Diversity of Chlamydiales detected in pet birds privately kept in individual homes in Japan.

Chlamydia-related bacteria of the Chlamydiales order have recently been described as emerging pathogens that cause pneumonia and abortion in animals and humans. We investigated the presence of Chlamydiales using real-time polymerase chain reaction (PCR) by targeting the 16S rRNA gene of a broad range of Chlamydiales in 827 fecal samples from pet birds kept in individual homes in Japan. Of the 827 samples, 493 (59.6%) tested positive for the Chlamydiales 16S rRNA gene in the real-time PCR assay. We determined the nucleic acid sequences of PCR products from 17 Chlamydiales strains. A homology search and phylogenetic analysis using these sequences confirmed that the detected Chlamydiales included C. pecorum and a broad range of Chlamydia-related bacteria. To the best of our knowledge, this is the first study to detect a wide range of Chlamydia-related bacteria in birds.

Balloon kyphoplasty combined with percutaneous pedicle screw (PPS) for the treatment of osteoporotic thoracolumbar fractures has minimum correction loss 2 years after surgery: compared to vertebroplasty using hydroxyapatite block combined with PPS.

BACKGROUND: Balloon kyphoplasty (BKP) is a useful treatment performed in patients with painful osteoporotic vertebral body fracture (OVF). However, in cases with large intra-vertebral clefts and cases with posterior spinal tissue damage, adjacent vertebral body fractures (AVFs), and cement migration may occur early after BKP, which may be a factor for poor results. In such cases, percutaneous vertebroplasty (PVP) combined with percutaneous pedicle screw (PPS) is useful treatment. This study compared BKP combined with PPS (BKP + PPS) compared to PVP using hydroxyapatite (HA) block combined with PPS (HAVP + PPS) for thoracolumbar OVF (TLOVF). METHODS: Twenty-eight patients who sustained painful TLOVFs without neurologic deficits underwent HAVP + PPS (group H, n=14) or BKP + PPS (group B, n=14). We evaluated time from injury to surgery, pre- and post-operative visual analogue scale (VAS) of low back pain, wedging angle of fractured vertebra, duration of operation, intraoperative blood loss, number of instrumented vertebra, and length of stay at hospital. RESULTS: Group B had significantly less surgery time and less blood loss during surgery. VAS of low back pain improved equally in both groups, but at 1 year and 2 years postoperatively, wedging angle of fractured vertebra progressed significantly in group H compared with group B. CONCLUSIONS: PPS fixation combined with percutaneous vertebral cement augmentation with BKP for OVF was suggested to be minimally invasive in the elderly patients. In addition, there is no correction loss of the fractured vertebral body after BKP + PPS, which is considered to be a useful surgical procedure.

Association of Lumbar Spondylolytic Spondylolisthesis With the Incidence and Prognosis of Anterior Ring Apophyseal Abnormalities of the Vertebrae in Young Gymnasts.

Background: Although anterior apophyseal abnormalities of the vertebrae and spondylolytic spondylolisthesis (SS) are prevalent in gymnasts during growth spurts, no studies have examined the relationship between apophyseal abnormalities and SS. Hypothesis: A significant relationship will exist between anterior apophyseal abnormalities and SS in young gymnasts. Study Design: Cohort study; Level of evidence, 2. Methods: A total of 306 gymnasts (123 male, 183 female; age range, 6-28 years) with >2 weeks of back pain were enrolled in this study. Apophyseal abnormalities were evaluated using radiography. In the primary analysis, multiple logistic regression analysis was performed to assess the odds ratio (OR) for multivariate factors (age, body mass index, sex, skeletal maturity, competitive level, and presence of spondylolysis or SS) influencing the incidence of apophyseal abnormalities. In the secondary analysis, 90 of the 306 gymnasts were followed up radiographically for a minimum of 2 years, and factors contributing to the worsening of apophyseal abnormalities were identified. Results: In the primary analysis, the chi-square test revealed a relationship between anterior ring apophyseal abnormalities and SS at the L5-S1 segment (OR, 7.6). Multiple logistic regression analysis demonstrated that the presence of SS at L5-S1 (OR, 9.5) and competitive level (international: OR, 6.7; national: OR, 4.5) correlated with the incidence of apophyseal abnormalities. The secondary analysis identified the presence of SS at L5-S1 (OR, 5.9) as a significant factor contributing to the worsening of apophyseal abnormalities. Conclusion: The presence of SS was a factor affecting the incidence and prognosis of anterior apophyseal abnormalities.

