Lee, Po-Chih

In this paper, a previously developed medical software using orthogonal frontal and lateral X-rays is employed to reconstruct the rib cage and thoracic volume for scoliosis patients. The thoracic volumes of ten adult scoliosis patients with different treatments during their adolescence are followed up. This study provides an evidence that thoracic volume measurement can be used to infer the pulmonary function for spine deformity patients with moderate to severe scoliosis Cobb angle. Based on the calculation of the thoracic volumes in scoliosis patients, we correlate the parameters in the pulmonary function test to the measured thoracic volume through our software. The findings show the strong correlation between total lung capacity and the thoracic volume, and a significant correlation between the vital capacity/residual volume and the thoracic volume. An interpretation of the findings, limitation, and the future application are pointed out.

In clinical settings, doctors classify pulmonary disorders into two main categories, obstructive lung disease and restrictive lung disease. The former is characterized by the airway obstruction which is associated with several disorders like chronic bronchitis, asthma, bronchiectasis, and emphysema [1]. The latter is caused by different conditions where one of the triggers is tied to the spine deformity. In general, a pulmonary function test (PFT) [2] is used to evaluate and diagnose lung function, and physicians depend on the test results to identify the disease patterns of the patients (obstructive or restrictive lung disease). In the PFT, some parameters including total lung capacity (TLC), vital capacity (VC), and residual volume (RV) can infer the lung volume and lung capacity. Other parameters, such as forced vital capacity (FVC) and forced expiratory volume in the first second (FEV1), are often employed to assess the pulmonary mechanics. Scoliosis is an abnormal lateral curvature of the spine which involves not only the curvature from side to side but also an axial rotation of the vertebrae. Restrictive lung disease often happens in scoliosis patients, especially with severe spine deformity. Spine deformity if left untreated may lead to progression of the spinal curve, respiratory complications, and the reduction of life expectancy due to the decrease in thoracic volume for lung expansion. However, the relationship between thoracic volume and pulmonary function is not broadly discussed, and anatomic abnormalities in spine deformity (ex: scoliosis, kyphosis, and osteoporosis) can affect thoracic volume. Adequate thoracic volume is needed to promote pulmonary function. Previous literature has shown that the deformity of the thoracic rib cage will have detrimental effects on the respiratory function in adolescent idiopathic scoliosis patients [3–4]. In this paper, we aim to correlate thoracic volume and the parameters in PFTs in adult scoliosis patients 25–35 years after receiving treatments during their adolescence, either with physical bracing or spinal fusion surgery.