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Objective:To investigate the related factors of vertebral body height reloss after pedicle screw fixation of thoracolumbar fracture and to determe the optimum prediction point.Methods:A retrospective case control study was made on 215 patients with thoracolumbar fracture admitted to Second Affiliated Hospital of Soochow University from January 2010 to December 2017. There were 155 males and 60 females，aged 21-80 years［（48.6±10.4）years］. According to Denis fracture classification，there were 73 patients with compression fractures（type A in 15 patients，type B in 51，type C in 7），135 burst fractures（type A in 28 patients，type B in 87，type C in 20）and flexion distraction fractures（type A in 4，type B in 2，type C in 1）. All patients were treated by pedicle screw fixation. Follow-up lasted for 12- 48 months［（23.8±8.2）months］. Vertebral body height loss occurred in 86 patients（loss group），but did not in 129 patients（non-loss group）. The two groups were compared concerning sex，age，osteoporosis self-assessment tool for Asians（OSTA），body mass index（BMI），fracture types，number of fractured vertebrae，preoperative sagittal Cobb angle，preoperative degree of vertebral compression，number of screws placed in injured vertebrae，extent of vertebral reset and other related factors. Univariate analysis was used to identify the correlation of those factors with vertebral body height reloss. Multivariate Logistic regression analysis was performed to identify the independent factors for the height reloss with the receiver operating characteristic curve（ROC）and area under the curve（AUC）calculated to evaluate the optimum point in prediction of vertebral height reloss.Results:The two groups showed no significant differences in sex，age，BMI，fracture types，number of injured vertebrae，preoperative sagittal Cobb angle and number of screws placed in injured vertebrae（ P>0.05），but the differences were statistically significant in OSTA，preoperative degree of vertebral compression and extent of vertebral reset（ P<0.05）. According to the univariate analysis，OSTA，preoperative degree of vertebral compression and extent of vertebral reset were significantly correlated with the occurrence of vertebral body height reloss（ P<0.05）. According to the multivariate Logistic regression，OSTA（ OR=1.109，95% CI 0.527-0.685， P<0.05）and preoperative degree of vertebral compression（ OR =0.038，95% CI 0.539-0.689， P<0.05）were significantly related to vertebral body height reloss. The AUC relating OSTA and preoperative degree of vertebral compression to vertebral body height reloss was 0.604 and 0.614，respectively. The optimum prediction point of OSTA and preoperative degree of vertebral compression for vertebral body height reloss was 1.9 and 31.3%，respectively. Conclusions:OSTA and the preoperative degree of vertebral compression are independent risk factors for vertebral body height reloss. OSTA≤1.9 or preoperative degree of vertebral compression ≥31.3% indicates a significantly higher risk of postoperative vertebral body height reloss.
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Objective To observe the three-dimensional structure changes of subchondral bone in early stage knee joint instability and the effect of diphosphonate intervention so as to test the role of early three-dimensional structure changes of subchondral bone in pathogenesis of osteoarthritis (OA).Methods Sixty healthy male New Zealand white rabbits were assigned to model group (n =24),diphosphonate group (n=24) and control group (n =12) according to random number table.Rabbit right knee destabilization (anterior cruciate ligament transection) is used to induce OA.Rabbits in diphosphonate group received subcutaneous injection of 0.01 mg/kg diphosphonate (risedronate) per day.Instead,isotonic saline solution of the same volume was subcutaneously given to rabbits in model and control groups.One third of the animals in each group were killed at week 4,8 and 12 respectively.Surgical knee joint with preservation of each 2 cm bone above and below joint surface was dissected to perform Micro-CT.Bone volume fraction (BVF),trabecular thickness (Tb.Th),trabecular spacing (Tb.Sp),trabecular number (Tb.N),volumetric bone mineral density (vBMD) and tissue BMD (tBMD) were measured and analyzed statistically.Results At week 4 following operation,BVF,Tb.N and Tb.Th were lowered significantly in model group as compared to control group (P ＜0.01) ;BVF was lower in model group than in diphosphonate group (P ＜ 0.05) and lower in diphosphonate group than in control group (P ＜ 0.05) ; Tb.Sp was increased in model group as compared to diphosphonate group and control group (P ＜0.01) and had obvious increase in diphosphonate group as compared to control group (P ＜0.01) ; vBMD was significantly lower in model group than in diphosphonate group and control group (P ＜ 0.05),but there was no statistical difference between diphosphonate group and control group.At week 12 following operation,model group presented higher BVF,Tb.Th and Tb.N (P ＜0.05),significantly lower Tb.Sp (P ＜ 0.05) and significantly higher vBMD (P ＜ 0.01) as compared to diphosphonate group and control group.Conclusions In knee joint instability,variations of subchondral bone are mainly characterized by osteoclasia in the early stage,followed by osteogenesis in later stage.Diphosphonate may improve the bone architecture of subcondral bone via inhibition of bone resorption.
