Laminar Closure in Double-door Laminoplasty for Cervical Spondylotic Myelopathy with Nonkyphotic Alignment.

STUDY DESIGN: A retrospective case series. OBJECTIVE: The aim of this study was to investigate the incidence and clinical features of laminar closure in patients with cervical spondylotic myelopathy (CSM) based on prospectively collected data. SUMMARY OF BACKGROUND DATA: Laminar closure after single open-door laminoplasty (LAMP) has been reported to result in poor clinical outcomes. However, no studies to date have examined the underlying mechanisms and frequency of laminar closure after double-door LAMP. METHODS: This study prospectively enrolled 128 consecutive patients with CSM scheduled for double-door LAMP without a laminar spacer at our hospital between 2008 and 2013. Sagittal parameters including C2-7 angle, T1 slope, and cervical sagittal vertical axis (C-SVA), which is defined as the distance between the anterior margin of the external auditory canal plumb line and the posterior-cranial corner of the C7 vertebral body on x-ray, were calculated before and after the operation. Laminar angle was also measured on magnetic resonance images preoperatively and at 1 week and 1 year postoperatively. Laminar closure was defined as > 20% decrease in laminar angle at 1 year compared with that at 1 week postoperatively. The Japanese Orthopedic Association score for cervical myelopathy and the recovery rate determined from the preoperative and postoperative scores were evaluated as clinical outcomes. RESULTS: In total, 110 patients were completely followed up for at least 1 year (follow-up rate: 85.9%). Laminar closure was observed in six cases (5.5%) at the 1-year follow-up. The recovery rate in these six cases was significantly lower than in cases without laminar closure (16.6% vs. 45.1%, respectively). Logistic regression analysis revealed age and C-SVA as significant risk factors for postoperative laminar closure. CONCLUSION: This study is the first to investigate the incidence of laminar closure after double-door LAMP without a laminar spacer. Laminar closure occurred exclusively in elderly patients with kyphotic deformity after LAMP.Level of Evidence: 4.

Comparison of Decompression, Decompression Plus Fusion, and Decompression Plus Stabilization for Degenerative Spondylolisthesis: A Prospective, Randomized Study.

STUDY DESIGN: This is a prospective, randomized controlled trial. OBJECTIVE: To prospectively assess the long-term clinical results of decompression alone, decompression plus fusion, and decompression plus stabilization for degenerative spondylolisthesis. SUMMARY OF BACKGROUND DATA: Symptoms of lumbar spinal stenosis due to degenerative spondylolisthesis originate from compression of the dural sac or nerve root. Essentially, this condition is treated by performing a decompression of neural structures. Posterolateral lumbar fusion and posterior pedicle-based dynamic stabilization are additional techniques performed to ensure improved prognosis. However, to date, the selection of a surgical procedure for lumbar spinal stenosis due to degenerative spondylolisthesis remains debatable, especially in terms of the addition of instrumentation because of the few available prospective, randomized studies. MATERIALS AND METHODS: We randomly assigned patients who had 1 level lumbar spinal stenosis due to degenerative spondylolisthesis at the L4/5 level to undergo either decompression alone (decompression group), decompression plus fusion (fusion group), or decompression plus stabilization (stabilization group). Outcomes were assessed using the Japanese Orthopaedic Association and Visual Analogue Scale scores. RESULTS: In total, 85 patients underwent randomization. The follow-up rate at 5 years was 86.4%. The fusion and stabilization groups showed higher blood loss and a longer operative time than the decompression group. The fusion group showed longer postoperative hospital stay than the decompression group. In terms of clinical outcomes, all scores significantly improved postoperatively, and these outcomes were maintained at 5 years postoperatively in each group. There were no significant differences among the groups at 1 and 5 years postoperatively. CONCLUSIONS: Additional instrumentation operation for low-grade (<30%) degenerative spondylolisthesis did not result in superior results to decompression alone at 1 and 5 years postoperatively. LEVEL OF EVIDENCE: Level II.

A Comparative Study of Anterior Decompression With Fusion and Posterior Decompression With Laminoplasty for the Treatment of Cervical Spondylotic Myelopathy Patients With Large Anterior Compression of the Spinal Cord.

