Objective To investigate the effect of the sequence of intermediate instrumentation with long screws and distraction-reduction on mild to moderate thoracolumbar fractures treated by posterior open and short-segmental fixation. MethodsThe clinical data of 68 patients with mild to moderate thoracolumbar burst fractures who met the selection criteria between January 2016 and June 2019 were retrospectively analyzed. The patients were divided into group ISDRF (intermediate screws then distraction-reduction fixation, 32 cases) and group DRISF (distraction-reduction then intermediate screws fixation, 36 cases) according to the different operation methods. There was no significant difference between the two groups in age, gender, body mass index, fracture segment, cause of injury, and preoperative load-sharing classification score, thoracolumbar injury classification and severity score, vertebral canal occupational rate, back pain visual analogue scale (VAS) score, anterior height of fractured vertebra, and Cobb angle (P>0.05). The operation time, intraoperative blood loss, complications, and fracture healing time were recorded and compared between the two groups. The vertebral canal occupational rate, anterior height of fractured vertebra, kyphosis Cobb angle, and back pain VAS score before and after operation were used to evaluate the effectiveness. Results There was no significant difference in intraoperative blood loss and operation time between the two groups (P>0.05). No vascular or spinal nerve injury and deep infections or skin infections occurred in both groups. At 1 week after operation, the vertebral canal occupational rate in the two groups was significantly improved when compared with that before operation (P<0.05), no significant difference was found in the difference of vertebral canal occupational rate before and after operation and improvement between the two groups (P>0.05). The patients in both groups were followed up 18-24 months, with an average of 22.3 months. All vertebral fractures reached bone union at 6 months postoperatively. At last follow-up, there was no internal fixation failures such as broken screws, broken rods or loose screws, but there were 2 cases of mild back pain in the ISDRF group. The intra-group comparison showed that the back pain VAS score, the anterior height of fractured vertebra, and the Cobb angle of the two groups were significantly improved at each time point postoperatively (P<0.05); the VAS scores at 12 months postoperatively and last follow-up were also improved when compared with that at 1 week postoperatively (P<0.05). At last follow-up, the anterior height of fractured vertebra in the ISDRF group was significantly lost when compared with that at 1 week and 12 months postoperatively (P<0.05), the Cobb angle had a significant loss when compared with that at 1 week postoperatively (P<0.05); the anterior height of fractured vertebra and Cobb angle in DRISF group were not significantly lost when compared with that at 1 week and 12 months postoperatively (P>0.05). The comparison between groups showed that there was no significant difference in the remission rate of VAS score between the two groups at 1 week postoperatively (P>0.05), the recovery value of the anterior height of fractured vertebra in ISDRF group was significantly higher than that in DRISF group (P<0.05), the loss rate at last follow-up was also significantly higher (P<0.05); the correction rate of Cobb angle in ISDRF group was significantly higher than that in DRISF group at 1 week postoperatively (P<0.05), but there was no significant difference in the loss rate of Cobb angle between the two groups at last follow-up (P>0.05). ConclusionIn the treatment of mild to moderate thoracolumbar burst fractures with posterior short-segment fixation, the instrumentation of long screws in the injured vertebrae does not affect the reduction of the fracture fragments in the spinal canal. DRISF can better maintain the restored anterior height of the fractured vertebra and reduce the loss of kyphosis Cobb angle during the follow-up, indicating a better long-term effectiveness.
