Objective To explore the safety and effectiveness of one-stage posterior eggshell osteotomy and long-segment pedicle screw fixation in the treatment of ankylosing spondylitis kyphosis combined with acute thoracolumbar vertebral fracture. Methods A clinical data of 20 patients with ankylosing spondylitis kyphosis combined with acute thoracolumbar spine fracture, who were treated with one-stage posterior eggshell osteotomy and long-segment pedicle screw fixation between April 2016 and January 2022, was retrospectively analyzed. Among them, 16 cases were male and 4 cases were female; their ages ranged from 32 to 68 years, with an average of 45.9 years. The causes of injury included 10 cases of sprain, 8 cases of fall, and 2 cases of falling from height. The time from injury to operation ranged from 1 to 12 days, with an average of 7.1 days. The injured segment was T11 in 2 cases, T12 in 2 cases, L1 in 6 cases, and L2 in 10 cases. X-ray film and CT showed that the patients had characteristic imaging manifestations of ankylosing spondylitis, and the fracture lines were involved in the anterior, middle, and posterior columns and accompanied by different degrees of kyphosis and vertebral compression; and MRI showed that 12 patients had different degrees of nerve injuries. The operation time, intraoperative bleeding, intra- and post-operative complications were recorded. The visual analogue scale (VAS) score and Oswestry disability index (ODI) were used to evaluate the low back pain and quality of life, and the American spinal cord injury association (ASIA) classification was used to evaluate the neurological function. X-ray films were taken, and local Cobb angle (LCA) and sagittal vertical axis (SVA) were measured to evaluate the correction of the kyphosis. Results All operations were successfully completed and the operation time ranged from 127 to 254 minutes (mean, 176.3 minutes). The amount of intraoperative bleeding ranged from 400 to 950 mL (mean, 722.5 mL). One case of dural sac tear occurred during operation, and no cerebrospinal fluid leakage occurred after repair, and the rest of the patients did not suffer from neurological and vascular injuries, cerebrospinal fluid leakage, and other related complications during operation. All incisions healed by first intention without infection or fat liquefaction. All patients were followed up 8-16 months (mean, 12.5 months). The VAS score, ODI, LCA, and SVA at 3 days after operation and last follow-up significantly improved when compared with those before operation (P<0.05), and the difference between 3 days after operation and last follow-up was not significant (P>0.05). The ASIA grading of neurological function at last follow-up also significantly improved when compared with that before operation (P<0.05), including 17 cases of grade E and 3 cases of grade D. At last follow-up, all bone grafts achieved bone fusion, and no complications such as loosening, breaking of internal fixation, and pseudoarthrosis occurred. Conclusion One-stage posterior eggshell osteotomy and long-segment pedicle screw fixation is an effective surgical procedure for ankylosing spondylitis kyphosis combined with acute thoracolumbar vertebral fracture. It can significantly relieve patients’ clinical symptoms and to some extent, alleviate the local kyphotic deformity.
ObjectiveTo compare the effectiveness and screw planting accuracy of percutaneous reduction and internal fixation with robot and traditional fluoroscopy-assisted in the treatment of single-level thoracolumbar fractures without neurological symptoms.MethodsThe clinical data of 58 patients with single-level thoracolumbar fractures without neurological symptoms between December 2016 and January 2018 were retrospectively analysed. According to different surgical methods, the patients were divided into group A (28 cases underwent robot-assisted percutaneous reduction and internal fixation) and group B (30 cases underwent fluoroscopy-assisted percutaneous reduction and internal fixation). There was no neurological symptoms, other fractures or organ injuries in the two groups. There was no significant difference in general data of age, gender, fracture location, AO classification, time from injury to surgery, and preoperative vertebral anterior height ratio, sagittal Cobb angle, visual analogue scale (VAS) score, and Oswestry disability index (ODI) score between the two groups (P>0.05). The screw placement time, operation time, intraoperative blood loss, intraoperative fluoroscopy frequency, hospitalization time, operation cost, postoperative complications, VAS score, ODI score, anterior vertebral height ratio, and sagittal Cobb angle before operation, at 3 days, 6 months after operation, and at last follow-up were recorded and compared between the two groups. The accuracy of the pedicle screw placement was evaluated by Neo’s criteria.ResultsThe screw placement time, operation time, and intraoperative fluoroscopy frequency of group A were significantly less than those of group B, and the operation cost was significantly higher than that of group B (P<0.05). But there was no significant difference in intraoperative blood loss and hospitalization time between the two groups (P>0.05). Both groups were followed up 12-24 months, with an average of 15.2 months. The accuracy rate of screw placement in groups A and B was 93.75% (150/160) and 84.71% (144/170), respectively, and the difference was significant (χ2=5.820, P=0.008). Except for 1 case of postoperative superficial infection in group A and wound healing after dressing change, there was no complication such as neurovascular injury, screw loosening and fracture in both groups, and there was no significant difference in the incidence of complications between the two groups (χ2=0.625, P=0.547). The anterior vertebral height ratio, sagittal Cobb angle, VAS score, and ODI score of the two groups were significantly improved (P<0.05); there was no significant difference between the two groups at all time points after operation (P>0.05).ConclusionThe spinal robot and traditional fluoroscopy-assisted percutaneous reduction and internal fixation can both achieve satisfactory effectiveness in the treatment of single-level thoracolumbar fractures without neurological symptoms. However, the former has higher accuracy, fewer fluoroscopy times, shorter time of screw placement, and lower technical requirements for the operator. It has wide application potential.
