Purpose: Formetric 4D dynamic system (F4D) is a radiation-free imaging system that can be used to detect static and dynamic back contour in children with adolescent idiopathic scoliosis (AIS). The aim of this paper is (1) to compare the F4D to other systems; (2) to review the correlation of spinal measurements taken by F4D with those taken by radiographs as well as the reproducibility of the F4D; (3) to present future clinical uses and suggest potential research studies utilizing F4D. Methods: MEDLINE (PubMed), ScienceDIRECT, SCOPUS, Cochrane, and Web of Science were queried for studies on AIS using surface topography. Papers were evaluated using PRISMA criteria. Results: Correlations between scoliosis angle as measured by F4D and Cobb angle by radiographs are from 0.7 to 0.872 in the thoracic spine and from 0.5 to 0.758 in the lumbar spine. The intraday reliability of F4D measurements by the same observer ranged from 0.65 to 0.996 across two studies. The study that evaluated reproducibility of F4D when segmented by patients with BMI below and above 24.99 kg/m2 found that the reproducibility was 0.990 and 0.995, respectively. There is potential for using F4D as a screening tool for scoliosis using an algorithm with 92% sensitivity and 74% specificity. Conclusions: F4D as a surface topography machine has great potential in screening and monitoring progression of the curvatures of AIS.
Spinal fusion on adolescent idiopathic scoliosis patients with the level of L4 or lower can increase lumbar disc degeneration with sagittal imbalance 35 years after surgery
