Objective To investigate the influence of axis pedicle and intra-axial vertebral artery (IAVA) alignment on C2 pedicle screw placement by measuring the data of head and neck CT angiography. MethodsThe axis pedicle diameter (D), isthmus height (H), isthmus thickness (T), and IAVA alignment types were measured in 116 patients (232 sides) who underwent head and neck CT angiography examinations between January 2020 and June 2020. Defined the IAVA offset direction by referencing the vertical line through the center of C3 transverse foramen on the coronal scan, it was divided into lateral (L), neutral (N), and medial (M). Defined the IAVA high-riding degree by referencing the horizontal line through the outlet of the C2 transverse foramen, it was divided into below (B), within (W), and above (A). The rate of pedicle stenosis, high-riding vertebral artery, and different IAVA types were calculated, and their relationships were analysed. Simulative C2 pedicle screws were implanted by Mimics 19.0 software, and the interrelation among the rates of pedicle stenosis, high-riding vertebral artery, IAVA types, and vertebral artery injury were analyzed. ResultsThe rate of C2 pedicle stenosis was 33.6% (78/232), and the rate of high-riding vertebral artery was 35.3% (82/232). According to the offset direction and the degree of riding, IAVA was divided into 9 types, among which the N-W type (29.3%) was the most, followed by the L-W type (19.0%) and the L-B type (12.9%), accounting for 60.9%. The vertebral artery injury rate of simulative implanted C2 pedicle screws was 35.3% (82/232). The vertebral artery injury rate in patients with pedicle stenosis and high-riding vertebral artery was significantly higher than that who were not (P<0.001). The rate of pedicle stenosis, high-riding vertebral artery, and vertebral artery injury were significantly different among IAVA types (P<0.001), and M-A type was the most common. ConclusionVertebral artery injury is more common in pedicle stenosis and/or high-riding vertebral artery and/or IAVA M-A type. Preoperative head and neck CT angiography examination has clinical guiding significance.
Objective
To evaluate the biomechanical stability of a newly-designed Y type pedicle screw (YPS) in osteoporotic synthetic bone.
Methods
The osteoporotic synthetic bone were randomly divided into 3 groups (n=20). A pilot hole, 3.0 mm in diameter and 30.0 mm in deep, was prepared in these bones with the same method. The YPS, expansive pedicle screw (EPS), and bone cement-injectable cannulated pedicle screw (CICPS) were inserted into these synthetic bone through the pilot hole prepared. X-ray film examination was performed after 12 hours; the biomechanical stability of YPS, EPS, and CICPS groups was tested by the universal testing machine (E10000). The test items included the maximum axial pullout force, the maximum running torque, and the maximum periodical anti-bending.
Results
X-ray examination showed that in YPS group, the main screw and the core pin were wrapped around the polyurethane material, the core pin was formed from the lower 1/3 of the main screw and formed an angle of 15° with the main screw, and the lowest point of the inserted middle core pin was positioned at the same level with the main screw; in EPS group, the tip of EPS expanded markedly and formed a claw-like structure; in CICPS group, the bone cement was mainly distributed in the front of the screw and was dispersed in the trabecular bone to form a stable screw-bone cement-trabecular complex. The maximum axial pullout force of YPS, EPS, and CICPS groups was (98.43±8.26), (77.41±11.41), and (186.43±23.23) N, respectively; the maximum running torque was (1.42±0.33), (0.96±0.37), and (2.27±0.39) N/m, respectively; and the maximum periodical anti-bending was (67.49±3.02), (66.03±2.88), and (143.48±4.73) N, respectively. The above indexes in CICPS group were significantly higher than those in YPS group and EPS group (P<0.05); the maximum axial pullout force and the maximum running torque in YPS group were significantly higher than those in EPS group (P<0.05), but there was no significant difference in the maximum periodical anti-bending between YPS group and EPS group (P>0.05).
Conclusion
Compared with EPS, YPS can effectively enhance the maximum axial pullout force and maximum rotation force in the module, which provides a new idea for the design of screws and the choice of different fixation methods under the condition of osteoporosis.