Objective To investigate the effects of different puncture levels on bone cement distribution and effectiveness in bilateral percutaneous vertebroplasty for osteoporotic thoracolumbar compression fractures. Methods A clinical data of 274 patients with osteoporotic thoracolumbar compression fractures who met the selection criteria between December 2017 and December 2020 was retrospectively analyzed. All patients underwent bilateral percutaneous vertebroplasty. During operation, the final position of the puncture needle tip reached was observed by C-arm X-ray machine. And 118 cases of bilateral puncture needle tips were at the same level (group A); 156 cases of bilateral puncture needle tips were at different levels (group B), of which 87 cases were at the upper 1/3 layer and the lower 1/3 layer respectively (group B1), and 69 cases were at the adjacent levels (group B2). There was no significant difference in gender, age, fracture segment, degree of osteoporosis, disease duration, and preoperative visual analogue scale (VAS) score, and Oswestry disability index (ODI) between groups A and B and among groups A, B1, and B2 (P>0.05). The operation time, bone cement injection volume, postoperative VAS score, ODI, and bone cement distribution were compared among the groups. Results All operations were successfully completed without pulmonary embolism, needle tract infection, or nerve compression caused by bone cement leakage. There was no significant difference in operation time and bone cement injection volume between groups A and B or among groups A, B1, and B2 (P>0.05). All patients were followed up 3-32 months, with an average of 7.8 months. There was no significant difference in follow-up time between groups A and B and among groups A, B1, and B2 (P>0.05). At 3 days after operation and last follow-up, VAS score and ODI were significantly lower in group B than in group A (P<0.05), in groups B1 and B2 than in group A (P<0.05), and in group B1 than in group B2 (P<0.05). Imaging review showed that the distribution of bone cement in the coronal midline of injured vertebrae was significantly better in group B than in group A (P<0.05), in groups B1 and B2 than in group A (P<0.05), and in group B1 than in group B2 (P<0.05). In group A, 7 cases had postoperative vertebral collapse and 8 cases had other vertebral fractures. In group B, only 1 case had postoperative vertebral collapse during follow-up. ConclusionBilateral percutaneous vertebroplasty in the treatment of osteoporotic thoracolumbar compression fractures can obtain good bone cement distribution and effectiveness when the puncture needle tips locate at different levels during operation. When the puncture needle tips locate at the upper 1/3 layer and the lower 1/3 layer of the vertebral body, respectively, the puncture sites are closer to the upper and lower endplates, and the injected bone cement is easier to connect with the upper and lower endplates.
