Three-Dimensional Analysis of Preoperative and Postoperative Rib Cage Parameters by Simultaneous Biplanar Radiographic Scanning Technique in Adolescent Idiopathic Scoliosis: Minimum 2-Year Follow-Up

Systematic review and meta-analysis for the impact of rod materials and sizes in the surgical treatment of adolescent idiopathic scoliosis

PURPOSE

To assess surgical and safety outcomes associated with different rod materials and diameters in adolescent idiopathic scoliosis (AIS) surgery.

METHODS

A systematic literature review and meta-analysis evaluated the surgical management of AIS patients using pedicle screw fixation systems (i.e., posterior rods and pedicle screws) with rods of different materials and sizes. Postoperative surgical outcomes (e.g., kyphosis and coronal correction) and complications (i.e., hyper/hypo-lumbar lordosis, proximal junctional kyphosis, revisions, reoperations, and infections) were assessed. Random-effects models (REMs) pooled data for outcomes reported in ≥ 2 studies.

RESULTS

Among 75 studies evaluating AIS surgery using pedicle screw fixation systems, 46 described rod materials and/or diameters. Two studies directly comparing titanium (Ti) and cobalt-chromium (CoCr) rods found that CoCr rods provided significantly better postoperative kyphosis angle correction vs. Ti rods during a shorter follow-up (0-3 months, MD = - 2.98°, 95% CI - 5.79 to - 0.17°, p = 0.04), and longer follow-up (≥ 24 months, MD = - 3.99°, 95% CI - 6.98 to - 1.00, p = 0.009). Surgical infection varied from 2% (95% CI 1.0-3.0%) for 5.5 mm rods to 4% (95% CI 2.0-7.0%) for 6 mm rods. Reoperation rates were lower with 5.5 mm rods 1% (95% CI 0.0-3.0%) vs. 6 mm rods [6% (95% CI 2.0-9.0%); p = 0.04]. Differences in coronal angle, lumbar lordosis, proximal junctional kyphosis, revisions, and infections did not differ significantly (p > 0.05) among rods of different materials or diameters.

CONCLUSION

For AIS, CoCr rods provided better correction of thoracic kyphosis compared to Ti rods. Patients with 5.5 mm rods had fewer reoperations vs. 6.0 and 6.35 mm diameter rods.

LEVEL OF EVIDENCE

III.

Factors affecting postoperative pulmonary function deterioration in adolescent idiopathic scoliosis: A prospective study using 3-dimensional image reconstruction by biplanar stereoradiography

This study aimed both to evaluate rib cage parameters in patients with adolescent idiopathic scoliosis (AIS) by three-dimensional (3D) image reconstruction using biplanar stereoradiography (EOS) (EOS Imaging, Paris, France) and identify factors associated with postoperative pulmonary function deterioration (PFD). A total of 67 patients with Lenke type 1 or 2 AIS (59 females and 8 males; mean age, 14.4 years) undergoing posterior corrective fusion with a rod rotation maneuver based on segmental pedicle screw fixation were recruited. 3D images and pulmonary function test results were analyzed preoperatively and at 2 years postoperatively. The following parameters were measured: maximum thickness, maximum width, thoracic index, rib hump, rib cage volume (RCV), spinal penetration index (SPI), endothoracic hump ratio (EHR), vertebra-sternum angle (VSA), rib-vertebra angle difference, vertebral lateral decentering (VLD), forced vital capacity (FVC), and percent predicted FVC (%FVC). PFD was defined as a postoperative %FVC decline of 5% or greater. Patients were divided into two groups, namely PFD and non-PFD. FVC increased from 2.62 L to 2.73 L, while %FVC decreased from 88.7% to 82.7%. The maximum width diminished postoperatively in the PFD group. Patients in the PFD group exhibited a significantly smaller increase in RCV and VLD as well as a significantly smaller decrease in SPI, EHR, and VSA than those in the non-PFD group. The rib cage parameters quantified on 3D images reconstructed using EOS are useful in identifying factors affecting PFD in patients with AIS.