Objective To compare the effectiveness of unilateral biportal endoscopy (UBE) technique assisted spinal canal decompression combined with percutaneous pedicle screw internal fixation versus traditional open decompression and internal fixation for treatment of lumbar burst fractures. MethodsA retrospective study was conducted on the clinical data of 61 patients with single-segment lumbar burst fractures who met the selection criteria and were admitted between October 2022 and December 2023. Of them, 25 patients received UBE technique assisted decompression combined with percutaneous pedicle screw fixation (UBE group), while 36 patients were treated with traditional posterior unilateral hemilaminectomy decompression and internal fixation (open group). There was no significant difference in baseline data between the two groups (P>0.05), including gender, age, body mass index, fracture segment, cause of injury, AO classification of lumbar fractures, and preoperative height ratio of the anterior margin of injured vertebra, segmental kyphosis angle, rate of spinal canal invasion, the classification of American Spinal Injury Association (ASIA) grading, visual analogue scale (VAS) score, and Oswestry disability index (ODI). The operation time, intraoperative blood loss, and postoperative complications were recorded and compared between the two groups. VAS score, ODI, and ASIA grading were used to evaluate the effectiveness before operation, at 1 week after operation, and at last follow-up. Lumbar anteroposterior and lateral X-ray films and CT were performed to measure the segmental kyphosis angle, height ratio of the anterior margin of injured vertebra, and the rate of spinal canal invasion.ResultsSurgery was successfully completed in both groups. No complication such as dural sac, nerve root, or vascular injury was found during operation, and all incisions healed by first intention. There was no significant difference in operation time between the two groups (P>0.05), the UBE group revealed significant less intraoperative blood loss when compared with open group (P<0.05). Patients in both groups were followed up 6-20 months, with an average of 13 months. There was no loosening, breakage, or failure of internal fixation in all patients. The ASIA grading, VAS score, ODI of the two groups significantly improved at 1 week after operation and further improved at last follow-up (P<0.05). There was no significant difference in ASIA grading at 1 week after operation and last follow-up between the two groups (P>0.05), but the VAS score and ODI in the UBE group were significantly superior to the open group (P<0.05). At 1 week after operation, the height ratio of the anterior margin of injured vertebra, segmental kyphosis angle, rate of spinal canal invasion significantly improved when compared to preoperative ones (P<0.05), the height ratio of the anterior margin of injured vertebra and segmental kyphosis angle significantly decreased at last follow-up when compared to the values at 1 week after operation (P<0.05), but the rate of spinal canal invasion was further significantly improved, and there was no significant difference between the two groups at different time point postoperatively. ConclusionUBE technique assisted spinal canal decompression combined with percutaneous pedicle screw fixation is a safe and effective treatment for lumbar burst fractures, which with little trauma and faster recovery when compared with traditional open decompression and internal fixation.
Objective To biomechanically compare the maximum pull-out strengths among two pedicle screws and three salvage techniques using poly methylmethacrylate (PMMA) augmentation in osteoporotic sacrum, and to determine which PMMA augmentation technique could serve as the salvage fixation for loosening sacral pedicle screws. Methods Eleven sacra were harvested from fresh adult donated cadavers, aged from 66 to 83 years (average 74.4 years) and included 5 men and 6 women. Radiography was used to exclude sacra that showed tumor or inflammatory or any other anatomic abnormal ities. Following the measurement of bone mineral density, five sacral screw fixations were sequentially establ ished on the same sacrum as follows: unicortical pedicle screw (group A), bicortical pedicle screw (group B), unicortical pedicle screw with the traditional PMMA augmentation (group C), ala screw with the traditional PMMA augmentation (group D), and ala screw with a kyphoplasty-assisted PMMA augmentation technique (group E). According to the sequence above, the axial pull-out test of each screw was conducted on a MTS-858 material testing machine. The maximum pull-out forces were measured and compared. The morphologies of PMMA augmented screws after being pulled-out were also inspected. Results The average bone mineral density of 11 osteoporotic specimens was (0.71 ± 0.08) g/cm2 . By observation of the pull-out screws, groups C, D, E showed perfect bonding with PMMA, and group E bonded more PMMA than groups C and D. The maximum pull-out forces of groups A, B, C, D, and E were (508 ± 128), (685 ± 126), (846 ± 230), (543 ± 121), and (702 ± 144) N, respectively. The maximum pull-out strength was significantly higher in groups B, C, and E than in groups A and D (P lt; 0.05), and in group C than in groups B and E (P lt; 0.05). There was no significant difference in pull-out strength between groups A and D, and between groups B and E (P gt; 0.05). Conclusion For sacral screw fixation of osteoporotic patients with bone mineral density more than 0.7 g/cm2, bicortical pedicle screw could acquire significantly higher fixation strength than the unicortical. Once the loosening of pedicle screw occurs, the traditional PMMA augmentation or ala screw with kyphoplasty-assisted PMMA augmentation may serve as a suitable salvage technique.
