1. Rigid Fixation Improves Outcomes of Spinal Fusion for C1- C2 Instability in Children with Skeletal Dysplasias by Ilkka Helenius, Haemish Crawford, Paul D. Sponseller, Thierry Odent, Robert M. Bernstein, Anthony A. Stans, Daniel Hedequist, and Jonathan H. Phillips J Bone Joint Surg Am Volume 97(3):232-240 February 4, 2015 ©2015 by The Journal of Bone and Joint Surgery, Inc.

2. Ilkka Helenius et al. J Bone Joint Surg Am 2015;97:232-240 ©2015 by The Journal of Bone and Joint Surgery, Inc.

3. Preoperative sagittal flexion (Fig. 1-A) and extension (Fig. 1-B) MRIs show a dysmorphic dens with C1-C2 instability and canal encroachment. Ilkka Helenius et al. J Bone Joint Surg Am 2015;97:232-240 ©2015 by The Journal of Bone and Joint Surgery, Inc.

4. Four-year lateral flexion radiograph shows nonunion and cable breakage. Ilkka Helenius et al. J Bone Joint Surg Am 2015;97:232-240 ©2015 by The Journal of Bone and Joint Surgery, Inc.

5. Radiograph made two years after revision surgery showing occiput-C5 instrumentation with rib autograft and solid fusion. Ilkka Helenius et al. J Bone Joint Surg Am 2015;97:232-240 ©2015 by The Journal of Bone and Joint Surgery, Inc.

6. Ilkka Helenius et al. J Bone Joint Surg Am 2015;97:232-240 ©2015 by The Journal of Bone and Joint Surgery, Inc.

7. Preoperative sagittal flexion (Fig. 2-A) and extension (Fig. 2-B) MRIs showing os odontoideum and translational movement between C1 and C2, demonstrating C1-C2 instability. Ilkka Helenius et al. J Bone Joint Surg Am 2015;97:232-240 ©2015 by The Journal of Bone and Joint Surgery, Inc.

8. Two-year lateral follow-up radiograph showing solid fusion after C1-C2 instrumentation (Harms technique). Ilkka Helenius et al. J Bone Joint Surg Am 2015;97:232-240 ©2015 by The Journal of Bone and Joint Surgery, Inc.