Safety and Efficacy of All-In-One Percutaneous Pedicle Screw System.

STUDY DESIGN: Retrospective study of the prospectively collected outcomes data. OBJECTIVE: The indications for PPS placement during minimally invasive spine stabilization (MISt) procedures have increased in recent years. To the best of our knowledge, no studies have documented the outcomes of PPS insertion using the all-in-one PPS system. This study compared the conventional methods and the use of all-in-one percutaneous pedicle screw (PPS) system with respect to the speed and accuracy of PPS placement. We also determined the advantages associated with the use of the all-in-one PPS system. METHODS: We evaluated 54 patients who underwent PPS insertion using the conventional method and the all-in-one PPS system during MISt procedures. We also assessed the number of implanted PPSs, the time taken to implant PPSs, and the accuracy of PPS placement based on postoperative computed tomography images. RESULTS: A total of 254 PPSs were inserted (126 using the conventional method and 128 using the all-in-one PPS system). The PPS insertion time with the all-in-one PPS system (mean, 25.3 ± 9.1 s) was significantly shorter than that using the conventional method (mean, 63.1 ± 13.0 s; P < 0.01). With respect to the accuracy of PPS insertion, ≥ 2 mm pedicle breach was noted in one case each in both groups. CONCLUSIONS: PPS placement using the all-in-one PPS system is as safe as conventional methods and has the potential to save the surgical time of MISt procedures.

Efficacy and Safety of Condoliase Disc Administration as a New Treatment for Lumbar Disc Herniation.

INTRODUCTION: Condoliase is a newly approved drug that improves symptoms associated with lumbar disk herniation (LDH) by intradiscal administration. This study aimed to evaluate the mid-term outcomes of condoliase injection, examine the adverse events, including cases that required surgery after condoliase administration, and verify cases in which condoliase could be effective. METHODS: We enrolled patients with LDH who were treated conservatively for at least six weeks and received condoliase. We assessed the visual analog scale (VAS) score, Japanese Orthopaedic Association Back Pain Evaluation Questionnaire, Oswestry Disability Index, disk height, and disk degeneration for up to 6 months, and we examined the complications. Furthermore, a 50% or more improvement in leg pain VAS score was considered effective. Factors related to symptom improvement were investigated by determining whether lower limb pain improved in six months. RESULTS: In total, 84 patients were recruited (52 men, 32 women; mean age, 44.2 ± 17.1 [16-86 years]). The duration of illness was 6.7 ± 6.8 (1.5-30) months. All patient-based outcomes significantly improved at 4 weeks after the administration compared with pretreatment. The intervertebral disc height decreased significantly at four weeks after condoliase administration compared with that before administration. Progression of intervertebral disc degeneration occurred in 50% of the patients. Eleven patients underwent herniotomy due to poor treatment effects. Moreover, treatment in 77.4% of the patients was considered effective. A logistic regression analysis revealed that L5/S1 disk administration (p = 0.029; odds ratio, 5.94; 95% confidence interval, 1.20-29.45) were significantly associated with clinical effectiveness. CONCLUSIONS: Condoliase disk administration improved pain and quality of life over time. Condoliase disk administration was more effective in L5/S1 intervertebral administration.

Validation of the usefulness of 26S rDNA D1/D2, internal transcribed spacer, and intergenic spacer 1 for molecular epidemiological analysis of Macrorhabdus ornithogaster.

