Membrane Reactor for Methanol Synthesis Using Si-Rich LTA Zeolite Membrane.

We successfully demonstrated the effect of a membrane reactor for methanol synthesis to improve one-pass CO2 conversion. An Si-rich LTA membrane for dehydration from a methanol synthesis reaction field was synthesized by the seed-assisted hydrothermal synthesis method. The H2O permselective performance of the membrane showed 1.5 × 10-6 mol m-2 s-1 Pa-1 as H2O permeance and around 2000 as selectivity of H2O/MeOH at 473 K. From the results of membrane reactor tests, the CO2 conversion of the membrane reactor was higher than that of the conventional packed-bed reactor under the all of experimental conditions. Especially, at 4 MPa of reaction pressure, the conversion using the membrane reactor was around 60%. In the case of using a packed-bed reactor, the conversion was 20% under the same conditions. In addition, the calculated and experimental conversion were in good agreement in both the case of the membrane reactor and packed-bed reactor.

Bench-Scale Membrane Reactor for Methylcyclohexane Dehydrogenation Using Silica Membrane Module.

Methylcyclohexane-toluene system is one of the most promising methods for hydrogen transport/storage. The methylcyclohexane dehydrogenation can be exceeded by the equilibrium conversion using membrane reactor. However, the modularization of the membrane reactor and manufacturing longer silica membranes than 100 mm are little developed. Herein, we have developed silica membrane with practical length by a counter-diffusion chemical vapor deposition method, and membrane reactor module bundled multiple silica membranes. The developed 500 mm-length silica membrane had high hydrogen permselective performance (H2 permeance > 1 × 10-6 mol m-2 s-1 Pa-1, H2/SF6 selectivity > 10,000). In addition, we successfully demonstrated effective methylcyclohexane dehydrogenation using a flange-type membrane reactor module, which was installed with 6 silica membranes. The results indicated that conversion of methylcyclohexane was around 85% at 573 K, whereas the equilibrium conversion was 42%.

The New Strategy for the Treatment of Cerebrospinal Fluid Leak Following Lumbar Surgery.

INTRODUCTION: Cerebrospinal fluid (CSF) leak is a common complication of surgery involving the lumbar spine. However, although there are various therapeutic options for CSF leak, there is currently no optimal technique, and the choice of therapy often depends on the surgeon's cumulative experience. The aim of this study was to describe the successful treatment of CSF leakage using blood injection therapy along the drain removal tract. TECHNICAL NOTE: We enrolled 7 consecutive patients who underwent lumbar surgery at our institute. The surgeries performed included decompression in two patients (one microendoscopic surgery), fusion in four, and an epidural cyst resection in one. After finding a CSF leak, we injected about 10 ml of blood from the patient into the drain tract. CSF leak did not recur after the blood injection in any of the seven patients. Following just one day of bed rest, the symptoms of intracranial hypotension disappeared with no instances of worsened symptoms of back pain, lower limb pain or fever. CONCLUSIONS: We propose this route of blood injection therapy as a novel method for the treatment of CSF leak after lumbar surgery.

Effect of Carbonic Anhydrase on CO2 Separation Performance of Thin Poly(amidoamine) Dendrimer/Poly(ethylene glycol) Hybrid Membranes.

