Surgical Outcomes of Full Endoscopic Posterior Cervical Foraminotomy for Proximal Cervical Spondylotic Amyotrophy.

STUDY DESIGN: Retrospective analysis of case series. PURPOSE: This study aimed to clarify the effects of full endoscopic posterior cervical foraminotomy (FPCF) on cervical spondylotic amyotrophy (CSA). OVERVIEW OF LITERATURE: The method for decompressing the ventral nerve root and anterior horn (AH) in CSA is controversial. METHODS: Patients without myelopathy who underwent FPCF for proximal CSA between 2017 and 2022 were analyzed. The outcome measure was the results of the manual muscle testing (MMT) of the deltoid and biceps. Preoperative nerve root and AH compression were evaluated by magnetic resonance imaging. The intervertebral foramen morphology and bony decompression extent were evaluated by computed tomography. RESULTS: FPCF was performed at the C4/5 level and at the C4/5 and C5/6 levels in 14 and 11 patients, respectively. The width of the narrowest intervertebral foramen was significantly narrower on the affected side than on the healthy side at the C4/5 (2.5 mm vs. 3.6 mm) and operated C5/6 (1.9 mm vs. 3.1 mm) levels. AH compression occurred at the C4/5 and C5/6 levels in 28% and 21% of the patients, respectively. Bony decompression was performed laterally beyond the narrowest foramen at the C4/5 and C5/6 levels in 96% and 91% of the patients, respectively. Compared with patients without AH compression, in those with AH compression, the lamina was resected medially by an average of >1.7 mm and >3.6 mm at the C4/5 and C5/6 levels, respectively. Furthermore, 76% and 81% of the facet joint surfaces were preserved at the C4/5 and C5/6 levels, respectively. Postoperative MMT grade improvement was excellent, good, and fair in 64%, 20%, and 16% of the patients, respectively. CONCLUSIONS: FPCF was effective for treating proximal CSA.

Accuracy and safety of percutaneous pedicle screw placement using the K-wireless minimally invasive spine percutaneous pedicle screw system in Japan: A randomized active controlled study.

Background: Minimally invasive lumbar fusion has recently become a widely used technique worldwide. This randomized active controlled study was conducted to demonstrate the non-inferiority of the K-wireless Minimally Invasive Spine (MIS) Percutaneous Pedicle Screw (PPS) system compared with use of the six pedicle screw systems currently used in our practices with respect to the accuracy of pedicle screw placement.Also to compare the screw-insertion time and number of fluoroscopic observations during screw insertion between the groups. Methods: A total of 80 patients with degenerative spinal diseases or vertebral fractures were assigned, including 41 patients in the K-wireless MIS PPS system group (K-wireless group) and 39 in the control group (K-wire group).The accuracy of the screw insertion, screw-insertion time, number of fluoroscopic observations during screw insertion, and the incidence of adverse events were compared between the K-wireless group and the K-wire group. The accuracy rate was calculated as the number of screws with no breach divided by the total number of screws. Results: The accuracy rates of screw insertion were 85.7% and 75.0% in the K-wireless and K-wire groups, respectively, with an intergroup difference of 10.7% (95% confidence interval: 2.3-19.1%). The K-wireless group demonstrated non-inferiority compared with the K-wire group. The mean screw-insertion time was significantly shorter in the K-wireless group (2.62 and 2.97 min in the K-wireless and K-wire groups, respectively; P=0.005). There were also significantly fewer fluoroscopies in the K-wireless group (10.7 and 17.4 in the K-wireless and K-wire groups, respectively; P<0.001). There were no device-related or study treatment-related adverse events in either group. Conclusions: The accuracy of pedicle screw insertion using the K-wireless MIS PPS system was not inferior to that of existing products. In terms of safety, no product-related or treatment-related adverse events were identified in this study and no new safety concerns were noted.

Risk Factors and Surgical Management of Recurrent Herniation after Full-Endoscopic Lumbar Discectomy Using Interlaminar Approach.

