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Hiroaki Nakamura, Yoshiki Yamano, Masahiko Seki, and Sadahiko Konishi

✓ For lesions involving the anterior and/or middle column of the spine, an anterior approach is adequate for curetting the lesion and restoring spinal stability. Materials such as autogenous bone grafts, cages with bone chips, some artificial materials, or allografts are used as strut materials. Rib material is usually removed when the anterior approach is conducted for thoracic or thoracolumbar lesions. A rib itself is not rigid enough to support the load, and a bone union is not easily obtained. The purpose of this paper is to describe a method of grafting vascularized rib in folded form to fill the defects left after removal of a spinal lesion.

The rib, with the artery and vein at two levels cranial to the involved vertebral body, was isolated from surrounding tissues such as the intercostal nerve, muscles, and pleura. After curetting the lesion, the rib was folded into three or four pieces to a length adequate to fill the defect and inserted as a pedicled vascularized graft.

A total of 23 cases, including 14 men and nine women, underwent surgery in which this grafting technique was used. The pathological conditions requiring anterior decompression and fusion were spinal trauma in nine cases, spinal infection in six cases, osteoporotic fracture in seven cases, and spinal metastasis in one case. In all cases a solid bone union was obtained and all infections resolved.

With vascularized rib graft folded into three to four pieces, solid bone union can be obtained without use of any other grafted materials even in cases of infection and osteoporosis.

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Hiromitsu Toyoda, Hiroaki Nakamura, Sadahiko Konishi, Hidetomi Terai, and Kunio Takaoka

Object. Although respiratory function is often impaired by acute cervical spinal cord injury, changes in respiratory function in patients with chronic cervical myelopathy (CCM) are not well documented. The purpose of this study was to evaluate the respiratory function of patients with CCM.

Methods. Spirometric parameters were measured in 94 patients with CCM before they underwent expansive laminoplasty. These measurements were compared with those obtained in age- and sex-matched control group patients without myelopathy. The study patients were also subdivided into two groups: those with spinal compressive lesions above or below the C3–4 disc level were compared in terms of respiratory function.

The vital capacity values measured in patients with CCM were significantly lower than those in the control group. In patients in whom spinal cord compression was present above C3–4, vital capacity values were lower than in patients in whom the compression level was below C3–4. The resting respiratory rate per minute was elevated in the CCM group. Peak expiratory flow rate was significantly decreased, and expiratory velocities at 50 and 25% of vital capacity were significantly increased in the CCM group.

Conclusions. The results indicated that expiratory flow may be impaired or incomplete in patients with CCM. An underlying subclinical respiratory dysfunction appears to be associated with CCM.

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Chikao Nagashima, Motohide Takahama, Toshikatsu Shibata, Hiroaki Nakamura, Keiichi Okada, Hitoshi Morita, and Hirokazu Kubo

✓ Three cases of cervical myeloradiculopathy associated with multiple calcified nodules containing identified calcium pyrophosphate dihydrate (CPPD) crystals in the ligamenta flava are described, with a comprehensive review of the 12 cases of this entity reported to date. The disease is characterized by: 1) oval or triangular areas of radiodensity in the posterior aspect of the cervical canal as seen in the lateral x-ray films and laminograms; 2) hemispherical areas of high density located almost symmetrically in the paramedial portion of the posterior spinal canal on computerized tomography scans; and 3) CPPD crystals in the nodules. It occurs independently or in association with cervical spondylosis or ossification of the posterior longitudinal ligament.

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Sho Dohzono, Akinobu Suzuki, Tatsuya Koike, Shinji Takahashi, Kentaro Yamada, Hiroyuki Yasuda, and Hiroaki Nakamura

OBJECTIVE

Increasing soft-tissue mass posterior to the odontoid process causes spinal cord compression. Retro-odontoid pseudotumors are considered to be associated with atlantoaxial instability in patients with rheumatoid arthritis (RA), but the exact mechanism by which these lesions develop has not been elucidated. The purpose of this study was to identify the relationships between retro-odontoid soft-tissue (ROST) thickness and radiological findings or clinical data in patients with RA.

