Clinical Application Of 3D Printing In The Treatment Of Old Type Ⅱ Odontoid Fractures With Posterior Atlantoaxial Dislocation And Pedicle Screw Fixation And Fusion

Objective:To evaluate the clinical value of 3D printing in old type II odontoid fracture with posterior pedicle screw fixation and fusion of posterior atlantoaxial dislocation.Methods:From September 2013 to November 2015,a total of 19 patients with old type II odontoid fracture and with atlantoaxial dislocation were enrolled in the department of Spine Surgery,Affiliated Chenggong Hospital of Xiamen University.The patients included₁0 males and 9 females,with ages ranging from 27 to 68 years old andan average of 46.9 years old.The patients were divided into two groups（experimental group of 13 cases,the control group of 6 cases）according to whether they were given 3D printing assisted surgery.The posterior pedicle screw implantation with 3D printing navigation template was performed in the experiment group and traditional X-ray-assisted posterior atlantoaxial pedicle screw fixation was carried out in the control group.The cervical spine was scanned by computed tomography（CT）after operation to evaluate the accuracy of the surgery in the two groups.The bleeding volume,wound drainage volume and operation time were also compared between the two groups.Results:All the 19 patients underwent posterior pedicle screw fixation with Cl-2 fusion.Among all the 19 cases,13 cases underwent posterior pedicle screw fixation with C1-2 fusion guided by 3D printing navigation template and 6 cases underwent conventional posterior pedicle screw fixation with C1-2 fusion.The 19 patients were implanted 76 pedicle screws together,of which 38 atlas pedicle screws and another 38 axial pedicle screws.Satisfactory results of pedicle screw fixation were achieved by intraoperative C-arm X ray perspective in the two groups.There was no intraoperative vertebral artery or nerve root injury.Postoperative CT was reviewed and evaluated according to Richter et al.’ scriteria.The accuracy rate of 52 screws in the experimental group was almost 100%,with 51（98.1%）screws in Grade 1 andlscrews（1.9%）in Grade 2,respectively.The accuracy rate of 24 screws in the control group was 95.8%with 21 screws（87.5%）in Grade 1,2 screws（8.3%）in Grade 2 and 1 screw（4.2%）in Grade 3,respectively.There were three screws implanted into the spinal canal with the invasion ≤ 2 mm.All of other screws were located in the pedicle cortical bone.The accuracy rate of the screws was significantly different（P<0.05）between the two groups.There were also significant differences in the postoperative blood loss,operation time and postoperative wound drainage between the two groups（P<0.05）.The bleeding volume in the experimental group（116 ± 37 ml）was significantly lower than that in the control group（192 ± 69 ml,P<0.05）.The wound drainage volume in the experimental group（79 ± 32 ml）was also markedly less than that in the control group（116 ± 35 ml,P<0.05）.The operation time in the experimental group（83 ± 20 min）was significantly shorter than that in the control group（116 ± 26 min,P<0.05）.There was no iatrogenic nerve injury at the final follow-up.According to the Frankel classification,there was 0 case in grade A,0 in grade B,0 in grade C,3 in grade D and 10 in grade E,in the experimental group whereas there was 0 case in grade A,0 in grade B,0 in grade C,1 in grade D and 5 in grade E in the control group.In addition,the VAS score of was（1.0±0.9）in the experimental group and（1.1 ± 1.0）in the control group,there was no significantly different in the preoperative and postoperative VAS score（p>0.05）between the two groups..Conclusion:This study clearly demonstrated that 3D printing navigation template technique is an accurate,safe and rapid method with promising potential in the clinical treatment of old type Ⅱ odontoid fracture with atlantoaxial dislocation.