Genetic predisposition is a key causal factor in adolescent idiopathic scoliosis (AIS), which is the most common form of spinal deformity. However, common quantitative genetic effect estimates such as hereditability have not been fully evaluated and reported for this disorder. We aimed to determine the sibling recurrent risk and hereditability of AIS in first-degree relatives of 513 Chinese patients with this disorder. Family members of 513 Chinese patients with AIS attending a scoliosis clinic were assessed. A diagnosis of AIS was made with the criteria of Cobb angle greater than 20°. The evaluation included clinical assessment and physical examination in a health screening centre by medical doctors with use of forward bending test. Any positive screening cases were referred to a scoliosis clinic for follow-up spinal radiograph. All radiographs were assessed by an orthopaedic surgeon in the scoliosis clinic. A population prevalence of scoliosis was obtained from the data of a territory-wide screening campaign. The prevalence of AIS among siblings of probands was measured both overall and divided by sex of siblings. The sibling recurrent risk (λs) was calculated for male and female siblings separately with reported population incidence of AIS.Introduction
Methods
Intra-operative 3-D fluoroscopy has limitations, including low resolution images, little soft tissue information and small working volume. Fusion of 3D data sets (MRI/ CT) had been developed in pre-operative planners. We employed the same principle and developed a new technique of navigation with fused images of pre-operative MRI/CT and intra-operative 3D fluoroscopy. Pre-op CT/MRI in DICOM was imported to the Stryker Leibinger Spine 3-D and segmentation of the intended bone performed. Patient tracker was mounted and 3-D fluoroscopy performed using Siemens ISO-C 3D. Fusion of CT/MRI with 3D fluoroscopy was performed using “surface matching image correlation” and this automatically registered the bone with MRI/CT. The fused images were then ready for 3D navigation procedures. Nine patients were included in the series. There were eight fracture cases and seven performed with fused CT and 3-D fluoroscopy (two PCL avulsion fractures, two tibial plateau fractures, one femoral condyle fracture and three pelvic-acetabular fractures). Total of twenty-three screws had been inserted without complication. One tibial plateau fracture fixation and one core decompression for avascular necrosis of femoral head were performed with fused MRI to 3D fluoroscopy. In conclusion, intra-operative 3-D navigated procedures with fused pre-operative MRI/CT and intra-operative 3-D fluoroscopy were all successful with (1) extended working volume (2) higher resolution images (3) more soft tissue information. We foresee more applications of this new technique in other areas of computer aided surgery
