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Study Design: Retrospective cohort study. Objective: Analysis of postoperative sagittal alignment of the unfused spine is lacking in patients with adult spinal deformity (ASD). The present study aims to evaluate the efficacy of the whole spine full-flexion lateral radiograph to predict the reciprocal change of the unfused spine after correction surgery. We hypothesized that the novel parameter (T1-UIV angle: angle between the upper vertebral endplate of the T1 and the upper vertebral endplate of the upper instrumented vertebra) of the preoperative whole spine full-flexion lateral radiograph is similar to that of the postoperative lateral radiograph if the patient has the ideal sagittal alignment. Methods: Twenty-six ASD patients who underwent correction surgery with a minimum 2-year follow-up were enrolled and separated into the Ideal and Non-Ideal groups according to the Scoliosis Research Society (SRS)-Schwab classification of the final follow-up radiograph. Radiographic parameters, including T1-UIV of the preoperative whole spine full-flexion lateral radiograph, were obtained. Results: Thirteen patients were included in the Ideal group and 13 were in Non-Ideal group. Preoperative T1-UIV of the whole spine full-flexion lateral radiograph exhibited significant correlations with the T1-UIV angles of the postoperative and final follow-up radiographs ( r = 0.64, P < .01, y = 0.800 x + 8.012, and r = 0.69, P < .01, y = 0.857 x + 2.960, respectively). Interestingly, this correlation was stronger for the Ideal group ( r = 0.77, P < .01, y = 1.207 x − 1.517, and r = 0.89, P < .01, y = 0.986 x + 0.694, respectively). Conclusion: A novel radiographic strategy (T1-UIV of preoperative the whole spine full-flexion lateral radiograph) could estimate the postoperative alignment of the unfused spine correctly.

Prospective feasibility study on consecutive patients.The aim of this study was to investigate the ability of regional BMD around the pedicle screw to predict the screw fixation.Pedicle screw fixation is the gold standard technique for spinal fusion. Despite the advantage of biomechanical stability, screw loosening is a common complication. In previous studies, pullout strength and screw insertional torque were correlated, and most importantly, affected by bone mineral density (BMD). Although the density and structure of the vertebral body are not homogeneous, no study has yet evaluated the relationship between screw insertional torque and regional BMD around the pedicle screw in vivo.Consecutive 50 patients, scheduled for transpedicular fixation, were evaluated preoperatively for BMD measured by dual-energy absorptiometry (DXA) and quantitative computed tomography (QCT). Regional volumetric BMD around the pedicle screw (PS-vBMD) using the novel QCT technique was also evaluated. Among all patients, 190 screws (diameter, 7.5 to 8.5 mm; length, 40 to 45 mm, inserted from L1 to L5) were eligible for this study and were analyzed to identify factors contributing to insertional torque. The following factors were investigated: age, body mass index, laboratory data, pedicle diameter, screw diameter, screw length, and 5 types of bone mineral density measures [DXA: spine-areal BMD (aBMD), total hip-aBMD, femoral neck-aBMD, QCT: central-vBMD, PS-vBMD].Insertional torque was significantly correlated with each BMD measurement and strongest with PS-vBMD (r=0.61, P0.001). Multiple regression analysis showed PS-vBMD was most strongly correlated with screw insertional torque (stdβ=0.494; P0.001). A model containing the following 5 predictors was significantly associated with screw insertional torque: age, pedicle diameter, screw diameter, screw length, and PS-vBMD.The preoperative measurement of PS-vBMD was technically feasible and reliably predictive of screw insertional torque during transpedicular fixation in a clinical setting.