STUDY DESIGN: This is a retrospective observational single-center study. OBJECTIVES: To compare anterior decompression and fusion (ADF) and laminoplasty (LAMP) for the treatment of cervical spondylotic myelopathy (CSM) patients with large anterior compression in terms of clinical and radiologic outcomes. SUMMARY OF BACKGROUND DATA: We have reported that insufficient posterior decompression could be often seen after laminoplasty for CSM patients with preoperative anterior clearance of the spinal cord, defined as an interval <4 mm between the preoperative the modified K-line and anterior structure of the spinal canal at most compressive segment on sagittal T1-weighted magnetic resonance imaging. Here we conduct a study comparing ADF and LAMP for the treatment of CSM patients with such a risk factor. MATERIALS AND METHODS: Of the 221 consecutive CSM patients treated with either ADF or LAMP between 2008 and 2012 at our hospital, 79 patients in whom the interval was <4 mm with age ranged from 50 to 79 years were enrolled. Patients with myelopathy caused by single-level disk herniation, tumor or ossification of posterior longitudinal ligament, or patients with a history of cervical spine injury were excluded. The Japanese Orthopedic Association (JOA) scoring system for cervical myelopathy, recovery rate of the JOA score at the time of 2 years after surgery were investigated as clinical outcomes to compare these 2 groups. RESULTS: Demographics were almost similar between ADF and LAMP groups. The mean preoperative and postoperative JOA scores were 10.9 and 13.8 points for ADF group and 10.1 and 12.4 points for LAMP group, indicating that the recovery rate of JOA score was significantly greater in ADF group (49.6%) than that in LAMP group (38.2%; P=0.047). In LAMP group, spinal cord deformity was a significant predictive factor for unsatisfactory clinical outcome. CONCLUSION: ADF provided better surgical treatment for the patients with absence of preoperative anterior clearance of the spinal cord.

After repeated division, bone marrow stromal cells express inhibitory factors with osteogenic capabilities, and EphA5 is a primary candidate.

The differentiation capability of human bone marrow stromal cells (hBMSCs) is thought to deteriorate over multiple doubling processes. To clarify the deterioration mechanisms, the multilineage differentiation capabilities of short- and long-term passaged BMSCs were compared. Predictably, long-term passaged BMSCs showed reduced differentiation capacities compared to short-term passaged cells. Furthermore, a non-human primate heterotopic bone formation model demonstrated that long-term passaged BMSCs have bone formation capabilities but also exert inhibitory effects on bone formation. This finding indicated that long-term passaged BMSCs express higher levels of inhibitory factors than short-term passaged BMSCs do. Co-culture assays of short- and long-term passaged BMSCs suggested that the inhibitory signals required cell-cell contact and would therefore be expressed on the cell membrane. A microarray analysis of BMSCs identified ephrin type-A receptor 5 (EphA5) as an inhibitory factor candidate. Quantitative PCR revealed that among all members of the ephrin and Eph receptor families, only the expression of EphA5 was increased by BMSC proliferation. A gene knockdown analysis using siRNAs demonstrated that knockdown of EphA5 gene expression in long-term passaged BMSCs led to an increase in ALP mRNA expression. These results indicate that EphA5 may be a negative regulator of bone formation. A better understanding of the roles of the ephrin and Eph receptor families in hBMSCs may lead to alternative approaches for manipulating hBMSC fate. In addition, this avenue of discovery may provide new therapeutic targets and quality-control markers of the osteogenic differentiation capabilities of hBMSCs.

Massive bone reconstruction with heat-treated bone graft loaded autologous bone marrow-derived stromal cells and ß-tricalcium phosphate composites in canine models.

Bone marrow-derived stromal cells (BMSCs) contain mesenchymal stem cells that are capable of forming various mesenchymal tissues. We hypothesized that BMSCs and ß-tricalcium phosphate (ß-TCP) composites would promote the remodeling of large-sized autologous devitalized bone grafts; therefore, the aim of this study was to evaluate the effects of the composites on the remodeling of autologous devitalized bone grafts. Autologous BMSCs cultured in culture medium containing dexamethasone (10(-7) M) were loaded into porous ß-TCP granules under low-pressure. Theses BMSC/TCP composites were put into the bone marrow cavity of autologous heat-treated bone (femoral diaphysis, 65-mm long, 100°C, 30 min) and put back to the harvest site. In the contralateral side, ß-TCP without BMSC were used in the same manner as the opposite side as the control. Treatment with the BMSC/TCP composites resulted in a significant increase in thickness, bone mineral density, and matured bone volume of the cortical bone at the center of the graft compared to the control. Histological analysis showed matured regenerated bone in the BMSC loaded group. These results indicate that BMSC/TCP composites facilitated bone regeneration and maturation at the graft site of large-sized devitalized bone. This method could potentially be applied for clinical use in the reconstruction of large bone defects such as those associated with bone tumors.

