The Clinical Applied Anatomy Study Of Occipital Condyle Screw Fixation

ObjectiveInvestigate the feasibility of Chinese people’s occipital-cervical fusion surgery withOccipital condyle screw fixation, proposed the channel parameters and the specification ofChinese people occipital condyle screw.Methods1、The Anatomy observe and measurements: Obtain the occipital herbarium60cases,they were classified according to the condylar shape in accordance with the classificationcriteria of the Ozer MA’s; and then measure the occipital condyle length, occipital condylewidth, occipital condyle height and the occipital condyle inclination angle.2、The occipital condyle imaging measurement: random sample of40cases CT dataof patients. Measuring the length, width, height of the occipital condyles, and the occipitalcondyle inclination angle.3、Digital technology analog pedicle screws:6fresh human specimens, continuousline occipital CT scan data, scan data is stored directly to the DICOM3.0standard establishthe occipital condyle data file, and then take the continuous CT scan data into Mimicssoftware, surgical simulation of pedicle screws.4、Operation of analog surgery: Use twelve cases(twenty-four sides) occipitalcondyles herbarium analog occipital condyle screw ideal pedicle screw, Measure the lengthof the bone screw observe the screws with or without perforation condyle cortical bonearound, whether injury hypoglossal canal; And use six cases of fresh head and neckspecimens after red latex perfusion, than three-dimensional CT scan. measure the length ofthe occipital condyle, width, height, ideal entrance point into the nail angle and the lengthof the implanted screws. Use digital technology to simulate the pedicle screws, under the guidance of the occipital condyle screw placement in the X-ray, CT scan again after toassess the accuracy of the occipital condyle screw placement to hypoglossal canal.Results1．The observe and measurement results of occipital condyle specimen：60specimens,the oval-shaped36cases; the kidney-shaped12cases; S-type3cases;"8"-shaped twocases; the triangular3cases; round2cases,1case of two points, irregular1cases; Theaverage condylar length was20.92±4.80mm, range16.12mm~26.03mm. The averagecondylar width in the axial plane was (10.81±4.19)mm, range9.02mm~13.51mm; Theaverage condylar height in the sagittal plane was9.71±3.77mm, range6.50mm~13.53mm.The average condylar angle in the axial plane was (32.3±6.8)°,range24.1°~42.5°.2．The imaging measurement results of occipital condyle: The average condylarlength was21.55±2.48mm,range16.52mm~26.52mm. The average condylar width was(11.07±1.13)mm, range9.12mm~13.62mm. The average condylar height was9.94±1.63mm,range7.02mm~13.92mm. The average condylar angle in the axial plane was(32.58±3.83)°,range24.31mm~42.62°.3．Digital technology analog pedicle screws operation: Placement the polyaxial screwwhich diameter is3.5mm in6fresh human specimens. The condylar entry point: Themidpoint of the condyle of the rear of the inner and outer,2mm below the bottom of theskull base; The angle of screws into occipital condyle: Keep the parallel with the base ofthe skull; Tilt inward (32.23±4.23)°,range25.23°~38.54°; The screw length (21.36±3.54)mm, range17.35mm~25.63mm. All screw located in the occipital condyle, did notperforate the cortical bone, and not damage the hypoglossal canal.4．Surgical simulation result of the operation: Placement the polyaxial screw whichdiameter is3.5mm in12cases occipital condyles herbarium, we found that24occipitalcondyle screw in good position. Occipital condyle can fully accommodate the diameter of3.5mm, the length of the bone screw placement was (20.10±2.11)mm in the range of17.51mm~25.02mm, not damage the hypoglossal canal; Placement the polyaxial screw six cases of fresh head and neck specimens for cranio-cervical fusion surgery surgicalsimulation, Standards into the best angle of the nail points after implantation of a suitablelength of the screw, the three-dimensional CT scan screws are located within the bonestructure again, uninjured hypoglossal canal and vertebral artery, did not penetrate theoccipital condyle.Conclusions1．Occipital condyle screw fixation is feasible in Chinese people; because of theoccipital condyle anatomical characteristics of individual differences, recommended theoccipital condyle detailed imaging investigations and personalized surgical planning beforesurgery.2． Chinese people the condylar entry point at the midpoint of the condyle of the rearof the inner and outer,2mm below the bottom of the skull base, the base of the skull intothe angle does not exceed10°; and the angle of screws into occipital condyle is(32.58±3.83)°with the sagittal plane,range24.31°~42.62°; The length of screws implantedin the bone: screws total length was (21.55±2.48)mm, the range is16.52mm~26.52mm,and the standard of the occipital condyle screw diameter3.5mm~4.0mm, length26mm~40mm of the half threaded cortical bone screws and cancellous bone screws.