Macrorhabdus ornithogaster (MO) is an infectious fungus that causes gastric damage in birds. In this study, we established nested and seminested polymerase chain reaction (PCR) methods that specifically amplify the domain D1/D2 region (D1/D2) of 26S ribosomal DNA (rDNA), internal transcribed spacer (ITS) of rDNA, and intergenic spacer (IGS) 1 region from avian feces. Phylogenetic analysis of MO collected from Japanese pet birds showed little genetic variation; analysis based on these regions did not distinguish between host species order, differences in MO shape, or host gastrointestinal symptoms. These regions were found to be unsuitable for molecular epidemiological studies of MO and further investigation into other genetic regions is required.

Long-term reoperation rates and causes for reoperations following lumbar microendoscopic discectomy and decompression: 10-year follow-up.

OBJECTIVE: To investigate the 10-year rates and causes of reoperations following lumbar microendoscopic discectomy for disc herniation (MEDH) and microendoscopic decompression for spinal stenosis (MEDS), as well as to define the reoperations at index and different lumbar levels. METHODS: Between June 2005 and May 2011, the same surgeon had been using MEDH and/or MEDS on 355 consecutive patients. The follow-up rate was 88.3%. The causes and rates of reoperations (RORs) were determined at 10 years after the initial operations. RESULTS: The 10-year reoperation rate for all patients combined was 22.1% (67/303). The 10-year reoperation rate for all cases that underwent repeat operations in the same segment was 16.5% (50/303); the most frequent reason for reoperation (FRR) was recurrence of disc herniation (ROR, 25/251 = 9.96%), the second FRR was an increase of postoperative spondylolisthesis and/or instability (ROR, 8/303 = 2.64%), and the third FRR was surgical site infection (ROR, 5/303 = 1.65%). Ten-year reoperation rate for all cases that underwent repeat operation at different lumbar levels was 5.61% (17/303); the most FRR was new disc herniation at another lumbar level (ROR, 10/303 = 3.30%), the second FRR was residual segmental stenosis (ROR, 4/303 = 1.32%), and the third FRR was new segmental stenosis at other lumbar levels (ROR, 2/303 = 0.66%). CONCLUSIONS: Three-fourths of all repeat operations were conducted in the same segment and one-fourth were performed at different lumbar levels. We believe that it is important to understand and prevent related problems.

Genetic characterization of Trichomonas gallinae (Rivolta, 1878) in companion birds in Japan and the genotypical relationship in the Asia region.

BACKGROUND/PURPOSE: Avian trichomonosis is a parasitic infection that affects a wide range of avian species, including free-ranging and pet birds worldwide, and Trichomonas gallinae has been considered as the only causative agent for decades. The sequence of the 5.8S ribosomal RNA with internal transcribed spacer (ITS) regions was widely used for identifying genotypes and determining inter-specific and intra-specific diversity. Moreover, the sequence of Fe-hydrogenase (FeHyd) was proposed as the second genetic marker for providing improved resolution of strain subtyping discrimination. Though the correlation between genetic variability and strain virulence is controversial, FeHyd analyses seemed to be useful to investigate the host or geographic origin of isolates. This study aimed to investigate the genetic characteristics of avian Trichomonas spp. METHODS: Forty-seven oral swabs and crop lavage fluids were collected from 9 avian genera, which were diagnosed as Trichomonas-positive by microscopy in animal hospitals in Japan, were analyzed. RESULTS: Genetic analysis of clonal isolates revealed the prevalence of the single genotype, ITS-OBT-Tg-1, by ITS region analysis, while two different subtypes, A2 and novel A3, were suggested by FeHyd gene analysis among Japanese companion birds. Phylogenetic analyses of available ITS sequences obtained from the Asia region (China, Iran, Iraq, and Saudi Arabia) were also preformed, revealing endemic ITS-OBT-Tg-1, ITS-OBT-Tg-2, ITS-OBT-Ttl-1, genotype III, and Saudi Arabia's unique lineages. Furthermore, ITS-OBT-Tg-2 predominance in these countries indicates different strains origination from Japan. CONCLUSION: This is the first report of the genetic characterization of T. gallinae in Japan with discovery of novel subtype A3.

