Biomechanical Analysis and Optimization of Minimally Invasive Pelvic Internal Fixation / 医用生物力学

Objective By comparing biomechanical properties of two-screw rod and three-screw rod for fixing pelvic fracture, the difference in mechanical effects of different screw rod fixation positions in pelvic minimally invasive surgery was studied.Methods The mechanical models of pelvis fixed by two-screw rod and three-screw rod were established, and biomechanical characteristics of the pelvis during standing on both legs, during single-legged standing on healthy side or affected side, as well as in sitting posture were compared and analyzed by finite element simulation, and the fixation effect of three-screw rod was verified by clinical experiments.Results Both fixation methods could restore mechanical transmission of the pelvis. But for three-screw rod fixation, the stress on both sides of the pelvis was more balanced, and the displacement of the whole body and fracture surface was also lower during single-legged standing.Conclusions The three-screw rod fixation has an excellent effect in stability, which is more beneficial for fracture recovery.

Posterior short-segmental pedicle screw fixation in treatment of 186 patients with single-level thoracolumbar burst fracture without nerologic deficit / 中国组织工程研究

BACKGROUND:There are many methods to treat thoracolumbar fractures However,it remains unclear whether a simple operation to treat a thoracolumbar burst fracture can decrease the trauma and obtain better effect to avoid the enlargement of operation.OBJECTIVE:To investigate the clinical outcome of posterior short-segmental transpedicular screw system internal fixation in treatment of single-level thoracolumbar burst fracture without nerologic deficit.METHODS:A total of 186 patients with single.level thoracolumbar burst fracture but without nerologic deficit treated in the First Affiliated Hospital of Soochow University between September 2003 and January 2008,including 152 males and 34 females,aged18 10 65 years.were treated by posterior pedicle screw The intraspinal bone fragments were treated with indirect decompression.All patients were checked with radiography and CT scan before/after operation as well as before implant removal.The correction of anterior vertebral body height and the ratio of bone fragment to cross section area of spinal canal were measured.RESULT AND CONCLUSION:Compared with normal.the anterior vertebral body height was 42%before operation,98%after operation,and 98%before implant removal The ratio of bone fragment to cross section area of spinal canal was 34%before operation,13%after operation.and 8%before implant removal.Internal posterior short-segmental transpedicular screw fixation treating single-level thoracolumbar burst fracture without nerologic deficit can obtain stability of spinal column,and it is beneficial to recovery of body height,physiologic postu ral contour and canal volumn .

Intertrochanteric fractures treated with proximal femoral nail antirotation / 中华创伤杂志

Objective To investigate the advantages, indications, operative techniques and pre-liminary curative effect of proximal femoral nail antirotation(PFNA) in surgical treatment of intertrochan-teric fractures. Methods From March 2006 to June 2007, PFNA fixation was done on 38 patients with intertrochanteric fractures including 17 males and 21 females, at an average age of 65. 4 years(35-93 years). According to AO/ASIF classification, there were 10 patients with type 31-A1 fractures, 21 with type 31-A2 and 7 with type 31-A3. All patients were reduced through longitudinal traction on the traction table, with implantation of PFNA via a mini-incision. Results The mean operation duration was 50 minutes(35-105 minutes)and mean blood loss 100 ml(50-300 ml). All patients were successful except for 1 patient with split lateral cortical bone of distal shaft of the femur during operation. All pa-fients were followed up for average 13 months(4-19 months), which showed long-team bed stay due to severe complieations in 1 patient. Function recovery in 32 and deterioration of the injured limbs in 5. Cer-ebral infarction was found 6 months after operation in 1 patient, who was able to walk under support. Pri-mary bone union was achieved in all patients, with average healing time of 9. 5 weeks. There were no complications such as infection of incisional wound, pulmonary infection, phlebothrombosis, over incision or coxa adducta, except that 2 patients had perioperative respiratory system disease. According to Harris hip rating scale system. The result was excellent in 20 patients, good in 13, common in 4 and poor in 1, with total excellence rate of 89%. Conclusions As a new technique, PFNA has advantages of litth trauma. Early get-out-of-bed exercise, few complications, rigid fixation and high bone union rate and is suitable for all kinds of intertrochanteric fractures especially for old patients with osteoporosis.