History of Management of Cervical Spine Anomalies in Children

Understanding of Disease

• Evolution of understanding due to imaging: For many decades, the anatomy and pathophysiology of congenital vertebral anomalies were poorly understood. Plain x-rays and tomograms were the only imaging studies available, and these provided, at best, rudimentary information about specific disorders. The gathering of information evolved slowly. A good example of this phenomenon is seen in Klippel-Feil syndrome. After its original description in 1912 by Klippel and Feil (14), little knowledge aside from case reports was gained until Nagib et al. proposed a classification and management scheme in the 1980s (20). Further work has led to a greater understanding of this disorder on many fronts, including its underlying genetic substrates (3, 16).
• Initial treatments of fusion with external fixation: The conditions were also difficult to treat with the available technologies. Bone and wire fusions, augmented by external halo orthoses, were the mainstays of surgical treatment but had high complication rates and suboptimal outcomes. Pioneering work in this area was primarily performed by Menezes and colleagues, who wrote many seminal papers on this topic (18, 19).
• Down syndrome and atlantoaxial instability: Work in the 1990s led to the American Academy of Pediatrics position statement in 1996 that patients with an atlantodental interval of 4.5 mm or greater should be excluded from participation in Special Olympics (21). Further work led to the awareness that patients with Down syndrome and os odontoideum had a high likelihood of severe atlantoaxial instability and should undergo fusion procedures at presentation. Recent work has contributed to our understanding of the pathophysiology of occipitoatlantal instability in Down syndrome. Browd et al. described the role that the flat shape of the occipitoatlantal joint in Down syndrome patients plays in creating instability at that level (5). Only further work will uncover the true underlying causes of occipitoatlantal and atlantoaxial instability in patients with Down syndrome.

Technological Development

• Imaging: Advances in imaging have allowed physicians to gain a deeper understanding of the underlying anatomy in many heretofore untreatable conditions.  Modern imaging investigations now include a combination of high-quality plain x-rays, thin-cut CT scanning with two-dimensional and three-dimensional reconstruction, and multiplanar MRI scanning. If necessary, these imaging modalities may also be used dynamically to determine the presence and extent of spinal instability. 
• Spinal instrumentation: Advances in spinal instrumentation have allowed almost all patients with these conditions to be treated with internal fixation without external halo orthoses. Early efforts in this area consisted of primarily bone and wire techniques (18,19). In 1995, Brockmeyer et al. (4) described the first routine use of internal spinal screw fixation in managing patients with cervical spine instability. Since that time, multiple significant papers have been published on this topic (2, 9, 10).
• Agents helpful in bone fusion: Bone biologics, including osteoinductive and osteoconductive products, continue to be developed and used in the treatment of these conditions.  One example is the growth factor recombinant bone morphogenic protein, a potent osteoinductive bone substance that promotes bone healing (2, 7).

Surgical Technique

• Internal fixation of unstable spines: Advances in surgical technique and spine instrumentation over the past few years have allowed most patients to be treated with internal fixation without an external halo orthosis.  Among these advances have been improvements in initial experience (4), technical development (9), choice of instrumentation (2) and long-term results (10). As surgical experience and techniques continue to evolve, it is hoped that standardized approaches can be identified for a given disease or patho-biomechanical condition.