Objective To evaluate the early cl inical outcomes of subtotal corpectomy and intervertebral bonegrafting through posterior approach alone in the treatment of thoracolumbar burst fracture or thoracolumbar fracturedislocation.Methods Between January 2009 and December 2010, 20 patients with thoracolumbar burst fracture orthoracolumbar fracture dislocation were treated with subtotal corpectomy and intervertebral bone grafting through posteriorapproach alone. There were 14 males and 6 females, with an average age of 36.1 years (range, 19-47 years). Fractures were causedby falling from height in 12 cases, traffic accident in 6 cases, and crushing in 2 cases. According to AO classification, there were10 cases of A3 type, 8 cases of B2 type, and 2 cases of C2 type. Single segment was involved in 8 cases, double segments in 12cases. Twelve cases complicated by fracture dislocation and 6 cases by lateral displacement. All patients had bones occupancyin vertebral canal. The preoperative Cobb angle was (30.2 ± 3.9)°. According to Frankel classification for neurological function,there were 4 cases of grade B, 9 cases of grade C, and 7 cases of grade D at preoperation. The mean time between injury andoperation was 4.5 days (range, 1-12 days). Results All incisions healed by first intention, and no infection occurred.Twenty patients were followed up 8-16 months (mean, 12 months). The interbody fusion time was 6-9 months (mean, 7months). Neurological function recovered 1 to 3 grades: 1 case of grade C, 2 cases of grade D, 17 cases of grade E at last followup.The Cobb angle was (6.5 ± 4.2)° at last follow-up, showing significant difference when compared with preoperative value(t=2.39, P=0.00). No breaking or loosening of screw and implant sinkage occurred. Conclusion A combination of subtotalcorpectomy and intervertebral bone grafting through posterior approach alone has the advantages of complete decompression,restoration of spinal stabil ity, restoration of vertebral body height, high bone healing rate, and good recovery of neurologicalfunction. However, this surgical technique has a relatively large amount of blood loss and high requirements for surgeons.
Objective To investigate the amount of bone grafting, bone defect gap residual rates, and biomechanical stability of the injured vertebral body after reduction of thoracolumbar burst fractures, pedicle screw-rods fixation, and bone graft by bilateral pedicle or unilateral spinal canal. Methods Eighteen fresh lumbar spine (L1-5) specimens of calves (aged 4-6 months) were collected to establish the burst fracture model at L3 and divided into 3 groups randomly. After reduction and fixation with pedicle screws, no bone graft was given in group A (n=6), and bone graft was performed by bilateral pedicles in group B (n=6) and by unilateral spinal canal in group C (n=6). The amount of bone grafting in groups B and C was recorded. The general situation of bone defect gaps was observed by the DR films and CT scanning, and the defect gap residual rates of the injured vertebrae were calculated with counting of grids. The compression stiffness was measured by ElectreForce-3510 high precision biological material testing machines. Results The amount of bone grafting was (4.58 ± 0.66) g and (5.72 ± 0.78) g in groups B and C respectively, showing signficant difference (t=2.707, P=0.022). DR films and CT scanning observation showed large bone defect gap was seen in injured vertebrae specimens of group A; however, the grafting bone grains was seen in the “eggshell” gap of the injured vertebral body, which were mainly located in the posterior part of the vertebral body, but insufficient filling of bone graft in the anterior part of the vertebral body in group B; better filling of the grafting bone grains was seen in injured vertebral body of group C, with uniform distribution. The bone defect gap residual rates were 52.0% ± 5.5%, 39.7% ± 2.5%, and 19.5% ± 2.5% respectively in groups A, B, and C; group C was significantly lower than groups A and B (P lt; 0.05), and group B was significantly lower than group A (P lt; 0.05). Flexion compressive stiffness of group C was significantly higher than that of groups A and B (P lt; 0.05), but no significant difference was found between groups A and B (P gt; 0.05). Extension compressive stiffness in group C was significantly higher than that in group A (P lt; 0.05), but no significant difference was found between groups A and B, and between groups B and C (P gt; 0.05). The compression stiffness of left bending and right bending had no significant difference among 3 groups (P gt; 0.05). Conclusion Thoracolumbar burst fracture pedicle screws fixation with bone grafting by unilateral spinal canal can implant more bone grains, has smaller bone defect gap residual rate, and better recovery of flexion compression stiffness than by bilateral pedicles.