Long-Term Outcomes Following Lumbar Microendoscopic Decompression for Lumbar Spinal Stenosis with and without Degenerative Spondylolisthesis: Minimum 10-Year Follow-Up.

OBJECTIVE: To determine whether preoperative presence of degenerative lumbar spondylolisthesis (DS) worsens the minimum 10-year outcome of patients undergoing microendoscopic decompression (MED) for lumbar spinal stenosis (SS). METHODS: Eighty patients undergoing MED were classified into 2 groups: DS group (34 SS with DS patients) and SS group (46 SS without DS patients). The degrees of improvement (DOIs) by the Japanese Orthopaedic Association Back Pain Evaluation Questionnaire (JOABPEQ) and intensities of improvement (IOIs) by Visual Analog Scale (VAS) at 120-159 (mean, 138.4) months after MED of the DS and SS groups were statistically compared. Patients with DS were classified into 2 groups based on the effectiveness by VAS or JOABPEQ: effective group (E group: IOI or DOI ≥20) and ineffective group (I group). All preoperative radiologic measurements were statistically compared between the E and I groups. RESULTS: Significant decreases in low back pain, leg pain, and numbness, as measured by VAS, were noted at follow-up in the DS and SS groups. The effectiveness rates of pain-related disorders, lumbar spine dysfunction, and gait disturbance by JOABPEQ were almost equally high in the DS and SS groups. Statistical comparisons of the DOIs in all 5 functional scores and IOIs in low back pain, leg pain, and numbness showed no significant differences between the DS and SS groups. No significant differences were confirmed between the E and I groups concerning preoperative spondylolisthesis and instability. CONCLUSIONS: Our study indicated that preoperative DS did not worsen the outcome of patients with SS undergoing MED.

Resurrection of the genus Eumonospora (Apicomplexa: Sarcocystidae) for Caryospora species without Stieda body.

The coccidian genus Eumonospora Allen, 1933 is re-established. Despite morphological features and host preference among species, coccidian with octasporozoic and monosporocystic oocysts are traditionally consider to belonging in the genus Caryospora Léger, 1904 (Apicomplexa: Eimeriidae). Recently, the genus Avispora Schuster et al., 2016 was proposed for above caryosporoids parasitizing birds based on combined morphological and phylogenetic analyses. However, diagnostic morphological characters of the genus Avispora, the absence of Stieda and substieda bodies, has already been mentioned in the description of the genus Eumonospora Allen, 1933 (Apicomplexa: Sarcocystidae), and thus Avispora is considered to be a junior synonym of Eumonospora. In this study, caryosporoid coccidians were detected from five owl species; Bubo scandiacus, Ptilopsis leucotis, Athene noctua, Strix nebulosa, and Pulsatrix perspicillata (Strigiformes: Strigidae) and identified as Avispora henryae (Yakimoff & Matikaschwaili, 1932) described from Bubo bubo (Strigiformes: Strigidae). Eumonospora henryae (Yakimoff & Matikaschwili, 1932) comb. nov. is redescribed for this species based not only on morphological features but also on phylogenetical analyses. The key of the genus Eumonospora and a list to the species known at present are also provided.

Achievement of stable negative ion production with Cs-seeded for long pulse beam operation in the prototype of Cs-seeded negative ion source for JT-60SA.

Long pulse negative ion beams of 500 keV and 154 A/m2 for 118 s have been achieved for the first time, which exceeds the requirement of the JT-60SA negative ion source. In order to solve the issues of such long pulse beams, the fast cutoff system of the power supply aims to reduce the surge current and to extend the lifetime of filaments and the suppression method of excess cesium (Cs) accumulation on the plasma grid (PG) to achieve stable negative ion production. By developing the fast cutoff system using a field programmable gate array unit for the arc power supply, the cutoff time has been reduced to 1/10 that of the original system and the lifetime of the filament was extended by three times. In order to achieve stable negative ion production, incoming Cs on the PG surface has been reduced by keeping the chamber wall temperature below 40 °C. As a result, a stable beam current drift of <6% has been achieved for the 118 s duration.