Repair of large osteochondral defects in rabbits using porous hydroxyapatite/collagen (HAp/Col) and fibroblast growth factor-2 (FGF-2).

Articular cartilage has a limited capacity for self-renewal. This article reports the development of a porous hydroxyapatite/collagen (HAp/Col) scaffold as a bone void filler and a vehicle for drug administration. The scaffold consists of HAp nanocrystals and type I atelocollagen. The purpose of this study was to investigate the efficacy of porous HAp/Col impregnated with FGF-2 to repair large osteochondral defects in a rabbit model. Ninety-six cylindrical osteochondral defects 5 mm in diameter and 5 mm in depth were created in the femoral trochlear groove of the right knee. Animals were assigned to one of four treatment groups: porous HAp/Col impregnated with 50 microl of FGF-2 at a concentration of 10 or 100 microg/ml (FGF10 or FGF100 group); porous HAp/Col with 50 microl of PBS (HAp/Col group); and no implantation (defect group). The defect areas were examined grossly and histologically. Subchondral bone regeneration was quantified 3, 6, 12, and 24 weeks after surgery. Abundant bone formation was observed in the HAp/Col implanted groups as compared to the defect group. The FGF10 group displayed not only the most abundant bone regeneration but also the most satisfactory cartilage regeneration, with cartilage presenting a hyaline-like appearance. These findings suggest that porous HAp/Col with FGF-2 augments the cartilage repair process.

Effects of gamma-ray irradiation on mechanical properties, osteoconductivity, and absorption of porous hydroxyapatite/collagen.

In this study, the effects of gamma-ray irradiation on the mechanical properties, absorbability, and osteoconductivity of porous hydroxyapatite/collagen (HAp/Col) were investigated. Porous HAp/Col was exposed to 16, 25, 35, or 50 kGy of gamma-ray irradiation. The compressive elastic modulus showed irradiation dose-dependence, with a particularly pronounced decrease in the 50-kGy treatment group. An in vitro enzymatic digestion test showed that gamma-ray irradiation of porous HAp/Col resulted in accelerated degradation by collagenase. For in vivo studies, porous HAp/Col was transplanted into the back muscles or bone defects in the femoral condyle of rats. Specimens were obtained at 2, 4, and 8 weeks postoperatively. Absorption of the implants in the muscle was time- and irradiation dose-dependent, with notable absorption for the 35- and 50-kGy groups at 2 weeks. At the skeletal sites, porous HAp/Col demonstrated high osteoconductivity in all irradiation treatment groups. Interestingly, not only implant absorption but also bone formation was irradiation dose-dependent at early time points.

Isolation of osteogenic progenitor cells from trabecular bone for bone tissue engineering.

Trabecular bone fragments can be percutaneously harvested from the ilium using methods that are similar in invasiveness to aspiration of bone marrow. In this study, we investigated the use of the trabecular bone as a cell source for bone tissue engineering. Trabecular bone-derived progenitor cells (TB cells) were isolated with a simple method in which trabecular fragments were first cultured as explants, and then the cells were released by trypsin digestion and advanced to a monolayer culture. The properties of TB cells prepared in this procedure were compared with bone marrow-derived progenitor cells (BM cells). A large number of TB cells could be obtained with less variation among donors, compared with BM cells. In multiple harvests of donor tissue through the same aspiration hole at the cortex, TB cells could be more consistently obtained in primary culture. The proliferative potential of BM and TB cells was similar in serial subculture. TB cells showed a higher alkaline phosphatase expression in the surface marker analysis and greater in vitro osteogenic abilities than BM cells after the initial 14 days of culture. In in vivo bone formation studies, TB cells also showed a higher osteogenic potential than BM cells. The results of this study suggest that TB cells can be considered an attractive source for clinical bone regeneration.

