Study Design. Prospective study. Objective. To analyze the effect of T1 slope on kyphotic alignment change after cervical laminoplasty in patients with cervical myelopathy. Summary of Background Data. Laminoplasty is a posterior method, and maintenance of both preoperative and postoperative lordotic alignment is prerequisite for the successful surgery. Unfortunately, patients who underwent laminoplasty tend to have kyphotic alignment change after operation despite sufficient preoperative lordosis, and such kyphotic alignment change after cervical laminoplasty can reduce surgical outcome and require additional surgery. Methods. Consecutive patients who underwent cervical laminoplasty for cervical myelopathy were enrolled. Cervical spine lateral radiography in neutral, flexion, and extension were taken before surgery and at 2-year follow-up. Patients were divided into 2 groups according to the preoperative T1 slope, and postoperative cervical alignment change was compared according to the preoperative T1 slope. Results. A total of 51 patients were enrolled in this study. The mean age was 57.2 years (range, 39–88 yr). There were 39 male patients and 12 female patients. There were no differences in age, sex, the presence and type of ossification of posterior longitudinal ligament, and operation level between the patients with higher and lower preoperative T1 slope. Patients with higher preoperative T1 slope had more lordotic preoperative cervical alignment; however, they had more kyphotic alignment changes after laminoplasty (P< 0.001). After univariate logistic regression, only higher preoperative T1 slope was associated with significantly increased odds ratio for postoperative kyphotic alignment changes. Conclusion. We hypothesized that kyphotic alignment change by posterior structural injury after cervical laminoplasty would be more marked in patients with high T1 slope, and demonstrated that patients with cervical myelopathy with high T1 slope had more kyphotic alignment changes after cervical laminoplasty at 2-year follow-up. Level of Evidence: 4

Retrospective study. To determine age-related changes in cervical sagittal alignment using whole-spine standing radiographs in asymptomatic adults. Modern surgical techniques have emphasized the importance of maintaining proper sagittal alignment. But there is a paucity of literature investigating age-related changes in cervical sagittal alignment. One hundred healthy unoperated adults who were free of spinal problems obtained whole-spine standing radiographs. They consisted of 2 groups divided by age: those in their 20s and those older than 60 years. Each group had an equal ratio of males and females. Distances from C2 as well as C7 plumb lines to the following points were measured: thoracic and lumbar apex as well as the posterior superior corner of the S1 vertebral body. In addition, Cobb angles for C0-C2, C2-C7, thoracic kyphotic angle, lumbar lordotic angle, and T1 sagittal slope angles were measured. The distance between the C2 and C7 plumb lines did not vary with age. The thoracic apex shifted caudally from T6 in the younger group to T7 in the older group. The most common lumbar apex was L4 for both groups. The distance from C2, as well as C7 plumb lines to the posterior superior corner of the S1 vertebral body, as well as the thoracic apex increased significantly in the older group. On the contrary, the distance from the 2 plumb lines to the lumbar apex decreased in the older group. Also, C2-C7 angle increased and T1 sagittal slope angle decreased in the older group compared with the younger group. However, no difference was found for the other Cobb angles between the 2 groups. The distances between the plumb lines from C2 and C7 were maintained but C2-C7 sagittal angle increased with aging.

Study Design. Retrospective analysis. Objective. The main objectives of this study were to analyze and compare cervical sagittal parameters, including the T1 slope, in a population of 45 patients with degenerative cervical spondylolisthesis (DCS) and to compare these patients with a control group of asymptomatic population. Summary of Background Data. Sagittal balance in the cervical spine is as important as the pelvic incidence and is related to the concept of T1 slope. Compared with degenerative lumbar spondylolisthesis, there are few studies evaluating DCS, and characteristic changes of the cervical sagittal parameters (including T1 slope) in patients with DCS are not well studied. Methods. We identified 45 patients with DCS (5.8%) from a database of 767 patients, using cervical radiograph in a standing position. All had radiograph and computed tomographic scan at the same time. Cervical sagittal parameters were analyzed on computed tomographic scan in a standardized supine position. The following cervical sagittal parameters were measured: T1 slope, neck tilt, thoracic inlet angle, and cervical lordosis (C2–C7 angle). The DCS group was compared with a control group of 45 asymptomatic age- and sex-matched adults to the DCS group, who were studied in a recently published study. Results. Of our initial group of 767 patients, 45 with anterolisthesis (5.8%) were included for this study. The T1 slope was significantly greater for DCS (26.06° ± 7.3°) compared with the control group (22.32° ± 7.0°). No significant difference of the neck tilt, thoracic inlet angle, and C2–C7 angle was seen between the DSC group and the control group. Therefore, the T1 slope of the DSC group was significantly greater than that of the control group (P < 0.005). Conclusion. The DCS group was characterized by a greater T1 slope than the control group; therefore, we suggest that a high T1 slope may be a predisposing factor in developing DCS. Level of Evidence: 3

