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OBJECTIVE: Although minimally invasive endoscopic surgery techniques are established standard treatment choices for various degenerative conditions of the lumbar spine, the surgical indications of such techniques for specific cases, such as segments with ossification of the ligamentum flavum (OLF) or calcification of the ligamentum flavum (CLF), remain under investigation. Therefore, the authors aimed to demonstrate the short-term outcomes of minimally invasive endoscopic surgery in patients with degenerative lumbar disease with CLF or OLF. METHODS: This is a retrospective cohort study including consecutive patients who underwent microendoscopic posterior decompression at the authors' institution, where the presence of OLF and CLF did not influence the surgical indication. Fifty-nine patients with OLF and 39 patients with CLF on preoperative CT were identified from the database. Subsequently, two matched control groups (one each matched to the OLF and CLF groups) were created using propensity scores to adjust for age, sex, preoperative Japanese Orthopaedic Association (JOA) score and Oswestry Disability Index, and diagnosis. The background, surgical outcomes, and changes in clinical scores were compared between the matched groups. If there was a significant difference in the improvement of clinical scores, a multivariate linear regression model was applied. RESULTS: On performing univariate analysis, patients with OLF were found to have a higher body mass index (Mann-Whitney U-test, p = 0.001), higher incidence of preoperative motor weakness (chi-square test, p = 0.019), longer operative time (Mann-Whitney U-test, p < 0.001), and lower improvement in the JOA score (mixed-effects model, p = 0.023) than the matched controls. On performing multivariate analysis, the presence of OLF was identified as an independent variable associated with a poor recovery rate based on the JOA score (multivariate linear regression, p < 0.001). In contrast, there were no significant differences between patients with CLF and their matched controls in terms of preoperative and surgical data and postoperative improvements in clinical scores. CONCLUSIONS: Although the perioperative surgical outcomes, including the surgical complications, and the in-hospital period did not significantly differ, the short-term improvement in the JOA score was significantly lower in patients with degenerative lumbar disease accompanied by OLF than in the patients from the matched control group. In contrast, there were no significant differences in the short-term improvement in clinical scores and perioperative outcomes between patients with CLF and their matched control group. Thus, the surgical indications of minimally invasive posterior decompression for patients with CLF can be the same as those for patients without CLF; however, the indications for patients with OLF should be further investigated in future studies, including the other surgical methods.

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OBJECTIVE: Although increased signal intensity (ISI) on MRI is observed in patients with cervical spinal cord injury (SCI) without major bone injury, alterations in ISI have not been evaluated. The association between postoperative ISI and surgical outcomes remains unclear. This study elucidated whether or not the postoperative classification and alterations in MRI-based ISI of the spinal cord reflected the postoperative symptom severity and surgical outcomes in patients with SCI without major bone injury. METHODS: One hundred consecutive patients with SCI without major bone injury (79 male and 21 female) with a mean age of 55 years (range 20-87 years) were included. All patients were treated with laminoplasty and underwent MRI pre- and postoperatively (mean 12.5 ± 0.8 months). ISI was classified into three groups on the basis of sagittal T2-weighted MRI: grade 0, none; grade 1, light (obscure); and grade 2, intense (bright). The neurological statuses were evaluated according to the Japanese Orthopaedic Association (JOA) scoring system and the American Spinal Injury Association Impairment Scale (AIS). RESULTS: Preoperatively, 8 patients had grade 0 ISI, 49 had grade 1, and 43 had grade 2; and postoperatively, 20 patients had grade 0, 24 had grade 1, and 56 had grade 2. The postoperative JOA scores and recovery rate (RR) decreased significantly with increasing postoperative ISI grade. The postoperative ISI grade tended to increase with the postoperative AIS grade. Postoperative grade 2 ISI was observed in severely paralyzed patients. The postoperative ISI grade improved in 23 patients (23%), worsened in 25 (25%), and remained unchanged in 52 (52%). Patients with an improved ISI grade had a better RR than those with a worsened ISI grade. CONCLUSIONS: Postoperative ISI reflected postoperative symptom severity and surgical outcomes. Alterations in ISI were seen postoperatively in 48 patients (48%) and were associated with surgical outcomes.

