Objective To analyze the therapeutic effect of the posterior pedicle screw system combined with interbody fusion cage on lumbarspondylolisthesis. Methods From February 2003 to March 2006, 37 lumbar spondylolisthesis patients were treated with this operation, including21 males and 16 females and aging 3969 years.The affected lumbars were L3(3cases)，L4(23 cases), and L5(11 cases). According to the Meyerdingevaluating system, 12 cases were lassified as degree Ⅰ, 20 cases as degree Ⅱ,and 5 cases as degree Ⅲ. Taillard index, Boxall index, slipping angle, lumbar lordosis angle and intervertebral height index were measured before operation, and 2 weeks and 3 months after operation. Results All patients were followed up 336 months. There were statistically significant differences in Taillard index, Boxall index, slipping angle, lumbar lordosis angle and intervertebral height index between before operation and 2 weeks after operation (P＜0.05),and no statistically significant differences between 2 weeks and 3 months afteroperation(P＞0.05). According to Dewei Zhou’s creterior for scoring, the results were excellent in 27 cases， good in 8 cases，and fair in 2 cases. Theexcellent and good rate was 94.6%. All of the embedded osseous were fused. Thefusing time was from 3 to 8 months (mean 3-9 months). There were no breakageof screw and rod. The position and configuration of the whole cages were good. Conclusion Applying the posterior pedicle screw system combined with interbody fusion cage may achieve synergism in the treatment of lumbar vertebral spondylolisthesis. Above procedure is served as solid internal fixationand offers a satisfactory reduction, and can improve the fusion rate of the spine. So it is an ideal procedure and worthily recommended method for treatment oflumbar vertebral spondylolisthesis.
ObjectiveTo explore the efficacy of percutaneous pedicle screw internal fixation and minimally invasive lateral small incisions lesion debridement and bone graft fusion via dilated channels in the treatment of lumbar tuberculosis.MethodsThe clinical data of 22 cases of lumbar tuberculosis treated with percutaneous pedicle screw internal fixation combined with dilated channels with minimally invasive lateral small incision lesion debridement and bone graft fusion between January 2016 and June 2018 were retrospectively analyzed. There were 12 males and 10 females, with an average age of 47.5 years (range, 22-75 years). The affected segments were L2, 3 in 5 cases, L3, 4 in 8 cases, and L4, 5 in 9 cases, with an average disease duration of 8.6 months (range, 4-14 months). Preoperative neurological function was classified according to the American Spinal Injury Association (ASIA), with 3 cases of grade C, 9 cases of grade D, and 10 cases of grade E. The operation time, intraoperative blood loss, and postoperative complications were recorded. At preoperation, 3 months after operation, and last follow-up, the C reactive protein (CRP) and erythrocyte sedimen- tation rate (ESR) were tested to evaluate tuberculosis control; the pain visual analogue scale (VAS) score was used to evaluate the recovery of pain, and the Oswestry disability index (ODI) was used to evaluate the function recovery of the patient’s lower back; the kyphosis Cobb angle was measured, and the loss of Cobb angle (the difference between the Cobb angle at last follow-up and 3 months after operation) was calculated. At last follow-up, the ASIA classification was used to evaluate the recovery of neurological function, and the effectiveness was evaluated according to the modified MacNab standard.ResultsThe operation time was 110-148 minutes (mean, 132.8 minutes) and the intraoperative blood loss was 70-110 mL (mean, 89.9 mL). Two patients experienced fat liquefaction of the incision and delayed healing; the incisions of the remaining patients healed by first intention. All patients were followed up 18-24 months, with an average of 21.3 months. All bone grafts achieved osseous fusion, the pedicle screws were fixed in reliable positions, without loosening, displacement, or broken rods. There was no recurrence of tuberculosis. The ESR, CRP, VAS scores, ODI scores, and kyphosis Cobb angle of the affected segment at 3 months after operation and last follow-up were significantly improved (P<0.05); there were no significant differences between at last follow-up and 3 months after operation (P>0.05), and the loss of Cobb angle was (0.6±0.5)°. The patient’s neurological function recovered significantly. At last follow-up, the ASIA grades were classified into 1 case with grade C, 1 case with grade D, and 20 cases with grade E, which were significantly improved when compared with preoperative grading (Z=−3.066, P=0.002). According to the modified MacNab standard, 16 cases were excellent, 3 cases were good, 2 cases were fair, and 1 case was poor. The excellent and good rate was 86.4%.ConclusionPercutaneous pedicle screw internal fixation combined with dilated channels with minimally invasive lateral small incisions lesion debridement and bone graft fusion has the advantages of less bleeding, less trauma, and faster recovery, which is safe and effective in the treatment of lumbar tuberculosis.
