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The principle and procedure of bi-directional evolutionary structural optimization (BESO) are stated in detail. A program based on BESO is introduced in conceptual bridge design. Topology optimizations are achieved for deck arch bridges with different rise-to-span ratios, half-through arch bridge, through tied arch bridge, bridge pier and bridge main beam. The results demonstrate rational structures with well-distributed stress and smooth force transmission, which indicates the efficient of the method.

To study the therapeutic method and effect of minimally invasive surgery for the thoracolumbar fractures.A retrospective review of the minimally invasive surgically treatment thoracolumbar fractures from February 2005 to June 2010 was performed. There were 183 cases, 126 males and 57 females, aged 18 to 68 years, average 38.9 years. The involved levels of fractures were T(11) in 22, T(12) in 61, L(1) in 71, L(2) in 29. According to Gertzbein classification, 145 cases were type A fractures, 34 cases were type B fractures, 4 cases were type C fractures; According to Load-sharing score, 51 cases were 4 scores, 56 cases were 5 scores, 17 cases were 6 scores, 12 cases were 7 scores, 24 cases were 8 scores, 23 cases were 9 scores. Different surgical methods were selected according to the minimally invasive surgical strategy, 22 patients were treated with the minimally invasive percutaneous pedicle screws osteosynthesis (MIPPSO group), 102 patients were treated with the small-incision pedicle screws osteosynthesis (SISPSO group), 31 patients were treated with the small incision anterior thoracolumbar surgery (SIATS group) assisted by thoracoscope or headlight, and 28 patients were treated with the 270° decompression and reconstruction surgery (270° DRS group) via a posterior small incision. Preoperative and postoperative neurological status, the correction and loss of Cobb's angle, the decompression scope of spinal canal, the location and union of bone graft were followed up and reviewed.All of 183 cases had successful surgery and were followed up. In the MIPPSO group, operative time was 52 - 100 min, blood loss was 35 - 55 ml. In the the SISPSO group, operative time was 48-68 min, the blood loss was 45 - 65 ml the correction of Cobb's angle in the two groups was 8° - 19°. In the SIATS group, operative time was 140 - 220 min, the blood loss was 160 - 1500 ml the correction of Cobb's angle was 15° - 25°, 1 case had pleural effusion, 1 had lateral femoral cutaneous nerve damage, the complications disappeared after treatment. In the 270° DRS group the operative time was 160-280 min, the blood loss was 700 - 4700 ml, the correction of Cobb's angle was 15° - 28°. The spinal canal mass was removed, the spinal canal was enlarged and completely decompressed. Neurological status improved in all of the preoperative incomplete paraplegia patients except 1 case whose neurological symptoms aggravated.It is satisfactory that the minimally invasive surgical strategy was rational used in the treatment of thoracolumbar fractures.

To study the morbidity factors of bilateral intertrochanteric fractures by analyzing medical records, so as to provide evidences for preventing the multiple intertrochanteric fractures.From Janurary 2000 to June 2009, 68 patients with bilateral intertrochanteric fractures were studied, including 31 males and 37 females, ranging in age from 42 to 95 years with an average age of 75 years. There were type A1 in 24 hips, type A2 in 96 hips, and type B3 in 16 hips. One hundred and twenty-eight hips had received surgical treatment, 8 hips were treated with conservative method. On the first injury, 67 patients discharged after treatment, 1 patients discharged after treatment in other department. On the second injury, 58 patients discharged after treatment, 2 patients died of complications, 8 patients dischagred after treatment in other department. The risk factors including age, cause of injury, fractures type, complications, osteoporosis and treatment were analyzed.The average age of two fractures were (73.6 +/- 9.25) and (76.7 +/- 6.74) years; the major injury cause was fall; the A2-type fractures went up to 80.88% on the secondary injury;and the proportion of complications was high, mainly geriatric cognitive disorders, hemiplegic paralysis, and dysopia. Bone mineral density measurement of 16 cases showed marked osteoporosis.Osteoporosis and fall injury contribute mostly to the multiple intertrochanteric fractures. Complication was the dominating risk factor. Treatment of osteoporosis, intensive care, postoperative rehabilitation and effective initial surgery are the key to prevent the secondary intertrochanteric fractures in old people.

