Study Design. Retrospective review of prospective case-control study. Objective. To compare minimally invasive scoliosis surgery (MIS) and posterior spinal fusion (PSF) in a large group of patients. Summary of Background Data. MIS, has been shown to have benefits over standard PSF in adolescent idiopathic scoliosis (AIS). Methods. Radiographic, clinical, and operative review of a multi-institutional prospective database from 2013 to 2018. MIS patients with minimum 2-year XR follow up were compared with open PSF technique patients. Results. Four hundred eighty five patients were included; 192 MIS and 293 PSF. Preoperative Cobb (P ¼ 0.231) and kyphosis were similar (P ¼ 0.501). Cobb correction was comparable (P ¼ 0.46), however percent improvement in thoracic kyphosis was significantly higher in MIS (P < 0.001). MIS had significantly lower blood loss (P < 0.001), transfusions (P < 0.001), fixation points (P < 0.001), opioid consumption (P ¼ 0.001), and hospital stay (P < 0.001). Operative time was shorter (P ¼ 0.001) and 30day complications rate was similar (P ¼ 0.81). Conclusion. This is the largest study comparing the surgical outcomes of MIS and PSF. MIS patients benefit from increased kyphosis, fewer transfusion, lower opioid consumption, and shorter hospital stay with similar Cobb correction. Increased postoperative kyphosis is likely from muscle sparing dissection in MIS.

Study Design. Single-center retrospective chart review with minimum 2-year follow up. Objective. To determine incidence of pulmonary hypertension in adolescent idiopathic scoliosis patients and to determine the effect of scoliosis surgery on pulmonary hypertension. Summary of Background Data. Spinal deformity in adolescent idiopathic scoliosis can increase right atrial and ventricular pressures secondary to restrictive lung disease. Pulmonary hypertension leading to cor pulmonale is the most feared outcome, however mild pulmonary hypertension in adolescent idiopathic scoliosis (AIS) patients has been reported. No study has previously examined changes in the improvement of right heart function following scoliosis surgery. Methods. Cobb angle, 2D-echo signs of structural heart disease, aortic root dimensions, tricuspid regurgitant jet velocity (TRV), pulmonary function tests (PFTs), arterial blood gas (ABG), and patient demographics reviewed. Right ventricular systolic pressure (RVSP) estimated using Bernoulli equation (4[TRV] 2 ) and right atrial pressure. RVSP !36 mmHg is a surrogate marker for pulmonary hypertension. All echocardiograms were read by board certified Pediatric Cardiologists. Logistic regression used to assess for differences in TRV between groups. Results. Mean preoperative RVSP was significantly elevated in AIS patients (26.9 AE 0.49; P < 0.001) compared with controls (17.25 þ 0.88). Only 47 (21%) Group 1 patients had elevated preoperative TRV (!2.8 m/s) versus none in Group 2 (P < 0.001). Additionally, logistic regression showed AIS patients have odds ratio of 3.29 for elevated TRV (P ¼ 0.007)-an indirect measure of pulmonary hypertension. In all Group 3 patients, the cardiac function normalized postoperatively (mean TRV ¼ 2.09 þ 0.23; P < 0.001). No association found between Cobb angle, aortic root parameters, or pulmonary function tests. Conclusion. This study found 13.9% of patients with adolescent idiopathic scoliosis had elevated TRV while controls had no TRV abnormalities. Additionally, RVSP measurements demonstrated mild pulmonary hypertension in AIS patients. These abnormal values normalized postoperatively, indicating the benefits of scoliosis surgery on cardiac function in adolescent idiopathic scoliosis.

Study Design. Porcine model. Objective. To quantify critical vascular and mechanical events that occur before and during an evolving spinal cord injury. Summary of Background Data. Spinal cord injuries are one of the most devastating complications in spine surgery. Intraoperative neuromonitoring changes can occur as a secondary event of spinal cord compression and decrease in spinal cord blood flow (SCBF). Laser Doppler flowmetry has been well validated for measuring blood flow. Methods. Seventeen pigs were studied, 14 of which completed the experiment. Multilevel, midthoracic laminectomies were performed. Laser Doppler flowmetry electrodes were placed on the dura to measure SCBF. Spinal cord injury was induced by incremental balloon inflation in the epidural space. The animals were separated into two groups. After motor-evoked potential (MEP) loss, group A underwent medical interventions and then balloon decompression approximately 20 minutes later. Group B underwent immediate balloon decompression followed by medical interventions. After interventions, wake-up test was performed and computed tomography scan measured thoracic spinal canal volume. Results. Median SCBF changes were seen 15.8 (5.4–25.1) minutes before MEP loss. However, the 20% threshold interval was often reached before. At the 20% threshold, median pressure was 7 psi, balloon volume was 0.5 cm3, and 50% of the spinal canal was compromised. In group A, no pigs moved and all had pathology indicating ischemia. In group B, 9 of 10 were found to be moving their hind legs with 7 indicating ischemia. Conclusion. Compression spinal cord injury is the end of a cascade involving increasing intracanal pressure, decreasing canal volume, and hypoperfusion. Rapid relief of compression leads to MEP return. SCBF monitoring can detect ischemia preinjury, giving surgeons an opportunity for early intervention. Level of Evidence: 4