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OBJECTIVE: The purpose of this study was to compare the clinical results of revision interbody fusion surgery between lateral lumbar interbody fusion (LLIF) and posterior lumbar interbody fusion (PLIF) or transforaminal lumbar interbody fusion (TLIF) with propensity score (PS) adjustments and to investigate the efficacy of indirect decompression with LLIF in previously decompressed segments on the basis of radiological assessment. METHODS: A retrospective study of patients who underwent revision surgery for recurrence of neurological symptoms after posterior decompression surgery was performed. Postoperative complications and operative factors were evaluated and compared between LLIF and PLIF/TLIF. Moreover, postoperative improvement in cross-sectional areas (CSAs) in the spinal canal and intervertebral foramen was evaluated in LLIF cases. RESULTS: A total of 56 patients (21 and 35 cases of LLIF and PLIF/TLIF, respectively) were included. In the univariate analysis, the LLIF group had significantly more endplate injuries (p = 0.03) and neurological deficits (p = 0.042), whereas the PLIF/TLIF group demonstrated significantly more dural tears (p < 0.001), surgical site infections (SSIs) (p = 0.02), and estimated blood loss (EBL) (p < 0.001). After PS adjustments, the LLIF group still showed significantly more endplate injuries (p = 0.03), and the PLIF/TLIF group demonstrated significantly more dural tears (p < 0.001), EBL (p < 0.001), and operating time (p = 0.04). The PLIF/TLIF group showed a trend toward a higher incidence of SSI (p = 0.10). There was no statistically significant difference regarding improvement in the Japanese Orthopaedic Association scores between the 2 surgical procedures (p = 0.77). The CSAs in the spinal canal and foramen were both significantly improved (p < 0.001). CONCLUSIONS: LLIF is a safe, effective, and less invasive procedure with acceptable complication rates for revision surgery for previously decompressed segments. Therefore, LLIF can be an alternative to PLIF/TLIF for restenosis after posterior decompression surgery.

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OBJECTIVE: Persistent lumbar foraminal stenosis (LFS) is one of the most common reasons for poor postoperative outcomes and is a major contributor to "failed back surgery syndrome." The authors describe a new surgical strategy for LFS based on anatomical considerations using 3D image fusion with MRI/CT analysis. METHODS: A retrospective review was conducted on 78 consecutive patients surgically treated for LFS at the lumbosacral junction (2013-2017). The location and extent of stenosis, including the narrowest site and associated pathology (bone or soft tissue), were measured using 3D image fusion with MRI/CT. Stenosis was defined as medial intervertebral foraminal (MF; inner edge to pedicle center), lateral intervertebral foraminal (LF; pedicle center to outer edge), or extraforaminal (EF; outside the pedicle). Lumbar (low-back pain, leg pain) and patient satisfaction visual analog scale (VAS) scores and Japanese Orthopaedic Association (JOA) scores were evaluated. Surgical outcome was evaluated 2 years postoperatively. RESULTS: Most instances of stenosis existed outside the pedicle's center (94%), including LF (58%), EF (36%), and MF (6%). In all MF cases, stenosis resulted from soft-tissue structures. The narrowest stenosis sites were localized around the pedicle's outer border. The areas for sufficient nerve decompression were extended in MF+LF (10%), MF+LF+EF (14%), LF+EF (39%), LF (11%), and EF (26%). No iatrogenic pars interarticularis damage occurred. The JOA score was 14.9 ± 2.6 points preoperatively and 22.4 ± 3.5 points at 2 years postoperatively. The JOA recovery rate was 56.0% ± 18.6%. The VAS score (low-back and leg pain) was significantly improved 2 years postoperatively (p < 0.01). According to patients' self-assessment of the minimally invasive surgery, 62 (79.5%) chose "surgery met my expectations" at follow-up. Nine patients (11.5%) selected "I did not improve as much as I had hoped but I would undergo the same surgery for the same outcome." CONCLUSIONS: Most LFS existed outside the pedicle's center and was rarely noted in the pars region. The main regions of stenosis were localized to the pedicle's outer edge. Considering this anatomical distribution of LFS, the authors recommend that lateral fenestration should be the first priority for foraminal decompression. Other surgical options including foraminotomy, total facetectomy, and hemilaminectomy likely require more bone resections than LFS treatment. The microendoscopic surgery results were very good, indicating that this minimally invasive surgery was suitable for treating this disease.

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OBJECTIVE: Cigarette smoking has been known to increase the risk of pseudarthrosis in spinal fusion. However, there is a paucity of data on the effects of smoking in dynamic stabilization following lumbar spine surgery. This study aimed to investigate the clinical outcomes and the incidence of screw loosening among patients who smoked. METHODS: Consecutive patients who had lumbar spondylosis, recurrent disc herniations, or low-grade spondylolisthesis that was treated with 1- or 2-level surgical decompression and pedicle screw-based Dynesys dynamic stabilization (DDS) were retrospectively reviewed. Patients who did not complete the minimum 2 years of radiological and clinical evaluations were excluded. All screw loosening was determined by both radiographs and CT scans. Patient-reported outcomes, including visual analog scale (VAS) scores of back and leg pain, Japanese Orthopaedic Association (JOA) scores, and Oswestry Disability Index (ODI), were analyzed. Patients were grouped by smoking versus nonsmoking, and loosening versus intact screws, respectively. All radiological and clinical outcomes were compared between the groups. RESULTS: A total of 306 patients (140 women), with a mean age of 60.2 ± 12.5 years, were analyzed during an average follow-up of 44 months. There were 34 smokers (9 women) and 272 nonsmokers (131 women, 48.2% more than the 26.5% of smokers, p = 0.017). Postoperatively, all the clinical outcomes improved (e.g., VAS back and leg pain, JOA scores, and ODI, all p < 0.001). The overall rate of screw loosening was 23.2% (71 patients), and patients who had loosened screws were older (61.7 ± 9.6 years vs 59.8 ± 13.2 years, p = 0.003) and had higher rates of diabetes mellitus (33.8% vs 21.7%, p = 0.038) than those who had intact DDS screws. Although the patients who smoked had similar clinical improvement (even better VAS scores in their legs, p = 0.038) and a nonsignificantly lower rate of screw loosening (17.7% and 23.9%, p = 0.416), the chances of secondary surgery for adjacent segment disease (ASD) were higher than for the nonsmokers (11.8% vs 1.5%, p < 0.001). CONCLUSIONS: Smoking had no adverse effects on the improvements of clinical outcomes in the pedicle screw-based DDS surgery. For smokers, the rate of screw loosening trended lower (without significance), but the chances of secondary surgery for ASD were higher than for the nonsmoking patients. However, the optimal surgical strategy to stabilize the lumbar spine of smoking patients requires future investigation.

