The spinal column of a human body must support the weight of the upper half of the body including the head and the upper limbs, befitting to the bipedal upright posture. Vertebral bodies of the lower lumbar are larger than the upper one for this support. Since the ventral side of the spinal column has a thorax, cervical and lumbar lordoses are indispensable to bring the center of gravity close to a centroidal line. Therefore, the thickness of the inferior lumbar vertebrae are greater ventrally, and an intervertebral disk is thick, and wedge-shaped. Since the weight shifts forward and backward as to the standing and the sitting position, the angle of a pelvis must be changed, and a sacrum and lumbar vertebrae cannot be unified. The lumbar vertebrae at the time of a walk should take the rotational shear, between an upper-limb-thorax block and a lower-limb-pelvis block, since they can hardly rotate due to the dissociation of the center of the rotary axis and the actual center of the vertebral bodies. The situation results in propensity for disk herniation or compressive fractures.

  Purpose : To compare the efficacy of hydroxyapatite (HAP) spacers and beta-triphosphate calcium-HAP complex (HAP-TCP) spacers in spinous process-splitting open-door cervical laminoplasty.

  Methods : Among 299 patients who underwent laminoplasty between January 2006 and December 2012, 83 patients with cervical spondylotic myelopathy without ossification of the longitudinal ligament or history of trauma were included in the study. In all patients, spacers were inserted into each split spinous process (C3-6). The patients were divided into two groups : the HAP spacer group (n=32) and the HAP-TCP spacer group (n=51). Computed tomography scans were obtained at 7 days, 3 months, and 6 months post-surgery to assess the extent of bone-spacer bonding and ossifications at the laminar hinges (the gutter). Bone-spacer bonding was classified according to Ichikawa's classification A-E¹⁾ , whereby grades above C represent bone growth, and grades above D represent bone union. Bone changes at the gutter were classified into three grades : none, growth, and union. The chi-square test was used to evaluate frequencies. Statistical significance was defined as p<0.05.

  Results : Bone growth and union were observed in the spacer-bone interface in the HAP-TCP spacer group in 98.0% and 61.3% at 3 months and 97.6% and 53.4% at 6 months. The corresponding rates in the HAP spacer group were 96.3% and 7.8% at 3 months and 88.3% and 6.3% at 6 months, respectively. Bone growth and union rates at the bone-spacer were higher in the HAP-TCP spacer group than in the HAP spacer group, with a significant difference between the two groups at 3 months (χ²=93.42, df=2, p<0.01) and 6 months (χ²=80.52, df=4, p<0.01)]. The bone-spacer bonding rates decreased from 3 to 6 months post-surgery in both groups [HAP group : χ²=2.97, df=3, p>0.05, HAP-TCP group : χ²=8.40, df=4, p<0.05). The bone regrowth and union rates at the gutter at 6 months post-surgery were 93.4% and 63.1% in the HAP-TCP spacer group, and 98.8% and 80.3%. The differences were significant between the two groups (χ²=16.90, df=2, p<0.05).

  Conclusion : Compared to the HAP spacers, the HAP-TCP spacers demonstrated superior bone-spacer bonding but inferior bone union at the gutter. The effectiveness of both spacers was comparable in spinous process-splitting open-door cervical laminoplasty.

  Objective : To identify efficacy of lumbar fusion and fixation in restoration of total sagittal alignment in adult patients with degenerative disc disease of the lumbar spine and to determine the optimal angle of lumbar lordosis for lumbar fusion and fixation.

  Background : Total sagittal alignment is increasingly recognized as a critical parameter in adult lumbar degenerative deformity. Adult degenerative disc disease of the lumbar spine may be one of the major causes of adult spinal deformity if the spinal misalignment remains uncorrected. Therefore, restoration of the total sagittal alignment should be the goal of surgery for lumbar degenerative disc disease.

  Methods : We conducted a retrospective radiological assessment of patients who underwent lumbar fusion and fixation for lumbar lordosis. Analysis of the total sagittal plane was based on multiple parameters : cervical lordosis, thoracic kyphosis, lumbar lordosis, C7 plumb line/sagittal vertical axis (SVA), pelvic incidence, sacral slope, and lumbosacral angle. Furthermore, spinopelvic harmony was used to analyze the optimal fixation angle.

  Results : Following lumbar fusion and fixation, both lumbar lordosis and thoracic kyphosis increased significantly, and there was significant posterior shift of the C7 plumb line/SVA. As a result, total sagittal alignment was improved following lumbar fusion and fixation, particularly in patients who had received fixation according to spinopelvic harmony.

  Conclusions : We have concluded that lumbar fusion and fixation improves total sagittal alignment in adult patients with degenerative disc disease of the lumbar spine. Furthermore, the intraoperative fixation angle of lumbar lordosis has proven to be a key component in the regulation of total sagittal alignment. Our results support the therapeutic strategy of lumbar fixation according to spinopelvic harmony in adult degenerative disc disease of the lumbar spine.

  Solitary fibrous tumor (SFT) is a spindle cell tumor, derived from mesenchymal cells, that arises most commonly in the pleura. Cases of SFT in the central nervous system, both intracranial and intraspinal, have been reported. We report a case of an intramedullary primary SFT of the thoracic spinal cord. A 65-year-old man presented with a 5-year history of lower back and left leg pain and 5-month history of rapid progressive weakness of the left lower leg. Thoracic magnetic resonance imaging indicated an intradural tumor at the Th8level. Intraoperative findings revealed that the tumor arose from an intramedullary site and had no attachment with the arachnoid membrane and dura mater. Histological examination and immunohistochemical staining confirmed the diagnosis of SFT. Although intramedullary SFT is rare, SFT should be considered during the differential diagnosis of intramedullary tumor.