The effect of carbonic anhydrase (CA) on the separation performance of thin poly(amidoamine) (PAMAM) dendrimer/poly(ethylene glycol) (PEG) hybrid membranes was investigated. CA, a type of enzyme, was used to promote CO2 hydration and dehydration reactions and to assess whether these reactions were the rate-limiting step in CO2 permeation through the membrane. The relationship between the membrane thickness and the CO2 permeance was evaluated in CO2/H2 or CO2/He separation using PAMAM/PEG hybrid membranes (thickness: 10-100 µm) with and without CA. Without CA, the CO2 permeance of PAMAM/PEG hybrid membranes was not inversely proportional to the membrane thickness. On the other hand, with CA, the CO2 permeance was inversely proportional to the membrane thickness. It was implied that, without CA, the rate-limiting step of CO2 transport was either the CO2 hydration reaction at the feed side or the CO2 dehydration reaction at the permeate side. On the other hand, with CA addition, the rate-limiting step of CO2 transport was diffusion, and CO2 permeance could be increased without sacrificing the selectivity by reducing membrane thickness. The effect of the position of CA (i.e., on the surface and/or reverse surface) on CO2 separation performance was investigated to evaluate which reaction was the rate-limiting step of CO2 permeation through the membrane. It was suggested that the rate-limiting step of CO2 permeation was CO2 dehydration reaction at the permeate side.

Development of CVD Silica Membranes Having High Hydrogen Permeance and Steam Durability and a Membrane Reactor for a Water Gas Shift Reaction.

Water gas shift reaction of carbon monoxide (CO) with membrane reactors should be a promising method for hydrogen mass-production because of its high CO conversion, high hydrogen purity and low carbon dioxide emission. For developing such membrane reactors, we need hydrogen permselective membranes with high hydrogen permeance with order of 10-6 mol m-2 s-1 Pa-1 at 573 K and high steam durability. In this study, we have optimized the kind of substrates, precursors, vapor concentration, and chemical vapor deposition (CVD) time using the counter-diffusion CVD method for developing such membranes. The developed membrane prepared from hexamethyldisiloxane has a hydrogen permeance of 1.29 × 10-6 mol m-2 s-1 Pa-1 at 573 K and high steam durability. We also conducted water gas shift reactions with membrane reactors installed the developed silica membranes. The results indicated that reactions proceed efficiently with the conversion around 95-97%, hydrogen purity around 94%, and hydrogen recovery around 60% at space velocity (SV) 7000.

Aqueous Two-Phase System Formation in Small Droplets by Shirasu Porous Glass Membrane Emulsification Followed by Water Extraction.

By utilizing water transport phenomena between two different water-in-oil (W/O) emulsion droplets through continuous oil phase, we developed a novel method of aqueous two-phase system (ATPS) formation in small droplets prepared by Shirasu porous glass (SPG) membrane emulsification technique. When we mixed W/O emulsion droplets containing poly(ethylene glycol) (PEG) and dextran (DEX) at concentrations below the threshold of the phase separation, with droplets containing other solutes at high concentrations, water extraction from the droplets containing PEG and DEX to those containing the other solutes occurred, owing to the osmotic pressure difference. This effect increased the concentrations of PEG and DEX in the droplets above the phase separation threshold. We demonstrated the feasibility of the preparation method by varying the pore sizes of the SPG membranes, the solutes, and their concentrations. Only when the concentration of the solute was high enough to extract sufficient amounts of water did the homogeneous disperse phase consisting of PEG and DEX in droplets turn into a PEG-rich phase and DEX-rich phase, showing ATPS. This result was irrespective of the solute itself and pore size of the SPG membrane. In particular, we successfully demonstrated monodisperse ATPS droplets with diameters of approximately 10 µm under a certain condition.

Direct Observation of Splitting in Oil-In-Water-In-Oil Emulsion Droplets via a Microchannel Mimicking Membrane Pores.

Direct observation of double emulsion droplet permeation through a microchannel that mimicked 100 µm membrane pores with a porosity of 66.7% provided insights regarding splitting mechanisms in porous membranes. The microchannel was fabricated by standard soft lithography, and the oil-in-water-in-oil double emulsion droplets were prepared with a glass capillary device. By changing the flow rate from 0.5 to 5.0 × 10-2 m s-1, three characteristic behaviors were observed: (a) passage into one channel without splitting; (b) division into two smaller components; and (c) stripping of the middle water phase of the double emulsion droplets into a smaller double emulsion droplet and a smaller water-in-oil single emulsion droplet. The mechanisms are discussed with respect to the balance of viscous forces and interfacial tension, the contact point with the tip of the channel, and the relative position of the innermost droplet within the middle droplet.