ObjectiveTo compare short-term effectiveness between robot-guided percutaneous minimally invasive pedicle screw internal fixation and traditional open internal fixation in the treatment of thoracolumbar fractures.MethodsThe clinical data of 52 cases of thoracolumbar fracture without neurological injury symptoms admitted between January 2018 and May 2018 were retrospectively analyzed. According to the different surgical methods, they were divided into minimally invasive group (24 cases, treated with robot-assisted percutaneous minimally invasive pedicle screw internal fixation) and open group (28 cases, treated with traditional open internal fixation). There was no significant difference between the two groups in the general data such as gender, age, cause of injury, fracture segment, thoracolumbar injury classification and severity score (TLICS), preoperative back pain visual analogue scale (VAS) score, Oswestry disability index (ODI) score, fixed segment height, and fixed segment kyphosis Cobb angle (P>0.05). The operation time, intraoperative blood loss, and hospitalization time of the two groups were recorded and compared; as well as the VAS score, ODI score, fixed segment height, and fixed segment kyphosis Cobb angle of the two groups before operation and at 3 days, 1 month, 6 months, and 10 months after operation. CT scan was reexamined at 1-3 days after operation, and the pedicle screw insertion accuracy rate was determined and calculated according to Gertzbein-Robbins classification standard.ResultsThe operation time of the minimally invasive group was significantly longer than that of the open group, but the intraoperative blood loss and hospitalization time were significantly shorter than those of the open group (P<0.05). There were 132 pedicle screws and 158 pedicle screws implanted in the minimally invasive group and the open group respectively. According to the Gertzbein-Robbins classification standard, the accuracy of pedicle screws was 97.7% (129/132) and 96.8% (153/158), respectively, showing no significant difference between the two groups (χ2=0.505, P=0.777). The patients in both groups were followed up 10 months, and there was no rejection or internal fixation fracture. In the minimally invasive group, the internal fixator was removed at 10 months after operation, but not in the open group. The VAS score, ODI score, fixed segment heigh, and fixed segment kyphotic Cobb angle of the two groups were improved in different degrees when compared with preoperative ones (P<0.05). Except that the VAS score and ODI score of the minimally invasive group were significantly better than those of the open group at 3 days after operation (P<0.05), there was no significant difference between the two groups at other time points (P>0.05).ConclusionRobot-assisted percutaneous minimally invasive pedicle screw internal fixation for thoracolumbar fractures has significant advantages in intraoperative blood loss, hospitalization time, and early postoperative effectiveness and other aspects, and the effect of fracture reduction is good.
ObjectiveTo compare the effectiveness of robot-assisted (RA) minimally invasive surgery versus traditional fluoroscopy-assisted (FA) open posterior fixation surgery in treating thoracolumbar fractures with ankylosing spondylitis (AS). MethodsA clinical data of 21 cases of thoracolumbar fractures with AS who met the selection criteria between December 2016 and December 2023 was retrospectively analyzed. Ten cases underwent RA minimally invasive surgery group (RA group) and 11 cases underwent FA open posterior fixation surgery (FA group). There was no significant difference in gender, age, fracture segment distribution, fracture type, time from injury to surgery, visual analogue scale (VAS) score, and American Spinal Injury Association (ASIA) grading between RA group and FA group (P>0.05). The operation time, intraoperative blood loss, radiation exposure time, radiation dose, hospital stay, and complications of the two groups were recorded. According to Gertzbein-Robbins criteria, the accuracy of screw implantation was evaluated by CT within 1 week after surgery. During follow-up, pain and nerve function were evaluated by VAS score and ASIA grading. ResultsAll patients underwent surgery successfully, and there was no significant difference in operation time (P>0.05). The intraoperative blood loss and hospital stay in the RA group were significantly less than those in the FA group (P<0.05), and the radiation exposure time and radiation dose were significantly more than those in the FA group (P<0.05). A total of 249 pedicle screws were implanted in the two groups, including 118 in the RA group and 131 in the FA group. According to the Gertzbein-Robbins criteria, the proportion of clinically acceptable screws (grades A and B) in the RA group was significantly higher than that in the FA group (P<0.05). Patients in both groups were followed up 3-12 months, with an average of 6.8 months. The VAS scores of the two groups after surgery were significantly lower than those before surgery, and the differences were significant (P<0.05). The RA group had lower scores than the fluoroscopy group at 1 week and 3 months after surgery (P<0.05). There was no significant difference in neurological function grading between groups at 1 week and 3 months after surgery (P>0.05). In the FA group, 1 case of deep infection and 1 case of deep vein thrombosis of lower extremity occurred, while no complication occurred in the RA group, and there was no significant difference in the incidence of complications between groups (P>0.05). Conclusion Both RA minimally invasive surgery and FA open posterior fixation surgery can achieve good effectiveness. Compared with the latter, the former has more advantages in terms of intraoperative blood loss, hospital stay, and accuracy of pedicle screw insertion.
