A simple approach to standardized spinal radiographs

Present methods of obtaining spine radiographs for the clinical assessment of scoliosis are inadequate. Routine quantitative measurements made on anterior-posterior (A-P) and lateral radiographs describing the spinal deformities are grossly inaccurate since they are two-dimensional measurements of three-dimensional deformities. The approach described in this paper uses a simple device, the "Throne," which ensures reproducible positioning of patients for sitting spine radiographs as well as exact orthogonality of A-P and lateral film exposures. These two views of the spine form the data in digitized form for input into a computer program which generates the 3-D geometry of the line passing through the centers of each vertebral body from L5 to T1. Parameters describing the 3-D deformities of the spine are calculated automatically and converted to printed form for detailed examination and to plotted form for clinical use. Approximately 80 postambulatory Duchenne muscular dystrophy patients are being followed using this method. Of these, 20 have been followed for periods of 2 to 3 years. Costs of the method are minimal. The "Throne" can be built for approximately $50 of materials and 30 hours of labor. Each set of A-P and lateral radiographs can be processed in less than 5 minutes, including digitizing time at a computer cost of about 50 cents. The computer program may be handled by a minicomputer.