To investigate the efficacy and possibly prognositic factors of anterior approach on two-level cervical spondylotic myelopathy.A retrospective review was performed on 44 cases of two-level cervical spondylotic mydopathy from Jun. 2007 to Sep. 2009. Among the patients, 24 cases were male and 20 cases female, with an average age of (60.072 +/- 10.77) years (ranged from 39 to 80 years). The affected segments ranged from C(3.4)-C(6.7). Improvements of cervical curvature and segmental height, preoperative sagittal diameter of the spinal cord at the site of maximal compression and signal intensity changes on T2WI were respectively measured. Function of nerves was assessed according to Japanese orthopaedic association system (JOA:17 score) before and after surgery. Operation by anterior approach including: anterior corpectomy and titanium cage fusion with internal fixation, anterior corpectomy body and auto iliac bone fusion with internal fixation. Statistical analysis was made on the correlation between JOA recovery rate and prognostic factors.Improvements of cervical curvature was -9.1 degrees to 16.6 degrees with the mean of (1.30 +/- 5.77) degrees and improvements of segmental height was -0.3 to 12.3 mm with the mean of (4.23 +/- 3.08) mm. Sagittal diameter of the spinal cord at the site of maximal compression was 1.6 to 7.2 mm with the mean of (4.01+/- 1.25) mm. T2WI with high signal changes was in 29 cases, no change in 15 cases. Bleeding amount was 50 to 700 ml with the mean of (242.05 +/- 148.22) ml. Operative time was 90 to 250 min with the mean of (153.75 +/- 34.54) min. All patients were followed up from 6 to 31 months with an average of (17.18 +/- 7.41) months. The mean JOA score preoperatively was (12.73 +/- 2.23); at the final follow-up, the JOA score was(15.09 +/- 1.91); and the recovery rate was (60.01 +/- 26.98)%. According to standard of JOA scoring, 16 cases obtained excellent result, 12 good, 15 fair and 1 poor. The effect of anterior approach had correlations with age, time of course, preoperative JOA score, sagittal diameter of the spinal cord at the site of maximal compression and signal intensity changes on T2WI, but had no correlations with operation time, bleeding amount and improvements of cervical curvature and segmental height.Two-level cervical spondylotic myelopathy can achieve good effect through anterior approach. The extent of the spinal cord compression may be a reliable and direct factor to judge effect.

To compare the outcome of two minimally invasive internal fixed methods for the treatment of distal tibio-fibula fractures.The clinical data of 50 patients with distal tibio-fibula fractures from March 2006 to March 2009 was analyzed retrospectively. Twenty-eight patients were treated with minimally invasive percutaneous locking compression plate fixing tibia combining elastic stable intramedullary nailing fixing fibular (Group P + E). There were 18 male and 10 female patients with a mean age of (45 ± 6) years. Twenty-two patients were treated with interlocking intramedullary nail fixing tibia combining elastic stable intramedullary nailing fixing fibular (Group N + E). There were 12 male and 10 female patients with a mean age of (43 ± 9) years. The index of peri-operation, pain score at 3 d postoperative, bone union time, the clinical outcomes and complications postoperative were statistically compared.There were no statistical significance on operation time, blood loss perioperative and pain score at 3 d postoperative. Bone union time in Group N + E was significantly longer than in Group P + E [(21.1 ± 3.0) weeks vs. (15.4 ± 2.9) weeks]. Meanwhile, the function of ankle score (44.3 ± 1.7 vs. 41.8 ± 2.5) and the line of foot score (8.6 ± 2.3 vs. 6.8 ± 3.6) in Group P + E were respectively significantly higher than that in Group N + E. However, there were no statistical difference on ankle pain, buckling add stretch restricted, turn inward add evaginate restricted and the rate of good and fair between the two groups. There were 3 cases of complications postoperation in Group P + E, significantly less than the 8 cases of Group N + E.Minimally invasive percutaneous locking compression plate fixing tibia combining elastic stable intramedullary nailing fixing fibular shows superiority in treatment of distal tibio-fibula fractures. However, interlocking intramedullary nail fixing tibia combining elastic stable intramedullary nailing fixing fibular has the advantages in worse soft tissue and multi-step tibio-fibula fractures.