Objective To study the methods of promoting the injectability of calcium phosphate cement.Methods Evaluation methods of bone cements, injectability and methods of promoting injectability were reviewed by extensive investigating of latest literatures.Results It was very important to improve the injectability of calcium phosphate cement. Commonly used methods to evaluate the injectability included testing injectability coefficient, pushing force and injection pressure.Injectability of calcium phosphatecement were promoted by increasing liquid/solid ratio, modulating the componentof solid or liquid phase, and adding various additives.Conclusion Promoting the injectability of calcium phosphate cement is the clinical requirement.
ObjectiveTo observe vertebral three-dimensional motion characteristics of adjacent segments in patients with symptomatic L4 isthmic spondylolisthesis (IS). MethodsFourteen symptomatic L4 IS patients who underwent surgery treatment (trial group) and 15 asymptomatic volunteers without back pain and other lesions of spine (control group) were recruited. There was no significant difference in gender, age, body mass index, and bone mineral density between the two groups (P>0.05). The three-dimensional reconstruction model of lumbar spine was acquired from the thin slice CT of the lumbar spine of the subjects by combining dual-X-ray fluoroscopy imaging system with spiral CT examination. The model was matched to the double oblique X-ray fluoroscopy images captured by dual-X-ray fluoroscopy imaging system at different active positions of the lumbar spine to reproduce the three-dimensional instantaneous of lumbar spondylolisthesis at different state of motion. The motion and relative displacement of adjacent segments (L3, 4 and L5, S1) of spondylolisthesis were measured quantitatively by establishing a three-dimensional coordinate system at the geometric center of the vertebral body. The results were compared with those of the control group. ResultsWhen L3, 4 in the control group were flexed flexion-extension, left-right twisting, and left-right bending, and when L5, S1 in the control group were flexed left-right twisting and left-right bending, the activity along the main axis of motion (main axis of motion) tended to increase compared with that along the corresponding coupled axis of motion (secondary axis of motion); however, this trend disappeared in the trial group, and the main and secondary movements were disordered. Because of the coronal orientation of the facet joints of L5, S1, the degree of motion along the main axis of motion decreased during flexion and extension, but this trend disappeared in the trial group. Compared with the control group, L3, 4 in the trial group exhibited displacement instability in flexion-extension, left-right twisting, and left-right bending (P<0.05); there was no significant difference in the relative displacement of L5, S1 intervertebral bodies along x, y, and z axes between the trial group and the control group in flexion-extension, left-right twisting, and left-right bending curvature (P>0.05). ConclusionPatients with symptomatic L4 IS have disorders of primary and secondary movement patterns in adjacent segments, while IS showed significantly displacement instability in L3, 4 and significantly decreased motion in L5, S1.
ObjectiveTo investigate the effectiveness of cervical pedicle screw implantation technique under regional method.MethodsThe clinical data of 85 patients who met the selection criteria between April 2010 and May 2018 were retrospectively analyzed. There were 57 males and 28 females, aged 35-68 years, with an average of 57.6 years. Among them, there were 10 cases of ossification of posterior longitudinal ligament, 68 cases of cervical spondylosis with multilevel stenosis, 3 cases of cervical tumor, 1 case of congenital malformation, and 3 cases of cervical trauma; the lower cervical spine lesions involved C3-C7. Preoperative Frankel spinal cord injury grading: 2 cases of grade C, 51 cases of grade D, and 32 cases of grade E. Cervical pedicle screw implantation technique under regional method was performed with a total of 618 pedicle screws. Postoperative changes in neurological symptoms were observed; cervical mouth opening anteroposterior and lateral X-ray films and cervical CT examinations were performed to evaluate the pedicle screws position.ResultsThe operation time was 2.5-4.0 hours, with an average of 3.0 hours. The intraoperative blood loss was 180-550 mL, with an average of 345 mL. No intraoperative vascular or nerve injury occurred. The patients with neurological symptoms were relieved to varying degrees. There were 2 cases of superficial incision infection after operation, the wound healed after enhanced dressing change. The postoperative hospital stay was 5-14 days, with an average of 8.4 days. At discharge, Frankel neurological grading was grade D in 26 patients and grade E in 59 patients. All the patients were followed up 6-24 months, with an average of 13 months. At last follow-up, cervical X-ray films showed the good pedicle screw fixation without loosening. Cervical CT evaluated the position of pedicle screws: 523 pedicle screws (84.7%) in grade Ⅰ, 80 (12.9%) in grade Ⅱ, and 15 (2.4%) in grade Ⅲ; the accuracy rate of the screw position was 97.6%.ConclusionCervical pedicle screw implantation technique under regional method can significantly improve the success rate of screw implantation. It is easy to operate, does not destroy the bone cortex, and has stable fixation.