Microendoscopic laminotomy versus conventional laminoplasty for cervical spondylotic myelopathy: 5-year follow-up study.

OBJECTIVE The goal of this study was to characterize the long-term clinical and radiological results of articular segmental decompression surgery using endoscopy (cervical microendoscopic laminotomy [CMEL]) for cervical spondylotic myelopathy (CSM) and to compare outcomes to conventional expansive laminoplasty (ELAP). METHODS Consecutive patients with CSM who required surgical treatment were enrolled. All enrolled patients (n = 78) underwent CMEL or ELAP. All patients were followed postoperatively for more than 5 years. The preoperative and 5-year follow-up evaluations included neurological assessment (Japanese Orthopaedic Association [JOA] score), JOA recovery rates, axial neck pain (using a visual analog scale), the SF-36, and cervical sagittal alignment (C2-7 subaxial cervical angle). RESULTS Sixty-one patients were included for analysis, 31 in the CMEL group and 30 in the ELAP group. The mean preoperative JOA score was 10.1 points in the CMEL group and 10.9 points in the ELAP group (p > 0.05). The JOA recovery rates were similar, 57.6% in the CMEL group and 55.4% in the ELAP group (p > 0.05). The axial neck pain in the CMEL group was significantly lower than that in the ELAP group (p < 0.01). At the 5-year follow-up, cervical alignment was more favorable in the CMEL group, with an average 2.6° gain in lordosis (versus 1.2° loss of lordosis in the ELAP group [p < 0.05]) and lower incidence of postoperative kyphosis. CONCLUSIONS CMEL is a novel, less invasive technique that allows for multilevel posterior cervical decompression for the treatment of CSM. This 5-year follow-up data demonstrates that after undergoing CMEL, patients have similar neurological outcomes to conventional laminoplasty, with significantly less postoperative axial pain and improved subaxial cervical lordosis when compared with their traditional ELAP counterparts.

Reduced blood loss and operation time in lumbar posterolateral fusion using a bipolar sealer.

PURPOSE: A bipolar sealer using Transcollation® technology, a combination of radiofrequency energy and saline, can provide hemostasis at 100 °C, which is lower than that used in standard electrocautery. Previous studies of joint arthroplasty have shown that use of the bipolar sealer reduces blood loss and tissue damage during the operation. However, it is unknown whether a bipolar sealer reduces blood loss and tissue damage in lumbar posterolateral fusion (PLF) surgery. The purpose of this study was to analyze the efficacy of this device in limiting blood loss during exposure of the lumbar spine in the treatment of PLF and postoperative pain. METHODS: Fifty patients who underwent PLF were prospectively enrolled between October 2011 and March 2013. Twenty-five patients were randomized to the bipolar sealer group (BS group) and 25 patients to the standard electrocautery group (control group). Operative time and blood loss during exposure of posterior bony elements including the transverse process for PLF, visual analog scale (VAS) to quantify postoperative pain, and the interval from the surgery to hospital discharge were compared. RESULTS: Operative time and blood loss expressed per level of exposure were significantly lower in the BS group than in the control group. There was a tendency toward a lower VAS at postoperative week 1 in the BS group. The duration of hospitalization was 15 and 26 days in the BS and control groups, respectively. CONCLUSIONS: A large randomized control trial adjusted for the number of fusion levels and body mass index is required to confirm the novelty value of this new bipolar sealers.

[Therapeutic agents for osteoporotic pain].

Low back pain (LBP) is one of the major symptoms of elderly patients with osteoporosis. Pain control is important because pain hinders quality of life. The pathogenesis of the osteoporosis-related LBP is divided as follows, (1) vertebral fracture with bone fragility, (2) imbalance of sagittal alignment, (3) osteoporotic bone pain, (4) reduction of the descending pain inhibition system of serotonine, (5) psychological condition, (6) neural pain. For the treatment of osteoporosis-related LBP, there are two types of medicine. One is a medicine for osteoporosis with an analgetic action, another is an analgetic agent. In this chapter, we explained various analgetic agents for osteoporosis-related LBP.