Experimental investigation of the Cs behavior in the cesiated H- ion source during high power long beam operation.

The behavior of the Cesium (Cs) in Cs-seeded negative ion sources has been investigated experimentally under the beam accelerations of up to 0.5 MeV. The pulse length was extended to 100 s to catch the precise variations in the Cs D2 emission, discharge power, negative ion current, and temperatures in the ion source. The variations of the negative ions were estimated by the beam current and the heat loads in the accelerator. This experiment shows that the buildup of temperature in the chamber walls lead to the evaporation of deposited Cs to enter the plasma region and influenced H- ion production. The H- ion beams were stably sustained by reducing the temperature rise of the chamber wall below 50 °C. A stable long pulse beam could be achieved through the temperature control of the surfaces inside the source chamber walls.

Five-year Reoperation Rates and Causes for Reoperations Following Lumbar Microendoscopic Discectomy and Decompression.

STUDY DESIGN: Retrospective study of prospectively collected outcome data. OBJECTIVE: The aim of this study was to investigate reoperation cases and determine whether or not the experience period of a single surgeon was associated with the causes of reoperations following lumbar microendoscopic discectomy for disc herniation (MEDH) and microendoscopic decompression for spinal stenosis (MEDS). SUMMARY OF BACKGROUND DATA: There have been few studies that investigated reoperation cases following MEDH and MEDS. METHODS: Between June 2005 (first experience of MEDH) and September 2013, the same surgeon had been using MEDH and/or MEDS on 441 consecutive patients. The follow-up rate was 89.3%. The causes and rates of reoperations (RORs) were determined at 5 years after the initial operations. We also investigated the experience period of a single surgeon (EPS, interval between June 2005 and initial operation: median, 37 months). RESULTS: The 5-year reoperation rate for all patients combined was 12.4% (49/394). The main causes for reoperations were recurrence of disc herniation (ROR, 7.01%) and increase of postoperative spondylolisthesis and/or instability (ROR, 9/394 = 2.28%); two of the nine cases were caused by excessive decompression, and the EPSs were 11 and 16 months. The other causes for reoperations were postoperative epidural hematoma (ROR, 0.76%; median EPS, 20 months), insufficient decompression (ROR, 0.25%; EPS, 17 months), and residual segmental scoliosis (ROR, 7.69%); two segmental scoliosis cases did not provide relief from sciatica, and therefore L4/5 transforaminal interbody fusions were performed. CONCLUSION: Postoperative epidural hematoma and excessive or insufficient decompression were often observed in the initial series of patients as the causes for reoperations. We think that it is important to be aware of and prevent such potential problems in any initial series of patients, as there are limitations to any surgical indications for the use of microendoscopic decompression for degenerative segmental scoliosis because of original traction and/or kinking of nerve roots. LEVEL OF EVIDENCE: 4.

Safety and Efficacy of Percutaneous Pedicle Screw Placement Using a Power Tool.

INTRODUCTION: This study compared traditional manual methods and power tool use with regard to the speed and accuracy of percutaneous pedicle screw (PPS) placement and determined the advantages associated with the use of power tools. Although the indication of PPS placement in minimally invasive spine stabilization (MISt) procedures has been recently expanded, there are no reports on PPS insertion using a power tool. METHODS: We evaluated 35 patients who underwent PPS insertion using a power tool during MISt procedures. On one side, PPS insertion was performed using the manual (M) method, whereas on the contralateral side, insertion was performed using the power tool (P) method. We assessed the number of implanted PPSs, time taken to implant PPSs after guidewire insertion, and accuracy of PPS placement as ranked postoperatively using computed tomography images. RESULTS: A total of 294 PPSs were inserted (147 using the M method and 147 using the P method). The mean PPS insertion time was 10.5 s using the P method and 27.4 s using the M method. The time required for inserting a screw using the P method remained consistent in the range of 10-15 s, whereas the time using the M method tended to increase from the second screw onward, with a range of 25-30 s. With regard to PPS insertion accuracy, a 2 mm or more pedicle breach was noted in 2 (1.4%) case after the P method and in 2 (1.4%) case after the M method. CONCLUSIONS: PPS placement using power tools has the potential to save the surgical time during MISt procedures.