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OBJECTIVE: Vertebral body sliding osteotomy (VBSO) is a safe, novel technique for anterior decompression in patients with multilevel cervical spondylotic myelopathy. Another advantage of VBSO may be the restoration of cervical lordosis through multilevel anterior cervical discectomy and fusion (ACDF) above and below the osteotomy level. This study aimed to evaluate the improvement and maintenance of cervical lordosis and sagittal alignment after VBSO. METHODS: A total of 65 patients were included; 34 patients had undergone VBSO, and 31 had undergone anterior cervical corpectomy and fusion (ACCF). Preoperative, postoperative, and final follow-up radiographs were used to evaluate the improvements in cervical lordosis and sagittal alignment after VBSO. C0-2 lordosis, C2-7 lordosis, segmental lordosis, C2-7 sagittal vertical axis (SVA), T1 slope, thoracic kyphosis, lumbar lordosis, sacral slope, pelvic tilt, and Japanese Orthopaedic Association scores were measured. Subgroup analysis was performed between 15 patients with 1-level VBSO and 19 patients with 2-level VBSO. Patients with 1-level VBSO were compared to patients who had undergone 1-level ACCF. RESULTS: C0-2 lordosis (41.3° ± 7.1°), C2-7 lordosis (7.1° ± 12.8°), segmental lordosis (3.1° ± 9.2°), and C2-7 SVA (21.5 ± 11.7 mm) showed significant improvements at the final follow-up (39.3° ± 7.2°, 13° ± 9.9°, 15.2° ± 8.5°, and 18.4 ± 7.9 mm, respectively) after VBSO (p = 0.049, p < 0.001, p < 0.001, and p = 0.038, respectively). The postoperative segmental lordosis was significantly larger in 2-level VBSO (18.8° ± 11.6°) than 1-level VBSO (10.3° ± 5.5°, p = 0.014). The final segmental lordosis was larger in the 1-level VBSO (12.5° ± 6.2°) than the 1-level ACCF (7.2° ± 7.6°, p = 0.023). Segmental lordosis increased postoperatively (p < 0.001) and was maintained until the final follow-up (p = 0.062) after VBSO. However, the postoperatively improved segmental lordosis (p < 0.001) decreased at the final follow-up (p = 0.045) after ACCF. CONCLUSIONS: Not only C2-7 lordosis and segmental lordosis, but also C0-2 lordosis and C2-7 SVA improved at the final follow-up after VBSO. VBSO improves segmental cervical lordosis markedly through multiple ACDFs above and below the VBSO level, and a preserved vertebral body may provide more structural support.

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OBJECTIVE: Percutaneous transforaminal endoscopic discectomy (PTED) is usually performed under fluoroscopic guidance and is associated with a large radiation dose. Ultrasonography (US)-MR image fusion navigation combines the advantages of US and MRI and requires significantly less radiation than fluoroscopy. The purpose of this study was to evaluate the safety and effectiveness of US-MR image fusion navigation for PTED. METHODS: From January to September 2018, patients with L4-5 lumbar disc herniation requiring PTED were randomized to have the procedure conducted with US-MR image fusion navigation or fluoroscopy. The number of fluoroscopies, radiation dose, duration of imaging guidance, intraoperative visual analog scale (VAS) pain score, intraoperative complications, and clinical outcomes were compared between the groups. RESULTS: There were 10 patients in the US-MR navigation group and 10 in the fluoroscopy group, and there were no significant differences in age, sex ratio, or BMI between the 2 groups (all p > 0.05). Intraoperatively, the total radiation dose, number of fluoroscopies performed, duration of image guidance, and VAS low-back and leg pain scores were all significantly lower in the US-MRI navigation group than in the fluoroscopy group (all p < 0.05). There were no intraoperative complications in either group. Postoperative improvements in Japanese Orthopaedic Association, Oswestry Disability Index, and VAS pain scale scores were similar between the 2 groups. CONCLUSIONS: US-MR image fusion navigation is a promising technology for performing PTED and requires significantly less radiation than fluoroscopy.Clinical trial registration no.: NCT03403244 (ClinicalTrials.gov).