ObjectiveTo evaluate the feasibility and safety of three-dimensional (3D) printed drill guide template-assisted percutaneous pedicle screw fixation for multiple-level thoracolumbar fractures.MethodsClinical data of 19 patients with multilevel thoracolumbar fracture without nerve injury who underwent surgical treatment between May 2017 and January 2019 were retrospectively analyzed. There were 9 males and 10 females and their age ranged from 22 to 63 years, with an average age of 43.6 years. Injury cause included traffic accident injury in 12 cases, and fall from height injury in 7 cases. A total of 40 fractured vertebrae were involved in T10 to L3 levels. According to AO classification, there were 29 fractures of type A1, 9 fractures of type A2, and 2 fractures of type A3. According to TANG Sanyuan classification, multiple-segment thoracolumbar fractures were classified as 17 cases of type ⅠA, 1 case of type ⅠB, and 1 case of type ⅡC. The time from injury to operation was 2-6 days, with an average of 3.1 days. The 3D-printed universal drill guide template was used for assisting percutaneous pedicle screw fixation during operation. Intraoperative blood loss, average operation time and fluoroscopy frequency of each screw were recorded. Visual analogue scale (VAS) score was used to evaluate the improvement of low back pain before operation, at 3 days after operation, and at last follow-up. According to the CT at 3 days after operation, the Gertzbein and Robbins scales were used to evaluate the accuracy of screw insertion (the grade A and grade B were regarded as accuracy, the grade A was regarded as excellent of screw insertion). The Cobb angle in sagittal plane of the fracture segment was measured, and the percentage of anterior edge of injured vertebral height was calculated. The consistency of the inclination of bilateral pedicle screws were analyzed postoperatively, and compared the angle of the intraoperative guide plate with the inclination of screw to verify the effectiveness of the guide plate in controlling the inclination.ResultsAll the 19 patients completed the operation successfully, and the intraoperative blood loss was 44-67 mL, with an average of 54.3 mL. The average operation time for each screw insertion was 7.3-11.1 minutes, with an average of 9.6 minutes. The average fluoroscopy frequency of each screw insertion was 1.6-2.5 times, with an average of 2.0 times. No spinal cord, nerve root injury, infection, and other complications occurred. All patients were followed up 24-38 months, with an average of 28.7 months. The accuracy of pedicle screws was evaluated by using Gertzbein and Robbins scales: 145 screws were grade A and 11 screws were grade B. The accuracy of screw insertion was 100% and the excellent rate was 92.9%. The CT data at 3 days after operation showed no significant difference in the inclination between the left and right screws in the same vertebral body (t=0.93, P=0.36). There was no significant difference between the angle of guide plate and the screw inclination (P>0.05). The VAS score, Cobb angle in sagittal plane, and the percentage of anterior edge of injured vertebral height were significantly improved at 3 days after operation and at last follow-up, and the VAS score was declined at last follow-up compared with 3 days after operation, all showing significant differences (P<0.05). There was no significant difference in the sagittal Cobb angle and the percentage of anterior edge of injured vertebral height between two postoperative time points (P>0.05). At last follow-up, no internal fixators were loosened or broken, and all fractures healed well.ConclusionFor the multiple-level thoracolumbar fractures, 3D-printed drill guide template assisting percutaneous pedicle screw fixation can reduce the operation time, intraoperative blood loss, and fluoroscopy frequency and the screw insertion is accurate and has a good reduction effect.
