlanto-dens interval (ADI), posterior atlanto-dens interval (PADI), and adjacent segment (i.e., C2–C3) anterior disc height (ADH) were retrospectively recorded from lateral X-ray imaging. The presence or absence of superior migration of the odontoid (SMO), cervical subaxial subluxation, C1–C2 bony fusion, screw pull-out, and screw breakage were also noted.Results: There was little difference between the pre- and postoperative studies regarding angles measured. Following TAS fixation, the mean ADI shortened, and mean PADI lengthened. There was no difference in the mean measures of C2–C3 ADH. There was no evidence of SMO pre- or postoperatively. Two patients developed anterior subluxation at C5–C6; one of the two also developed anterior subluxation at C2–C3. All patients subsequently showed C1–C2 bony fusion without screw pull-out or breakage.Conclusion: In RA patients who have undergone C1–C2 TAS fixation, eliminating a supplementary posterior fusion resulted in adequate stability.

Design a novel integrated screw for minimally invasive atlantoaxial anterior transarticular screw fixation: a finite element analysis

PurposeTo design a new type of screw for minimally invasive atlantoaxial anterior transarticular screw (AATS) fixation with a diameter that is significantly thicker than that of traditional screws, threaded structures at both ends, and a porous metal structure in the middle. The use of a porous metal structure can effectively promote bone fusion and compensate for the disadvantages of traditional AATSs in terms of insufficient fixation strength and difficulty of bone fusion. The biomechanical stability of this screw was verified through finite element analysis. This instrument may provide a new surgical option for the treatment of atlantoaxial disorders.MethodsAccording to the surgical procedure, the new type of AATS was placed in a three-dimensional atlantoaxial model to determine the setting of relevant parameters such as the diameter, length, and thread to porous metal ratio of the structure. According to the results of measurement, the feasibility and safety of the new AATS were verified, and a representative finite element model of the upper cervical vertebrae was chosen to establish, and the validity of the model was verified. Then, finite element-based biomechanical analysis was performed using three models, i.e., atlantoaxial posterior pedicle screw fixation, traditional atlantoaxial AATS fixation, and atlantoaxial AATS fixation with the new type of screw, and the biomechanical effectiveness of the novel AATS was verified.ResultsBy measuring the atlantoaxial parameters, the atlantoaxial CT data of the representative 30-year-old normal adult male were selected to create a personalized 3D printing AATS screw. In this case, the design parameters of the new screw were determined as follows: diameter, 6 mm; length of the head thread structure, 10 mm; length of the middle porous metal structure, 8 mm (a middle porous structure containing an annular cylinder ); length of the tail thread structure, 8 mm; and total length, 26 mm. Applying the same load conditions to the atlantoaxial complex along different directions in the established finite element models of the three types of atlantoaxial fusion modes, the immediate stability of the new AATS is similar with Atlantoaxial posterior pedicle screw fixation.They are both superior to traditional atlantoaxial anterior screw fixation.The maximum local stress on the screw head in the atlantoaxial anterior surgery was less than those of traditional atlantoaxial anterior surgery.ConclusionsBy measuring relevant atlantoaxial data, we found that screws with a larger diameter can be used in AATS surgery, and the new AATS can make full use of the atlantoaxial lateral mass space and increase the stability of fixation. The finite element analysis and verification revealed that the biomechanical stability of the new AATS was superior to the AATS used in traditional atlantoaxial AATS fixation. The porous metal structure of the new AATS may promote fusion between atlantoaxial joints and allow more effective bone fusion in the minimally invasive anterior approach surgery.

Comparison of Atlantoaxial Fusion with Transarticular Screws and C1 Lateral Mass–C2 Screws Using Intraoperative O-Arm Navigation

This study compared the surgical outcomes of atlantoaxial fusion with transarticular screws (TASs) and C1 lateral mass-C2 screws (screw-rod constructs [SRCs]) using the intraoperative O-arm navigation system (O-arm). Among a total of 28 patients who underwent atlantoaxial fixation, 13 underwent TAS fixation and 15 underwent SRC fixation using the O-arm. All patients underwent Brooks procedure with iliac bone graft in addition to screw fixation. TAS fixation was performed for cases without high-riding vertebral artery (hVA). In the SRC group, pars or lamina screws were inserted for the side with a C2 hVA. Operative time, intraoperative bleeding, perioperative complications, screw accuracy, and bone union were evaluated. There were statistically significant differences in mean operative time between the 2 procedures (166 minutes in the TAS group vs. 212 minutes in the SRC group, P < 0.05) and in mean blood loss (80 vs. 185 mL, respectively; P < 0.01). Two patients developed temporary postoperative occipital neuralgia probably related to C2 nerve root in the SRC group. No screws violated the cortex in either group. Complete bone union was observed in all cases. O-arm-assisted TAS fixation had less intraoperative blood loss, shorter operative time, and fewer screw insertion complications than O-arm-assisted SRC fixation. O-arm-assisted TAS fixation is preferable for atlantoaxial fusion in patients without hVA.

