Aims. Anchorage of pedicle screw rod instrumentation in the elderly spine with poor bone quality remains challenging. Our study aims to evaluate how the screw bone anchorage is affected by screw design, bone quality, loading conditions, and cementing techniques. Methods. Micro-finite element (µFE) models were created from micro-CT (μCT) scans of vertebrae implanted with two types of pedicle screws (L: Ennovate and R: S. 4. ). Simulations were conducted for a 10 mm radius region of interest (ROI) around each screw and for a full vertebra (FV) where different cementing scenarios were simulated around the screw tips. Stiffness was calculated in pull-out and anterior bending loads. Results. Experimental pull-out strengths were excellently correlated to the µFE pull-out stiffness of the ROI (R. 2. > 0.87) and FV (R. 2. > 0.84) models. No significant difference due to screw design was observed. Cement augmentation increased pull-out stiffness by up to 94% and 48% for L and R screws, respectively, but only increased bending stiffness by up to 6.9% and 1.5%, respectively. Cementing involving only one screw tip resulted in lower stiffness increases in all tested screw designs and loading cases. The stiffening effect of cement augmentation on pull-out and bending stiffness was strongly and negatively correlated to local bone density around the screw (correlation coefficient (R) = -0.95). Conclusion. This combined experimental, µCT and µFE study showed that regional analyses may be sufficient to predict
Objectives. This presentation discusses the experience at our Centre with treating traumatic thoracolumbar fractures using percutaneous pedicle screw
The study is been conducted to compare the outcome of pedicle screw
In a prospective observational study we compared the two-year outcome of lumbar fusion by a simple technique using translaminar screws (n = 57) with a more extensive method using transforaminal lumbar interbody fusion and pedicular screw
The purpose of this study was to determine whether
it would be feasible to use oblique lumbar interbody
8 patients with cervical myelopathy treated by French-door laminoplasty and internal
We reviewed seven children with torticollis due to refractory atlanto-axial rotatory
Introduction. Isolated U-shaped sacral fractures are rare entities, mostly seen in polytraumatized patients, and hence, they are difficult to diagnose. While the pelvic ring remains intact across S2/S3, the U-shaped fracture around S1 leads to marked instability between the base of the spine and the pelvis. As severe neurological deficits can occur, timely treatment of these fractures is crucial. We present a novel technique of percutaneous reduction and trans-sacral screw
We reviewed the outcome of a retrospective case series of eight patients with atlantoaxial instability who had been treated by percutaneous anterior transarticular screw
We have reviewed 81 patients with fractures of the odontoid process treated between May 1983 and July 1997, by anterior screw
Introduction. Internal transpedicular
The aim of this study was to systematically compare the safety and accuracy of robot-assisted (RA) technique with conventional freehand with/without fluoroscopy-assisted (CT) pedicle screw insertion for spine disease. A systematic search was performed on PubMed, EMBASE, the Cochrane Library, MEDLINE, China National Knowledge Infrastructure (CNKI), and WANFANG for randomized controlled trials (RCTs) that investigated the safety and accuracy of RA compared with conventional freehand with/without fluoroscopy-assisted pedicle screw insertion for spine disease from 2012 to 2019. This meta-analysis used Mantel-Haenszel or inverse variance method with mixed-effects model for heterogeneity, calculating the odds ratio (OR), mean difference (MD), standardized mean difference (SMD), and 95% confidence intervals (CIs). The results of heterogeneity, subgroup analysis, and risk of bias were analyzed.Aims
Methods
Objective. The use of all pedicle screw constructs for the management of spinal deformities has gained widespread popularity. However, the placement of pedicle screws in the deformed spine poses unique challenges for the spinal surgeon. The purpose of this study was to evaluate the complications and radiological outcomes of surgery in 124 consecutive patients with spinal deformity. These patients underwent correction of coronal and sagittal imbalance with segmental pedicle screw
We analysed the complications encountered in 102 consecutive patients who had posterolateral lumbosacral fusion performed with transpedicular screw and rod
The purpose of this study was to determine whether
patients with a burst fracture of the thoracolumbar spine treated
by short segment pedicle screw
To describe a modification of the existing technique for C2 translaminar screw
Many operations have been recommended to treat Pars Interarticularis fractures that have separated and are persistently symptomatic, but little other than conservative treatment has been recommended for symptomatic incomplete fractures. 10 consecutive patients aged 15–28 [mean 21.7 years] were treated operatively between 2010–2014. All but one were either professional athletes [3 cricketers, 2 athletics, 1 soccer] or academy cricketers [3 patients]. 8 patients had unilateral fractures, and two had bilateral fractures at the same level. The duration of pre-operative pain and disability with exercise ranged from 4–24 months [mean 15.4 months]. The operation consists of a percutaneous compression screw inserted through a 1.5cm midline skin incision under fluoroscopic guidance: 6 cases were also checked with the O-arm intra-operatively. Post-operation the patients were mobilised with a simple corset and discharged the following day with a customised rehabilitation program. All 12 fractures in 10 patients healed as demonstrated on post-operative CT scans at between 3–6 months. One patient had the screw revised at 24 hours for an asymptomatic breach, and one patient developed a halo around the fracture site without screw loosening, and had a successful revision operation to remove the screw and graft the pars from the screw channel. All patients achieved a full return to asymptomatic activity, within a timescale of 4–12 months post-surgery, depending on the sport. Athletes that have persistent symptoms from incomplete pars interarticularis fractures should consider percutaneous
The aim of this study was to prospectively assess the outcome of patients with metastatic spinal disease who underwent minimally invasive
We investigated the effects of hydroxyapatite (HA) coating on the purchase of pedicle screws. A total of 23 consecutive patients undergoing lumbar fusion was randomly assigned to one of three treatment groups. The first received uncoated stainless-steel screws, the second screws which were partly coated with HA, and the third screws which were fully coated. The insertion torque was recorded. After 11 to 16 months, 21 screws had been extracted. The extraction torque was recorded. Radiographs were taken to assess fusion and to detect loosening of the screws. At removal, the extraction torques exceeded the upper limit of the torque wrench (600 Ncm) for many HA-coated screws. The calculated mean extraction torque was 29 ± 36 Ncm for the uncoated group, 447 ± 114 Ncm for the partly-coated group and 574 ± 52 Ncm for the fully-coated group. There were significant differences between all three groups (p <
0.001). There were more radiolucent zones surrounding the uncoated screws than the HA-coated screws (p <
0.001). HA coating of pedicle screws resulted in improved
In patients with osteoporosis there is always
a strong possibility that pedicle screws will loosen. This makes
it difficult to select the appropriate osteoporotic patient for
a spinal fusion. The purpose of this study was to determine the
correlation between bone mineral density (BMD) and the magnitude
of torque required to insert a pedicle screw. To accomplish this,
181 patients with degenerative disease of the lumbar spine were
studied prospectively. Each underwent dual-energy x-ray absorptiometry
(DEXA) and intra-operative measurement of the torque required to
insert each pedicle screw. The levels of torque generated in patients
with osteoporosis and osteopenia were significantly lower than those
achieved in normal patients. Positive correlations were observed between
BMD and T-value at the instrumented lumbar vertebrae, mean BMD and
mean T-value of the lumbar vertebrae, and mean BMD and mean T-value
of the proximal femur. The predictive torque (Nm) generated during pedicle
screw insertion was [-0.127 + 1.62 × (BMD at the corresponding lumbar
vertebrae)], as measured by linear regression analysis. The positive
correlation between BMD and the maximum torque required to insert
a pedicle screw suggests that pre-operative assessment of BMD may
be useful in determining the ultimate strength of