Size-dependent interaction of cells and hemoglobin-albumin based oxygen carriers prepared using the SPG membrane emulsification technique.

Hemoglobin-based oxygen carriers (HBOCs) of various sizes have been developed so far, but their optimum size has not been clarified yet. Here, we examined the effect of HBOCs size on their interaction with cells using Shirasu porous glass (SPG) membrane emulsification technique, which enables precise tuning of particle size. Microspheres composed of bovine hemoglobin (bHb) and bovine serum albumin (BSA) was fabricated with the average diameters of 1.2-18.3 µm and the coefficient of variation of below 13%. Cellular uptake of the microspheres by RAW264.7 was observed at a diameter below 5 µm; however, uptake of the microspheres by HepG2 and HUVEC were not observed at any diameter. No enhancement of the generation of reactive oxygen species in the cytoplasm was detected at diameters above 9.8 µm in the three cell lines, due to their low cellular uptake. In addition, cytotoxicity of the microspheres decreased with increasing microsphere diameter in the three cell lines and microspheres of 18.3 µm showed good cellular compatibility regardless of the oxyhemoglobin percentage. Since cytotoxicity is a crucial factor in their applications, our systemic investigation would provide a new insight into the design of HBOCs.

Membrane-Integrated Glass Capillary Device for Preparing Small-Sized Water-in-Oil-in-Water Emulsion Droplets.

In this study, a membrane-integrated glass capillary device for preparing small-sized water-in-oil-in-water (W/O/W) emulsion droplets is demonstrated. The concept of integrating microfluidics to prepare precise structure-controlled double emulsion droplets with the membrane emulsification technique provides a simple method for preparing small-sized and structure-controlled double emulsion droplets. The most important feature of the integrated device is the ability to decrease droplet size when the emulsion droplets generated at the capillary pass through the membrane. At the same time, most of the oil shell layer is stripped away and the resultant double emulsion droplets have thin shells. It is also demonstrated that the sizes of the resultant double emulsion droplets are greatly affected by both the double emulsion droplet flux through membranes and membrane pore size; when the flux is increased and membrane pore size is decreased, the generated W/O/W emulsion droplets are smaller than the original. In situ observation of the permeation behavior of the W/O/W emulsion droplets through membranes using a high-speed camera demonstrates (1) the stripping of the middle oil phase, (2) the division of the double emulsion droplets to generate two or more droplets with smaller size, and (3) the collapse of the double emulsion droplets. The first phenomenon results in a thinner oil shell, and the second division phenomenon produces double emulsion droplets that are smaller than the original.

Preparation of uniform-sized hemoglobin-albumin microspheres as oxygen carriers by Shirasu porous glass membrane emulsification technique.

We have developed a new type of artificial oxygen carrier composed of bovine hemoglobin (bHb) and bovine serum albumin (BSA) prepared by Shirasu porous glass (SPG) membrane emulsification technique. The resultant emulsion droplets containing 10 wt% bHb and 5-20 wt% BSA were subsequently cross-linked by glutaraldehyde to form the microspheres. Due to the uniform pore structure of SPG membranes, the average diameters of bHb10-BSAm microspheres were successfully controlled at around 5 µm with a coefficient of variation of around 10%. In addition, the biocompatibility of the carriers depended on their oxyhemoglobin percentage regardless of their same size. Finally, the P50 values of these microspheres ranged from 8.08 to 11.60 mmHg, which showed a high oxygen affinity and an oxygen delivery function.

Gait abnormality due to spinal instability after lumbar facetectomy in the rat.