METHODS

A total of 201 patients with RA who had been followed up at the outpatient clinic of the authors' institution were enrolled in this study. ROST thickness was evaluated on midsagittal T1-weighted MRI. The correlations between ROST thickness and radiographic findings or clinical data on RA were examined. The independent factors related to ROST thickness were analyzed using stepwise multiple regression analysis.

RESULTS

The average thickness of ROST was 3.0 ± 1.4 mm. ROST thickness showed an inverse correlation with disease duration (r = −0.329, p < 0.01), Steinbrocker stage (r = −0.284, p < 0.01), the atlantodental interval (ADI) in the neutral position (r = −0.326, p < 0.01), the ADI in the flexion position (r = −0.383, p < 0.01), and the ADI in the extension position (r = −0.240, p < 0.01). On stepwise multiple regression analysis, ADI in the flexion position and Steinbrocker stage were independent factors associated with ROST thickness.

CONCLUSIONS

Although the correlations were not strong, ROST thickness in patients with RA was inversely correlated with ADI and Steinbrocker stage. In other words, ROST thickness tends to be smaller as atlantoaxial instability and peripheral joint destruction worsen.

Clinical trial registration no.: UMIN000000980 (UMIN Clinical Trials Registry)

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Yusuke Hori, Masahiko Seki, Tadao Tsujio, Masatoshi Hoshino, Koji Mandai, and Hiroaki Nakamura

Chondromas are benign tumors that are rarely located in the spine. The authors present a rare occurrence of a spinal chondroma that developed as an intradural but extramedullary tumor in a 60-year-old woman. The location of the tumor at C4–5 was confirmed by MRI, with hyperintensity on T2-weighted images and isointensity on T1-weighted images. The tumor was completely contained intradurally, with no continuity to any vertebrae. It adhered to the anterior dura, indicative of its likely origin from the dura mater. The tumor was completely resected, with no sign of recurrence after 3 years postoperatively. Although reports of chondromas originating from the dura mater have been previously described, these have all been intracranial tumors. To the best of the authors' knowledge, this is the first report of an intradural chondroma located in the spine. Therefore, chondromas should be considered in the differential diagnosis of intradural spinal tumors.

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Akira Matsumura, Takashi Namikawa, Minori Kato, Yusuke Hori, Noriaki Hidaka, and Hiroaki Nakamura

OBJECTIVE

The object of this study was to analyze the prevalence of postoperative coronal imbalance (CIB) and related factors in patients with adult lumbar scoliosis.

METHODS

This was a retrospective single-center study of data from patients with adult spinal deformity (ASD) who had undergone corrective surgery performed by a single surgeon between 2009 and 2017. The inclusion criteria were as follows: 1) age at surgery > 40 years, 2) Cobb angles of the thoracolumbar/lumbar (TL/L) curve > 40°, 3) upper instrumented vertebra of T9 or T10, 4) lowest instrumented vertebra of L5 or the pelvis, and 5) minimum 2-year follow-up period. Radiographic parameters were measured before surgery, 2 weeks after surgery, and at the latest follow-up. Curve flexibility was also assessed using side bending radiographs. Clinical outcomes were evaluated using the 22-Item Scoliosis Research Society Outcomes Questionnaire (SRS-22) and the SF-36. CIB was considered to have occurred if the C7 plumbline was more than 2.5 cm lateral to the central sacral vertical line (i.e., coronal vertical axis [CVA] > 2.5 cm) at the final follow-up. Parameters between the patients with (CIB group) and without (coronal balance [CB] group) CIB were compared, and factors related to CIB were evaluated.

