Feasibility Analysis Of Modified Pedicle Subtraction Osteotomy For Cervicothorcic Kyphosis

Objective To illustrate the feasibility of modified pedicle subtraction osteotomy(PSO)technique for the treatment of cervicothoracic kyphosis by evaluating radiographic results of healthy volunteers,and performing the technique on a patient with cervicothoracic kyphosis and animals.Methods Radiographic results: a retrospective study on radiographic data of CT three-dimensional reconstruction on healthy volunteers in our hospital from2012-2015.On the sagittal plane,we simulate osteotomy with modified PSO technique and document the angle of osteotomy?accommodating space of C7C8 nerve after osteotomy and the proportion of injury of C6T1 pedicle.Reviewing anatomical literature,we illustrate the theoretical feasibility of modified PSO technique.Animal experiments: using 50 kg Bama Mini Pigs as experimental subjects,we perform cervical osteotomy with modified PSO technique.Combining intraoperative electrophysiological monitoring results and scores on postoperative spinal cord function,we demonstrate the feasibility and safety of the technique.Clinical application: a patient with cervicothoracic kyphosis was performed exploratory surgery by using modified PSO technique.Personalized osteotomy was designed according to the chin-brow to vertical angle of the patient.Intraoperative electrophysiological monitoring helped evaluate the security of the technique.Clinical values of the technique was explored by comparing pre-operative and post-operative values of radiographicparameters and quality of life questionnaire.Results Radiographic results: a total of 100 healthy cervical CT reconstruction imaging data was included in the study.We measured that the modified PSO technique can improve the angle with 60±6.2°,and 4.7±2.1mm of C6 Inferior facet and 6.5±2.6mmof T1 superior facet need resection during the surgery.Results of simulating osteotomy show that the ratio of C7?C8 nerve compression after osteotomy is 74%,and the ratio of adjacent vertebral segment pedicle without injury after complete osteotomy is 82%.Theoretically,the feasible ratio of osteotomy is 68%.Animal experiments: 5 Bama Mini Pigs over 50 kg is included in the study.Intraoperative electrophysiological monitoring showed that the safety ratio is80%.Electrophysiological alarm has not occurred in the course of osteotomy.According to the spinal cord function score results of experimental animals,evidence of nerve injury was not found one week after surgery.Clinical application: We performed individualized modified PSO on one patient with cervicothoracic kyphosis caused by ankylosing spondylitis.Intraoperative electrophysiological monitoring shows no nerve damage.Radiographic studies suggests that the chin-brow to vertical angle of patient improved from 45°to 0°after surgery.The Cobb angle of C6 and T1 improved from +5° to-40°(kyphosis+,lordosis-).Questionnaire scores improved from 27 to 82.Conclusion Radiographic results: Radiographic measurements combined with anatomical data analysis concluded that modified PSO technique applied on C7 segment is feasible.Animal experiments: Animal experiments show that modified PSO technique applied on C7 is feasible and safe in neurological function.Electrophysiological intraoperative alarm rate is low with a significant neurological damage ratio appears to 0.Clinical application: Clinical application tentative results show that the modified PSO technique applied on C7 with cervicothoracic kyphosis is safe and effective.As an ideal technique for large angle osteotomy of vertebral,it needs more researches.