Fusion Length Requiring Spinopelvic Fixation in Lumbosacral Fusion with Anterior Column Support at L5-S1: Assessment of Fusion Status Using Computed Tomography.

Background: The lumbosacral (LS) junction has a higher nonunion rate than other lumbar segments, especially in long-level fusion. Nonunion at L5-S1 would result in low back pain, spinal imbalance, and poor surgical outcomes. Although anterior column support at L5-S1 has been recommended to prevent nonunion in long-level LS fusion, fusion length requiring additional spinopelvic fixation (SPF) in LS fusion with anterior column support at L5-S1 has not been evaluated thoroughly. This study aimed to determine the number of fused levels requiring SPF in LS fusion with anterior column support at L5-S1 by assessing the interbody fusion status using computed tomography (CT) depending on the fusion length. Methods: Patients who underwent instrumented LS fusion with L5-S1 interbody fusion without additional augmentation and CT > 1 year postoperatively were included. The fusion rates were assessed based on the number of fused segments. Patients were divided into two groups depending on the L5-S1 interbody fusion status: those with union vs. those with nonunion. Binary logistic regression analyses were performed to identify risk factors for LS junctional nonunion. Results: Fusion rates of L5-S1 interbody fusion were 94.9%, 90.3%, 80.0%, 50.0%, 52.6%, and 43.5% for fusion of 1, 2, 3, 4, 5, and ≥ 6 levels, respectively. The number of spinal levels fused ≥ 4 (p < 0.001), low preoperative bone mineral density (BMD; adjusted odds ratio [aOR], 0.667; p = 0.035), and postoperative pelvic incidence (PI) - lumbar lordosis (LL) mismatch (aOR, 1.034; p = 0.040) were identified as significant risk factors for nonunion of L5-S1 interbody fusion according to the multivariate logistic regression analysis. Conclusions: Exhibiting ≥ 4 fused spinal levels, low preoperative BMD, and large postoperative PI-LL mismatch were identified as independent risk factors for nonunion of anterior column support at L5-S1 in LS fusion without additional fixation. Therefore, SPF should be considered in LS fusion extending to or above L2 to prevent LS junctional nonunion.

Perioperative Transthoracic Lung Ultrasound for Assessment of Pulmonary Outcome in Adolescent Idiopathic Scoliosis Patients: Prospective, Observational Pilot Study.

The purpose of study was to evaluate the perioperative lung ultrasound findings of patients undergoing scoliosis correction. LUS examination was performed examined three 3 times for each patient: 20 min after starting mechanical ventilation of the lungs(preoperative), after surgery when the patient was placed in the supine position(postoperative), and 20 min after arrival in the post-anaesthesia care unit. Arterial blood gas analyses, mechanical ventilation parameters, peripheral oxygen saturation(SpO2) were also checked. Twenty-six patients completed the study. The changes of LUS score(20 min) was significantly negatively correlated with the partial pressure of arterial oxygen(PaO2)/fraction of inspired oxygen(FiO2) ratio change(P = 0.039, r = -0.40). The change in mean convex side LUS score was significantly greater than that of the concave side as determined by two-factor repeated measures analysis of variance(p = 0.001). Multiple regression analysis revealed perioperative LUS change was the significant factor related to the oxygen index change (p = 0.042). One case of pneumothorax was diagnosed and pleural thickening more than 5 mm was detected in 8 patients and five patients of those were diagnosed pleural effusion and performed thoracentesis after surgery. Postoperative increase of LUS score was related with deteriorating of oxygenation at one day after surgery, and it suggests that lung ultrasound allows prediction of postoperative hypoxia and facilitates the diagnosis of pulmonary complications at operation room in AIS patients.

Biomechanical assessment of a novel bone lengthening plate system - a cadaveric study.

BACKGROUND: Although many types of external fixators have been developed for distraction osteogenesis, all have some drawbacks. We recently developed a novel bone lengthening plate to overcome these problems. The purpose of this study is to conduct biomechanical analyses using cadavers to assess the stability of the bone lengthening plate in relation to distraction length and femoral bone mineral density. METHODS: We used human cadaveric femurs (n=18) to assess the effects of distraction length and bone mineral density on the biomechanical stability of the bone lengthening plate. After establishing control (n=6, 0mm lengthening) and experimental groups (n=12, 30 mm lengthening), we measured biomechanical stability (structural stiffness, ultimate load, and displacement) under a compressive load. The experimental group was subdivided into a group with normal bone mineral density (n=6) and a group with osteoporosis (n=6), and the biomechanical stability of these groups was compared. FINDING: Structural stiffness differed significantly between the control (417.6 N/mm) and combined experimental groups (185.6 N/mm, p=0.002). Ultimate load also differed significantly between the control (1327.8 N) and combined experimental (331.4 N, p=0.002) groups. Bone mineral density was unrelated to structural stiffness (p=0.204), ultimate load (0.876), or displacement (0.344). In all cases, failure of the bone lengthening plate occurred at the longitudinal connectors, such as the connecting columns between the upper and lower plates, and the lengthening shaft of the bone lengthening plate. INTERPRETATION: The biomechanical stability of the bone lengthening plate was affected by the lengthening length but not by bone mineral density. In addition, biomechanical stability during lengthening was most strongly influenced by the longitudinal connectors.