Risk management in posterior spinal endoscopic surgery in lumbar diseases.

BACKGROUND: Minimally invasive posterior spinal endoscopic surgery has increased in popularity. However, a steep learning curve may result in a high frequency of complications. Additionally, device failure may occur during routine use. We retrospectively investigated the incidence of such safety issues in a population of patients undergoing endoscopic spinal surgery at our institution. PATIENTS/MATERIALS AND METHODS: A total of 611 cases were included. Underlying diseases that required endoscopic surgery were lumbar disc herniation in 382 patients, lumbar spinal stenosis in 123 patients, lumbar degenerated spondylolisthesis in 100 patients, and lumbar facet joint cysts in 6 patients. Surgical complications, anatomic abnormality, and mechanical failure and/or damage of surgical instruments were considered adverse events associated with the surgery. The time period was divided into first and second halves in order to investigate the effects of the learning curve. RESULTS AND CONCLUSION: Complications were divided into perioperative and postoperative complications. Due to operator inexperience, complications such as intraoperative dural tear, wrong disc level surgery, and contralateral symptoms due to lack of nerve decompression were more common during the first 5 years. In contrast, no improvement was seen in the frequency of epidural hematoma in the late phase. This report indicates that during endoscopic spinal surgery, some safety issues and surgical complications are independent of surgeon experience, and may include radicular anomaly, postoperative hematoma, and mechanical damage of instruments.

Enhancement of tissue engineered bone formation by a low pressure system improving cell seeding and medium perfusion into a porous scaffold.

To obtain more extensive bone formation in composites of porous ceramics and bone marrow stromal cells (BMSCs), we hypothesized that a low-pressure system would serve to facilitate the perfusion of larger number of BMSCs into the porous scaffold, enhancing bone formation within the composites. After culturing BMSCs in osteogenic medium, porous blocks of beta-tricalcium phosphate (beta-TCP) were soaked in the cell suspension. Composites of the block and BMSCs were put immediately into a vacuum desiccator. Low pressure was applied to the low pressure group, while controls were left at atmospheric pressure. Composites were incubated in vitro or subcutaneously implanted into syngeneic rats, then analyzed biologically and histologically. In the in vitro group, cell suspension volume, cell seeding efficiency, alkaline phosphatase (ALP) activity, and DNA content in the beta-TCP blocks were significantly higher in low pressure group than in the controls. Scanning electron microscopy (SEM) demonstrated that a greater number of cells covered the central parts of the composites in the low pressure group. ALP activity in the composites was increased at 3 and 6 weeks after implantation into rats. Histomorphometric analysis revealed more uniform and extensive bone formation in the low pressure group than in the controls. The application of low pressure during the seeding of BMSCs in perfusing medium into a porous scaffold is useful for tissue-engineered bone formation.

Beta-tricalcium phosphate (beta-TCP) graft combined with bone marrow stromal cells (MSCs) for posterolateral spine fusion.

Macaque lumber posterolateral spine fusion (PLF) was performed by using beta-TCP graft combined with bone marrow derived stromal cells (MSCs), to evaluate whether a beta-TCP/MSCs hybrid can be used for PLF instead of autogenous bone graft. Nine crab-eating macaque underwent bilateral PLF at L4-L5. The implants were divided into three groups: 1) beta-TCP/MSCs hybrid, 2) autogenous bone, and 3) beta-TCP. Six monkeys were sacrified at 12 weeks and three monkeys were sacrificed at 24 weeks after implantation. Manual palpation, radiography, micro computed tomography, peripheral quantitative computed tomography (pQCT), and histology were used to assess bone formation. Manual palpation and X-ray showed that 83.3% of hybrid groups and 66.7% of autogenous groups achieved solid spine fusion, whereas none of other groups fused. Histological analysis showed that all of the hybrid groups achieved massive bone formation. Bone mineral density (BMD) evaluated with pQCT in the hybrid groups increased by additional new bone. Beta-TCP/MSCs hybrid can be used for PLF instead of autogenous bone graft. Thus it can be hypothesized that the monkey PLF can simulate human PLF.

Correlation of in vivo bone formation capability and in vitro differentiation of human bone marrow stromal cells.

Although human bone marrow stromal cells (MSCs) have been used for clinical bone reconstruction, how the physiological status of patients and culture conditions of MSCs affect the result of bone reconstruction must be clarified to use MSCs in a clinical stage. If in vitro parameters of the status of MSCs may be correlate with in vivo bone formation capability, the better cells for clinical bone reconstruction can be defined by the parameters. In order to explore the parameters and define the optimum cells for clinical use, the proliferation and differentiation capabilities in vitro and the in vivo bone formation capability of MSCs were analyzed. An age-related proliferation capability was found. The in vitro alkaline phosphatase activity of bone formation finding groups was higher than that of the no bone formation group. This may be provide a parameter to obtain the optimum cells for clinical use to benefit improving the cure efficiency. In this study, it is preferable that MSCs of passage 1 have stronger osteogenic potential than those of passage 2 and 3 in vitro, and might be suitable for clinical application to bone tissue engineering.

Traumatic neuroma of the anterior cervical nerve root with no subjective episode of trauma. Report of four cases.

The authors report four cases of traumatic neuroma in the cervical nerve root in patients with no history of trauma. In one case the patient presented with intractable pain in the left upper extremity and motor paresis of the left shoulder, and in another case the patient suffered neuropathic pain in the left forearm. In both cases, magnetic resonance (MR) imaging revealed an intradural extramedullary mass lesion in the ipsilateral cervical nerve root; these MR imaging signals were similar to the intensity of the spinal cord. Intraoperatively, fusiform enlargement of the anterior cervical nerve root was detected in the subarachnoid space. Histological examination showed a meandering change of axons accompanied by mild axonal swelling and a thin myelin sheath, which are consistent with the typical pathological features of traumatic neuroma. Postoperatively, pain resolved in both cases. The authors also investigated two traumatic neuromas of the anterior cervical nerve root in autopsy cases in which there was no history of trauma and no significant neurological signs suggestive of traumatic neuroma. The authors conclude that traumatic neuroma of the anterior cervical nerve root may develop following an unnoticed minor brachial plexus injury at birth or a forgotten traction injury of the upper extremity in childhood, and the lesion may be accompanied by various case-specific clinical features.