Objective To discuss the effectiveness of anterolateral decompression and three column reconstruction through posterior approach for the treatment of unstable thoracolumbar fracture. Methods Between March 2009 and October 2011, 39 patients with unstable burst thoracolumbar fracture were treated. Of them, there were 32 males and 7 females, with an average age of 43.8 years (range, 25-68 years). The injury causes included falling from height in 17 cases, bruise in 10 cases, traffic accident in 4 cases, and other in 8 cases. The fracture was located at the T10 level in 1 case, T11 in 9 cases, T12 in 6 cases, L1 in 14 cases, L2 in 7 cases, L3 in 1 case, and L4 in 1 case. According to Frankel classification before operation, 5 cases were classified as grade A, 5 as grade B, 9 as grade C, 14 as grade D, and 6 as grade E. Before operation, the vertebral kyphosis Cobb angle was (26.7 ± 7.1)°; vertebral height loss was 37.5% ± 9.5%; and the space occupying of vertebral canal was 73.7% ± 11.3%. The time between injury and operation was 1-4 days (mean, 2.5 days). All patients underwent anterolateral decompression of spinal canal by posterior approach and three column reconstruction. After operation, the vertebral height restoration, correction of kyphosis, decompression of the spinal canal, and the recovery of nerve function were evaluated. Results Increase of paraplegic level, urinary infection, and pressure sore occurred in 1 case, 1 case, and 2 cases, respectively; no incision infection or neurological complications was observed in the other cases, primary healing of incision was obtained. The patients were followed up 12-36 months (mean, 27 months). The patients had no aggravation of pain of low back after operation; no loosening and breaking of screws and rods occurred; no titanium alloys electrolysis and titanium cage subsidence or breakage was observed. The imaging examination showed that complete decompression of the spinal canal, satisfactory restoration of the vertebral height, and good physiological curvature of spine at 2 years after operation. At last follow-up, 1 case was classified as Frankel grade A, 2 as grade B, 2 as grade C, 10 as grade D, and 24 as grade E, which was significantly improved when compared with preoperative one (Plt; 0.05). At immediate after operation and last follow-up, the Cobb angle was (6.3 ± 2.1)° and (6.5 ± 2.4)° respectively; the vertebral height loss was 7.9% ± 2.7% and 8.2% ± 3.0% respectively; and the indexes were significantly improved when compared with preoperative ones (P lt; 0.05). Conclusion The technique of anterolateral decompression and three column reconstruction through posterior approach is one perfect approach to treat unstable thoracolumbar fracture because of complete spinal cord canal decompression, three column reconstruction, and immediate recovery of the spinal stability after operation.
Objective To investigate the effectiveness of Wiltse approach with fulcrum reduction technique and pedicle internal fixation in the treatment of AO-A type thoracolumbar fractures. Methods The clinical data of 16 patients with AO-A type thoracolumbar fractures treated with Wiltse approach with fulcrum reduction technique and pedicle internal fixation between September 2013 and January 2019 were retrospectively analyzed. There were 9 males and 7 females, the age ranged from 38 to 60 years, with an average age of 50.7 years. Causes of injury included 9 cases of falling from height, 3 cases of traffic accidents, 3 cases of falling, and 1 case crushed by heavy objects. Fractured segment involved T11 in 2 cases, T12 in 5 cases, L1 in 7 cases, and L2 in 2 cases. There were 6 cases of type A1, 3 cases of type A2, 5 cases of type A3, and 2 cases of type A4 according to AO fracture classification. The operation time, intraoperative blood loss, and removal time of internal fixator were recorded. Before operation, immediately after operation, before and after removal of internal fixator, the local kyphotic angle (LKA), anterior vertebral height (AVH), and posterior vertebral height (PVH) of fractured vertebral body were measured; visual analogue scale (VAS) score of back pain were evaluated before operation, at 3 days after operation, before and after removal of internal fixator. Results The operation time of the patients was 50-95 minutes, with an average of 70.7 minutes; the intraoperative blood loss was 50-230 mL, with an average of 132.9 mL; the internal fixator was removed after 18-30 months, with an average of 23.6 months. All patients were followed up 20-32 months, with an average of 25.6 months. No incision infection, hematoma, and other surgery-related complications, and internal fixator rupture residual complications occurred. All 16 patients achieved satisfactory reduction results. Immediate postoperative LKA, AVH, and PVH were significantly improved when compared with preoperative ones (P<0.05). There was a certain degree of reduction loss before internal fixator removal, and the difference in LKA was significant (P<0.05), but the difference in AVH and PVH were not significant (P>0.05). There was a certain degree of reduction loss after internal fixator removal, but only the difference in AVH was significant (P<0.05), and there was no significant difference in LKA and PVH (P>0.05). The VAS score of the back pain significantly improved at 3 days after operation and before internal fixator removal when compared with preoperative score (P<0.05). The pain after internal fixator removal was significantly worse than that before internal fixator removal (P<0.05). ConclusionThe Wiltse approach with fulcrum reduction technique and pedicle internal fixation in the treatment of AO-A thoracolumbar fractures has a short operation time, less intraoperative blood loss, and the posterior soft tissue and other structures are well protected during the operation. It can provide satisfactory clinical reduction results.
