The three-dimensional easy morphological (3-DEMO) classification of scoliosis, part II: repeatability

The aim of this study is to present procedures and results obtained within the repeatability of 3-DEMO classification for scoliosis analysis.We acquired the data of 100 pathological and 20 normal spines with an optoelectronic system (AUSCAN) and of two dummies with simulated spine deformity. On the obtained 3D reconstruction of the spine, we considered the coronal view with a spinal reference system (Top View) and its three related parameters, defined in part I, constituting the 3-DEMO classification. We calculated the repeatability coefficient for the subjects (two acquisitions for each subject with a time interval of 26 ± 12 sec), whereas we evaluated the system measurement error calculating the standard deviation of 50 consecutive acquisitions for each dummy.Comparing the results of the two types of acquisition, it emerged that the main part of parameters variability was due to postural adjustments The proportion of agreement for the 3-DEMO parameters gives a k value above 0.8; almost 10% of patients changed classification because of postural adjustments, but none had a "mirror-like" variation nor a change in more of one parameter at a time Repeatability coefficient is lower than the previously calculated normative limits.The 3-DEMO classification has a high repeatability when evaluated with an optoelectronic system such as the AUSCAN System, whose systematic error is very low. This means that the implied physiological phenomenon is consistent and overcomes the postural variability inherent in the measured object (normal or pathological subject).The third dimension today is a clinical problem to be solved every time surgery [1-3], bracing [4,5], or exercises are proposed [6,7], but today clinicians lack tools to three-dimensionally understand the scoliotic spine, partly because of complexity, costs and reduced diffusion of involved instruments, but also because the existing proposed classifications [8,9] are very complex and born mainly outside the clinical field