Retrospective study. To determine the frequency of facet arthrosis according to age, sex, and cervical level. In addition, we propose and evaluate a new grading system for cervical facet degeneration. Cervical facets can play an important role in symptomatology. However, there is only one computed tomographic grading system for cervical facet joints. From January 2003 to January 2012, 1944 patients underwent computed tomography of the cervical spine in our institution. We randomly selected 40 males and 40 females from each of the following age groups: 40 to 49, 50 to 59, 60 to 69, and 70 to 79, such that we had a total of 320 patients. We then graded the degree of arthrosis of the facet joints from C2 to C7 on the axial, sagittal, or coronal images according to 4 grades. These categories were: grade I, normal; grade II, degenerative changes including joint space narrowing, cyst formation, small osteophytes without joint hypertrophy seen; grade III, facet joint hypertrophy from large osteophytes without fusion; and grade IV, bony fusion of the facet joint. The intra- and interobserver reliabilities for the grading system were calculated using reliability statistics by intraclass correlation. Facet arthrosis is common with older patients and at C2-C3, C3-C4, and C4-C5. Facet arthrosis was more common on the left side and in males. Greater than grade III facet joint arthrosis was common in patients older than 60 and at C2-C3, C3-C4, and C4-C5. The reliability statistics by intraclass correlation for the grading system was 0.878 for the intraobserver reliability and 0.869 for the interobserver reliability. It seems that upper cervical levels are more likely to degenerate and to have more advanced degrees of degeneration than the lower cervical levels. As expected, age correlates with worsening degeneration. The proposed computed tomographic grading system for cervical facet arthrosis seemed to be reliable.

A prospective cohort study. To demonstrate the changes in vitamin D status after surgery in female patients with lumbar spinal stenosis (LSS), and its correlation with surgical outcomes. In patients with LSS, general health including walking ability and nutritional status can be markedly improved by decompressive surgery. It can be hypothesized that such improvement may have a positive effect on their vitamin D status. In total, 31 female patients who underwent decompression and instrumented posterolateral fusion for LSS were enrolled. Serum 25-hydroxyvitamin D (25-OHD) level was measured before the surgery and at 1 year postoperative visit. According to serum 25-OHD level, patients were classified into 3 groups: (1) deficient group, when 25-OHD level was less than 20 ng/mL (< 50 nmol/L); (2) insufficient group, when 25-OHD level was between 20 to 30 ng/mL (50 nmol/L ≤ 25-OHD < 75 nmol/L); (3) and normal group, when 25-OHD level was 30 ng/mL or more (≥75 nmol/L). The Oswestry Disability Index (ODI) score and health-related quality of life (EQ-5D) were compared according to the level of 25-OHD at 1 year postoperatively. Preoperatively, there were 20 patients in the deficient group, 11 patients in the insufficient group and no patient in the normal group. There were no differences in age, body mass index, preoperative ODI scores, preoperative EQ-5D index scores, and EQ-5D visual analogue scale scores between the 2 groups. Mean preoperative 25-OHD level was 15.8 ng/mL (range, 5.2–29.4 ng/mL) and increased to 19.5 ng/mL (range, 6.3–47.7 ng/mL) 1 year after surgery (P = 0.075). Significant increase of 25-OHD was noted only in the deficient group (P = 0.017). Postoperatively, there were 18 patients in the deficient group, 8 patients in the insufficient group, and 5 patients in the normal group. In the postoperative deficient group, postoperative ODI scores and EQ-5D index scores showed significantly worse outcomes than those in the other groups. The changes in serum 25-OHD level were significantly correlated with the changes in ODI scores (r = −0.580; P = 0.001) and with the changes in EQ-5D index scores (r = 0.379; P = 0.035). In all the groups, postoperative ODI scores (r = −0.665; P < 0.001) and EQ-5D index scores (r = 0.601; P < 0.001) were significantly correlated with postoperative 25-OHD level. Vitamin D deficiency was common in patients with LSS. However, vitamin D status was improved after decompressive surgery, and postoperative 25-OHD level was significantly correlated with surgical outcomes.