Axis vertebral dimensions for safe screw placement: A CT normative data analysis

IntroductionMorphometric evaluation of the pedicle and isthmus of second cervical vertebra (C2) (Axis) is extremely vital before contemplating any surgical stabilization involving the Craniovertebral region, in view of its proximity to the vertebral artery and the cervical nerve root. The dimensions of pedicles and isthmuses in C2 vary between individuals and there is paucity of data in the Indian population. This study strives to measure the average pedicle and isthmus dimensions in a sample of population, which would enable selection of screws with safest diameters to be used in C2; thereby avoiding injury to adjacent neurovascular structures. Materials and methodsOne Hundred patients in the age group between 18 and 70 years who underwent CT scan of head and neck region were included in the study. The aim of this study was to assess the anatomic suitability of transarticular and pedicle screw placement in Axis vertebrae of Indian population and determine the maximum safe diameter for screw placement. The following parameters were measured in millimeters: Pedicle width, Pedicle angle, Internal height and Isthmic height. ResultsThe Mean maximum diameter of potential pedicle screw was 4.99 ± 1.1 mm for the right side with the left side being slightly wider at 5.20 ± 1.16 mm. Twenty eight (28%; 56 out of 200 pedicles) had a measurement < 4.5 mm. The internal height in sagittal images representing the pedicle height was found to be 4.79 ± 0.96 mm on the right side and 4.75 ± 1.04 mm on the left side. Sixty five (65) out of 200 pedicles (32.5%) had measurements < 4.5 mm in sagittal plane. The Mean maximum diameter of potential Transarticular screw (outer diameter of isthmus) was 5.05 ± 0.78 mm for the right side and 5.18 ± 0.84 mm on the left side. DiscussionIsthmic height < 4.5 mm could potentially violate the vertebral foramen when a 3.5 mm screw is used. In our study 22.5% isthmuses were narrow (<4.5 mm). The mean maximum safe diameter for a potential transarticular screw in the present study was 5.11 mm. Though our patients had smaller isthmus dimensions compared with literature, 77.5% of C2 could take a 4 mm transarticular screw quite comfortably considering the 0.5 mm margin on either side. In the present study, 28% of pedicles were found to be inappropriately sized (<4.5 mm) to accommodate the standard 3.5 mm screw. The mean maximum diameter of a potential pedicle screw in our study was 5.09 mm; and in 72% of patients a 4 mm screw could be placed with confidence. Though our patients on an average can accommodate a 4 mm screw comfortably, we suggest a protocol of obtaining CT measurements of C2 prior to operative intervention for identifying those individuals at risk of neurovascular injury; 22.5% for transarticular screw and 28% for pedicle screw.

Outcomes of Lisfranc Injuries Treated with Joint-Preserving Fixation.

Open reduction and internal fixation (ORIF) with transarticular screws to stabilize Lisfranc injuries may increase the risk of arthritis or affect outcomes. Joint-preserving fixation using staples, bridge plating, or Lisfranc screws avoids iatrogenic articular damage. This study analyzes functional outcomes and complications in Lisfranc-injury patients who underwent joint-preserving fixation. We conducted a retrospective review of patients treated for Lisfranc injury at a Level 1 trauma center from July 2008 to October 2015. Patients over 18 years of age, with no concomitant procedures in the lower extremities, were included. Functional outcomes were evaluated through American Orthopaedic Foot and Ankle Society (AOFAS) scores. Fourteen patients met the inclusion criteria. The average followup time was 57 months (range 22-102 months). AOFAS scores averaged 80.4 (standard deviation [SD] 16) at the time of the latest followup, with time to return to regular activities averaging 34 weeks (SD 25 weeks). Five patients had their hardware removed, and two required subsequent fusion during the followup period. The single complication involved a screw backing out, with subsequent removal. In this case series, joint-preserving fixation for Lisfranc injuries offered similar AOFAS scores as those reported for ORIF with transarticular screws but with a decreased rate of hardware removal and need for midfoot fusion.

Clinical and Radiological Outcomes after Open Reduction and Internal Fixation of Lisfranc Injuries: A Single Centre Experience.

Lisfranc injuries are uncommon and can be challenging to manage. There is considerable variation in opinion regarding the mode of operative treatment of these injuries, with some studies preferring primary arthrodesis over traditional open reduction and internal fixation (ORIF). We aim to assess the clinical and radiological outcomes of the patients treated with ORIF in our unit. This is a retrospective study, in which all 27 consecutive patients treated with ORIF between June 2013 and October 2018 by one surgeon were included with an average followup of 2.4years. All patients underwent ORIF with joint-sparing surgery by a dorsal bridging plate (DBP) for the second and third tarsometatarsal (TMT) joint, and the first TMT joint was fixed with transarticular screws. Patients had clinical examination and radiological assessment and completed American Orthopaedic Foot and Ankle Society (AOFAS) midfoot score and Foot Function Index (FFI) questionnaires. Our early results of 22 patients (5 lost to followup) showed that 16 (72%) patients were pain free, walking normally without aids, and wearing normal shoes and 68% were able to run or play sports. The mean AOFAS midfoot score was 78.1 (63-100) and the average FFI was 19.5 (0.6-34). Radiological assessment confirmed that only three patients had progression to posttraumatic arthritis at the TMT joints though only one of these was clinically symptomatic. Good clinical and radiological outcomes can be achieved by ORIF in lisfranc injuries with joint-sparing surgery using DBP.