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• Systematic training and structured protocol are required to conduct measurement. • Complicated methods and intervertebral disc degeneration affected the inter-rater agreement on measurements. • Method 7 is the best reproducible method to measure disc height index for all intervertebral disc segmental levels with a good-to-excellent intra- and inter-rater reliability and agreement. To evaluate intra- and inter-rater agreement and reliability of seven reported disc height index (DHI) measurement methods on standing lateral X-ray of lumbar spine. The adult patients who had standing lateral X-ray of lumbar spine were recruited. Seven methods were used to measure DHI of each lumbar intervertebral disc level, including a ratio of sum of anterior and posterior disc height (DH) to disc diameter (Method 1), a ratio of middle DH to mid-vertebral body height (Method 2), a ratio of middle DH to disc diameter (Method 3), a ratio of the mean of anterior, middle, and posterior DH to the sagittal diameter of the proximal vertebral body (Method 4), a ratio of DH to vertebral height which cross the centre of adjacent vertebral bodies (Method 5), a ratio of the mean of anterior, middle, and posterior DH to the mean of proximal and distal vertebral body height (Method 6), and a ratio of the sum of anterior and posterior DH to the sum of superior and inferior disc depth (Method 7). Two raters conducted the measurements (one medical student (SS) and the other an experienced spine surgeon (XC)). Bland and Altmańs Limits of Agreement (LOA) with standard difference were calculated to examine intra- and inter-rater agreements between two out of seven methods for DHI. Intra-class correlations (ICC) with 95% confidence intervals were calculated to assess intra- and inter-rater reliability. The intra-rater reliability in DHI measurements for 288 participants were ICCs from 0.807 (0.794, 0.812) to 0.922 (0.913, 0.946) by rater 1 (SS) and from 0.827 (0.802, 0.841) to 0.918 (0.806, 0.823) by rater 2 (XC). Method 2, 3, and 5 on all segmental levels had bias (95 % CI does not include zero) or/and out of the acceptable cut-off proportion (>50 %). A total of 609 outliers in 9174 segmental levels' LOA range. Inter-rater reliability was good-to-excellent in all but method 2 (0.736 (0.712, 0.759)) and method 5 (0.634 (0.598, 0.667)). ICCs of related lines to good-to-excellent reliability methods was excellent in all but only indirect lines in method 1 and 4 (ICCs lie in the range from 0.8 to 0.9). Following a structured protocol, intra- and inter-rater reliability was good-to-excellent for most DHI measurement methods on X-ray. However, the complicated methods (more indirect lines) and IVD degeneration (nucleus pulposus degeneration and disc herniation) potentially affected the agreement on inter-rater measurements. Method 7 is the best reproducible method to measure disc height index for all intervertebral disc segmental levels with a good-to-excellent intra- and inter-rater reliability and agreement. [ABSTRACT FROM AUTHOR]

• This article discusses direct lateral interbody fusion in patients with osteopenia. • Clinical and radiological outcomes were comparable in the osteopenia group. • DLIF is a reliable procedure for patients with osteopenia. Subsidence of the interbody graft into the vertebral bodies is one of the major complications of direct lateral interbody fusion (DLIF), resulting in pseudoarthrosis and severe pain. Low bone mineral density (BMD) has been known to increase the risk of subsidence. This study aims to determine whether or not the osteopenia should influence the surgical results in DLIF surgery. We retrospectively reviewed the data collected prospectively on all patients who underwent single-level DLIF at our institution. A total of 84 patients were included in this study, comprised of 41 in the osteopenia group and 43 in the normal BMD group. The clinical and radiologic characteristics were compared at preoperative and postoperative 1 and 2 years. At postoperative two years, there was a statistically significant difference in disc height and intervertebral foramen height at index level between the two groups (p = 0.039, 0.044, respectively), but there was no significant difference in total lumbar lordosis (p = 0.179). At 24-month postoperative, 92.7% of the osteopenia group and 95.3% of the normal BMD group were solidly fused (p = 0.672). All postoperative clinical scores (VAS back pain, VAS leg pain, and ODI) improved similarly in both groups without significant difference. The overall incidence of cage subsidence with >3 mm was 17.1% in the osteopenia group and 9.3% in the normal BMD group (p = 0.345). Patients with osteopenia who undergo single-level DLIF combined with posterior fixation exhibited comparable clinical and radiological outcomes as patients with normal BMD. [ABSTRACT FROM AUTHOR]

