Objective: To investigate appropriate ways for screw placement of pedicle of vertebral arch in the horizontal plane. Methods: Fifteen preserved thoracolumbar spine specimens (T 11 L 5) were used and divided into three...Objective: To investigate appropriate ways for screw placement of pedicle of vertebral arch in the horizontal plane. Methods: Fifteen preserved thoracolumbar spine specimens (T 11 L 5) were used and divided into three groups at random. Firstly four anatomic parameters indicating screw positions in the horizontal plane were measured. Secondly the methods of Roy camille, Magerl, and authors’segmental differences were used to place successively the screws of the pedicles with 5 mm, 6 mm, and 7 mm in diameter. Coincidences between the drilling point, drilling direction and pedicle axis, and ruptures of the pedicle as well as the length of the screw in the vertebral body were observed. Results: Four anatomic parameters at various segments showed significant differences (P < 0.05 ). The drilling point by the Roy camille’s method deviated medial to pedicle axis in most segments, and its drilling direction did not coincide well with most E angles of the pedicles. The drilling point by Magerl’s method coincided relatively well with pedicle axis in lumbar vertebrae, but there were still some differences between its drilling direction and E angles of the pedicles. The method of segmental differences coincided the best with the pedicle axis. The lengths of screw in the vertebra were relatively long by both Magerl and segmental difference methods. When 5 mm diametral screw was used by the three methods, the rupture rate was very low. When 6 mm and 7 mm diametral screws were placed, the rupture rate was accordingly increased. Of the three methods, Roy camilles method showed a relatively high rupture rate, while the method of segmental differences a comparatively low rupture rate. Various degrees of rupture of the pedicle of vertebral arch were found at the juncture of the thoracic and lumbar vertebrae when 6 mm or 7 mm diametral screws was used by any screw placement method. In contrast, the rupture was seldom seen at the lower lumbar vertebrae when 7 mm diametral screws were used.Conclusions: The segmental difference method is proved to have the anatomic safety and screw biomechanical stability. It is appropriate to choose different diametral screws, different drilling points and directions according to different segments of the vertebra.展开更多
Objective： To investigate the efficacy of the locking internal fixator （LIF）, which includes the locking compression plate （LCP） and the less invasive stable system （LISS）, in the proximal and distal tibial fra...Objective： To investigate the efficacy of the locking internal fixator （LIF）, which includes the locking compression plate （LCP） and the less invasive stable system （LISS）, in the proximal and distal tibial fractures. Methods： We did a retrospective study on a total of 98 patients with either proximal or distal tibial fractures from January 2003 to January 2007, who had received the opera- tion with LIF by the minimally invasive plate osteosynthe- sis （MIPO） technique. The data consisted of 43 proximal tibial fractures （type AO41 C3） and 55 distal tibial fractures （type AO43C3）. Results： No complications were observed in all patients after operation. The mean healing time was 8.4 months （range 5-14 months）. Only two cases of delayed union oc- curred at postoperative 10 months. No infections were re- ported after the definitive surgery even in the cases of open fractures. All patients reached a full range of motion at post- operative 6 to 9 months and regained the normal functions of knee and ankle joints. Conclusion： Using LIF in MIPO technique is a reliable approach towards the proximal and distal tibial fractures that are not suitable for intramedullary nailing.展开更多
Objective: To understand the relationship between porosity, collagen fiber orientation and strength of the plated bone after rigid plate fixation and removal. Methods: Seventy two New Zealand white rabbits were used i...Objective: To understand the relationship between porosity, collagen fiber orientation and strength of the plated bone after rigid plate fixation and removal. Methods: Seventy two New Zealand white rabbits were used in this experiment. Eight animals served as control and the other sixty four were plated on their intact left tibiae with stainless steel (316L) 4 hole plates to induce early osteoporosis. The plates were removed 2 months after internal fixation in 40 plated animals, 8 of which were sacrificed immediately following plate removal and the other 32 were killed in successive groups with 8 in each group 1,2,3 and 4 months after plate removal. The remaining 24 plated animals were killed at 3,4 and 6 months after plate fixation. After sacrifice, the samples of plated bone were prepared for light microscope, quantitative histological analysis, polarized light microscope and biomechanical test. Results: The internal fixation with a rigid plate could induce the regional osteoporosis which manifested both bone loss and disorganized bone structure (loss of the orientation of the collagen fibers) leading to decreased strength of the plated bone. Although the regional osteoporosis could recover gradually after plate removal, the bone structure remained disorderly even when the bone mass returned to normal. Delayed restoration of bone structure was related to delayed restoration of bone strength. Conclusions: Besides the bone loss, the disorganized bone structure is the main cause of decrease of bone strength after rigid plate fixation and removal.展开更多