Objective To investigate the effect of preventing the loss of correction and vertebral defects after thoracolumbar burst fractures treated with recombinant human bone morphogenetic protein 2 (rhBMP-2) and allogeneic bone grafting in injured vertebra uniting short-segment pedicle instrumentation. Methods A prospective randomized controlled study was performed in 48 patients with thoracolumbar fracture who were assigned into 2 groups between June 2013 and June 2015. Control group (n=24) received treatment with short-segment pedicle screw instrumentation with allogeneic bone implanting in injured vertebra; intervention group (n=24) received treatment with short-segment pedicle screw instrumentation combining with rhBMP-2 and allogeneic bone grafting in injured vertebra. There was no significant difference in gender, age, injury cause, affected segment, vertebral compression degree, the thoracolumbar injury severity score (TLICS), Frankel grading for neurological symptoms, Cobb angle, compression rate of anterior verterbral height between 2 groups before operation (P>0.05). The Cobb angle, compression rate of anterior vertebral height, intervertebral height changes, and defects in injured vertebra at last follow-up were compared between 2 groups. Results All the patients were followed up 21-45 months (mean, 31.3 months). Bone healing was achieved in 2 groups, and there was no significant difference in healing time of fracture between intervention group [(7.6±0.8) months] and control group [(7.5±0.8) months] (t=0.336, P=0.740). The Frankel grading of all patients were reached grade E at last follow-up. The Cobb angle and compression rate of anterior verterbral height at 1 week after operation and last follow-up were significantly improved when compared with preoperative ones in 2 groups (P<0.05). There was no significant difference in Cobb angle and compression rate of anterior verterbral height between 2 groups at 1 week after operation (P>0.05), but the above indexes in intervention group were better than those in control group at last follow-up (P<0.05). At last follow-up, there was no significant difference of intervertebral height changes of internal fixation adjacent upper position, injured vertebra adjacent upper position, injured vertebra adjacent lower position, and internal fixation adjacent lower position between 2 groups (P>0.05). Defects in injured vertebra happened in 18 cases (75.0%) in control group and 5 cases (20.8%) in intervention group, showing significant difference (χ2=14.108, P=0.000); and in patients with defects in injured vertebra, bone defect degree was 7.50%±3.61% in control group, and was 2.70%±0.66% in intervention group, showing significant difference (t=6.026, P=0.000). Conclusion Treating thoracolumbar fractures with short-segment pedicle screw instrumentation with rhBMP-2 and allogeneic bone grafting in injured vertebra can prevent the loss of correction and vertebral defects.
ObjectiveTo investigate the short-term effectiveness of balloon vertebroplasty combined with short-segment pedicle screw instrumentation for the treatment of thoracolumbar burst fractures. MethodsBetween June 2011 and December 2013, 22 patients with thoracolumbar burst fractures were included. There were 14 males and 8 females, aged 20-60 years (mean, 42.5 years). The fracture segments included T11 in 1 case, T12 in 4 cases, L1 in 10 cases, L2 in 6 cases, and L3 in 1 case. According to AO classification system, there were 13 cases of type A and 9 cases of type B. Spinal cord injury was classified as grade C in 2 cases, grade D in 3 cases, and grade E in 17 cases according to Frankel scale. The time from injury to operation was 3-10 days (mean, 5.5 days). All patients underwent posterior reduction and fixation via the injured vertebra, transpedicular balloon reduction of the endplate and calcium sulfate cement (CSC) injection. The ratio of anterior vertebral height, the ratio of central vertebral height, the sagittal Cobb angle, the restoration of nervous function, and internal fixation failure were analyzed. ResultsPrimary healing of incision was obtained in the others except 2 cases of poor healing, which was cured after dressing change or debridement. All the patients were followed up 9-40 months (mean, 15 months). CSC leakage occurred in 2 cases. Absorption of CSC was observed at 8 weeks after operation with complete absorption time of 12-16 weeks (mean, 13.2 weeks). The mean fracture healing time was 18.5 weeks (range, 16-20 weeks). The ratio of anterior vertebral height, ratio of central vertebral height, and sagittal Cobb angle were significantly improved at 1 week and 3 months after operation and last follow-up when compared with preoperative values (P<0.01), but no significant difference was found among 3 time points after operation (P>0.01). There was no internal fixation failure or Cobb angle loss more than 10°. Frankel scale was improved with no deterioration of neurologic function injury. ConclusionBalloon vertebroplasty combined with short-segment pedicle screw instrumentation is simple and safe for the treatment of thoracolumbar burst fractures, and it can improve the quality of reduction, restore vertebral mechanical performance effectively, and prevent the loss of correction and internal fixation failure.