PURPOSE: Spinal instability of the lumbar spine causes various clinical symptoms. Among them, spinal instability is thought to contribute to low back pain, but the pathophysiological mechanisms are controversial. Although experimental animal models of spinal instability have been reported, it is unknown whether these models produce pain and whether spinal instability affects walking ability. We used the CatWalk system to investigate whether lumbar facetectomy causes gait abnormalities and low back pain. METHODS: Thirty male Sprague-Dawley rats were divided into three experimental groups. In the sham group, only the bilateral L4-L5 facet joints were exposed. In the experimental group, rats underwent complete resection of the bilateral L4-L5 facet joints without neural tissue injury. The control group comprised naïve rats. The CatWalk system was used to analyze gait in postoperative weeks 3, 4.5, 6, and 7. Radiological and histological analyses were also performed. RESULTS: At 7 weeks postoperatively, the rats in the experimental group showed the gait abnormalities seen in low back pain and neuropathic pain models. Radiological examination of the same rats revealed spinal instability with histological evidence of intervertebral disc degeneration. CONCLUSIONS: These results suggest that spinal instability and/or intervertebral disc degeneration induce gait abnormalities and low back pain. This experimental model may be useful for elucidating the mechanisms underlying clinical symptoms, such as low back pain, in patients with spinal instability.

A novel microendoscopically assisted approach for the treatment of recurrent lumbar disc herniation: transosseous discectomy surgery.

BACKGROUND AND OBJECT: Microendoscopic discectomy (MED) is still regarded as contraindicated for the treatment of recurrent lumbar disc herniation by many surgeons. Moreover, the presence of epidural scar tissue makes surgical manipulation difficult. To successfully remove the herniated disc in such cases, an open technique with a wide exposure may be required. We devised a new minimally invasive endoscopic approach, which is using a transosseous route. This is a retrospective review of a consecutive case series to examine the operative and clinical results of this new approach. MATERIAL AND METHODS: Fifty-seven patients who underwent surgery for recurrent lumbar disc herniation were divided into two groups based on the operative procedure. Thirty patients underwent microendoscopic transosseous discectomy (TD) and 27 underwent MED. We graded operative results and clinical outcomes using the Japanese Orthopaedic Association (JOA) score for low-back pain before surgery and 1 year after surgery and compared the scores of the two groups. RESULTS: No conversion to open procedure was necessary in either group. The mean TD operative time was 89.2 minutes with a mean intraoperative blood loss of 16.5 mL. Mean MED operative time was 92.0 minutes with a mean blood loss of 19.3 mL. There were two dural tears in the MED group, and one tear was combined with a fracture of the inferior articular process. No dural tears occurred in the TD group. No patients in either group had experienced re-recurrence of lumbar disc herniation at the time of the last follow-up. The JOA score improved significantly after surgery in both groups (p < 0.001). CONCLUSION: TD is a safe and effective surgical approach for the treatment of recurrent lumbar disc herniation. Operative time, intraoperative blood loss, and clinical results compare favorably with MED.

Modified Marmot operation versus spinous process transverse cutting laminectomy for lumbar spinal stenosis.