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OBJECTIVE: Surgical management of massive ossification of the posterior longitudinal ligament (OPLL) is challenging. To reduce surgical complications, the authors have performed anterior selective stabilization combined with laminoplasty (antSS+LP) for massive OPLL since 2012. This study aimed to elucidate the short-term outcome of the antSS+LP procedure. METHODS: The authors' analysis was based on data from 14 patients who underwent antSS+LP for cervical myelopathy caused by massive OPLL and were followed up for at least 2 years after surgery (mean follow-up duration 3.3 years). Clinical outcome was evaluated preoperatively, at 6 months and 1 year postoperatively, and at the final follow-up using the Japanese Orthopaedic Association (JOA) scoring system for cervical myelopathy and the recovery rate of the JOA score. The following radiographic parameters were measured preoperatively, immediately after surgery, at 1 year after surgery, and at the final follow-up: the C2-7 angle, measured on lateral plain radiographs, and the segmental lordosis angle (SLA), measured on sagittal CT scans. The correlation between radiographic parameters and clinical outcomes was evaluated. RESULTS: The mean JOA score increased from 10.4 before surgery to 13.6 and 13.8 at 6 months and 1 year after surgery, respectively; at the final follow-up the mean score was 13.4. This postoperative recovery was significant (p = 0.004) and was maintained until the final follow-up. No patient required revision surgery due to postoperative neurological deterioration. However, the C2-7 angle gradually deteriorated postoperatively. Similarly, the SLA was significantly increased immediately after surgery, but the improvement was not maintained. The recovery rate at the final follow-up correlated positively with the change in C2-7 angle (r = 0.60, p = 0.03) and the change in SLA (r = 0.72, p < 0.01). CONCLUSIONS: AntSS+LP is safe and effective and may be an alternative to anterior decompression and fusion for the treatment of patients with massive OPLL. No postoperative neurological complications or significant postoperative exacerbation of neck pain were observed in our case series. Not only reducing intervertebral motion and decompressing the canal at the maximal compression level but also acquiring segmental lordosis at the maximal compression level are crucial factors for achieving successful outcomes of antSS+LP.

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OBJECTIVE: The use of indirect decompression surgery for severe canal stenosis remains controversial. The purpose of this study was to investigate the efficacy of lateral interbody fusion (LIF) without posterior decompression in degenerative lumbar spinal spondylosis with severe stenosis on preoperative MRI. METHODS: This is a retrospective case series from a single academic institution. The authors included 42 patients (45 surgical levels) who were preoperatively diagnosed with severe degenerative lumbar stenosis on MRI based on the previously published Schizas classification. These patients underwent LIF with supplemental pedicle screw fixation without posterior decompression. Surgical levels were limited to L3-4 and/or L4-5. All patients satisfied the minimum 1-year MRI follow-up. The authors compared the cross-sectional area (CSA) of the thecal sac and the clinical outcome scores (Japanese Orthopaedic Association [JOA] score) preoperatively, immediately postoperatively, and at the 1-year follow-up. Fusion status and disc height were evaluated based on CT scans obtained at the 1-year follow-up. RESULTS: The CSA improved over time, increasing from 54.5 ± 19.2 mm2 preoperatively to 84.7 ± 31.8 mm2 at 3 weeks postoperatively and to 132.6 ± 37.5 mm2 at the last follow-up (average 28.3 months) (p < 0.001). The JOA score significantly improved over time (preoperatively 16.1 ± 4.1, 3 months postoperatively 24.4 ± 4.0, and 1-year follow-up 25.7 ± 2.9; p < 0.001). The fusion rate at the 1-year follow-up was 88.8%, and disc heights were significantly restored (preoperative, 6.3 mm and postoperative, 9.6 mm; p < 0.001). Patients showing poor CSA expansion (< 200% expansion rate) at the last follow-up had a higher prevalence of pseudarthrosis than patients with significant CSA expansion (> 200% expansion rate) (25.0% vs 3.4%, p < 0.001). No major perioperative complications were observed. CONCLUSIONS: LIF with indirect decompression for degenerative lumbar disease with severe canal stenosis provided successful clinical outcomes, including restoration of disc height and indirect expansion of the thecal sac. Severe canal stenosis diagnosed on preoperative MRI itself is not a contraindication for indirect decompression surgery.

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Degenerative spondylotic myelopathy is the most common cause of spinal dysfunction, as well as nontraumatic spastic paraparesis and quadriparesis. Although conventional MRI is the gold standard for radiographic evaluation of the spinal cord, it has limited application for determining prognosis and recovery. In the last decade, diffusion tensor imaging (DTI), which is based on the property of preferential diffusion of water molecules, has gained popularity in evaluating patients with cervical spondylotic myelopathy (CSM). The use of DTI allows for evaluation of microstructural changes in the spinal cord not otherwise detected on routine conventional MRI. In this review, the authors describe the application of DTI in CSM evaluation and its role as an imaging biomarker to predict disease severity and prognosis.