文摘Objective: To investigate appropriate ways for screw placement of pedicle of vertebral arch in the horizontal plane. Methods: Fifteen preserved thoracolumbar spine specimens (T 11 L 5) were used and divided into three groups at random. Firstly four anatomic parameters indicating screw positions in the horizontal plane were measured. Secondly the methods of Roy camille, Magerl, and authors’segmental differences were used to place successively the screws of the pedicles with 5 mm, 6 mm, and 7 mm in diameter. Coincidences between the drilling point, drilling direction and pedicle axis, and ruptures of the pedicle as well as the length of the screw in the vertebral body were observed. Results: Four anatomic parameters at various segments showed significant differences (P < 0.05 ). The drilling point by the Roy camille’s method deviated medial to pedicle axis in most segments, and its drilling direction did not coincide well with most E angles of the pedicles. The drilling point by Magerl’s method coincided relatively well with pedicle axis in lumbar vertebrae, but there were still some differences between its drilling direction and E angles of the pedicles. The method of segmental differences coincided the best with the pedicle axis. The lengths of screw in the vertebra were relatively long by both Magerl and segmental difference methods. When 5 mm diametral screw was used by the three methods, the rupture rate was very low. When 6 mm and 7 mm diametral screws were placed, the rupture rate was accordingly increased. Of the three methods, Roy camilles method showed a relatively high rupture rate, while the method of segmental differences a comparatively low rupture rate. Various degrees of rupture of the pedicle of vertebral arch were found at the juncture of the thoracic and lumbar vertebrae when 6 mm or 7 mm diametral screws was used by any screw placement method. In contrast, the rupture was seldom seen at the lower lumbar vertebrae when 7 mm diametral screws were used.Conclusions: The segmental difference method is proved to have the anatomic safety and screw biomechanical stability. It is appropriate to choose different diametral screws, different drilling points and directions according to different segments of the vertebra.
文摘Objective： To investigate the efficacy of the locking internal fixator （LIF）, which includes the locking compression plate （LCP） and the less invasive stable system （LISS）, in the proximal and distal tibial fractures. Methods： We did a retrospective study on a total of 98 patients with either proximal or distal tibial fractures from January 2003 to January 2007, who had received the opera- tion with LIF by the minimally invasive plate osteosynthe- sis （MIPO） technique. The data consisted of 43 proximal tibial fractures （type AO41 C3） and 55 distal tibial fractures （type AO43C3）. Results： No complications were observed in all patients after operation. The mean healing time was 8.4 months （range 5-14 months）. Only two cases of delayed union oc- curred at postoperative 10 months. No infections were re- ported after the definitive surgery even in the cases of open fractures. All patients reached a full range of motion at post- operative 6 to 9 months and regained the normal functions of knee and ankle joints. Conclusion： Using LIF in MIPO technique is a reliable approach towards the proximal and distal tibial fractures that are not suitable for intramedullary nailing.
文摘Objective: To understand the relationship between porosity, collagen fiber orientation and strength of the plated bone after rigid plate fixation and removal. Methods: Seventy two New Zealand white rabbits were used in this experiment. Eight animals served as control and the other sixty four were plated on their intact left tibiae with stainless steel (316L) 4 hole plates to induce early osteoporosis. The plates were removed 2 months after internal fixation in 40 plated animals, 8 of which were sacrificed immediately following plate removal and the other 32 were killed in successive groups with 8 in each group 1,2,3 and 4 months after plate removal. The remaining 24 plated animals were killed at 3,4 and 6 months after plate fixation. After sacrifice, the samples of plated bone were prepared for light microscope, quantitative histological analysis, polarized light microscope and biomechanical test. Results: The internal fixation with a rigid plate could induce the regional osteoporosis which manifested both bone loss and disorganized bone structure (loss of the orientation of the collagen fibers) leading to decreased strength of the plated bone. Although the regional osteoporosis could recover gradually after plate removal, the bone structure remained disorderly even when the bone mass returned to normal. Delayed restoration of bone structure was related to delayed restoration of bone strength. Conclusions: Besides the bone loss, the disorganized bone structure is the main cause of decrease of bone strength after rigid plate fixation and removal.
