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STUDY DESIGN: An anatomic study evaluating the feasibility of posterior screw fixation on the lateral mass of the atlas and comparing the pullout force of C1 posterior lateral mass screws with that of occipital and C2 pedicle screws. OBJECTIVES: To study the feasibility, anatomy, and biomechanics of posterior screw fixation within the lateral mass of the atlas. SUMMARY OF BACKGROUND DATA: Occipitocervical fusion is a common choice for atlantoaxial dislocations. After that the movement of occipitocervical region will be restricted. If screws could be placed in the lateral mass of the atlas, 1) the movement of C0-C1 junction will be preserved; 2) through the screw the dislocated atlas could be pulled backward; and 3) the fractured lateral mass can be fixed using the posterior lateral mass screw directly. METHODS: Thirty atlas specimens of native adults were used to measure pertinent clinical data. Six fresh upper cervical specimens were used to observe the association of the C2 nerve and the lateral mass of the atlas. The pullout force of the C1 lateral mass was measured and compared with that of screws placed into the occiput and C2 pedicle, respectively. RESULTS: The distances from the midline to the midpoint of the C1 lateral mass, to the inner wall of the transverse foramen, and to the inner edge of the pedicle were 17.6 +/- 1.2 mm, 23.0 +/- 1.7 mm, and 14.2 +/-1.1 mm, respectively. The width and height of the C1 lateral mass were 11.6 +/- 1.4 mm and 12.7 +/- 1.0 mm, respectively. The distance between the inferior midpoint of the C1 lateral mass in the transverse plane of the midposterior arch of the atlas to the edge of the inferior atlas joint line was 4.1 +/- 0.7 mm. The width of the posterior arch at the point of vertebral artery overpass was 4.7 +/- 1.0 mm. The observation on the fresh specimens showed that the C2 nerve passes inferolateral to the C1-C2 joint and could be pulled sideways. The screw pullout force within the lateral mass of the atlas was 1818.16 +/- 422.67 N. This is significantly less than that of screws within the occiput, and there was no difference with that of a C2 pedicle screw. CONCLUSION: The width and height of the atlas lateral mass were larger than that of the C2 pedicle, and there was enough space to insert a 3.5-mm diameter screw in the atlas lateral mass over the C2 nerve. The pullout force of the screw on the lateral mass of the atlas was the same as that of the C2 pedicle screw. It is possible toinsert a 3.5-mm screw in the lateral mass of the atlas. The direction of the screw should be about 20 degrees anterosuperior in the vertical plane and 15 degrees inward in the horizontal plane. The suitable length of the screw should be approximately 22 mm inside the lateral mass.
Subject(s)
Bone Screws , Cervical Atlas , Anthropometry , Axis, Cervical Vertebra , Bone Screws/classification , Device Removal , Equipment Design , Feasibility Studies , Humans , Implants, Experimental , Materials Testing , Spinal Fusion/instrumentation , Stress, MechanicalABSTRACT
Objective To evaluate the clinical effect and application value of internal fixation of Magerl combined with Brooks technique for atlantoaxial instability. Methods A total of 18 patients with atlantoaxial instability, reducible atlantoaxial dislocation with reduction after traction and irreducible atlantoaxial dislocation with traction reduction after anterior laxation were treated with internal fixation of Magerl combined with Brooks technique using autologous bone grafts. Results The patients were followed up for an average 18 months (6-36 months). Screw was probably cut into the vertebral artery in one case. The guide needle was cut into the pharynx due to incorrectly penetrating the C 1 anterior arch of atlas for 3.5 cm in one case but no early complications such as spinal cord injury and local infection occurred. The spinal cord function improvement was marked in 3 cases, good in 9, mild in 4 but unchanged in 2. No case got worse. There were no loosening or break of the screw and cable. Conclusions Combined fixation of Magerl and Brooks techniques reaches three-point fixation and improves the reduction effect. It is necessary to use the combined fixation with best biomechanical stability for atlantoaxial dislocation patient with reduction or near reduction if the structure of the posterior arch of C 1,2 is intact.