STUDY DESIGN: Retrospective comparative cohort study. OBJECTIVE: To compare clinical outcomes for lumbar spinal stenosis (≥3 levels) treated with posterior decompression without exposing the paravertebral muscles (PVM) with outcomes from surgery with PVM exposure. SUMMARY OF BACKGROUND DATA: Exposure of the PVM can cause muscle injury and denervation, which may induce failed back syndrome. However, it is unknown whether lumbar spinal stenosis is more likely to lead to clinical improvement after PVM preservation than the procedure involving exposure of the PVM. METHODS: Fifty-three patients with lumbar spinal stenosis were divided on the basis of the timing of the surgery into 2 groups: modified split-spinous process laminotomy (Marmot operation) (MM) group (26 patients) and spinous process transverse cutting laminectomy through a unilateral approach (control) group (27 patients). The Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, visual analogue scale score of low back pain, and patients' satisfaction were assessed preoperatively and 1 year postoperatively. Operation time, blood loss, and creatine phosphokinase and C-reactive protein levels were measured 7 days postoperatively. Magnetic resonance imaging changes in the PVM were evaluated at the follow-up. RESULTS: The preoperative visual analogue scale and Japanese Orthopaedic Association Back Pain Evaluation Questionnaire scores did not differ between groups. The operation time did not differ between groups, but blood loss was less in the MM group than in the control group (129 vs. 205 mL) (P < 0.05). C-reactive protein (1.1 vs. 2.8 mg/dL) and creatine phosphokinase (68 vs. 253 IU/L) levels were lower in the MM group (P < 0.05). The visual analogue scale score for low back pain and patient satisfaction did not differ between groups. The Japanese Orthopaedic Association Back Pain Evaluation Questionnaire scores for pain-related disorders, gait disturbance, and social life disturbance improved significantly in the MM group compared with the control group (P < 0.05). Nine patients in the control group showed positive changes in the PVM. CONCLUSION: The MM operation was less invasive and produced superior clinical outcomes compared with laminectomy involving exposure of the PVM.

Size-controlled and monodisperse enzyme-encapsulated chitosan microspheres developed by the SPG membrane emulsification technique.

Lysozyme-encapsulated chitosan microspheres with micron-size diameters were successfully prepared for the first time by employing the Shirasu porous glass (SPG) membrane emulsification technique followed by cross-linking with glutaraldehyde, and the relationships between the preparation conditions and characteristics of the microspheres were studied in detail. This preparation method provided size-controllability and monodispersity of the microspheres, owing to the sharpness of the pore sizes of the SPG membranes. It was also possible to predict the average diameters of the enzyme-encapsulated microspheres using no fitting parameters, on the basis that each microsphere is prepared in an emulsion containing chitosan and lysozyme, without any collisions or aggregation occurring. X-ray photoelectron spectroscopy measurements indicated that the amount of encapsulated lysozyme was controlled by the concentrations of chitosan and lysozymes in the dispersion phase used for preparing the emulsions from which the enzyme-encapsulated microspheres are formed. Finally, the apparent activity of the encapsulated lysozymes was measured by the viscosimetric method, using ethyleneglycolchitin. Results showed that about half of the activity of the encapsulated lysozymes was maintained during the preparation procedure when employing the SPG membrane emulsification technique.

Drastic difference in porous structure of calcium alginate microspheres prepared with fresh or hydrolyzed sodium alginate.

Fresh or hydrolyzed sodium alginate was used as a material for preparing calcium alginate microspheres, and a drastic difference in porous structure was observed between them, even though the other materials and the preparation method except for the sodium alginate were exactly the same. When fresh sodium alginate was used, nonporous microspheres were obtained. In contrast, when 82-day-hydrolyzed sodium alginate, whose molecular weight became 7% of the molecular weight of the fresh sodium alginate, was used, porous microspheres with 6.5 times larger BET surface area were obtained. XPS studies indicated that the atomic ratio of Ca, the crosslinker of the alginic acid polymer, was almost the same in both cases. Therefore, the difference in porous structure was not attributed to the amount of crosslinking points, but to the low-molecular-weight compounds formed by hydrolysis, and they would work as pore-generating agents.

The influence of alendronate on spine fusion in an osteoporotic animal model.

