Improved Safety and Accuracy of Ilizarov/Orthofix Assisted Cervical Osteotomies for Patients with Ankylosing Spondylitis**

Introduction: Cervicothoracic deformities have been corrected by osteotomies as described by Urist in 1958 and Simmons in 1972.

Purpose: The purpose of this project was to develop a safer and more accurate technique for the surgical correction of these deformities.

Material and Methods: 11 patients with ankylosing spondylitis were treated surgically by osteotomy. 4 patients had combined anterior and posterior osteotomies while 7 had a posterior approach only. The osteotomy was performed with the patient in a sitting position under general anesthetic with spinal cord monitoring. After the bony resection is completed the deformity was corrected gradually using Ilizarov bars and clickers attached to the halo ring and vest in 9 patients and orthofix external fixator for the last 2. Follow up was a minimum of 2 year on the 9 Ilizarov and 1 year for the Orthofix technique.

Results: The chin-brow angle improved from 43 degrees preop to 8 degrees post op. The lateral tilt was corrected from 9 degrees on average to 2 degrees post op. Four patients had complications. One patient had a nonunion of his osteotomy and had a recurrence of his deformity requiring repeat surgery. One patient had severe C8 dysesthesias from insufficient pedicle resection at C7 and require reexploration to enlage the foraminotomy. 2 other patients had minor complications (mild transient C8 symptoms in one and excessive neck pain for 1 week in another). There were no cord injuries. Patient satisfaction was high.

Discussion: The basic osteotomy technique remains unchanged but since the correction is assisted with the distraction devices more precise alignment of the spine can be obtained while maintaining its stability. At no time during the procedure is the head not stabilized by the halo. Use of the Orthofix device permits a variation of distration moments and directions. The devices are already available for other use and do not require extensive preoperative preperation.

Conclusion: Use of external distractive devices to assist cervical osteomies for ankylosing spondylitis deformities is safe and accurate.

**The FDA has not cleared a drug and/or medical device for the use described in this presentation (i.e., the drug or medical device is being discussed in an "off label" use).