ObjectiveTo explore the safety and effectiveness of polymethylmethacrylate-augmented screw fixation (PASF) in the treatment of elderly thoracolumbar tuberculosis combined with severe osteoporosis.MethodsThe clinical data of 20 elderly patients with thoracolumbar tuberculosis and severe osteoporosis who underwent PASF after anterior or posterior debridement and bone grafting and met the selection criteria between December 2012 and December 2014 were retrospectively analyzed. There were 8 males and 12 females with an average age of 68.5 years (range, 65-72 years). T value of bone mineral density was ?4.2 to ?3.6, with an average of ?3.9. There were 12 cases of thoracic tuberculosis, 3 cases of thoracolumbar tuberculosis, and 5 cases of lumbar tuberculosis. The diseased segments involved T3-L4, including 11 cases of single-segment disease, 6 cases of double-segment disease, and 3 cases of multi-segment disease. The disease duration was 3-9 months, with an average of 6 months. The preoperative spinal nerve function of the patients was evaluated by the American Spinal Injury Association (ASIA) grading. There were 2 cases of grade A, 5 cases of grade B, 6 cases of grade C, 4 cases of grade D, and 3 cases of grade E. Postoperative imaging examination was used to evaluate the bone graft fusion and paravertebral abscess absorption, and to measure the Cobb angle of the segment to evaluate the improvement of kyphosis. The levels of erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) were tested. The visual analogue scale (VAS) score, Oswestry disability index (ODI), and ASIA grading were used to evaluate the effectivreness before operation, at 1 month after operation, and at last follow-up. The clinical cure of tuberculosis was also evaluated.ResultsAll operation successfully completed. The operation time was 154-250 minutes, with an average of 202 minutes; the intraoperative blood loss was 368-656 mL, with an average of 512 mL. All 20 patients were followed up 18-42 months, with an average of 26.8 months. The postoperative pain and symptoms of tuberculosis in all patients relieved, and the paravertebral abscess was absorbed, reaching the cure standard for spinal tuberculosis. All bone grafts fusion achieved within 1 year after operation. Only 1 case had asymptomatic bone cement leakage into the paravertebral veins, and the remaining patients had no serious complications such as bone cement leakage in the spinal canal, pulmonary embolism, and neurovascular injury. At last follow-up, spinal cord nerve function significantly improved when compared with preoperative one. Among them, ASIA grading were 7 cases of grade C, 8 cases of grade D, and 5 cases of grade E, showing significant difference when compared with preoperative one (Z=2.139, P=0.000). VAS score, ODI score, segmental Cobb angle, ESR, and CRP at 1 month after operation and at last follow-up were significantly improved when compared with preoperative ones (P<0.05); there was no significant difference between 1 month after operation and last follow-up (P>0.05). During the follow-up, no complications such as failure of internal fixation, proximal junctional kyphosis, or tuberculosis recurrence occurred.ConclusionFor elderly patients with thoracolumbar tuberculosis and severe osteoporosis, PASF treatment is safe and effective.
ObjectiveTo investigate reliability and short-term effectiveness of axis laminar screws for reducible atlantoaxial dislocation (RAAD).MethodsA clinical data of 41 patients with RAAD who were admitted between February 2013 and February 2018 and met the inclusion criteria was retrospectively analyzed. The atlases in all patients were fixated by lateral mass screws, and the axes were fixed by laminar screws in 13 cases (LS group) and by pedicle screws in 28 cases (PS group). There was no significant difference in gender, age, and preoperative Japanese Orthopedic Association (JOA) score between the two groups (P>0.05). The effectiveness was estimated by post-operative JOA score; and the accuracy of the axis screw, atlantoaxial bone graft fusion, and the fixation stability were examined by X-ray film and CT.ResultsAll incisions healed by first intention. All patients were followed up 12-17 months (mean, 13.8 months) in LS group and 12-20 months (mean 14.1 months) in PS group, and the difference in follow-up time was not significant (Z=?0.704, P=0.482). At last follow-up, JOA scores were 13.9±1.6 in LS group and 14.3±1.8 in PS group, which significantly improved when compared with the pre-operative scores in the two groups (t=?9.033, P=0.000; t=?15.835, P=0.000); while no significant difference was found between the two groups (t=?0.630, P=0.532). Twenty-five screws of 26 screws in LS group and 54 screws of 56 screws in PS group were implanted accurately, with no significant difference in the accuracy of the axis screw between the two groups (Z=?0.061, P=0.951). All patients obtained atlantoaxial bone graft fusion, except 1 case in PS group. There was no significant difference in the atlantoaxial bone graft fusion between the two groups (Z=?0.681, P=0.496).ConclusionFor RAAD, Axis laminar screws can maintain the atlantoaxial primary stability and had a good short-term effectiveness. So, it could be an alternative and reliable technique for axis screw.