Full-endoscopic lumbar discectomy (FED) is one of the least invasive procedures for lumbar disc herniation. Patients who receive FED for lumbar disc herniation may develop recurrent herniation at a frequency similar to conventional procedures. Reoperation and risk factors of recurrent lumbar disc herniation were investigated among 909 patients who received FED using an interlaminar approach (FED-IL). Sixty-five of the 909 patients received reoperation for recurrent herniation. Disc height, smoking, diabetes mellitus (DM), subligamentous extrusion (SE) type, and Modic change were identified as the risk factors for recurrence. Other indicators such as LL, Cobb angle, disc migration, age, sex, and body mass index (BMI) did not reach significance. Among 65 patients, reoperation was performed within 14 days following FED-IL (very early) in 7 patients, from 15 days to 3 months (early) in 14 patients, from 3 months to 1 year (midterm) in 17 patients, and after more than 1 year (late) in 27 patients. The very early group included a greater number of males, and the mean age was significantly lower in comparison to other groups. All patients in the very early group received FED-IL for reoperation. Reoperation within 2 weeks allows FED-IL to be performed without adhesion. Fusion surgery was performed on three cases in the early and midterm groups and on 10 cases in the late group, which increased over time as degenerative change and adhesion progressed. The procedure selected to treat recurrent herniation mostly depends on the surgeon's preference. Revision FED-IL is the first choice for recurrent herniation in terms of minimizing surgical burden, whereas fusion surgery offers the advantage that discectomy can be performed through unscarred tissues. FED-IL is recommended for recurrent herniation within 2 weeks before adhesion progresses.

C-arm fluoroscopy for tracheal intubation in a patient with severe cervical spine pathology.

Tracheal intubation is challenging in patients with severe cervical spine pathology. In such cases, awake fiberoptic intubation is the gold standard and safest option for tracheal intubation. However, this technique requires the patient's understanding and cooperation, and therefore, may be contraindicated in patients with refusal or poor tolerance. Herein, we report successful orotracheal intubation in a patient with limited mouth opening and severe cervical spine rigidity under general anesthesia using an extraglottic airway device and a gum-elastic bougie under C-arm fluoroscopic guidance.

Clinical and Radiological Outcomes of Corrective Surgery on Adult Spinal Deformity Patients: Comparison of Short and Long Fusion.

Despite the accumulated knowledge of spinal alignment and clinical outcomes the full corrective surgery cannot be applied to all the deformity patients as it requires considerable surgical burden to the patients. The aim of this study was to investigate the clinical and radiological outcomes of the patients who have received short and long fusion for ASD. A total of 21 patients who received surgical reconstructive spinal fusion procedures and were followed up for at least one year were retrospectively reviewed. Sixteen cases have received spinal corrective surgery that upper instrumented vertebrate (UIV) was thoracic level (group T), or 5 cases were with UIV in lumbar level (group L). Group L had shorter operation time, smaller intraoperative estimated blood loss, and shorter postoperative hospitalization days. Group T tends to improve more in the magnitude of VAS of lumbar pain compared to group L. Improvement of spinal alignment revealed the advantage of long fusion compared to short fusion, in Cobb angle, sagittal vertical axis (SVA), lumbar lordosis (LL), PI-LL C7 plum line (C7PL), and center sacral vertebral line (CSVL). Pelvic tilt (PT) did not differ between the groups. Disc lordosis was the most acquired in XLIF compared to TLIF and PLF and maintained one year. There were 9 adverse events, 3 cases of pulmonary embolism (PE), one case of delirium, and 6 cases of proximal junctional kyphosis. Current study elucidated that long fusion, UIV, is thoracic and can achieve better spinal alignment compared to short fusion, UIV, in lumbar. XLIF demonstrated strong ability to reconstruct the deformity on intervertebral space that is better to apply as much intervertebral space as possible. For the ASD patients with complications, short fusion can be one of the options.