ObjectiveTo discuss the security and effectiveness of fixing the unstable region of sagittal injured unit symmetrically with pedicle screws combined with bone graft fusion for treating thoracolumbar fractures.MethodsA series of 65 patients with a single level thoracolumbar fracture between November 2011 and November 2015 were included in the study. There were 41 males and 24 females with an average age of 36.7 years (range, 23-60 years). The fracture segments included T7 1 case, T9 in 2 cases, T10 in 4 cases, T11 in 8 cases, T12 in 14 cases, L1 in 19 cases, L2 in 13 cases, L3 in 3 cases, and L4 in 1 case. According to AO classification, there were 34 cases classified as type A, 27 cases type B, and 4 cases type C. The neurological function was evaluated by American Spinal Injury Association (ASIA) grade score, there were 1 case at grade A, 2 cases grade B, 6 cases grade C, 15 cases grade D, and 41 cases grade E. The thoracolumbar injury severity score (TLICS) was 4 in 9 cases, 5 in 29 cases, 6-8 in 23 cases, 9-10 in 4 cases. The time form injury to operation was 2-12 days (mean, 5.3 days). The fractured vertebra, along with the superior and inferior discs were defined as a injured unit and divided into three parts on the sagittal position: region Ⅰ mainly including the superior disc, cephalic 1/3 of injured vertebra, and posterior ligamentous complex as to oppose; region Ⅱ mainly including the middle 1/3 of injured vertebra, pedicles, lamina, spinous process, and supraspinal ligament; region Ⅲ mainly including the inferior disc, caudal 1/3 of injured vertebra, and posterior ligamentous complex as to oppose. The unstable region was defined as the key injured region of the vertebra. Pedicle screws were fixed symmetrically and correspondingly with bone grafting to treat thoracolumbar fractures. The neurological status, ratio of anterior body height, and sagittal Cobb angle were collected at preoperation, immediate after operation, and last follow-up to evaluate surgical and clinical outcomes.ResultsAll patients accepted operation safely and were followed up 12-24 months (mean, 17.3 months). Cerebrospinal fluid leakage occurred in 3 patients, and cured by symptomatic treatment. There was no complications such as loosening, displacement, and breakage of internal fixator. Bony fusion was achieved in all patients at 10-13 months (mean, 11.4 months) after operation. At last follow-up, according to ASIA grading, 1 case was grade A, 1 grade B, 3 grade C, 9 grade D, and 51 grade E, showing significant difference when compared with preoperative data (Z=–2.963, P=0.014). The ratio of anterior body height at preoperation, immediate after operation, and last follow-up were 53.2%±6.8%, 91.3%±8.3%, 89.5%±6.6% respectively; and the sagittal Cobb angle were (16.3±8.1), (2.6±7.5), (3.2±6.8)° respectively. The ratio of anterior body height and the sagittal Cobb angle at immediate after operation and at last follow-up were significantly improved when compared with preoperative values (P<0.05), but no significant difference was found between at immediate after operation and at last follow-up (P>0.05).ConclusionIt is safe and reliable to treat thoracolumbar fractures under the principle of fixing the unstable region of injured unit symmetrically with pedicle screws combined with bone grafting.
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 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.