RESULTS

From among 66 consecutively treated ASD patients, a total of 37 patients (mean age at surgery 66.3 years, average follow-up 63 months) met the study inclusion criteria. CIB was found in 6 patients at the final follow-up (16.2%), and the CVA of all patients in the CIB group shifted to the convex side of the TL/L curve. A comparative analysis between the CB and CIB groups, respectively, at the final follow-up indicated the following factors were related to CIB: lumbosacral (LS) curve, 11.0°/16.5° (p = 0.02); LS correction rate (CR), 61%/47% (p = 0.02); and CR ratio (LS vs TL/L), 0.93/0.67 (p = 0.0002). Regarding clinical outcomes, the satisfaction domain of the SRS-22 (CB 4.4 vs CIB 3.5) showed a significant difference between the CIB and CB groups (p = 0.02), and patients in the CB group tended to score better on the pain domain (CB 4.3 vs CIB 3.7), but the difference was not significant (p = 0.06).

CONCLUSIONS

Postoperative CIB negatively impacted patients’ HRQOL. An imbalanced correction ratio between the TL/L and LS curves may cause postoperative CIB. Therefore, adequate correction of the LS curve may prevent postoperative CIB.

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Koji Tamai, Kunikazu Kaneda, Masayoshi Iwamae, Hidetomi Terai, Hiroshi Katsuda, Nagakazu Shimada, and Hiroaki Nakamura

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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Akira Matsumura, Takashi Namikawa, Minori Kato, Tomonori Ozaki, Yusuke Hori, Noriaki Hidaka, and Hiroaki Nakamura

The purpose of this study was to assess the clinical results of posterior corrective surgery using a multilevel transforaminal lumbar interbody fusion (TLIF) with a rod rotation (RR) and to evaluate the segmental corrective effect of a TLIF using CT imaging. The medical records of 15 consecutive patients with degenerative lumbar kyphoscoliosis (DLKS) who had undergone posterior spinal corrective surgery using a multilevel TLIF with an RR technique and who had a minimum follow-up of 2 years were retrospectively reviewed. Radiographic parameters were evaluated using plain radiographs, and segmental correction was evaluated using CT imaging. Clinical outcomes were evaluated with the Scoliosis Research Society Patient Questionnaire-22 (SRS-22) and the SF-36.

The mean follow-up period was 46.7 months, and the mean age at the time of surgery was 60.7 years. The mean total SRS-22 score was 2.9 before surgery and significantly improved to 4.0 at the latest follow-up. The physical functioning, role functioning (physical), and social functioning subcategories of the SF-36 were generally improved at the latest follow-up, although the changes in these scores were not statistically significant. The bodily pain, vitality, and mental health subcategories were significantly improved at the latest follow-up (p < 0.05).

Three complications occurred in 3 patients (20%). The Cobb angle of the lumbar curve was reduced to 20.3° after surgery. The overall correction rate was 66.4%. The pelvic incidence–lumbar lordosis (preoperative/postoperative = 31.5°/4.3°), pelvic tilt (29.2°/18.9°), and sagittal vertical axis (78.3/27.6 mm) were improved after surgery and remained so throughout the follow-up. Computed tomography image analysis suggested that a 1-level TLIF can result in 10.9° of scoliosis correction and 6.8° of lordosis.

Posterior corrective surgery using a multilevel TLIF with an RR on patients with DLKS can provide effective correction in the coronal plane but allows only limited sagittal correction.

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Kosuke Shintani, Takuya Uemura, Kiyohito Takamatsu, Takuya Yokoi, Ema Onode, Mitsuhiro Okada, and Hiroaki Nakamura

OBJECTIVE

Peripheral nerve adhesion caused by extraneural and intraneural scar formation after neurolysis leads to nerve dysfunction. The authors previously developed a novel very flexible biodegradable nerve conduit composed of poly(L-lactide) and poly(ε-caprolactone) for use in peripheral nerve regeneration. In the present study, they investigated the effect of protective nerve wrapping on preventing adhesion in a rat sciatic nerve adhesion model.