ObjectiveTo investigate the effectiveness of posterior microscopic mini-open technique (MOT) decompression in patients with severe spinal canal stenosis resulting from thoracolumbar burst fractures.MethodsThe clinical data of 28 patients with severe spinal canal stenosis caused by thoracolumbar burst fractures, who were treated by posterior microscopic MOT, which performed unilateral or bilateral laminectomy, poking reduction, intervertebral bone graft via spinal canal, and percutaneous pedicle screw fixation between January 2014 and January 2016 were retrospectively analyzed. There were 21 males and 7 females with a mean age of 42.1 years (range, 16-61 years). The involved segments included T11 in 1 case, T12 in 4 cases, L1 in 14 cases, and L2 in 9 cases. According to AO classification, there were 19 cases of type A3, 9 of type A4. According to American Spinal Injury Association (ASIA) grading, 12 cases were grade C, 13 grade D, and 3 grade E. The time between injury and operation was 3-7 days (mean, 3.6 days). To evaluate effectiveness, the changes in the visual analogue scale (VAS), percentage of anterior height of injured vertebrae, Cobb angle, rate of spinal compromise (RSC), and ASIA grading were analyzed.ResultsAll patients were performed procedures successfully. The operation time was 135-323 minutes (mean, 216.4 minutes). The intraoperative blood loss was 80-800 mL (mean, 197.7 mL). The hospitalization time was 10-25 days (mean, 12.5 days). The incisions healed primarily, without wound infection, cerebrospinal fluid leakage, or other early complications. All the 28 patients were followed up 12-24 months (mean, 16.5 months). No breakage or loosening of internal fixation occurred. All fractures healed, and the healing time was 3-12 months (mean, 6.5 months). Compared with preoperative ones, the percentage of anterior height of injured vertebrae, Cobb angle, and RSC at immediate after operation and at last follow-up and the VAS scores at 1 day after operation and at last-follow were significantly improved (P<0.05). There was no significant difference in the percentage of anterior height of injured vertebrae and Cobb angle between at immediate after operation and at last follow-up (P>0.05). But the RSC at immediate after operation and VSA score at 1 day after operation were significantly improved when compared with those at last follow-up (P<0.05). The ASIA grading at last follow-up was 1 case of grade C, 14 grade D, and 13 grade E, which was significantly improved when compared with preoperative ones (Z=3.860, P=0.000).ConclusionMOT is an effective and minimal invasive treatment for thoracolumbar AO type A3 and A4 burst fractures with severe spinal canal stenosis, and it is beneficial to early rehabilitation for patients.
ObjectiveTo compare the effectiveness of short segmental pedicle screw fixation with and without fusion in the treatment of thoracolumbar burst fracture. MethodsA retrospective analysis was made on the clinical data of 57 patients with single segment thoracolumbar burst fractures, who accorded with the inclusion criteria between February 2012 and February 2014. The patients underwent posterior short segmental pedicle screw fixation with fusion in 27 cases (fusion group) and without fusion in 30 cases (non-fusion group). There was no significant difference in gender, age, cause of injury, time between injury and admission, fracture segment and classification, and neurologic function America Spinal Injury Association (ASIA) classification between 2 groups, which had the comparability (P > 0.05). The operative time, blood loss, and hospitalization days were compared between 2 groups. The height of the injured vertebra, the kyphotic angle, and the range of motion (ROM) were measured on the X-ray film. The functional outcomes were evaluated by using the Greenough low-back outcome score and the visual analogue scale (VAS) for back pain. The neurologic functional recovery was assessed by ASIA grade. ResultsThe operative time was significantly shortened and the blood loss was significantly reduced in the non-fusion group when compared with the fusion group (P < 0.05), but no significant difference was found in hospitalization days between 2 groups (P > 0.05). The patients were followed up for 2.0-3.5 years (mean, 3.17 years) in the fusion group and for 2-4 years (mean, 3.23 years) in the non-fusion group. X-ray films showed that 2 cases failed bone graft fusion, the fusion time was 12-17 weeks (mean, 15.6 weeks) in the other 25 cases. Complication occurred in 2 cases of the fusion group (1 case of incision deep infection and 1 case of hematoma at iliac bone donor site) and in 1 case of the non-fusion group (fat liquefaction); primary healing of incision was obtained in the others. The Cobb angle, the height of injured vertebrae showed no significant difference between 2 groups at pre-operation, immediate after operation, and last follow-up (P > 0.05). The ROM of injured vertebrae showed no significant difference between 2 groups at 1 year after operation (before implants were removed) (P > 0.05). The implants were removed at 1 year after operation in all cases of the non-fusion group, and in 11 cases of the fusion group. At last follow-up, the ROM of injured vertebrae in the non-fusion group was significantly higher than that in the fusion group (P < 0.05), but no significant difference was found in Greenough low-back outcome score, VAS score, and ASIA grade between 2 groups (P > 0.05). ConclusionFusion is not necessary when thoracolumbar burst fracture is treated by posterior short segmental pedicle screw fixation, which can preserve regional segmental motion, shorten the operative time, decrease blood loss, and eliminate bone graft donor site complications.
