ABSTRACT
OBJECTIVE@#To compare accuracy of anterior cervical pedicle screws between assist of rapid prototyping 3D guide plate and free-hand insertion, and evaluate the safety of two methods.@*METHODS@#Eight adult cervical cadaver specimens after formaldehyde immersion, including 4 males and 4 females, aged 32 to 65(40.3±5.6) years old. After X-ray examination to exclude bone damage and deformity, 4 of them (3D guide plate group) randomly selected were for CT scan to obtain DICOM format data, and the data was imported into Mimics software for model, designed the ideal entry point and nail path for anterior cervicaltranspedicular screw (ATPS). After obtaining the personalized guide plate of the nail channel, it was exported as STL data, and the individual guide plate was printed by rapid prototyping and 3D printing technology. In turn, with the assistance of 3D guide plates, one-to-one personalized ATPS screws were placed on the four lower cervical cadaver specimens. Another 4 (free-hand group) lower cervical cadaver specimens were implanted with ATPS screws using free-hand technique. All specimens were performed CT thin-layer scanning and three-dimensional reconstruction after operation. The Tomasino method was used to evaluate the safety of the screws on the CT cross-sectional and sagittal images, to determine whether there was a cortical puncture of the lower and inner edges of the pedicle. According to the CT rating results, gradeⅠandⅡwere safe, and grade Ⅲ- Ⅴ were dangerous.And the accuracy of screws was recorded and analyzed between two groups.@*RESULTS@#Two screws were inserted in each segment from C@*CONCLUSION@#The 3D printing rapid prototyping guide plate assisted insertion of the anterior cervical pedicle screw can significantly improve the accuracy and safety, and provide a theoretical basis for further clinical application.
Subject(s)
Adult , Aged , Female , Humans , Male , Middle Aged , Bone Plates , Cervical Vertebrae/surgery , Cross-Sectional Studies , Pedicle Screws , Printing, Three-DimensionalABSTRACT
<p><b>OBJECTIVE</b>To measure the correlative parameters of vertebral pedicles from L₁ to S₁ by CT scan in the patients with thoracolumbar kyphosis secondary to ankylosing spondylitis(AS) and disc degenerative disease(DDD), and analyze their anatomical difference in order to provide the selection and placement of pedicle screw during operation.</p><p><b>METHODS</b>The clinical data of 30 male AS patients (AS group) with the mean age of(35.7±9.5) years (ranged, 23 to 51) and 30 male DDD patients (DDD group) with the mean age of(52.4±8.9) years(ranged, 39 to 64) underwent surgery in our institution from March 2012 to November 2014 were analyzed. The CT scans of lumbar and sacrum were performed before surgery. The parameters of vertebral pedicle from L₁ to S₁ were measured and compared, including pedicle width (PW), pedicle screw path length (PL), pedicle height (PH), pedicle transverse angle (EA), and pedicle inclined angle (FA). Paired sample t-test was used to detect the divergence in the above-mentioned data between left and right sides. In addition, results between two groups were compared using independent sample t-test.</p><p><b>RESULTS</b>The study showed that a gradual increase in the average pedicle width both AS group and DDD group from L₁ to S₁. The average PW of AS group was bigger than DDD group in L₅ and S₁(<0.05), it was(16.47±2.66) mm and (21.76±2.97)mm vs. (14.51±2.11)mm and (18.87±2.14) mm respectively;the average PL of DDD group was smaller than AS group from L₁ to S₁(<0.05); the both maximum of PL were in L₃ segment; the average EA of AS group was smaller than DDD group from L₁ to S₁; the average FA of AS group was significantly smaller than DDD group from L₃ to S₁, (<0.05), was(-2.88±10.24)°, (-7.88±10.22)°, (-7.70±10.40)°, (-5.15±10.25)° vs. (4.05±2.21)°, (7.79±4.38)°, (7.07±3.21)°, (12.62±3.21)°, respectively.</p><p><b>CONCLUSIONS</b>Increasing the strength of internal fixation is feasible to insert the larger and bigger pedicle screws in low lumbar and S₁ among AS patients, while the EA should be decreased properly and the direction on the sagittal plane should be adjusted.</p>