34.1 Area One

We need a clear and concise method to classify and describe our patients in a manner that allows practitioners to communicate accurately. This classification system should apply to the untreated patient, but a classification is also necessary for our treatment methods. Concerning the etiology, the symptoms we can readily see are the deformities of the skeletal system, but of a more subtle nature, what is the position of the body habitus with regard to balance and gait, the ambulatory status, and the sagittal alignment, and of greatest importance, what is the impact of the deformity upon the lungs?

Many of the children with these disorders whom we treat do not follow the usual rules for normal progression through the phases of skeletal maturity; how does this aberration fit into our classification systems? The physiologic development of the respiratory tree is an important factor in the treatment of patients with early onset scoliosis because we are aware that the major part of parenchymal cell duplication occurs before the age of 8 years, so the importance of instituting a treatment method before this age becomes critical. Is there also a difference in the maturational age of the lung parenchyma in children who have a delay in their skeletal maturation? How do we place these factors into a classification system that includes DeMeglio’s caution to use the fourth dimension of respiratory capacity—namely, the expansion of the ribs that encircle the lungs and provide a cavity in which the lungs develop and prosper? ^{1 ,​ 2} The three-dimensional impact of a scoliotic deformity upon respiration is indeed complex. The spine, ribs, and lungs have been characterized by Robert Campbell as analogous to the structural components of a room where for many years spinal surgeons have focused on the corner of the room—namely, the spine—while neglecting the growth capacity of the walls (ribs) attached to the corner and the enormous importance of what happens inside the room itself (respiratory function). ³

With this in mind, if a classification system is based upon the severity of lung dysfunction, how is lung function to be measured? Pulmonary function studies in children before the age of 6 years, as we perform them now, are suspect at best. ⁴ Do computed tomographic (CT) scans of the lungs truly correlate with lung function? Does improved space lead to improved breathing? Dr. Campbell has further encouraged us to look closely at dynamic magnetic resonance images to truly understand the function of the respiratory tree and its association with spinal deformity. How is this to be calibrated? What metric should we use? This is indeed an area for further exploration because there is little understanding of how to measure respiratory function in children, especially those too young or cognitively unable to cooperate with pulmonary function studies.

Dr. Vitale and his group have made a first attempt to arrive at a consensus on the important components of a classification system. Through a process known as equipoise, in which experts, through a series of encounters over time, are able to arrive at a point of agreement upon the key essentials that best permit the description of a specific deformity, they have settled upon five components (age, etiology, size of curve, kyphosis, and progression) that fulfill this requirement with the greatest succinctness. ⁵ Whether the classification system will be adopted universally has yet to be proved. It does not include measures of curve flexibility or metrics reflecting a child’s nutrition. Neither does it describe three-dimensional deformity of the chest and torso. It does not consider, in any manner, the respiratory function of an individual. All of these components are intimately involved in and affect a child’s treatment.