Clinical application of a novel assessment for lumbosacral stability.

OBJECT: To evaluate the grade of lumbosacral stability, shape analysis was conducted on plain radiographs of the lumbar spine. METHODS: One hundred twenty-six patients were classified into 2 groups: those with a single-segment disc space narrowing at L5-S1 or at L4-5. Stability was evaluated using the discriminant function (z score) derived from the analysis of radiographic parameters-that is, relative thickness of transverse process of L-5 and the sacral table angle. RESULTS: In patients with a space narrowing at L5-S1, the author observed a significantly slender L-5 transverse process and acute obliquity of the sacral endplate; accordingly, the z score was negative. In patients with a broad transverse process and a positive z score, the segment associated with disc height loss was L4-5. Thus, a close correlation was found between the site of the disc height loss and the bony characteristics of L-5 and S-1. Furthermore, it could be expected with a high degree reliability that when young adult patients had a z score less than -2 or -3, their L-5 vertebra would develop degenerative spondylolisthesis after middle age and the L5-S1 segment could be saved from age-related alterations as long as the z score was greater than 2.5. The constitutional characteristics of the lumbosacral junction may exert a major influence on the site of disc degeneration. CONCLUSIONS: Stability at the lumbosacral junction was thought to be quantitatively represented by the z score, with z being designated the lumbosacral stability score.

Synchronous multifocal osteosarcoma involving the skull presenting with intracranial hemorrhage -case report-.

A 40-year-old man presented with a rare case of synchronous multifocal osteosarcoma involving the skull associated with intracerebral hemorrhage, manifesting as sudden headache and left homonymous hemianopia. Computed tomography revealed a skull tumor in the right occipital bone and intracerebral hemorrhage in the right occipital lobe. Gross total resection of the skull tumor with hematoma was performed. The histological diagnosis was osteosarcoma. The tumor cells had invaded into the surrounding brain parenchyma, resulting in intracerebral hemorrhage.

Expression of developmentally regulated endothelial cell locus 1 was induced by tumor-derived factors including VEGF.

Developmentally regulated endothelial cell locus 1 (Del1) is a new angiogenic molecules expressed specifically in early embryonic endothelial cells. We investigated the relationship between Del1 and tumor cell-derived vascular endothelial growth factor (VEGF). Dunn osteosarcoma cells and high- and low-metastatic murine sarcoma cells did not express Del1. However, the expression of Del1 was observed in these primary tumor tissues and the pulmonary metastatic tissues after subcutaneous inoculation in vivo. Every tumor cell-conditioned medium containing VEGF induced the expression of Del1 in murine lung microvascular endothelial (MLE) cells, although control MLE cells did not express Del1. The anti-mouse VEGF monoclonal antibody inhibited the induction of the Del1 expression. In addition, mouse recombinant interleukin-1alpha and tumor necrosis factor-alpha also induced Del1 in MLE cells. Del1 may play an important role in tumor angiogenesis through the effects of tumor-derived factors including VEGF.

Cytogenetic and molecular cytogenetic findings in 43 aneurysmal bone cysts: aberrations of 17p mapped to 17p13.2 by fluorescence in situ hybridization.