We analysed 100 patients following anterior cervical discectomy and fusion with interbody stabilisation with PEEK cages. Radiographs obtained preoperatively and during the 12-month follow-up were compared to track changes in overall and local cervical lordosis and disk space height. Subsidence was defined as cage migration ≥ 3 mm into the adjacent endplates. Mean change in operated disk space height was 1.13 ± 1.33 mm. Subsidence was detected in 10.23% of the operated spaces. Mean change in overall cervical lordosis was 1.31 ± 5.71 degrees, and mean change in local lordosis was 0.19 ± 4.71 degrees. Change in overall cervical lordosis correlated with change in local lordosis (r = 0.61, p < 0.01). The greatest changes in lordosis and disk space height were noted immediately post-surgery. Baseline values were approximated gradually over time, but the post-operative values at 12 months were still higher than baseline. Disk space height change did not correlate with changes in patient-reported pain intensity at baseline (VAS 0) vs. at 12 months post-operatively (VAS 12) (r = 0.12, p < 0.05) or changes in the Neck Disability Index (NDI) at baseline (NDI 0) vs. at 12 months post-operatively (NDI 12) (r = −0.02, p = 0.05). Changes in overall cervical lordosis did not directly influence treatment outcomes assessed by comparing VAS 0 vs. VAS 12 (r = 0.13, p = 0.24) or NDI 0 vs. NDI 12 (r = −0.0005, p = 0.96). Surgical outcomes depend primarily on adequate decompression of the spinal cord and nerve roots. Post-operative radiological changes did not directly influence patients’ pain level or quality of life. [ABSTRACT FROM AUTHOR]

The purpose of this study was to find whether excessive distraction of the disc space for cage insertion was a risk factor for adjacent segment degeneration (ASD) after anterior cervical decompression and fusion (ACDF). One hundred and sixteen consecutive patients who underwent ACDF for single-level cervical disc herniation between June 2006 and November 2008 were retrospectively reviewed. Preoperative, postoperative and final follow-up disc height (DH), sagittal segmental alignment (SSA), and sagittal alignment of the cervical spine (SACS) were measured and compared between the ASD group and non-ASD group. In 116 patients, ASD was radiographically proven in 28 (24.1%) patients. The clinical outcomes were significantly improved compared to the preoperative scores in both groups. However, the postoperative and final follow-up DH of the ASD group were significantly higher than in the non-ASD group ( p < 0.05). In addition, the postoperative DH was significantly correlated with the postoperative or final follow-up SSA ( p < 0.05). However, postoperative DH was not found to significantly correlate with postoperative or final follow-up SACS ( p = 0.072 and p = 0.096, respectively). Multivariate analysis showed that postoperative DH was the most significant risk factor for ASD. The clinical outcomes of ACDF for single-level degenerative cervical disc disease were satisfactory. Postoperative DH (the distracted distance) had the greatest impact on the incidence of ASD. Excessive disc space distraction is a considerable risk factor for the development of radiographic ASD. [ABSTRACT FROM AUTHOR]

Disc height has been described as indicator of disc degeneration and regeneration. This study reviews a single surgeon's series of anterior cervical discectomy and interbody cage implantation. The aim of this study was to examine the disc height of the adjacent segment before surgery and at follow-up and to determine the influence on clinical outcome.Lateral radiographs were used to evaluate postoperative intervertebral height. The disc height was measured with a ruler. Only 1 cranial adjacent segment was studied. On each radiograph, the posterior height of the body and the height of the operated disc space were measured. The ratio between these 2 measurements was taken.The preoperative posterior height of the body to the height of the adjacent disc space ratio was 0.31±0.11, which postoperatively decreases to 0.30±0.008. The difference from preoperative to postoperative adjacent disc height was statistically significant (P=0.000).A longer period of evaluation is needed, to see if all these radiographic changes will translate to symptomatic adjacent-level disease. [ABSTRACT FROM AUTHOR]

Electroacupuncture (EA) has long been used as conservative treatment for low back pain (LBP). Its effect on relief of back pain has been demonstrated in many clinical studies. However, whether it has any effect on the biological properties of an intervertebral disc, which is one of the major causes of LBP, is still unclear. The aim of this study was, therefore, to investigate the effects of EA with different simulation frequencies on an intervertebral disc with simulated degeneration using an in vivo rat tail model. In this study, 33 rats were used. Disc degeneration was simulated in the rat caudal 8–9 disc via continuous static compressive loading of 11 N for 2 weeks. EA with a frequency of 2 or 100 Hz was then applied to the degenerated disc for 3 weeks with 3 sessions/week and 20 min/session. The intervertebral disc height was measured before and after compression as well as after EA intervention for 3 weeks. The static compression was found to result in a reduction in the disc height of about 22 per cent. There was no evidence that this change could be reversed after resting or the EA intervention. However, EA at 100 Hz was found to induce a further decrease in disc height, which was not shown for the rats after resting or EA at 2 Hz. The results of this study showed that effects of EA on disc degeneration are frequency dependent and adverse effects could result if EA at a certain frequency was used. [ABSTRACT FROM AUTHOR]