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OBJECTIVE: This retrospective study aimed to clarify the influence of comorbid severe knee osteoarthritis (KOA) on surgical outcome in terms of sagittal spinopelvic/lower-extremity alignment in elderly patients with degenerative lumbar spondylolisthesis (DLS). METHODS: In total, 110 patients aged at least 65 years (27 men, 83 women; mean age 74.0 years) who underwent short-segment lumbar fusion were included in the present study. Using the Kellgren-Lawrence (KL) grading system, patients were categorized into those with no to mild KOA (the mild-OA group: KL grades 0-2), moderate KOA (moderate-OA group: KL grade 3), or severe KOA (severe-OA group: KL grade 4). Surgical results were assessed using the Japanese Orthopaedic Association (JOA) scoring system, and spinopelvic/lower-extremity parameters were compared among the 3 groups. Adjacent-segment disease (ASD) was assessed over a mean follow-up period of 4.7 years (range 2-8.1 years). RESULTS: The study cohort was split into the mild-OA group (42 patients), the moderate-OA group (28 patients), and the severe-OA group (40 patients). The severe-OA group contained significantly more women (p = 0.037) and patients with double-level listhesis (p = 0.012) compared with the other groups. No significant differences were found in mean postoperative JOA scores or recovery rate among the 3 groups. The mean postoperative JOA subscore for restriction of activities of daily living was only significantly lower in the severe-OA group compared with the other groups (p = 0.010). The severe-OA group exhibited significantly greater pelvic incidence, pelvic tilt, and knee flexion angle (KFA), along with a smaller degree of lumbar lordosis than the mild-OA group both pre- and postoperatively (all p < 0.05). Overall, the rate of radiographic ASD was observed to be higher in the severe-OA group than in the mild-OA group (p = 0.015). Patients with ASD in the severe-OA group exhibited significantly greater pelvic tilt, pre- and postoperatively, along with less lumbar lordosis, than the patients without ASD postoperatively (all p < 0.05). CONCLUSIONS: A lack of lumbar lordosis caused by double-level listhesis and knee flexion contracture compensated for by far greater pelvic retroversion is experienced by elderly patients with DLS and severe KOA. Therefore, corrective lumbar surgery and knee arthroplasty may be considered to improve sagittal alignment, which may contribute to the prevention of ASD, resulting in favorable long-term surgical outcomes.

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OBJECTIVE: Compression of the spinal cord by thoracic ossification of the posterior longitudinal ligament (T-OPLL) often causes severe thoracic myelopathy. Although surgery is the most effective treatment for T-OPLL, problems associated with surgical intervention require resolution because surgical outcomes are not always favorable, and a small number of patients experience deterioration of their neurological status after surgery. The aim of the present study was to examine the surgery-related risk factors contributing to poor clinical outcomes for myelopathy caused by T-OPLL. METHODS: Data were extracted from the records of 55 patients with thoracic myelopathy due to T-OPLL at institutions in the Fukuoka Spine Group. The mean follow-up period was 5.3 years. Surgical outcomes were assessed using the Japanese Orthopaedic Association (JOA) scale. To investigate the definitive factors associated with surgical outcomes, univariate and multivariate regression analyses were performed with several patient-related and surgery-related factors, including preoperative comorbidities, radiological findings, JOA score, surgical methods, surgical outcomes, and complications. RESULTS: Neurological status improved in 33 patients (60.0%) and deteriorated in 10 patients (18.2%) after surgery. The use of instrumentation was significantly associated with an improved outcome. In the comparison of surgical approaches, posterior decompression and fusion resulted in a significantly higher neurological recovery rate than did anterior decompression via a posterior approach and fusion or decompression alone. It was also found that postoperative neurological status was significantly poorer when there were fewer instrumented spinal levels than decompression levels. CSF leakage was a predictable risk factor for deterioration following surgery. CONCLUSIONS: It is important to identify preventable risk factors for poor surgical outcomes for T-OPLL. The findings of the present study suggest that intraoperative CSF leakage and a lower number of instrumented spinal fusion levels than decompression levels were exacerbating factors for the neurological improvement in T-OPLL surgery.

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OBJECTIVE: The pathomechanism of C5 palsy after cervical open-door laminoplasty is unknown despite the relatively common occurrence of this condition postoperatively. The aim of this study was to review clinical and imaging findings in patients with C5 palsy and to propose countermeasures for prevention of this complication. METHODS: Between 2001 and 2018, 326 patients with cervical myelopathy underwent cervical laminoplasty at the authors' hospital, 10 (3.1%) of whom developed C5 palsy. Clinical features and radiological findings of patients with and without C5 palsy were analyzed. RESULTS: In patients with C5 palsy, the width of the C5 intervertebral foramen was narrower and the position of the bony gutter was wider beyond the medial part of the C5 facet joint. The distance between the lateral side of the spinal cord and bony gutter was significantly greater in patients with C5 palsy. Patient characteristics, disease, cervical alignment, spinal canal expansion rate, anterior protrusion of the C5 superior articular process, high-intensity area in the spinal cord on T2-weighted MR images, posterior shift of the spinal cord, and operative time did not differ significantly between patients with and without C5 palsy. CONCLUSIONS: The position of the bony gutter may have a central role in the pathomechanism of postoperative C5 palsy, especially in patients with a narrow C5 intervertebral foramen. Making an excessively lateral bony gutter might be a cause of C5 nerve root kinking at the intervertebral foramen. To prevent the occurrence of C5 palsy, it is important to confirm the medial line of the facet joint on the preoperative CT scan, and a high-speed burr should be started from inside of the facet joint and manipulated in a direction that allows the ligamentum flavum to be identified.