METHODS

Rat sciatic nerves were randomly assigned to one of the following four groups: a no-adhesion group, which involved neurolysis alone without an adhesion procedure; an adhesion group, in which the adhesion procedure was performed after neurolysis, but no treatment was subsequently administered; a nerve wrap group, in which the adhesion procedure was performed after neurolysis and protective nerve wrapping was then performed with the nerve conduit; and a hyaluronic acid (HA) group, in which the adhesion procedure was performed after neurolysis and nerve wrapping was then performed with a 1% sodium HA viscous solution. Six weeks postoperatively, the authors evaluated the extent of scar formation using adhesion scores and biomechanical and histological examinations and assessed nerve function with electrophysiological examination and gastrocnemius muscle weight measurement.

RESULTS

In the adhesion group, prominent scar tissue surrounded the nerve and strongly adhered to the nerve biomechanically and histologically. The motor nerve conduction velocity and gastrocnemius muscle weight were the lowest in this group. Conversely, the adhesion scores were significantly lower, motor nerve conduction velocity was significantly higher, and gastrocnemius muscle weight was significantly higher in the nerve wrap group than in the adhesion group. Additionally, the biomechanical breaking strength was significantly lower in the nerve wrap group than in the adhesion group and HA group. The morphological properties of axons in the nerve wrap group were preserved. Intraneural macrophage invasion, as assessed by the number of CD68- and CCR7-positive cells, was less severe in the nerve wrap group than in the adhesion group.

CONCLUSIONS

The nerve conduit prevented post-neurolysis peripheral nerves from developing adhesion and allowed them to maintain their nerve function because it effectively blocked scarring and prevented adhesion-related damage in the peripheral nerves.

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Ema Onode, Takuya Uemura, Kiyohito Takamatsu, Kosuke Shintani, Takuya Yokoi, Mitsuhiro Okada, and Hiroaki Nakamura

OBJECTIVE

Treatment of painful neuroma remains difficult, despite the availability of numerous surgical procedures. Recently, nerve capping treatment for painful neuroma using artificial nerve conduits has been introduced in clinical and basic research. However, the appropriate length of the nerve conduit and the pain relief mechanism have not been determined. In this study the authors aimed to investigate nerve capping treatment with a bioabsorbable nerve conduit using the rat sciatic nerve amputation model. Using histological analysis, the authors focused on the nerve conduit length and pain relief mechanism.

METHODS

Sixteen Sprague Dawley rats were evaluated for neuropathic pain using an autotomy (self-amputation) score and gross and histological changes of the nerve stump 2, 4, 8, and 12 weeks after sciatic nerve neurectomy without capping. Forty-five rats were divided into 3 experimental groups, no capping (control; n = 15), capping with a 3-mm nerve conduit (n = 15), and capping with a 6-mm nerve conduit (n = 15). All rats were evaluated using an autotomy score and nerve stump histology 12 weeks after neurectomy. The nerve conduit was approximately 0.5 mm larger than the 1.5-mm diameter of the rat sciatic nerves to prevent nerve constriction.

RESULTS

The autotomy scores gradually exacerbated with time. Without capping, a typical bulbous neuroma was formed due to random axonal regeneration 2 weeks after neurectomy. Subsequently, the adhesion surrounding the neuroma expanded over time for 12 weeks, and at the 12-week time point, the highest average autotomy scores were observed in the no-capping (control) group, followed by the 3- and the 6-mm nerve conduit groups. Histologically, the distal axonal fibers became thinner and terminated within the 6-mm nerve conduit, whereas they were elongated and protruded across the 3-mm nerve conduit. Minimal perineural scar formation was present around the terminated axonal fibers in the 6-mm nerve conduit group. Expressions of anti–α smooth muscle actin and anti–sigma-1 receptor antibodies in the nerve stump significantly decreased in the 6-mm nerve conduit group.

CONCLUSIONS

In the rat sciatic nerve amputation model, nerve capping treatment with a bioabsorbable nerve conduit provided relief from neuroma-induced neuropathic pain and prevented perineural scar formation and neuroinflammation around the nerve stump. The appropriate nerve conduit length was determined to be more than 4 times the diameter of the original nerve.