BACKGROUND:Pedicle is the strongest bone structure for the connection between vertebrae and lamina, and the screw fixation through pedicle can provide reliable mechanical basis for the reconstruction of spinal stabilization.
OBJECTIVE:To analyzed the three-dimensional analogue measurement parameters of lumbar pedicle, in order to improve the accuracy and stability of the clinical application of pedicle screw fixation.
METHODS:The original CT data of the spine (L 1-L 5 ) related diseases patients who treated with pedicle screw were analyzed, and the three-dimensional multiplanar reconstruction imaging model was established with Mimics software. By the using of the Mimics software, the lumbar three-dimensional construction was conducted, and the screw length, diameter, transverse section angle and sagittal section angle were predicted, and then statistical y compared with the actual data of the patient postoperative.
RESULTS AND CONCLUSION:Case analysis showed that the position and the length of the screw were good without screw offset and fracture after internal fixation. There were no significant differences in the screw length, diameter, transverse section angle and sagittal section angle between the preoperative predicted parameters and the actual parameter after fixation (P>0.05), while the sagittal section angle of partial segments were smal er than the actual measure value (P<0.05). The lumbar three-dimensional reconstruction and simulation of pedicle screws placement through Mimics software can precisely guide the actual screw placement and improve the safety of pedicle screws placement.

BACKGROUND:Resection of femoral neck in the conventional total hip replacement greatly influences the equilibrium of forces jn the proximal fetour and causes disequilibrium of bone reconstruction,easily resulting in bone absorption,prosthesis loosening and dislocation.OBJECTIVE:To investigate the biocompatibility between materials and host in the total hip replacement with femoral neck preserved.DESIGN,TIME AND SETTING:A retrospective case analysis was performed in the Department of Orthopedics,the 180 Hospital of Chinese PLA between September 2000 and December 2006.PARTICIPANTS:Twenty-five patients.10 males,15 females,aged 47 years old(range 31-56 years old)were recruited for this study.Twelve patients suffered from femoral head necrosis-caused hip joint disease and osteoarthrosis(bilaterally affected in 5 patients),eight femoral head necrosis(femoral head necrosis subsequent to femoral neck fracture healing in 2 patients),three acetabular dysplasia necrosis of femoral head,and two infra-head femoral neck fracture nonunion.The course of disease averaged 6 years old ranging from 2-10 years.METHODS:Modified hip ioint posterior approach was used to expose the hip joint.Femoral head was resected from the femoral head-neck iuncture.Cartilago acetabularis was stripped and then artificial acetabulum was installed.Femoral proximal medullary cavity was expanded.Artificial femoral head was installed.Finally,all artificial joints were reduced.MAIN OUTCOME MEASURES:(1)Biocompatibility between prosthesis and host.(2)Function recovery of hip joint.RESULTS:All wounds were primarily healed.Patients were followed up for 0.5-6 years on average.Follow-up results demonstrated good hip joint motion and normal walking gait.X-ray showed well-positioned artificial hip joint,absence of prosthesis loosening and dislocation,as well as good femoral neck sclerotin.CONCLUSl0N:The preservation of femoral neck in total hip replacement is fit to the physiological compliance of proximal femar and prevents osteoporosis-induced prosthesis loosening and dislocation in the proximal femur.