Objective To compare the effectiveness of percutaneous short-segment injured vertebra pedicle screw fixation combined with bone grafting versus percutaneous short-segment injured vertebra pedicle screw fixation alone for the treatment of thoracolumbar fractures. Methods The clinical data of 54 patients with single-level thoracolumbar fractures who met the selection criteria between January 2023 and February 2024 were retrospectively analysed. Based on whether bone grafting was performed on the injured vertebra, the patients were divided into a control group (28 cases, percutaneous short-segment injured vertebra pedicle screw fixation alone) and a study group (26 cases, percutaneous short-segment injured vertebra pedicle screw fixation combined with bone grafting using a self-made minimally invasive bone grafting funnel). No significant difference was observed between the two groups (P>0.05) in baseline data, including age, gender, surgical segment, cause of injury, AO classification, and preoperative anterior-vertebral height compression ratio, mid-vertebral height compression ratio, Cobb angle, visual analogue scale (VAS) score, and Oswestry Disability Index (ODI). The operation time, intraoperative blood loss, fracture healing status, removal time of internal fixator, and complications were recorded and compared between the two groups. Effectiveness was assessed using anterior-vertebral height compression ratio, mid-vertebral height compression ratio, Cobb angle, VAS scores, and ODI taken preoperatively, at 1 week postoperatively, and at last follow-up. ResultsAll patients in both groups successfully underwent surgery. The operation time and intraoperative blood loss in the control group were significantly less than those in the study group (P<0.05). No significant difference was observed in the follow-up time between the study group [(14.46±2.00) months] and control group [(14.36±1.83) months] (P>0.05). The fracture healing time of the study group was significantly shorter than that of the control group (P<0.05). One patient in the study group was found to have bilateral titanium rod breakage by X-ray reexamination at 8 months after operation, and there was no subsequent vertebral height collapse occurred, and the internal fixator was removed following complete fracture healing. The other patients had no complication such as spinal cord injury, internal fixator loosening and breakage. There was no significant difference in the removal time of internal fixator between the two groups (P<0.05). The anterior-vertebral height compression ratio, mid-vertebral height compression ratio, Cobb angle, VAS score, and ODI significantly improved in both groups at 1 week after operation and at last follow-up (P<0.05). Among them, the VAS score, and ODI further improved at last follow-up when compared with at 1 week after operation, Cobb angle lost a little at 1 week after operation, while anterior-vertebral height compression ratio and mid-vertebral height compression ratio slightly increased when compared with 1 week after operation, and the differences were significant (P<0.05). There was no significant difference between the two groups in Cobb angle at last follow-up, VAS score and ODI at 1 week after operation (P>0.05), while the other indicators in the study group were significantly better than those in the control group at all time points (P<0.05). Conclusion Compared to percutaneous short-segment injured vertebra pedicle screw fixation alone, the technique combined with intravertebral bone grafting can shorten fracture healing time, effectively restore and maintain vertebral body height, correct kyphotic deformity, and improve clinical outcomes for patients with thoracolumbar fractures.
Objective To evaluate the fixation strength of expansive pedicle screw (EPS) at different bone mineral density (BMD) levels, further to provide theoretical evidence for the clinical application of the EPS in patients with osteoporosis. Methods Fresh human cadaver spines (T12-L5 spines) were divided into 4 levels: normal BMD, osteopenia, osteoporosis, and severe osteoporosis according to the value of BMD, 12 vertebra in each level. Conventional pedicle screw (CPS) or EPS was implanted into the bilateral vertebra in CPS group and EPS group, respectively, 12 screws in each group per BMD level. Screw pullout tests were conducted. The maximum pullout strength, stiffness, and energy absorption were determined by an AG-IS material testing machine with constant rate of loading in a speed of 5 mm/ min. Results With the decline of BMD from normal to severe osteoporosis level, the maximum pullout strength and the stiffness correspondingly declined (P lt; 0.05). In CPS group, the energy absorption gradually decreased (P lt; 0.05); in EPS group, significant difference was found between other different BMD levels (P lt; 0.05) except between normal BMD and osteopenia and between osteoporosis and severe osteoporosis (P gt; 0.05). At the same BMD level, the maximum pullout strength of EPS group was significantly larger than that of CPS group (P lt; 0.05); the stiffness of EPS group was significantly higher than that of CPS group (P lt; 0.05) except one at normal BMD level; and no significant difference was found in the energy absorption between 2 groups (P gt; 0.05) except one at osteopenia level. No significant difference was found in maximum pullout strength, stiffness, and energy absorption between EPS group at osteoporosis level and CPS group at osteopenia level (P gt; 0.05); however, the maximum pullout strength, stiffness, and energy absorption of EPS group at severe osteoporosis level were significantly lower than those of CPS group at osteopenia level (P lt; 0.05). Conclusion Compared with CPS, the EPS can significantly improve the fixation strength, especially in patients with osteopenia or osteoporosis.