Objective To discuss the improved method and effectiveness of posterior pedicle-screw fixation combined with restoring and grafting through the injured vertebrae for treating thoracolumbar burst fracture. Methods Between March 2008 and September 2010, 21 patients with thoracolumbar burst fracture were treated by posterior pedicle-screw fixationcombined with restoring and grafting through the injured vertebrae. Of 21 cases, 15 were male and 6 were female with an age range of 20-61 years (mean, 38.4 years). Affected segments included T12 in 5 cases, L1 in 7 cases, L2 in 5 cases, and T12-L1 in 4 cases. According to Frankel classification for neurological function, 2 cases were rated as grade A, 4 cases as grade B, 6 cases as grade C, 5 cases as grade D, and 4 cases as grade E; based on Denis classification, all 21 cases were burst fractures, including 7 cases of type A, 11 cases of type B, and 3 cases of type C. The X-ray film was taken to measure the relative height of fractured vertebrae and Cobb’s angle, and the function of the spinal cord was evaluated at preoperation, postoperation, and last followup. Results All the incisions healed primarily. The 21 patients were followed up 12-30 months (mean, 26 months). No loosening or breakage of screws and rods occurred. X-ray films showed good bone heal ing with the heal ing time from 12 to 23 months (mean, 16 months). The Cobb’s angles at 1 week and 1 year postoperatively were (3.4 ± 2.4)° and (5.2 ± 3.2)° respectively, showing significant differences when compared with preoperative angle (22.1 ± 1.2)° (P lt; 0.05), while no significant difference between 1 week and 1 year after operation (P gt; 0.05). The anterior height of injured vertebrae recovered from (14.6 ± 2.1) mm (40.2% ± 1.5% of the normal) at preoperation to (36.0 ± 2.0) mm (95.3% ± 1.3% of the normal) at 1 week, and to (35.0 ± 2.4) mm (94.4% ± 2.5% of the normal) at 1 year; significant differences were found between preoperation and postoperation (P lt; 0.05), while no significant difference between 1 week and 1 year after operation (P gt; 0.05). At 1 year after operation, the Frankel neurological function grade was improved in varying degrees, showing significant difference when compared with preoperative grade (χ2=11.140, P=0.025). Conclusion Improved method of posterior pedicle-screw fixation combined with restoring and grafting through the injured vertebrae in treatment of thoracolumbar burst fracture can reconstructthe anterior and middle column stabil ity and prevent loss of Cobb’s angle and height of vertebrae.
ObjectiveTo investigate the efficacy and safety of over-bending rod reduction and fixation technique via posterior approach in the treatment of unstable fresh thoracolumbar burst fracture.MethodsA clinical data of 27 patients with unstable fresh thoracolumbar burst fracture, who were met the inclusive criteria and admitted between January 2018 and October 2019, was retrospectively analyzed. There were 15 males and 12 females with an average age of 41.8 years (range, 26-64 years). The fractures were caused by falling from height in 14 cases, traffic accident in 8 cases, and crushing by a heavy objective in 5 cases. The interval between injury and operation was 1-7 days (mean, 3.2 days). The injured fracture was located at T10 in 1 case, T11 in 3 cases, T12 in 6 cases, L1 in 7 cases, L2 in 7 cases, and L3 in 3 cases. According to AO classification, there were 11 cases of type A3, 7 cases of type B, and 9 cases of type C. Neurological function was rated as grade A in 3 cases, grade B in 7 cases, grade C in 5 cases, and grade D in 12 cases according to the American Spinal Injury Association (ASIA) grading. All cases were treated by over-bending rod reduction and fixation technique via posterior approach, and 16 cases were combined with limited fenestration decompression. The evaluation indicators consisted of operation time, intraoperative blood loss, the compression ratio of the anterior vertebral height, the invasion rate of the injured vertebra into the spinal canal, the Cobb angle of segmental kyphosis, visual analogue scale (VAS) score, and Oswestry Disability Index (ODI).ResultsThe operation time was 67-128 minutes (mean, 81.6 minutes), and the intraoperative blood loss was 105-295 mL (mean, 210 mL). All patients were followed up 12-23 months (mean, 17.2 months). A total of 178 pedicle screws were implanted during operation, and the accuracy of the implantation was 98.9% (176/178). The compression ratios of the anterior vertebral