Background:Pedicle screw instrumentation of the deformed cervical and thoracic spine is challenging to even the most experienced surgeon and associated with increased incidence of screw misplacement. Iso-C3D based navigation has been reported to improve the accuracy of pedicle screw placement, however, there are very few studies assessing its efficacy in the presence of deformity. We conducted a study to evaluate the accuracy of Iso-C3D based navigation in pedicle screw fixation in the deformed cervical and thoracic spine.Materials and Methods:We inserted 98 cervical pedicle screws (18 patients) and 242 thoracic pedicle screws (17 patients) using Iso-C3D based navigation for deformities of spine due to scoliosis, ankylosing spondylitis, post traumatic and degenerative disorders. Two independent observers determined and graded the accuracy of screw placement from postoperative computed tomography (CT) scans.Results:Postoperative CT scans of the cervical spine showed 90.8% perfectly placed screws with 7 (7%) grade I pedicle breaches, 2 (2%) grade II pedicle breaches and one anterior cortex penetration (< 2mm). Five lateral pedicle breaches violated the vertebral artery foramen and three medial pedicle breaches penetrated the spinal canal; however, no patient had any neurovascular complications. In the thoracic spine there were 92.2% perfectly placed screws with only six (2%) grade II pedicle breaches, eight (3%) grade I pedicle breaches and five screws (2%) penetrating the anterior or lateral cortex. No neuro-vascular complications were encountered.Conclusion:Iso-C3D based navigation improves the accuracy of pedicle screw placement in deformities of the cervical and thoracic spine. The low incidence of pedicle breach implies increased safety for the patient.

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A 19 year-old boy presented with Type II odontoid fracture and subsequently underwent anterior odontoid screw fixation. Odontoid process fractures account for 10%-15% of all cervical fractures. Two thirds of all odontoid process fractures are type II according to the Anderson-D'Alonso classification. Anterior odontoid screw fixation provides osteosynthesis and hence best functional and anatomical outcome. In surgical approach skin incision is usually placed at the level of C5-C6, working pathway created to reach the C2 level. During entire surgical procedure simultaneous AP and lateral image intensifiers are required to facilitate the operating surgeon. High expertise and skill is required to prevent damage to the vital structures along with good theater set up. During this procedure there is high chance of iatrogenic injury to the vital structures like carotid artery, trachea and oesophagus.