Objective To investigate the safety and accuracy of robot-assisted pedicle screw implantation in the adolescent idiopathic scoliosis (AIS) surgery. Methods The clinical data of 46 patients with AIS who were treated with orthopedics, bone graft fusion, and internal fixation via posterior approach between June 2018 and December 2019 were analyzed retrospectively. Among them, 22 cases were treated with robot-assisted pedicle screw implantation (robot group) and 24 cases with manual pedicle screw implantation without robot assistance (control group). There was no significant difference in gender, age, body mass index, Lenke classification, and preoperative Cobb angle of the main curve, pain visual analogue scale (VAS) score, Japanese Orthopaedic Association (JOA) score between the two groups (P>0.05). The intraoperative blood loss, pedicle screw implantation time, intraoperative pedicle screw adjustment times, and VAS and JOA scores after operation were recorded. The Cobb angle of the main curve was measured on X-ray film and the spinal correction rate was calculated. The screw position and the accuracy of screw implantation were evaluated on CT images. Results The operation completed successfully in the two groups. The intraoperative blood loss, pedicle screw implantation time, and pedicle screw adjustment times in the robot group were significantly less than those in the control group (P<0.05). There was 1 case of poor wound healing in the robot group and 2 cases of mild nerve root injury and 2 cases of poor incision healing in the control group, and there was no significant difference in the incidence of complications between the two groups (P=0.667). All patients in the two groups were followed up 3-9 months (mean, 6.4 months). The VAS and JOA scores at last follow-up in the two groups were superior to those before operation (P<0.05), but there was no significant difference in the difference of pre- and post-operative scores between the two groups (P>0.05). The imaging review showed that 343 screws were implanted in the robot group and 374 screws in the control group. There were significant differences in pedicle screw implantation classification and accuracy between the two groups (89.5% vs 79.1%)(Z=−3.964, P=0.000; χ2=14.361, P=0.000). At last follow-up, the Cobb angles of the main curve in the two groups were significantly lower than those before operation (P<0.05), and there was significant difference in the difference of pre- and post-operative Cobb angles between the two groups (t=0.999, P=0.323). The spinal correction rateswere 79.82%±5.33% in the robot group and 79.62%±5.58% in the control group, showing no significant difference (t=0.120, P=0.905). Conclusion Compared with manual pedicle screw implantation, robot-assisted pedicle screw implantation in AIS surgery is safer, less invasive, and more accurate.
Objective To explore the surgical feasibil ity and cl inical outcome of transpedicle screw fixation in treatment of atlantoaxial instabil ity and dislocation. Methods From January 2007 to June 2009, 16 patients with atlantoaxial instabil ity and dislocation were treated with transpedicle screw fixation. There were 13 males and 3 females, with a mean age of 42 years (range, 24-61 years). The transpedicle screw fixation was employed in 5 patients with old odontoid fracture (4 of Anderson type II and 1 of type III), in 4 patients with fresh odontoid fracture, in 4 patients with traumatic disruption of transverse atlantal l igament, and in 3 patients with congenital odontoid disconnection for atlantoaxial instabil ity. All patients had symptoms of cervical pain and l imition of cervical motion, 10 patients compl icated by dyscinesia and hypoesthesia of extremities. The Japanese Orthopaedic Association (JOA) score before operation was from 5 to 13, with an average of 8.5. The image examination showed atlantoaxial instabil ity or dislocation in all patients. Granulated autogenous il ium (20-30 g) was placed onto the surface of the posterior arches of both atlas and axis in some patients with old fracture of odontoid process or disruption of transverse atlantal l igament. Results The mean operative time and bleeding amount were 1.6 hours (1.2-2.5 hours) and 100 mL (50-200 mL), respectively. All the incision healed by first intension. All patients were followed up for 3-18 months, with an average of 11.5 months. The JOA score 3 months after operation was from 12 to 17, with an average of 14.2. All screws were successfully placed in atlas and axis. No postoperative compl ications such as vertebral artery injury, dural rupture, exacerbation of neurological symptoms, wound infection, and broken srews were observed in 16 cases. Postoperative radiograph and CT showed that only one screw penetrated into vertebral canal, but there was no neurological symptoms. Bony fusion was observed after 6 to 18 months of operation, and atlantoaxial rotational function in all patients restored satisfactorily, but axial rotation was partially lost. Conclusion Transpedicle screw fixation in upper cervical spine for treatment of atlantoaxial instabil ity and dislocation is safe and rel iable
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.