Safe Optimal Tear Drop View for Spinopelvic Fixation Using a Three-Dimensional Reconstruction Model of the Pelvis

Background@#Spinopelvic fixation (SPF) has been a challenge for surgeons despite the advancements in instruments and surgical techniques. C-arm fluoroscopy-guided SPF is a widely used safe technique that utilizes the tear drop view. The tear drop view is an image of the corridor from the posterior superior iliac spine to the anterior inferior iliac spine (AIIS) of the pelvis. This study aimed to define the safe optimal tear drop view using three-dimensional reconstruction of computed tomography images. @*Methods@#Three-dimensional reconstructions of the pelvises of 20 individuals were carried out. By rotating the reconstructed model, we simulated SPF with a cylinder representing imaginary screw. The safe optimal tear drop view was defined as the one embracing a corridor with the largest diameter with the inferior tear drop line not below the acetabular line and the lateral tear drop line medial to the AIIS. The distance between the lateral border of the tear drop and AIIS was defined as tear drop index (TDI) to estimate the degree of rotation on the plane image. Tear drop ratio (TDR), the ratio of the distance between the tear drop center and the AIIS to TDI, was also devised for more intuitive application of our simulation in a real operation. @*Results@#All the maximum diameters and lengths were greater than 9 mm and 80 mm, respectively, which are the values of generally used screws for SPF at a TDI of 5 mm and 10 mm in both sexes. The TDRs were 3.40 ± 0.41 and 3.35 ± 0.26 in men and women, respectively, at a TDI of 5 mm. The TDRs were 2.26 ± 0.17 and 2.14 ± 0.12 in men and women, respectively, at a TDI of 10 mm. @*Conclusions@#The safe optimal tear drop view can be obtained with a TDR of 2.5 to 3 by rounding off the measured values for intuitive application in the actual surgical field.

Anterolateral and Posterior versus Posterior-Only Approaches for the Correction of Degenerative Adult Spinal Deformity

Objectives@#This study was conducted to demonstrate the reliability of mini-open anterior lumbar interbody fusion (ALIF) combined with lateral lumbar interbody fusion (LLIF) followed by 2-stage posterior fixation in patients with adult spinal deformity (ASD).Summary of Literature Review: Although the correction of ASD using LLIF has become more widespread, the amount of sagittal plane correction has been reported to be suboptimal.Materials and Method: Thirty ASD patients who underwent ALIF with LLIF followed by 2-stage posterior fixation (AP group) were compared to 60 patients who underwent posterior-only surgery (PO group) and were matched according to age, sex, diagnosis, fusion level, pelvic incidence, and follow-up duration. Spinopelvic parameters, hospitalization data, clinical outcomes, and complications were compared between the 2 groups. @*Results@#Postoperative lumbar lordosis was greater in the AP group than in the PO group (p<0.001). The reduction in the sagittal vertical axis was also greater in the AP group than in the PO group (p=0.005). Postoperatively, 90.0% of the AP group had a pelvic incidence– lumbar lordosis value within 9°, whereas only 50.0% of the PO group met that criterion (p<0.001). The operation time of the AP group was longer than that of the PO group, while estimated blood loss and red cell transfusion were lower in the AP group. Postoperative medical complications and delayed surgical complications developed more frequently in the PO group. @*Conclusions@#Mini-open ALIF with LLIF followed by 2-stage posterior fixation can restore sagittal balance more appropriately, with a lower rate of complications, than posterior-only surgery for the correction of ASD.

Animal Models of Orthopedic Research: A Spinal Fusion Model / 대한정형외과학회잡지

The incidence of spinal fusion surgery has increased due to an increase in the incidence of degenerative spinal disease or trauma. Moreover, the development of various kinds of implants and bone graft substitutes has also increased. The animal models of spinal fusion are useful methods in evaluating the effectiveness of the newly developed spinal implants or bone graft substitutes. The most widely used animal models of spinal fusion are posterolateral fusion model, posterior fusion model, and anterior interbody fusion model. Mice, rats, rabbits, dogs, pigs, goats, sheep, and primates are frequently used in animal models of spinal fusion. Small animals are implanted with a bone graft substitute without internal fixation; however middle- or large-sized animals are implanted with a bone graft substitute using pedicle screws or cages. Small animals are easy to handle due to their size, but have different anatomical or biomechanical reactions with the human body. Middle- or large-sized animals have characteristics like the human body, but they are difficult to handle or there is an ethical problem. The fusion status is evaluated by manual palpation, mechanical testing using Instron, and radiologic techniques such as computed tomography, micro-computed tomography or undecalcified histology. The fusion rate and duration required for successful fusion differ according to the species and anatomical site. We have identified and reviewed several typical animal models of spinal fusion.