Objective To compare the effectiveness of spinal robot-assisted pedicle screw placement through different surgical approaches and to guide the clinical selection of appropriate robot-assisted surgical approaches. MethodsThe clinical data of 14 patients with thoracolumbar vertebral diseases who met the selection criteria between January 2023 and August 2023 were retrospectively analyzed, and all of them underwent pedicle screw placement under assistant of the Mazor X spinal surgery robot through different surgical approaches. The patients were divided into posterior median approach (PMA) group (n=6) and intermuscular approach (IMA) group (n=8) according to the surgical approaches, and there was no significant difference in age, gender, body mass index, disease type, and fixed segment between the two groups (P>0.05). The operation time, intraoperative blood loss, screw-related complications, and reoperation rate were recorded and compared between the two groups; the inclination angle of the screw, the distance between the screw and the midline, and the caudal inclination angle of the screw were measured based on X-ray films at immediate after operation. Results There was no significant difference in operation time and intraoperative blood loss between the two groups (P>0.05). There was no screw-related complication such as nerve injury in both groups, and no patients underwent secondary surgery. At immediate after operation, the inclination angle of the screw, the distance between the screw and the midline, and the caudal inclination angle of the screw in the IMA group were significantly greater than those in the PMA group (P<0.05). ConclusionThere are differences in the position and inclination angle of screws placed with robot-assisted surgery through different surgical approaches, which may be due to the obstruction of the screw path by soft tissues such as skin and muscles. When using spinal robot-assisted surgery, selecting the appropriate surgical approach for different diseases can make the treatment more reasonable and effective.
ObjectiveTo evaluate the clinical efficacy of domestic minimally-invasive percutaneous screw system for thoracolumbar fractures without neurological damage.
MethodsSixty patients suffering from unstable thoracolumbar fractures without obvious neurologic deficits treated from January 2011 to April 2012 were studied retrospectively. The patients were divided into two groups:group A (domestic minimally-invasive percutaneous screw system) and group B (imported minimally-invasive percutaneous screw system). Perioperative parameter, pre-and post-operative imaging indexes, visual analog scale (VAS) and modified MacNab evaluation standard were studied for comparison.
ResultsAll the patients were followed up from 6 to 18 months with an average of (12.2±3.0) months. The Cobb's angle and anterior height of the fracture vertebral body changed significantly in each group (P<0.05). There was no significant difference in incision size, surgical time, postoperative improvement of Cobb's angle, anterior height of the fracture vertebral body and accuracy of pedicle screw placement between the two groups (P>0.05).
ConclusionDomestic minimally-invasive percutaneous screw system is reliable with minimal invasion, which is comparable to imported minimally-invasive percutaneous screw system.
ObjectiveTo investigate the effectiveness of cervical pedicle screw implantation technique under regional method.MethodsThe clinical data of 85 patients who met the selection criteria between April 2010 and May 2018 were retrospectively analyzed. There were 57 males and 28 females, aged 35-68 years, with an average of 57.6 years. Among them, there were 10 cases of ossification of posterior longitudinal ligament, 68 cases of cervical spondylosis with multilevel stenosis, 3 cases of cervical tumor, 1 case of congenital malformation, and 3 cases of cervical trauma; the lower cervical spine lesions involved C3-C7. Preoperative Frankel spinal cord injury grading: 2 cases of grade C, 51 cases of grade D, and 32 cases of grade E. Cervical pedicle screw implantation technique under regional method was performed with a total of 618 pedicle screws. Postoperative changes in neurological symptoms were observed; cervical mouth opening anteroposterior and lateral X-ray films and cervical CT examinations were performed to evaluate the pedicle screws position.ResultsThe operation time was 2.5-4.0 hours, with an average of 3.0 hours. The intraoperative blood loss was 180-550 mL, with an average of 345 mL. No intraoperative vascular or nerve injury occurred. The patients with neurological symptoms were relieved to varying degrees. There were 2 cases of superficial incision infection after operation, the wound healed after enhanced dressing change. The postoperative hospital stay was 5-14 days, with an average of 8.4 days. At discharge, Frankel neurological grading was grade D in 26 patients and grade E in 59 patients. All the patients were followed up 6-24 months, with an average of 13 months. At last follow-up, cervical X-ray films showed the good pedicle screw fixation without loosening. Cervical CT evaluated the position of pedicle screws: 523 pedicle screws (84.7%) in grade Ⅰ, 80 (12.9%) in grade Ⅱ, and 15 (2.4%) in grade Ⅲ; the accuracy rate of the screw position was 97.6%.ConclusionCervical pedicle screw implantation technique under regional method can significantly improve the success rate of screw implantation. It is easy to operate, does not destroy the bone cortex, and has stable fixation.
Accurate placement of pedicle screws is a key factor of spinal surgery. Investigation of a new real-time intra-operative monitoring method is an important area of clinical application research which makes a contribution to planting pedicle screw accurately. Porcine spines were chosen as experimental objects.The changes of reduced scattering coefficient (μ's) along normal puncture path, medial perforation path and lateral perforation path were measured and studied. A conclusion is drawn that there are two distinct peaks throughout the puncture process, appearing at the junction of cancellous bone and cortical bone, at the beginning and at the end, respectively. The reduced scattering coefficient is proved to be a good monitoring factor which can identify whether the screw is about to reach the critical position of the spine puncture. Moreover, the variation provides an important reference for spinal surgical navigation process.
