The incidence of adjacent segment problems after lumbar fusion has been found to vary, and risk factors for these problems have not been precisely verified, especially based on structural changes determined by magnetic resonance imaging. The purpose of this retrospective clinical study was to describe the incidence and clinical features of adjacent segment disease (ASD) after lumbar fusion and to determine its risk factors. We assessed the incidence of ASD in patients who underwent lumbar or lumbosacral fusions for degenerative conditions between August 1995 and March 2006 with at least a 1-year followup. Patients less than 35 years of age at the index spinal fusion, patients with uninstrumented fusion, and patients who had not achieved successful union were excluded. Of the 1069 patients who underwent fusions, 28 (2.62%) needed secondary operations because of ASD and were included in this study. In order to identify the risk factors, we matched a disease group and a control group. The disease group consisted of 26 of the 28 patients with ASD, excluding the 2 patients for whom we did not have initial MRI data. Each patient in the disease group was matched by age, sex, fusion level and follow-up period with a control patient. The assumed risk factors included disc and facet degeneration, instability, listhesis, rotational deformity, and disc wedging. The mean age of the 28 patients with ASD requiring surgical treatment was 58.4 years, which did not differ significantly from that of the population in which ASD did not develop (58.2 years, p = 0.894). Of the 21 patients who underwent floating fusion, only 1 developed distal ASD. Facet degeneration was a significant risk factor (p \ 0.01) on logistic regression analysis. The incidence of distal ASD was much lower than that of proximal ASD. Pre-existing facet degeneration may be associated with a high risk of adjacent segment problems following lumbar fusion procedures.

3.

Background: Failed back surgery syndrome (FBSS) is a frequently encountered disease entity following lumbar spinal surgery. Although many plausible reasons have been investigated, the exact pathophysiology remains unknown. Various medications, reoperations, interventions such as spinal cord stimulation, epidural adhesiolysis or epidural injection, exercise therapy, and psychotherapy have been suggested treatment options. However, the evidence of the clinical outcome for each treatment has not been clearly determined. Objectives: To evaluate the outcomes of each treatment modality and to present treatment guidelines for patients with FBSS. Study Design: A systematic review of each treatment regimen in patients with FBSS. Methods: The available literature regarding each modality for the treatment of refractory back pain or radiating pain for FBSS was reviewed. The quality assessment and the level of evidence were analyzed using the “Methodology Checklist” of SIGN (Scottish Intercollegiate Guidelines Network). Data sources included relevant English language literature identified through searches of Pubmed, EMBASE, and Cochrane library from 1980 to Feb 2016. The primary outcome measure was pain relief of back pain or radiating pain for at least 3 months. Secondary outcome measures were improvement of the patient’s functional status, health-related quality of life, return to work, and reduction of opioid use. Results: Twenty-three articles were finally identified and reviewed. Based on our analysis, epidural adhesiolysis showed a short-term (6 to 24 months) effect (grade A) and spinal cord stimulation showed a mid-term (2 or 3 years) effect (grade B). Epidural injections showed a short-term (up to 2 years) effect (grade C). However, other treatments were recommended as grade D or inconclusive. Limitations: The limitations of this systematic review included the rarity of relevant literature. Conclusions: Epidural adhesiolysis or spinal cord stimulation can be effective in order to control chronic back pain or leg pain due to FBSS, and its recommendation grades are A and B, respectively. Other treatments showed poor or inconclusive evidence. Key words: Failed back surgery syndrome, post spinal surgery syndrome, chronic low back pain, post lumbar surgery syndrome, epidural adhesiolysis, spinal cord stimulation, epidural injection, revision

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The present study was performed to determine the optimal entry points and trajectories for cervical pedicle screw insertion into C3-7. The study involved 40 patients (M:F = 20:20) with various cervical diseases. A surgical simulation program was used to construct three-dimensional spine models from cervical spine axial CT images. Axial, sagittal, and coronal plane data were simultaneously processed to determine the ideal pedicle trajectory (a line passing through the center of the pedicle on coronal, sagittal, and transverse CT images). The optimal entry points on the lateral masses were then identified. Horizontal offsets and vertical offsets of the optimal entry points were measured from three different anatomical landmarks: the lateral notch, the center of the superior edge and the center of lateral mass. The transverse angle and sagittal angles of the ideal pedicle trajectory were measured. Using those entry points and trajectory results, virtual screws were placed into the pedicles using the simulation program, and the outcomes were evaluated. We found that at C3-6, the optimal entry point was located 2.0-2.4 mm medial and 0-0.8 mm inferior to the lateral notch. Since the difference of 1 mm is difficult to discern intra-operatively, for ease of remembrance, we recommend rounding off our findings to arrive at a starting point for the C3-6 pedicle screws to be 2 mm directly medial to the lateral notch. At C7, by contrast, the optimal entry point was 1.6 mm lateral and 2.5 mm superior to the center of lateral mass. Again, for ease of remembrance, we recommend rounding off these numbers to use a starting point for the C7 pedicle screws to be 2 mm lateral and 2 mm superior to the center of lateral mass. The average transverse angles were 45° at C3-5, 38° at C6, and 28° at C7. The entry points for each vertebra should be adjusted according to the transverse angles of pedicles. The mean sagittal angles were 7° upward at C3, and parallel to the upper end plate at C4-7. The simulation study showed that the entry point and ideal pedicle trajectory led to screw placements that were safer than those used in other studies.

3.

There is significant variability in sagittal profile of the cervical spine in asymptomatic children. Cervical kyphosis was found in approximately 40% of our study cohort.

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