OBJECTIVEInterbody fusion cages are widely used to achieve initial fixation and secure spinal fusion; however, there are certain technique-related complications. Although anterior cage dislodgement can cause major vascular injury, the incidence is extremely rare. Here, the authors performed a review of anterior cage dislodgement following posterior lumbar interbody fusion (PLIF) surgery.METHODSThe authors retrospectively reviewed the cases of 4625 patients who had undergone PLIF at 6 institutions between December 2007 and March 2015. They investigated the incidence and causes of surgery-related anterior cage dislodgement, salvage mechanisms, and postoperative courses.RESULTSAnterior cage dislodgement occurred in 12 cases (0.26%), all of which were caused by technical errors. In 9 cases, excessive cage impaction resulted in dislodgement. In 2 cases, when the cage on the ipsilateral side was inserted, it interacted and pushed out the other cage on the opposite side. In 1 case, the cage was positioned in an extreme lateral and anterior part of the intervertebral disc space, and it postoperatively dislodged. In 3 cases, the cage was removed in the same operative field. In the remaining 9 cases, CT angiography was performed postoperatively to assess the relationship between the dislodged cage and large vessels. Dislodged cages were conservatively observed in 2 cases. In 7 cases, the cage was removed because it was touching or compressing large vessels, and an additional anterior approach was selected. In 2 patients, there was significant bleeding from an injured inferior vena cava. There were no further complications or sequelae associated with the dislodged cages during the follow-up period.CONCLUSIONSAlthough rare, iatrogenic anterior cage dislodgement following a PLIF can occur. The authors found that technical errors made by experienced spine surgeons were the main causes of this complication. To prevent dislodgement, the surgeon should be cautious when inserting the cage, avoiding excessive cage impaction and ensuring cage control. Once dislodgement occurs, the surgeons must immediately address this difficult complication. First, the possibility of a large vessel injury should be considered. If the patient’s vital signs are stable, the surgeon should continue with the surgery without cage removal and perform CT angiography postoperatively to assess the cage location. Blind maneuvers should be avoided when the surgical site cannot be clearly viewed. When the cage compresses or touches the aortic artery or vena cava, it is better to remove the cage to avoid late-onset injury to major vessels. When the cage does not compress or touch vessels, its removal is controversial. The risk factors associated with performing another surgery should be evaluated on a case-by-case basis.

Anterior dislodgement of the transforaminal lumbar interbody fusion (TLIF) cage is one of the severe complications seen in this procedure, which may cause an intraoperative major vessel injury. The objective of this report is to present a rare case of inferior vena cava (IVC) injury during revision surgery for removal of the anteriorly migrated cage. The authors describe a case of 74-year-old woman with lumbar spinal canal stenosis and degenerative scoliosis. During the TLIF surgery, an inserted titanium cage at the L4–5 level dislodged anteriorly to the retroperitoneal space without massive bleeding from the disc space. In the second surgery, which was performed via an anterior retroperitoneal approach to remove the migrated cage, massive torrential bleeding occurred because of IVC injury. The laceration in the posterior wall of the IVC necessitated ligation of this vessel and both common iliac veins by a vascular surgeon. Postoperative edema of the lower extremities after ligation of the vessels was well tolerated, and the patient showed almost full recovery. For removal surgery of an anteriorly migrated cage, the surgeon should be well prepared for the risk of IVC injury, including requesting the attendance of a vascular surgeon. Ligation of the infrarenal IVC is an acceptable solution in irreparable IVC injury.

The Oswestry Disability Index (ODI) is one of the most used assessment scales for patients with spine conditions, and translations into several languages have already been available. However, the scale’s discriminative validity and responsiveness to the clinical change was somewhat understudied in these translated versions of the ODI. In this study, we independently developed a Japanese version of the ODI, and tested its discriminative and responsive performances among outpatients with various spinal conditions. We recruited 167 outpatients from seven participating clinics, and concurrently measured the translated ODI and MOS Short Form 36 (SF36) as a reference scale. We also obtained from medical records clinical information such as diagnoses, the past history of surgery, and existence of subjective symptoms and clinical signs. For testing discriminative validity, scores were compared by the number of symptoms and signs, with the trend test. Receiver operating characteristics (ROC) analysis was also conducted to compare ODI and SF36 in their performance to discriminate the existence of signs/symptoms, by chi-square test on the area under ROC curve (AUC). For 35 patients (17 clinically stable, 18 undergoing surgery and clinically significantly changed), the two scales were repeatedly administered after 3–6 months to compare responsiveness by using ROC analysis. The translated ODI and the SF36 Physical Function (PF) subscale showed a significant trend increase as the numbers of symptoms/signs increased. They also showed comparable performance in discriminating the existence of signs/symptoms (AUC=0.70–0.76 for ODI, 0.69–0.70 for SF36 PF, P=0.15–0.81), and clinical status change over time (AUC=0.82 for ODI, 0.72 for SF36 PF, P=0.31). Our results showed that the translated Japanese ODI showed fair discriminative validity and responsiveness as the original English scale showed.

The morbid conditions of unstable lumbar spine that are not associated with hypermobility in postlaminectomy cases were studied. The dura and the nerve roots with adhesion could be affected by minimal movement of the spine, which seemed to be the mechanism of symptoms of instability without hypermobility. The effects of spinal instrumentation on this particular instability were studied. The spinal instrumentation provides instantaneous rigid fixation, and maintains it until fusion is obtained, which might prevent adhesion, new bone formation, and re-stenosis. Spinal instrumentation seemed to be the effective treatment for this particular instability.