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OBJECTIVE: The objective of this study was to investigate the relationship between morphological changes in thoracic ossification of the posterior longitudinal ligament (T-OPLL) and postoperative neurological recovery after thoracic posterior fusion surgery. Changes of OPLL morphology and postoperative recovery in cases with T-OPLL have not been examined. METHODS: In this prospective study, the authors evaluated data from 44 patients (23 male and 21 female) who underwent posterior decompression and fusion surgery with instrumentation for the treatment of T-OPLL at our hospital. The patients' mean age at surgery was 50.7 years (range 38-68 years). The minimum duration of follow-up was 2 years. The location of thoracic ossification of the ligamentum flavum (T-OLF), T-OLF at the OPLL level, OPLL morphology, fusion range, estimated blood loss, operative time, pre- and postoperative Japanese Orthopaedic Association (JOA) scores, and JOA recovery rate were investigated. Reconstructed sagittal multislice CT images were obtained before and at 3 and 6 months and 1 and 2 years after surgery. The basic fusion area was 3 vertebrae above and below the OPLL lesion. All parameters were compared between patients with and without continuity across the disc space at the OPLL at 3 and 6 months after surgery. RESULTS: The preoperative morphology of OPLL was discontinuous across the disc space between the rostral and caudal ossification regions on sagittal CT images in all but one of the patients. Postoperatively, these segments became continuous in 42 patients (97.7%; occurring by 6.6 months on average) without progression of OPLL thickness. Patients with continuity at 3 months had significantly lower rates of diabetes mellitus (p < 0.05) and motor palsy in the lower extremities (p < 0.01). The group with continuity also had significantly higher mean postoperative JOA scores at 3 (p < 0.01) and 6 (p < 0.05) months and mean JOA recovery rates at 3 and 6 months (both p < 0.01) after surgery. CONCLUSIONS: Preoperatively, discontinuity of rostral and caudal ossified lesions was found on CT in all patients but one of this group of 44 patients who needed surgery for T-OPLL. Rigid fixation with instrumentation may have allowed these segments to connect at the OPLL. Such OPLL continuity at an early stage after surgery may accelerate spinal cord recovery.

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OBJECTIVE: Cortical bone trajectory (CBT) screw insertion through a caudomedial starting point provides advantages in limiting dissection of the superior facet joints and reducing muscle dissection and the risk of superior-segment facet violation by the screw. These advantages of the cephalad CBT screw can result in lower rates of early cephalad adjacent segment degeneration (ASD) after posterior lumbar interbody fusion (PLIF) with CBT screw fixation (CBT-PLIF) than those after PLIF using traditional trajectory screw fixation (TT-PLIF). Here, the authors investigated early cephalad ASD after CBT-PLIF and compared these results with those after TT-PLIF. METHODS: The medical records of all patients who had undergone single-level CBT-PLIF or single-level TT-PLIF for degenerative lumbar spondylolisthesis (DLS) and with at least 3 years of postsurgical follow-up were retrospectively reviewed. At 3 years postoperatively, early cephalad radiological ASD changes (R-ASD) such as narrowing of disc height (> 3 mm), anterior or posterior slippage (> 3 mm), and posterior opening (> 5°) were examined using lateral radiographs of the lumbar spine. Early cephalad symptomatic adjacent segment disease (S-ASD) was diagnosed when clinical symptoms such as leg pain deteriorated during postoperative follow-up and the responsible lesion suprajacent to the fused segment was confirmed on MRI. RESULTS: One hundred two patients underwent single-level CBT-PLIF for DLS and were followed up for at least 3 years (CBT group). As a control group, age- and sex-matched patients (77) underwent single-level TT-PLIF for DLS and were followed up for at least 3 years (TT group). The total incidence of early cephalad R-ASD was 12.7% in the CBT group and 41.6% in the TT group (p < 0.0001). The incidence of narrowing of disc height, anterior slippage, and posterior slippage was significantly lower in the CBT group (5.9%, 2.0%, and 4.9%) than in the TT group (16.9%, 13.0%, and 14.3%; p < 0.05). Early cephalad S-ASD developed in 1 patient (1.0%) in the CBT group and 3 patients (3.9%) in the TT group; although the incidence was lower in the CBT group than in the TT group, no significant difference was found between the two groups. CONCLUSIONS: CBT-PLIF, as compared with TT-PLIF, significantly reduced the incidence of early cephalad R-ASD. One of the main reasons may be that cephalad CBT screws reduced the risk of proximal facet violation by the screw, which reportedly can increase biomechanical stress and lead to destabilization at the suprajacent segment to the fused segment.