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Objective To observe the biomechanical changes of subchondral bone in the early stage of knee joint instability and effect of diphosphonate therapy so as to investigate the role of the early biomechanical changes of subchondral bone in the onset and development of osteoarthritis (OA).Methods Sixty healthy male New Zealand white rabbits were assigned to model group (n =24),diphosphonate group (n =24) and control group (n =12) according to random number table.Joint destabilization by anterior cruciate ligament transection of the right knee of the rabbits was performed to induce OA models.Rabbits in diphosphonate group received subcutaneous injection of 0.01 mg/kg diphosphonate (risedronate) per day,and isotonic saline solution of the same volume was subcutaneously given to rabbits in model and control groups.Half the animals in each group were killed by aeroembolism at postoperative 4 weeks and 12 weeks respectively.Surgical knee joint with preservation of each 2 cm bone above and below joint surface was dissected to perform gross scoring.Thereafter,two-dimensional image profile was achieved by Micro-CT examination and converted into Ansys for limit element analysis after fitting in Mimics software.Results At four weeks,bone volume fraction (BVF),elastic modulus (EM),reaction force (RF),and mean Von Mises stress were all declined in three groups,the lowest level in the model group (P ＜ 0.01).The diphosphonate group also had lower levels than the control group,with insignificant difference.Bone mineral density (BMD) in the model group was obviously declined in contrast with the diphosphonate and control groups (P ＜ 0.01),but there were no significant difference between the diphosphonate group and the control group.At 12 weeks,the model group showed higher level of BVF and BMD,but lower level of EM,RF and Von Mises stress in comparison with the control and diphosphonate groups (P ＜ 0.01).EM,RF,and Von Mises stress were lower in the diphosphonate group than those in the control group as well,but the difference was statistically insignificant.The model group showed that BVF,BMD,EM,RF,and Von Mises stress at 12 weeks were improved from those at 4 weeks (P ＜ 0.01).Conclusions Biomechanical properties of subchondral bone are affected in the early stage of knee joint instability and a notable decrease of EM is observed in the early stage,followed by an enhancement in late stage.It means that the biomechanical changes of subchondra,l bone in the early stage of knee joint instability may be connected with the bone resorption resulting from abnormal stress.On the contrary,diphosphonate may markedly improve EM of subchondral bone through inhibiting bone resorption.
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Objective To discuss the operation skills and clinical effects of C-arm fluoroscopy in arthroscopic reconstruction of anterior cruciate ligament(ACL)with the Ligament Advancement Reinforcement System(LARS)artificial ligaments.Methods The study involved 36 patients with acute ACL rupture treated with the LARS artificial ligaments from June 2006.There were 25 males and 11 females,at age range of 22-51 years(average 28.3 years),involving 19 left knees and 17 right knees.The results of preoperative MRI of all patients suggested discontinuation of ACL,with average score of Lysholm on knee joint for 50.The operation was completed under arthroscope.While the locations of the femoral tunnel portal and the tibial tunnel exit were mainly determined by the C-arm fluoroscopy.The diameter of the LARS artificial ligament was 7.5 mm while that of the interference screw 8 mm.Results All 36 patients were followed up for a mean duration of 18 months(9-20 months).The average Lysholm Score was 52 preoperatively and 92 at the 12th week after operation.The clinical results were graded as excellent in 23 patients,good in nine and fair in four according to the Lysholm's classification,with excellence rate of 89%.Conclusions Arthroscopic reconstruction of anterior cruciate ligament with LARS artifical ligament under C-arm fluoroscopy takes advantages of convenient operation,accurate location and satisfactory clinical effect.
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Objective To specify the diagnostic accuracy of low-field MRI on meniscal tears. Methods Meniscal lesions were examined by using 0.2 T MRI and checked arthroscopically in 171 cases. The results were recorded and compared. Results From the calculation of the arthroscopic findings and the results by MRI, we obtained the diagnostic accuracy rate of 95.91% for both the medial and lateral menisci, sensitivity of 95.60% for the medial menisci and 96.47% for the lateral menisci, and specificity of 96.25% for the medial menisci and 95.35% for the lateral menisci. Conclusions The low-field MRI can bring about high diagnostic accuracy for meniscal tears and has a good price-performance ratio.