Apolipoprotein E2 and E3, but Not E4, Promote Retinal Pathologic Neovascularization.

Purpose: To determine the relationship between the different isoforms of apolipoprotein E (ApoE) and retinal neovascularization. Methods: The concentrations of ApoE and VEGF in vitreous humor samples with either a macular hole (MH), or diabetic macular edema (DME), or proliferative diabetic retinopathy (PDR) with or without intravitreal injection of bevacizumab (IVB) were measured by ELISA. The effects of each isoform of ApoE on human retinal microvascular endothelial cells (HRMECs) in culture or on the retina of oxygen-induced retinopathy (OIR) mice were investigated. Results: The concentrations of ApoE and VEGF were significantly higher in the vitreous humor of patients with PDR and DME than in patients with an MH. There was a significant positive correlation between the concentrations of ApoE and VEGF in vitreous humor of patients. In vitro assays showed that ApoE2 and ApoE3, but not ApoE4, promoted the VEGF-induced cell proliferation and migration. In vivo assays showed that intravitreal injections of ApoE2 and ApoE3 increased the number and area of nodes in the retina of OIR mice. Moreover, ApoE was expressed in the vascular endothelial cell in both normal and OIR retinas, but their expression levels were different at postnatal day (P) 12 and P17. Conclusions: These results demonstrate that ApoE2 and ApoE3, but not ApoE4, have proangiogenic effects, and the increased expression of ApoE in the vitreous humor of patients with PDR and DME indicates that ApoE2 and ApoE3 are involved in the development of retinal neovascularization in eyes.

Isospora lunaris n. sp. (Apicomplexa: Eimeriidae) from the domestic Java sparrow in Japan.

Five individuals of the domestic Java sparrows, Lonchura oryzivora (Aves: Estrildidae), were examined for coccidian parasites. Sporulated oocysts had two sporocysts containing four sporozoites each. Sporulated oocysts (n=30) were spherical, with a two splinter-like polar granules. Oocyst size was 22.1×20.7 (20.0-25.0×20.0-22.5)µm. They had a thick wall that consisted of a pale yellow outer layer and a dark yellow inner layer, and lacked micropyle and residuum. Sporocysts (n=60) were elongated ovoid 14.1×9.8 (12.5-15.0×7.5-10.0)µm, smooth walled, and colorless, with crescent-shaped Stieda and indistinct substieda bodies. Sporocyst residuum was interspersed between sporozoites. Sporozoites were oriented transverse to the sporocyst longitudinal axis. On the basis of morphological data, the species isolated in the present study is a new species of Isospora and propose the name Isospora lunaris n. sp.

Quantification of L5 radiculopathy due to foraminal stenosis using three-dimensional magnetic resonance myelography.

