Relevance of the cranioaxial angle in the occipitocervical stabilization using an original construct: a retrospective study on 50 patients

Abstract

We present a retrospective study on a series composed of 50 patients, treated between 1992 and 2006, affected by pathologies of the craniocervical junction. All the patients were treated using an innovative procedure based on a cranial claw made up of low profile hooks, conceived by one of the authors. Advantages of this technique are, to our point of view, a higher resistance to cranial hooks dislodgment, when compared with screw fixation instrumentation, especially in pathological conditions, such as rheumatoid arthritis that leads to a qualitative deterioration of the bone stock and to the reduction of the occipital wall thickness. Occipitoaxial alignment was assessed radiographically using the McGregor line. We observed an improvement in the subjective evaluation of pain in all treated patients with a 46% improvement from the initial values. Moreover, patient stabilized with an occipitoaxial angle included in the physiological range showed better results either for the survival of the instrumentation or the onset of junctional pathology. Patients have been followed up afterwards and evaluated by the visual analogue scale for the assessment of pain and by the Nurick scale for the cases associated with myelopathy. We believe that cranial anchorage with a hook claw allows for an instrumentation provided with high stability, particularly useful in revision surgery and major instabilities. The study of the occipitoaxial angles showed that the better results and the long-lasting stability of the implant are correlated to a fusion angle included in the physiological range.

Impact of the O-C2 Angle on the Oropharyngeal Space in Normal Patients

“…We measured O-C2 angle, however, because it is much more popular to perform O-C2 fusion than O-C1 fusion, and O-C2 angle has been widely used as a landmark of O-C alignment. 1,7,8,18,19,20 In their previous study, the authors recommended that the O-C2 angle in O-C fusion should be kept at least at more than the preoperative O-C2 angle in the neutral position to prevent postoperative dysphagia and/or dyspnea. 7 Ataka et al showed that most of the OSA in RA patients with an upper cervical lesion is of an obstructive type because of a decreased O-C2 angle and subsequent oropharyngeal stenosis.…”

A retrospective study of congenital osseous anomalies at the craniocervical junction treated by occipitocervical plate-rod systems

“…The O-C2 angle indicates the angle between McGregor's line [8] and the line of the endplate of the axis (Fig. 1e, g).…”

A novel method for measurement of the occipital-cervical distance via the occiput-C4 distance

“…Conceptually, the occipitocervical neutral position is the functional and balanced position of the head atop the cervical spine. We considered that patients should [3,[8][9][10]. However, it remains unknown whether dysphagia and/or dyspnea are mostly due to mechanical airway obstruction caused by a non-normal occipitocervical angle.…”