Bone regeneration with autologous plasma, bone marrow stromal cells, and porous beta-tricalcium phosphate in nonhuman primates.

To potentiate the bone formation capability of bone marrow stromal cell (BMSC)/beta-tricalcium phosphate (beta-TCP) constructs, we devised an autologous plasma-based construct. We tested its effectiveness and investigated the effects of its components on a monkey ectopic bone formation model. The autologous plasma (platelet-rich plasma, PRP, or platelet-poor plasma, PPP)/BMSC/beta-TCP construct (R group or P group) showed significantly more bone formation at 3 and 6 weeks after implantation than a conventional BMSC/beta-TCP construct using a culture medium (M group). There was no significant difference between the P and R groups. Moreover, the P group constructs with a 10-fold lower cell concentration yielded equivalent bone formation to the M group at 5 weeks after implantation. To elucidate the effect of fibrin and serum contained in the plasma, five constructs were prepared using the following cell vehicles: autologous serum + fibrinogen (0, 1, 4, or 16 mg/mL) or phosphate-buffered saline + fibrinogen (4 mg/mL). The serum + fibrinogen (4 mg/mL, physiological concentration of monkeys) construct showed the most abundant bone formation at 3 weeks after implantation, though at 5 weeks no statistical difference existed among the groups. Autologous plasma efficiently promoted osteogenesis of BMSCs/porous beta-TCP constructs, and both fibrin and serum proved to play significant roles in the mechanism.

Fresh bone marrow introduction into porous scaffolds using a simple low-pressure loading method for effective osteogenesis in a rabbit model.

Recent advances in tissue engineering techniques have allowed porous biomaterials to be combined with osteogenic cells for effective bone regeneration. We developed a simple low-pressure cell-loading method using only syringes and stopcocks, and examined the effect of this method on osteogenesis when applied to the combination of highly porous beta-tricalcium phosphate (beta-TCP) and fresh autologous bone marrow. Both block and granule beta-TCP scaffolds were used to prepare implants in three different ways: without bone marrow as a control, with bone marrow that was allowed to penetrate spontaneously under atmospheric pressure (AP group), and with bone marrow that was seeded under low pressure (ULP group). These implants were transplanted into rabbit intramuscular sites, and the samples were examined biologically and histologically. The penetration efficiency of the block implants after marrow introduction was significantly higher in the ULP group than in the AP group. In the transplanted block samples, alkaline phosphatase activity was significantly higher in the ULP group at 2 weeks after implantation, and significantly more newly formed bone was observed in the ULP group at both 5 and 10 weeks compared with the AP group. Similar results were observed even in the experiment using beta-TCP granules, which are smaller than the blocks and frequently used clinically. Because of its convenience and safety, this low-pressure method might be a novel, effective treatment to promote osteogenesis with bone marrow in clinical bone reconstruction surgeries.

Effects of continuous dexamethasone treatment on differentiation capabilities of bone marrow-derived mesenchymal cells.

Human bone marrow-derived mesenchymal cells (hBMMCs) originate from cell populations in the bone marrow and are capable of differentiating along multiple mesenchymal lineages. To differentiate hBMMCs into osteoblasts, adipocytes and chondrocytes, dexamethasone has been used as a differentiation reagent. We hypothesized that dexamethasone would augment the responsiveness of BMMCs to other differentiation reagents and not define the lineage. This study investigated the effect of continuous treatment with 100 nM dexamethasone on the differentiation of BMMCs into three different lineages. hBMMCs cultured with continuous dexamethasone treatment (100 nM) exhibited higher mRNA expression levels of osteogenic markers and higher positive rates of colony forming unit assays for osteogenesis compared to hBMMCs treated with dexamethasone only during the differentiation culture. Furthermore, continuous dexamethasone treatment augmented bone formation capability of monkey-derived BMMCs in a bone induction experimental model at an extra skeletal site. In addition, continuously dexamethasone-treated hBMMCs formed larger chondrogenic pellets and expressed SOX9 at higher level than the control BMMCs. Likewise, continuous dexamethasone treatment facilitated adipogenic differentiation based on mRNA level and colony forming unit analysis. To investigate the mechanism of the augmentation of differentiation, further studies on apoptosis were conducted. The studies indicated that dexamethasone selectively induced apoptosis of some populations of hBMMCs which were thought to have poor differentiation capability.