height at the early postoperatively and last follow-up were significantly increased when compared with preoperative one (P<0.05), and the invasion rate of the injured vertebra into the spinal canal, Cobb angle, VAS score, and ODI were significantly lower than those preoperatively (P<0.05). Except that the ODI at last follow-up was significantly lower than that of the early postoperative period (P<0.05), there was no significant difference between the last follow-up and the early postoperative period for other indicators (P>0.05). At last follow-up, the neurological function was rated as grade A in 1 case, grade B in 2 cases, grade C in 4 cases, grade D in 9 cases, and grade E in 11 cases according to the ASIA grading, showing significant difference when compared with that before operation (Z=–3.446, P=0.001).ConclusionOver-bending rod reduction and fixation technique can effectively restore vertebral height, reset the invaded vertebral block, and selectively perform limited decompression and posterolateral bone grafting to ensure the completeness of intravertebral decompression and stability, which is one of the effective methods to treat unstable fresh thoracolumbar burst vertebral fracture.
ObjectiveTo evaluate the feasibility and the effectiveness of minimally invasive passage in posterior laminotomy decompression and intervertebral bone grafting combined with percutaneous pedicle screw fixation for the treatment of Denis type B thoracolumbar burst fractures. MethodsBetween January 2013 and March 2015, 53 patients with Denis type B thoracolumbar burst fractures were treated by minimally invasive passage in posterior laminotomy decompression and intervertebral bone grafting combined with percutaneous pedicle screw fixation. There were 37 males and 16 females with a mean age of 43 years (range, 16-57 years). The causes included falling injury from height in 23 cases, traffic accident injury in 15 cases, heavy pound injury in 7 cases, and falling injury in 8 cases. The time between injury and operation was 7 hours to 12 days (mean, 6.7 days). The involved segments included T11 in 2 cases, T12 in 7 cases, L1 in 20 cases, L2 in 18 cases, and L3 in 6 cases; based on the neurological classification of spinal cord injury by American Spinal Injury Association (ASIA), 3 cases were rated as grade A, 5 cases as grade B, 12 cases as grade C, 24 cases as grade D, and 9 cases as grade E. The operation time, bleeding volume, and postoperative drainage were recorded; postoperative visual analogue scale (VAS) was used for pain evaluation, and ASIA for neurological function assessment; CT and X-ray films were taken to observe fracture healing, bone fusion, and grafted bone absorption; The vertebral canal patency rate was calculated; the relative height of fractured vertebrae and Cobb angle were measured. ResultsThe operation was successfully completed in all patients; the average operation time was 150 minutes (range, 90-240 minutes); the average bleeding volume was 350 mL (range, 50-500 mL); the average postoperative drainage was 80 mL (range, 20-150 mL); and the average VAS score was 2.3 (range, 1.5-4.7) at 3 days after operation. The incisions healed primarily. All the patients were followed up 12-19 months (mean, 15 months). All fractures healed at 3-9 months (mean, 6 months). No complications of broken nails, broken rod, and screw loosening occurred. At last follow-up, the vertebral canal patency rate was significantly improved when compared with preoperative value (t=27.395, P=0.000). The Cobb angle, and the anterior and posterior heights of of traumatic vertebra were significantly improved at 1 week, 1 year, and last follow-up when compared with preoperative ones (P < 0.05), but there was no significant difference between different time points after operation (P > 0.05). The neurological function was improved in different degrees; 1 case was rated as grade A, 4 cases as grade B, 7 cases as grade C, 15 cases as grade D, and 26 cases as grade E, showing significant difference when compared with preoperative one (Z=-5.477, P=0.000). ConclusionMinimally invasive passage in posterior laminotomy decompression, bone graft in the injured vertebrae combined with percutaneous pedicle screw fixation is an effective method to treat Denis type B thoracolumbar burst fractures, which not only can fully decompression, but also can effectively maintain the postoperative injured vertebral height, reduce the postoperative failure risk of internal fixation and decrease operation trauma.