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<p><b>OBJECTIVE</b>To study mosaicplasty a as method of autogenous osteochondral transplantation in the treatment of cartilaginous defects.</p><p><b>METHODS</b>The technique involves obtaining small cylindrical grafts from the non-weight bearing periphery of the femur at the patellar femoral joint, and transporting them to the prepared recipient site by arthroscopy.</p><p><b>RESULTS</b>Fifteen patients with defects cartilaginous received mosaicptasty osteochondral grafting. Follow up for 12 to 21 months (mean 15 months) showed good results.</p><p><b>CONCLUSION</b>The treatment is indicated for patients with focal cartilaginous defects under the age of 45.</p>
Subject(s)
Adult , Female , Humans , Male , Arthroscopy , Bone Transplantation , Methods , Cartilage, Articular , Wounds and Injuries , Transplantation , Follow-Up StudiesABSTRACT
To summarize the clinical results of combined transoral anterior decompression and posterior decompression and internal fixation of irreducible atlantoaxial dislocation with spinal cord compression. 12 cases of irreducible atlantoaxial dislocation with spinal cord compression were operated on with transoral anterior decompression combined with posterior decompression and occipitocervical internal fixation with occipitocervical CD rod or Cervifix. With an average of 20 month follow up, clinical cure rate was evaluated according to Symon and Lavender . Vertebral canal vector diameters in MR were measured. The results showed that the total clinical effective rate was 91.6%, and the remarkable effective rate was 50%. The average improvement rate of vertebral canal decompression was 73.6 %. These results suggest that transoral anterior decompression combined with posterior decompression and internal fixation is more suitable for irreducible atlantoaxial dislocation with spinal cord compression.
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Objective To explore the possibility of expending indications of VATS though auxiliary mini-incision. Methods 54 patients with thoracic injury underwent pulmonary lobectomy or pulmonary wedge resection or pulmonary rupture repair or diaphragm rupture repair using VATS combined with auxiliary mini-incition. Results All of 54 patients were cured. with primary wound healing .Hospital stay was 8d~10d with a mean of 10d.. No complication occurred. Conclusions VATS combined with auxiliary mini-incision could provide a possibility of simultaneous diagnosis and treatment and obtains as the same therapeutic result as conventional open surgery and expends indication of VATS.
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Objective A design of guide wire localization apparatus for the internal fixation of dens fractures. Methods From October 1999 to February 2000, 5 cases of dens fractures were treated by anterior internal fixation using cannulated compression screws; 4 cases were of Anderson typeⅡ and 1 case was typeⅢ . The guide wire localization apparatus was used for all of the patients during operations. Results The operating time was 2 to 2.5 hours, averaging 2 hours 15 minutes. The amount of bleeding was 20 to 100 ml, averaging 60 ml. The time of follow-up was 5 to 9 months, averaging 6.7 months. The locations of all the 5 cannulated compression screws were excellent, positioning in the center of the odontoid process without deviation. 4 cases healed normally and 1 had delayed bone healing. Conclusion The use of a guide wire location apparatus increased the accuracy of internal fixation of screws in dens fracture, decreased X-ray to radiation to the bodies, and reduced the possibility of pollution in operation.
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Objective To evaluate the clinical results of subtotal vertebrectomy of the axis for spinal canal decompression by transoral anterior approach in the treatment of atlanto-axial dislocation with spinal cord compression. Method fifteen cases of atlanto-axial dislocation with spinal cord compression caused by congenital deformity or trauma were subjected to subtotal vertebrectomy of the axis via transoral anterior approach . Results After an average follow-up of 20 months, curative effect was evaluated according to Symon and Lavender. Vertebral canal vector diameters in MRI were measured. The total clinical effective rate was 100%, and the remarkable effective rate reached 60%. The average improvement rate of vertebral canal decompression was 79.8%. No sign of spinal cord and arteries injury and infection were observed. Conclusion Subtotal vertebrectomy of the axis via transoral anterior approach is proved to be feasible to treat cervical spinal cord compression on C 2 vertebra level.
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Objective To summarize the experience of preventing infection in atlanto-axial operations via transoropharyngeal approach. Methods The methods and experiences of prevention of infection in 80 cases of atlanto-axial dislocation operated on via transoropharyngeal approach were retrospectively summarized and analyzed. Result There was no infection in all the 80 cases. Conclusion As long as preventive measures were perfectly taken, the post-operative infection could be effectively prevented and the transoropharyngeal operation would be safe.
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53cases of patients were treated a variety of internal fixation apparatuses, including the occipito-cervical CD (OCCD), the Cervifix, Apofix, Orion or AO cervical plates and screws, and were followed-up for 6 to 23 months (average 12 months). Good osteal fusion was obtained in 52 cases of patients after the internal fixation. Absorption of grafted bone was observed in one patient who had the atla-axis fusion with the Apofix fixation. Secondary operation of decompression was done in one patient who had the occipito-cervical fusion with the fixation of OCCD without removal of the postenor arch of the atlas. According to the JOA criterion for spinal function, the improvement rates were 14.3% to 100% (average 80%).
