Endoscopic anterior transcervical approach for Atlanta-axial dislocation скачать в хорошем качестве

Endoscopic anterior transcervical approach for Atlanta-axial dislocation

Pearls Endoscopic Trans-cervical approach for cranio-vertebral junction • Trans-cervical approach is especially useful for anomalies difficult to completely reduce from posterior approach when C2-C3 disc space is at or below angle of mandible • Especially useful when there is difficulty in reduction of AAD with tissue in between C1 arch and odontoid, fused C1-C2 joints, contracted tissue anterior to C1 and C2, mal-union with fibrosis or callous, injury to facet which precludes facet manipulation, oblique C1-C2 joint, and severe anterior posterior or cranial dislocation • Identify and mark 3 structures in the beginning of the procedure: A; The midline of Anterior arch of C1, B; Midline of lower part of C2 vertebral body, C; Bilateral C1- C2 facet joint. • Realignment of C1-C2 is tried by inserting a curve curette or osteotome into the atlantoaxial joint and using it as a lever-arm under fluoroscopic guidance. Bilateral C1-C2 lateral mass fixation is achieved if the dislocation is corrected. Odontoidectomy and C2 corpectomy with C1-C2 fusion done if not reduced. • Put first screw in C2 lateral mass and then in C1 lateral mass, whereas final tightening of C1 screw should be done before C2 for reduction. • This technique allows bi- cortical purchase with longer screw 18-24 mm at C2 and 16-20 at C1 which is better than mono-cortical purchase and prevents screw pull out. • Both decompression including excision of odontoid and C2 body and fusion can be done in single approach. • Avoids contaminated corridor • There is less bleeding, and minimal tissue dissection compared to posterior approach. • Approach preserves posterior tension band, and the risk of vertebral artery injury is less. • It permits better patient positioning in supine with neck extension, compared to prone position with some neck flexion in posterior approach which can damage cord. • Large mandible or mandible angle lying at or below C2-C3 disc level even after extension of neck is a limitation, posterior compression in Chiari Malformation and involvement of facet joints by trauma or other disease are other limitations of the approach.