Clinical Application Of Computer-assisted Navigation System

Part I Empirical study of computer-assisted navigation systemInfluence of different registration mode to accuracy and registration-time of computer-assisted navigation systemObjective:To investigate influence of accuracy and registration-time of different registration style in operation of computer-assisted navigation system.Methods:We used cervical vertebra of fresh calf, randomized to point-registration group and surface registration group by reconstructing three-dimensional image of cervical vertebra of calf. PA (Predicted Accuracy) and registration-time were evaluated.The PA was direct displayed by navigation system.The registration-time was the time from beginning of registration to getting a satisfactedaccuracy.Results:①Among computer-assisted navigation surgery,registration-time of point-registration was292±45s,registration-time of surface-registration was245±32s,which have no difference between two groups (p>0.05).②Among computer-assisted navigation surgery,predicted accuracy (PA)of point-registration was1.1±0.23mm,and PA of surface-registration was0.8±0.11mm. Difference between two groups have statistically significant (P=0.031)Conclusion:①In the operation of computer-assisted navigation system, different registration style make the difference in the accuracy and registration-time.②Registration-time of point-registration and surface-registration have no difference, but surface-registration can improve accuracy in navigation operation. Part II Clinical application of computer-assisted navigation system-Pedicle Screw fixation of spine assisted by CT-based navigation systemObjective:To investigate security and accuracy in pedicle screw fixation of spine assisted by CT-based navigation system.Methods:24patients with thoracic vertebra fracture and29patients with isthmic spondylolisthesis were treated by posterior pedicle screws and randomized to CT-based navigation group and control group.The accuracy of pedicle screws insertion postoperatively CT scan were analyzed.The registration-time of both series and X-ray exposure time was compared.Results:Of the102screws inserted by CT-based navigation system,99were I grade(97.1%);3were II grade;0was III grade.Of the98screws inserted by X-ray fluoroscopy,88were I grade (89.8%);8were II grade;2was III grade.One patient of III grade had the pain of refractoriness chest-back. Neural damage were not demonstrated in the study. The difference was statistically significant(P<0.05).A11the thoracic pedicle screws were provided from USS serial products of AO company.The pedicle screw position was graded post-operatively with CT scanning into two groups and the accuracy of screw placemen with the use of navigation was superior to without (P=0.038<0.05). From2006October to2008May, computer-assisted image-guided spine surgery has shorter mean operative times (79.04±13.74minutes) when compared with conventional pedicle screw insertion technique(85.93±12.86minutes); but missed being statistically significant (P=0.0503).But from2007April, the mean operative times were72.95±10.70minutes and87.14±11.23minutes respectively, the difference was statistically significant(P=0.00). Computer-assisted spine navigation has overall demonstrated shorter mean radioactive ray exposure time when compared with conventional technique; an average of6.6seconds less per case (P=0.000.)Conclusion:①Computer-assisted navigation system can increase accuracy of thoracic pedicle screw fixation obviously.②Computer-assisted navigation system obviously decurtate the operation time and exposure time of X-ray.③This study confirm that computer-assisted navigation system is a useful technique and deserved to be spreaded. PartⅢClinical application of computer-assisted navigation system-Total knee arthroplasty assisted by CT-based navigation systemObjective:To investigate accuracy of prothesis in total knee arthroplasty assisted by CT-based navigation system.Methods:32cases(36joints) of TKA were perform utilizing CT-based navigation system. From January of2006to December of2006,10cases (12joints) of TKA were performed with conventional method. The differences between two groups in clinical results and blood loss and operating time and mechanical axes were statistically analyzed.Results:There were significant differences(P<0.05) in parameters about the surgery time and the blood loss and HSS at postoperative3months between control group and navigation assisted group; Radiographic examination between these two groups:the MFTA and STCA of control groups and navigation assisted group with significant difference.Conclusion:①Computer-assisted navigation system in TKA can obtain reliable clinical results with better mechanical axes.②Computer-assisted navigation system in TKA can decrease blood loss,it is a safe and reliable procedure in TKA.