Aneurysmal bone cyst is a benign, cystic lesion of bone composed of blood-filled spaces separated by fibrous septa. Relatively few cases of aneurysmal bone cyst have been cytogenetically characterized, yet abnormalities of the short arm of chromosome 17 appear to be recurrent. In this study, conventional cytogenetic analysis of 43 aneurysmal bone cyst specimens from 38 patients over a 12-year period revealed clonal chromosomal abnormalities in 12 specimens. Karyotypic anomalies of 17p, including a complex translocation and inversion, were identified in eight of these 12 specimens. In an effort to further define the aberrant 17p breakpoint, fluorescence in situ hybridization (FISH) analyses were performed using a series of probe combinations spanning a 5.1 Mb region between the TP53 (17p13.1) and Miller-Dieker lissencephaly syndrome (17p13.3) gene loci. These studies revealed the critical breakpoint locus at 17p13.2, flanked proximally by an RP11-46I8, RP11-333E1, and RP11-457I18 bacterial artificial chromosome (BAC) probe cocktail and distally by an RP11-198F11 and RP11-115H24 BAC and RP5-1050D4 P1 artificial chromosome (PAC) probe cocktail. Overall, abnormalities of the 17p13.2 locus were identified by metaphase and/or interphase cell FISH analysis in 22 of 35 (63%) aneurysmal bone cyst specimens examined including 26 karyotypically normal specimens. These cytogenetic and molecular cytogenetic findings expand our knowledge of chromosomal alterations in aneurysmal bone cyst, further localize the critically involved 17p breakpoint, and provide an alternative approach (ie FISH) for detecting 17p abnormalities in nondividing cells of aneurysmal bone cysts. The latter could potentially be utilized as an adjunct in diagnostically challenging cases.

Giant cell tumor of the sternum: a case report.

We report a rare case of giant cell tumor (GCT) of the sternum in a 55-year-old man. He presented with a bony mass in the body of the sternum that had been slowly growing over 6 months. The patient was treated by surgical curettage and cementation. Histological study showed typical GCT findings with cytogenetic abnormalities of many telomeric associations of chromosomes, predominantly the 19q arm.

Characteristics of nerve root compression caused by degenerative lumbar spinal stenosis with scoliosis.

BACKGROUND CONTEXT: In degenerative lumbar spinal stenosis with scoliosis (DLS), many authors stated that nerve root compression is almost always seen on the concave side of the scoliosis, and L4 and L5 nerve roots are the most often involved. However, there are few reports on the relationship between nerve root compression and the pattern of scoliosis. PURPOSE: To investigate the factors that may contribute to radiculopathy in DLS and their association with the pattern of the scoliosis. STUDY DESIGN: Retrospective analysis. METHODS: Twenty-two consecutive patients with DLS with radiculopathy were examined. The symptomatic nerve roots were determined by pain distribution, neurological findings and nerve root infiltration using lidocaine. The compressive factors were diagnosed by magnetic resonance imaging or myelography, discography, computed tomography after myelography or discography and radiculography. The pattern of scoliosis was determined in plain radiographs. We evaluated the correlation between the affected nerve root and the compressive factors or the pattern of the scoliosis. RESULTS: The L3 root was affected in 23% of patients; L4 root in 68%, L5 root in 55% and S1 root in 18%. L3 and L4 roots were more compressed by foraminal or extraforaminal stenosis on the concave side of the curve, whereas L5 and S1 roots were commonly affected by lateral recess stenosis on the convex side. The Cobb angle and the lateral slip of the cases in which L3 or L4 root was affected were significantly larger than in cases in which L5 or S1 root was compressed. CONCLUSIONS: In the treatment of radiculopathy caused by DLS, it is important to bear in mind that L3 or L4 roots were more strongly compressed by foraminal or extraforaminal stenosis at the concave side of the curve, whereas L5 or S1 nerve roots were affected more by lateral recess stenosis at the convex side of the curve.

Pathomechanism of myelopathy and surgical results of laminoplasty in elderly patients with cervical spondylosis.