INTRODUCTION: This study aimed to evaluate morphological changes in the L5 nerve roots in control and symptomatic patients using magnetic resonance myelography [MRM]. Moreover, the utility of MRM for the diagnosis of intraforaminal or extraforaminal lesions in patients with L5 radiculopathy was evaluated using healthy subjects as controls. METHODS: Of 270 subjects who underwent MRM of the lumbar spine at our institution between April 2007 and December 2010, 135 patients (78 men and 57 women; average age: 61.3 years) with no history of spinal surgeries and nerve roots without infections, tumors, or malformations were selected for this study. The end-point measurements included the bifurcation angle of inclination (proximal tilting angle [PTA]) of the L5 nerve root as observed via MRM, lateral angle of inclination (lateral tilting angle [LTA]), bifurcation diameter (proximal nerve root width [PW]), and dorsal root ganglion (DRG) diameter (DRG width [DW]). DW ratio was then calculated for healthy controls and symptomatic subjects. We measured each parameter using the image information unification system ShadeQuest (Yokogawa, Tokyo, Japan). Two spinal surgeons conducted the magnetic resonance imaging evaluation. RESULTS: Swelling of the L5 DRG was detected in cases with intraforaminal or extraforaminal stenosis. With regard to the cutoff value of 6.5 mm for L5 DW, foraminal stenosis can be confirmed if DW is ≥6.5 mm or more via MRM. In cases where L5 DRG was swollen to ≥1.2 times the size in healthy subjects, L5 radiculopathy with foraminal lesions can be diagnosed. CONCLUSIONS: Our findings indicated that 3D MRM is a noninvasive technique and a useful tool for the diagnosis of intraforaminal or extraforaminal lesions in the lumbar spine. Therefore, it can be combined with other diagnostic methods used for the identification of intraforaminal or extraforaminal L5 nerve root lesion.

Measurement of heat load density profile on acceleration grid in MeV-class negative ion accelerator.

To understand the physics of the negative ion extraction/acceleration, the heat load density profile on the acceleration grid has been firstly measured in the ITER prototype accelerator where the negative ions are accelerated to 1 MeV with five acceleration stages. In order to clarify the profile, the peripheries around the apertures on the acceleration grid were separated into thermally insulated 34 blocks with thermocouples. The spatial resolution is as low as 3 mm and small enough to measure the tail of the beam profile with a beam diameter of ∼16 mm. It was found that there were two peaks of heat load density around the aperture. These two peaks were also clarified to be caused by the intercepted negative ions and secondary electrons from detailed investigation by changing the beam optics and gas density profile. This is the first experimental result, which is useful to understand the trajectories of these particles.

Sagittal Alignment of Spine and Spinal Cord for Upper Cervical Irreducible Atlantoaxial Kyphosis in Elderly Patients.

STUDY DESIGN: Retrospective study. OBJECTIVE: To evaluate clinical and radiographic outcome of posterior decompression and occipito-cervical/thoracic (OCT) fusion in patients with irreducible atlantoaxial kyphosis (IAK). SUMMARY OF BACKGROUND DATA: Posterior OCT fusion is an effective surgical procedure for treating IAK in the elderly. However, it is unclear whether correction can be obtained by the strong corrective force provided by implants, even in patients in whom reduction cannot be obtained preoperatively. There are no reports of improvement in patients in whom correction could not be achieved by a rigid system. METHODS: Twenty-five patients with IAK with mild vertical subluxation due to rheumatoid arthritis and 3 patients with IAK due to os odontoideum were treated with fossa magnum decompression, C1 laminectomy and OCT fusion. RESULTS: Mean follow-up period was 4.2 years. Preoperative and postoperative neurological findings revealed improvement by 1 or more grades in 18 of 28 (64.2%) patients. The parameters of spinal alignment, sagittal spinal cord alignment, and basilar invagination were evaluated on radiographs. No significant difference between preoperative and postoperative status was seen for the clivo-axial angle, occipito-upper cervical angle, atlantodental interval, or occipito-cervical 2 angle, whereas significant improvement was seen in the cervico-medullary and dorsal CM angles (both P<0.05). No significant postoperative change in the vertical direction was seen for any of the parameters. Width of the spinal cord at the C1 level was significantly increased postoperatively, with a significant expansion of the cerebral spinal fluid space at the same level (P<0.05). CONCLUSIONS: Posterior decompression with fusion for the treatment of IAK in the elderly did not produce significant change in spinal alignment, but did significantly improve spinal cord alignment and local spinal cord compression at the C1 level, achieving satisfactory clinical outcomes.