Pulmonary failure is the leading cause of death in adults with OI, and it is closely associated with thoracic scoliosis. Widmann et al. [19] found a high negative correlation between pulmonary function and thoracic scoliosis and but not with chest wall deformity or kyphosis. They also found diminution in vital capacity below 50% in thoracic curve of 60° or more.

Spinal deformity in OI is directly related to the severity of osseous involvement [20–22], though body weight is also a factor in bone density [23]. Anissipour et al. [20] recently evaluated progression of scoliosis in a large cohort of patients with various types of OI and found the most rapid progression in the more severe type III. While ligamentous laxity, also from type I collagen deficiency, may also contribute, a series of patients with various types of OI found less scoliosis in those with ligamentous laxity [21]. There is a tendency for later development of scoliosis in those with early development of motor milestones, particularly supported sitting [21]. Overall, the worse the osseous involvement in terms of intrinsic vertebral body deformity and decreased Z-scores for bone density, the worse the scoliosis and the more difficultly achieving good fixation for correction [22, 23]. The morphology of the vertebral bodies ranges from normal contours to flattened, wedged, and biconcave with the biconcave vertebra more likely to develop severe scoliosis [23–25]. Six or more biconcave vertebra before puberty appears prognostic of developing scoliosis of greater than 50° [23]. The spine may also become kyphotic particularly [26] in those with more severe involvement [27]. Cervical fractures [28] including spontaneous paraplegia from chiropractic manipulation [29], thoracic fractures with spinal cord injury [30], and multiple flexion stress endplate fractures of the thoracic and lumbar spine [31] have been reported. Daivajna et al. [32] reported a modified anterolateral approach for decompression of myelopathy from severe cervical kyphosis in a 9-year-old with OI.

Bracing has been attempted for spinal deformity from OI. However, the corrective force applied through the pathological ribs only leads to further rib deformity and may contribute to worsening pulmonary function [33–35]. Current braces cannot achieve this. Patients who are not operative candidates can be fitted with custom seating for comfort and function [36, 37]. Bracing’s role in OI is primarily limited to postoperative temporary support though there is some suggestion that an orthosis can slow the progression of basilar impression [3].

Positioning patients for surgery can be very difficult and must be carefully supervised because of chest wall deformities, fragile extremities, ribs, and frequent contractures. Unpadded blood pressure cuffs can result in fractures. Surgery for these patients should typically occur in institutions accustomed to their care [38]. Fatality has been reported from intraoperative rib fractures [39]. Classically, correcting curves in severely soft bone has been difficult at best with most authors recommending stabilization rather than relying upon correction [34]. The stability of fixation depends upon both the strength of the bone and the quality of the fixation’s purchase. Polymethylmethacrylate has been used for additional fixation [33, 40, 41]. Historically, each new type of fixation has been attempted. As might be expected, the greater the purchase and the more segmental the fixation, the less stress required on any single level and the greater the correction achieved [42] (Figs. 19.1a–c and 19.2a–d). Preoperative halo gravity traction using multiple pins may be useful [43, 44] though both sixth and fourth nerve palsies have been reported in OI patients [45]. Postoperatively, there is little change from preoperative ambulatory ability or activity [34, 37, 46], though patients report less pain, fatigue, and dyspnea [47], and the improvements gained at surgery are usually maintained into adulthood [43, 47]. Spondylolysis [48] or an elongated pars with spondylolysthesis [49] can occur below a long spinal fusion. Anterior interbody fusion has been described [49], but the spondylolisthesis may not be symptomatic (Fig. 19.3).