Objective To evaluate the effectiveness of using pedical screw at the fracture level, intervertebral distraction, and Cage insertion by posterior approach to treat thoracolumbar kyphosis caused by old fracture. Methods Between June 2008 and June 2010, 15 cases of thoracolumbar kyphosis caused by old fracture were treated with pedical screw at the fracture level, intervertebral distraction, and Cage insertion by posterior approach. There were 9 males and 6 females with a mean age of 54.6 years (range, 39-65 years). The disease duration was 5 months to 3 years with an average of 1.5 years. Fractured segments included T11 in 1 case, T12 in 4 cases, L1 in 5 cases, and L2 in 5 cases. Ten patients had nerve symptom, according to American Spinal Injury Association (ASIA) grading, 3 cases were classified as grade B, 4 cases as grade C, and 3 cases as grade D, of which 3 cases had sexual and sphincter dysfunction. At preoperation, the Cobb angle was (47.4 ± 10.2)°; the Oswestry disability index (ODI) score was 67.9% ± 6.9%; and the visual analogue scale (VSA) was 8.6 ± 1.4. Results The wounds obtained primary healing. The mean follow-up time was 28 months (range, 13-60 months). X-ray films showed intervertebral bone fusion was obtained within 6-11 months (mean, 10.2 months). No fixation loosening or breaking occurred during follow-up. Kyphosis was corrected, and lumbar back pain was relieved. At 1 year after operation, Cobb angle was significantly corrected to (13.3 ± 7.7)° (t=72.80, P=0.00); ODI score was significantly improved to 25.2% ± 4.6% (t=48.04, P=0.00); VAS score was significantly decreased to 2.3 ± 0.6 (t=26.52, P=0.00). According to ASIA grading in 10 patients with spinal cord injury, the spinal cord function was improved by 1 grade in 8 cases (3 cases from grade B to C, 3 cases from grade C to D, and 2 cases from grade D to E); 3 patients with sexual and sphincter dysfunction recovered in different degrees. Conclusion Using pedical screw at the fracture level, intervertebral distraction, and Cage insertion by posterior approach is an effective method to treat thoracolumbar kyphosis caused by old fracture.
Objective To introduce a scout view scanning technique of back-forward bending CT (BFB-CT) in simulated surgical position for evaluating the remaining real angle and flexibility of thoracolumbar kyphosis secondary to old osteoporotic vertebral compression fracture. Methods A total of 28 patients with thoracolumbar kyphosis secondary to old osteoporotic vertebral compression fracture who met the selection criteria between June 2018 and December 2021 were included in the study. There were 6 males and 22 females with an average age of 69.5 years (range, 56-92 years). The injured vertebra were located at T10-L2, including 11 cases of single thoracic fracture, 11 cases of single lumbar fracture, and 6 cases of multiple thoracolumbar fractures. The disease duration ranged from 3 weeks to 36 months, with a median of 5 months. All patients received examinations of BFB-CT and standing lateral full-spine X-ray (SLFSX). The thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), local kyphosis of injured vertebra (LKIV), lumbar lordosis (LL), and the sagittal vertical axis (SVA) were measured. Referring to the calculation method of scoliosis flexibility, the kyphosis flexibility of thoracic, thoracolumbar, and injured vertebra were calculated respectively. The sagittal parameters measured by the two methods were compared, and the correlation of the parameters measured by the two methods was analyzed by Pearson correlation. Results Except LL (P>0.05), TK, TLK, LKIV, and SVA measured by BFB-CT were significantly lower than those measured by SLFSX (P<0.05). The flexibilities of thoracic, thoracolumbar, and injured vertebra were 34.1%±18.8%, 36.2%±13.8%, and 39.3%±18.6%, respectively. Correlation analysis showed that the sagittal parameters measured by the two methods were positively correlated (P<0.001), and the correlation coefficients of TK, TLK, LKIV, and SVA were 0.900, 0.730, 0.700, and 0.680, respectively. Conclusion Thoracolumbar kyphosis secondary to old osteoporotic vertebral compression fracture shows an excellent flexibility and BFB-CT in simulated surgical position can obtain the remaining real angle which need to be corrected surgically.