STUDY DESIGN: A posterolateral lumbar fusion model in osteoporotic rats. OBJECTIVE.: To assess the effect of alendronate on spine fusion in an osteoporotic animal model. SUMMARY OF BACKGROUND DATA: The effect of alendronate on spine fusion is still controversial. Also, there are no studies using an osteoporotic animal model to assess the effect of alendronate on spine fusion. METHODS: Forty-six female Sprague-Dawley rats underwent either sham-operation (sham) (N = 24) or bilateral ovariectomy (OVX)(N = 22). Eight weeks after the first surgery, animals underwent intertransverse spine fusion at L4-L5. Animals received saline or alendronate 70 µg/kg/wk by subcutaneous administration once a week for 8 weeks after spinal arthrodesis. All animals were divided into four groups: sham-control, sham-alendronate, OVX-control, and OVX-alendronate. After that the animals were killed and the fusion mass was assessed by radiographic, peripheral quantitative computed tomography (pQCT) scanning, and biomechanical and histologic analysis. RESULTS: In the radiographic study and the pQCT scanning, the area of fusion masses of animals treated with alendronate was considerably larger and denser than that of the control animals in both sham and OVX groups. In the biomechanical study, the ultimate load of the fusion mass of alendronate-treated animals was higher than that of control animals in the osteoporotic groups. Histologic analysis of sagittal sections of fusion mass revealed greater new bone formation in alendronate-treated animals in osteoporotic models and significant inhibition of osteoclasts among the grafted area of alendronate-treated animals compared with the control models. CONCLUSION: Alendronate was effective for radiologic, biomechanical, and histologic success of spine fusion in an osteoporotic animal model. Though much of the graft bone was not resorbed, alendronate increased biomechanical strength with ingrowth of new bone formation in osteoporotic animals. This study suggests the alendronate may improve spine fusion healing in the presence of osteoporosis.

A new 3-dimensional computed tomography imaging method to diagnose extraforaminal stenosis at the lumbosacral junction.

STUDY DESIGN: A prospective study using a newly developed imaging diagnosis method to examine the patients with L5 radiculopathy. OBJECTIVE: To confirm the efficacy of a new 3-dimensional computed tomography (3D CT) imaging method to diagnose extraforaminal stenosis at the lumbosacral junction. SUMMARY OF BACKGROUND DATA: The lack of recognition of extraforaminal stenosis at the lumbosacral junction is a cause of failed back surgery syndrome. A clear method to diagnose this condition is essential. METHODS: The participants were 75 consecutive patients (mean age 69.5 y) with or without cauda equina symptoms who were treated by microendoscopic spinal surgery for L5 radiculopathy. The lesion responsible for the symptoms was identified by a combination of neurologic findings, selective radiculography, (3D MRI), and intraoperative neurophysiological findings. Multislice CT scanning was carried out preoperatively from the L1 vertebral body to the sacrum in all patients. The CT scan images were transferred to a remote computer workstation, and the reconstructed images were examined after surgery by an investigator blinded to the clinical diagnoses. In the reconstructed plane, we measured the minimum cross-sectional area of the de novo bony tunnel formed by the L5 transverse process, sacral ala, and L5 vertebral body, that is, lumbosacral bony tunnel (LSBT) and determined a cutoff value to diagnose extraforaminal stenosis. The shape of the LSBT was also evaluated in relation to the diagnosis. RESULTS: In 3D CT analysis, the LSBT was found on the ipsilateral side in 51 of the 75 patients. The bony tunnel was outside the foramen in all patients diagnosed clinically with extraforaminal stenosis, but in only 60% of the patients without extraforaminal stenosis. The minimum cross-sectional area of the bony tunnel was significantly smaller in patients with an extraforaminal stenosis than in those without extraforaminal stenosis. The cutoff value was set at 0.8 cm2. The cross-sectional area was <0.8 cm2 in all patients with extraforaminal stenosis. The specificity of this diagnostic procedure was 89.6%, and the sensitivity was 100%. All true-positive cases had the spur-type shape of the bony tunnel, and all false-positive cases had the round-type shape. CONCLUSIONS: All patients with extraforaminal stenosis had an LSBT. The minimum cross-sectional area of the bony tunnel was significantly smaller in patients with an extraforaminal lesion than in those without an extraforaminal lesion. 3D CT is a useful tool for diagnosing extraforaminal stenosis at the lumbosacral junction.