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OBJECTIVE: Preoperative mood disorders such as depression and anxiety are known to be associated with poor health-related quality of life (HRQOL) outcomes after lumbar spine surgery. However, the effects of preoperative depression and anxiety on postoperative HRQOL outcomes and patient satisfaction in cervical compressive myelopathy are yet to be clarified. This study aimed to investigate the effect of depression and anxiety on HRQOL outcomes and patient satisfaction following surgery for cervical compressive myelopathy. METHODS: The authors reviewed the cases of all consecutive patients with cervical compressive myelopathy who had undergone surgical treatment in the period between January 2012 and March 2017 at their institution. Using the Hospital Anxiety and Depression Scale (HADS), the authors classified patients as depressed (HADS-D+) or not depressed (HADS-D-) and anxious (HADS-A+) or not anxious (HADS-A-). Patient HRQOL was evaluated preoperatively and at the end of at least 1 year after surgery using the physical and mental component summaries of the SF-12 Health Survey, EQ-5D (EuroQol health survey of five dimensions), Neck Disability Index, and Japanese Orthopaedic Association scale. Patient satisfaction was evaluated on the basis of a seven-item questionnaire and divided into two categories: satisfied and dissatisfied. Preoperative HRQOL statuses, postoperative improvements in HRQOL outcomes, and patient satisfaction were compared between the groups. RESULTS: Among the 121 patients eligible for inclusion in the study, there were 69 patients (57.0%) without depression (HADS-D-) and 52 (43.0%) with depression (HADS-D+) and 82 patients (67.8%) without anxiety (HADS-A-) and 39 (32.2%) with anxiety (HADS-A+). All patients who completed both the preoperative and postoperative questionnaires had significant postoperative improvements in all HRQOL outcomes. The HADS-D+ and HADS-A+ patients had poorer preoperative HRQOL statuses than the HADS-D- and HADS-A- patients, respectively. However, statistically significant improvements in all HRQOL outcomes were observed in both HADS-D+ and HADS-A+ patients. Patient satisfaction was comparable between the HADS-D or HADS-A groups. CONCLUSIONS: Cervical compressive myelopathy patients with preoperative depression or anxiety according to the HADS tool had worse preoperative HRQOL statuses. However, patients with cervical compressive myelopathy showed significant improvements in HRQOL outcomes and had sufficient levels of satisfaction after surgery regardless of the presence of preoperative depression or anxiety.

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OBJECTIVE: Although the importance of spinopelvic sagittal balance and its implications for clinical outcomes of spinal fusion surgery have been described, to the authors' knowledge there have been no reports of the relationship between spinopelvic alignment and clinical outcomes for 2-level posterior lumbar interbody fusion (PLIF). The purpose of this study was to elucidate the relationship between clinical outcomes and spinopelvic sagittal parameters after 2-level PLIF for 2-level degenerative spondylolisthesis (DS). METHODS: This study was limited to patients who were treated with 2-level PLIF for 2-level DS at L3-4-5. Between 2005 and 2014, 33 patients who could be followed up for at least 2 years were included in this study. The average age at the time of surgery was 72 years, and the average follow-up period was 5.6 years. Based on clinical assessments, the Japanese Orthopaedic Association (JOA) score and recovery rate were evaluated. The patients were divided into 2 groups based on the recovery rate: the good outcome group (G group; n = 19), with recovery rate ≥ 50%, and the poor outcome group (P group; n = 14) with recovery rate < 50%. Spinopelvic parameters were measured using lateral standing radiographs of the whole spine as follows: sagittal vertical axis (SVA), thoracic kyphosis (TK), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), lumbar lordosis (LL), and segmental lordosis (SL) at L3-4-5. The clinical outcomes and radiological parameters were assessed preoperatively and at the final follow-up. Radiological parameters were compared between the 2 groups. RESULTS: The mean JOA score improved significantly in all patients from 10.8 points before surgery to 19.6 points at the latest follow-up (mean recovery rate 47.7%). For radiological outcomes, no difference was observed from preoperative assessment to final follow-up in any of the spinopelvic parameters except SVA. Although no significant difference between the 2 groups was detected in any of the spinopelvic parameters, there were significant differences in the change in SL and LL (ΔSL 3.7° vs -2.1° and ΔLL 1.2° vs -5.6° for the G and P groups, respectively). In addition, the number of patients in the G group was significantly larger for the patients with ΔSL-plus than those with ΔSL-minus (p = 0.008). CONCLUSIONS: The clinical outcomes of 2-level PLIF for 2-level DS limited at L3-4-5 appeared to be satisfactory. The results indicate that acquisition of increased SL in surgery might lead to better clinical outcomes.

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OBJECTIVE: The treatment of atlantoaxial dislocation (AAD) and basilar invagination (BI) is challenging, especially in symptomatic patients with a history of previous surgery. Although seldom reported, posterior revision surgery to revise prior constructs can be advantageous over an anterior or combined approach. The authors describe their experience in performing posterior revision surgery using Goel's technique. METHODS: The authors reviewed patients with AAD and BI who had undergone previous posterior surgery at the cranio-cervical junction between January 2016 and September 2017. All of these patients underwent revision surgery from a posterior approach. The Japanese Orthopaedic Association (JOA) score was used to assess clinical symptoms before and after surgery. The distance from the tip of the odontoid to Chamberlain's line, atlantodental interval (ADI), and clivus-canal angle (CCA) were used for radiographic assessment before and after surgery. RESULTS: Twelve consecutive patients were reviewed. Prior surgeries were as follows: 4 patients (4/12) with posterior osseous decompression without fusion, 7 (7/12) with reduction and fusion without decompression, and 1 (1/12) with posterior osseous decompression and reduction and fusion. With the use of Goel's technique for revision in these cases, distraction using facet spacers afforded release of the anterior soft tissue from a posterior approach. The occiput was fixated to C2 using a cantilever technique, and autologous cancellous bone was grafted into the intraarticular joints. In all 12 patients, complete reduction of BI and AAD were achieved without injury to nerves or vessels. All patients had evidence of bony fusion on CT scans within 18 months of follow-up. CONCLUSIONS: Posterior revision surgery using Goel's technique is an effective and safe revision salvage surgery for symptomatic patients with AAD and BI.

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OBJECTIVE: Surgical management of thoracic ossification of the posterior longitudinal ligament (OPLL) remains challenging because of the anatomical complexity of the thoracic spine and the fragility of the thoracic spinal cord. Several surgical approaches have been described, but it remains unclear which of these is the most effective. The present study describes the microsurgical removal of OPLL in the middle thoracic level via the transthoracic anterolateral approach without spinal fusion, including the surgical outcome and operative tips. METHODS: Between 2002 and 2017, a total of 8 patients with thoracic myelopathy due to OPLL were surgically treated via the transthoracic anterolateral approach without spinal fusion. The surgical techniques are described in detail. Clinical outcome, surgical complications, and the pre- and postoperative thoracic kyphotic angle were assessed. RESULTS: The mean patient age at the time of surgery was 55 years (range 47-77 years). There were 5 women and 3 men. The surgically treated levels were within T3-9. The clinical symptoms and Japanese Orthopaedic Association (JOA) score improved postoperatively in 7 cases, but did not change in 1 case. The mean JOA score increased from 6.4 preoperatively to 7.5 postoperatively (recovery rate 26%). Intraoperative CSF leakage occurred in 4 cases, and was successfully treated with fibrin glue sealing and spinal drainage. The mean follow-up period was 82.6 months (range 15.3-169 months). None of the patients had deterioration of the thoracic kyphotic angle. CONCLUSIONS: Anterior decompression is the logical and ideal procedure to treat thoracic myelopathy caused by OPLL on the concave side of the spinal cord; however, this procedure is technically demanding. Microsurgery via the transthoracic anterolateral approach enables direct visualization of the thoracic ventral ossified lesion. The use of microscopic procedures might negate the need for bone grafting or spinal instrumentation.

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OBJECTIVE: The published clinical trials of cervical disc arthroplasty (CDA) have unanimously demonstrated the success of preservation of motion (average 7°-9°) at the index level for up to 10 years postoperatively. The inclusion criteria in these trials usually required patients to have evident mobility at the level to be treated (≥ 2° on lateral flexion-extension radiographs) prior to the surgery. Although the mean range of motion (ROM) remained similar after CDA, it was unclear in these trials if patients with less preoperative ROM would have different outcomes than patients with more ROM. METHODS: A series of consecutive patients who underwent CDA at the level of C5-6 were followed up and retrospectively reviewed. The indications for surgery were medically refractory cervical radiculopathy, myelopathy, or both, caused by cervical disc herniation or spondylosis. All patients were assigned to 1 of 2 groups: a less-mobile group, which consisted of those patients who had an ROM of ≤ 5° at C5-6 preoperatively, or a more-mobile group, which consisted of patients whose ROM at C5-6 was > 5° preoperatively. Clinical outcomes, including visual analog scale, Neck Disability Index, and Japanese Orthopaedic Association Scale scores, were evaluated at each time point. Radiological outcomes were also assessed. RESULTS: A total of 60 patients who had follow-up for more than 2 years were analyzed. There were 27 patients in the less-mobile group (mean preoperative ROM 3.0°) and 33 in the more-mobile group (mean ROM 11.7°). The 2 groups were similar in demographics, including age, sex, diabetes, and cigarette smoking. Both groups had significant improvements in clinical outcomes, with no significant differences between the 2 groups. However, the radiological evaluations demonstrated remarkable differences. The less-mobile group had a greater increase in ΔROM than the more-mobile group (ΔROM 5.5° vs 0.1°, p = 0.001), though the less-mobile group still had less segmental mobility (ROM 8.5° vs 11.7°, p = 0.04). The rates of complications were similar in both groups. CONCLUSIONS: Preoperative segmental mobility did not alter the clinical outcomes of CDA. The preoperatively less-mobile (ROM ≤ 5°) discs had similar clinical improvements and greater increase of segmental mobility (ΔROM), but remained less mobile, than the preoperatively more-mobile (ROM > 5°) discs at 2 years postoperatively.

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