STUDY DESIGN: Clinical and radiologic analyses in elderly patients with cervical myelopathy. OBJECTIVE: To investigate the pathomechanism of cervical myelopathy and the surgical results of laminoplasty in elderly patients older than 70 years old. SUMMARY OF BACKGROUND DATA: To date, there have been no reports on the pathomechanism of cervical myelopathy in elderly patients. Further, the surgical results and postoperative complications of laminoplasty have not been fully evaluated in elderly patients. METHODS: Eighty-nine patients who underwent cervical laminoplasty were reviewed. The patients were divided into 2 groups according to the age at the time of operation (the elderly patient group: 20 patients who were older than 70 years old, and the control group: 69 patients who were younger than 69 years old). Pre- and postoperative neurologic status (the Japanese Orthopedic Association score) and postoperative complications were compared between the two groups. Radiologic features were also examined. RESULTS: There was no statistical difference in the recovery rate of Japanese Orthopedic Association score between the elderly patient group and the control group. Activities of daily living improved in the elderly patients. Several complications, such as delirium and worsening hypertension, were found in the elderly patient group. In the preoperative radiographs, the incidence of either retrolisthesis or anterolisthesis in the elderly patient group was significantly higher than that in the control group. CONCLUSIONS: Retrolisthesis and anterolisthesis are often the cause of myelopathy in elderly patients. Surgical decompression for cervical myelopathy was beneficial even in elderly patients older than 70 years old. Laminoplasty achieves stability of the cervical spine, and this procedure is reasonable for the treatment.

Minimum 10-year followup after en bloc cervical laminoplasty.

The long-term outcome (> 10 years) after cervical laminoplasty was assessed and the postoperative problems were clarified. One hundred thirty-three patients had laminoplasty between 1981 and 1989 for treatment of cervical myelopathy and 126 patients were available for the current study. The clinical results were evaluated using the Japanese Orthopaedic Association score. The radiologic findings were analyzed by postural anomalies and range of motion. The average preoperative score was 9.1 points, and the postoperative score improved to 13.7 points within a year. The Japanese Orthopaedic Association score and recovery rate were maintained at 13.4 points and 55.1% at the last followup. In 20 patients, the Japanese Orthopaedic Association score worsened during the followup. The causes of deterioration were axial spread of ossification of the posterior longitudinal ligament, other spinal lesions, cerebral infarction, and peripheral neuropathy. Postoperative cervical radiculopathy occurred in nine patients. Postoperative radiculopathy resolved in five patients, but remained in four patients. Kyphotic changes were observed in eight patients. The recovery rate in patients with kyphosis was poor. The postoperative range of motion decreased to 25.1% of preoperative range of motion. Sixty one percent of patients had a reduction of range of motion. Satisfactory results of cervical laminoplasty were maintained for more than 10 years after surgery; however, there were several postoperative problems, such as neurologic deterioration, postoperative radiculopathy, progression of kyphosis, and range of motion limitation.

Significance of bone formation markers in patients with ossification of the posterior longitudinal ligament of the spine.

STUDY DESIGN: Serum concentrations of bone formation markers were correlated with the type, location, and progression of ossification of the posterior longitudinal ligament. OBJECTIVE: To determine the relation between bone formation markers and ossification of the posterior longitudinal ligament. SUMMARY OF BACKGROUND DATA: Few reports have correlated bone formation markers with ossification of the posterior longitudinal ligament. METHODS: In this study, 43 patients with cervical ossification of the posterior longitudinal ligament and myelopathy underwent laminoplasty. The patients were observed for more than 10 years, after which plain radiographs and tomograms of the cervical region were taken. The radiographs were selectively performed to address thoracic and lumbar ossification of the posterior longitudinal ligament. Serum concentrations of bone formation markers (intact osteocalcin, osteocalcin, carboxyterminal propeptide of human type 1 procollagen, and bone-specific alkaline phosphatase) were measured and correlated with these radiographic studies. RESULTS: A positive correlation was observed between intact osteocalcin, osteocalcin, and carboxyterminal propeptide of human type 1 procollagen in patients with combinations of cervical, thoracic, or lumbar ossification of the posterior longitudinal ligament. CONCLUSIONS: Serum concentrations of intact osteocalcin, osteocalcin, and carboxyterminal propeptide of human type 1 procollagen may reflect the activity of general ectopic bone formation in patients with ossification of the posterior longitudinal ligament.

Radiologic findings of the lumbar spine in patients with rheumatoid arthritis, and a review of pathologic mechanisms.

We have analyzed the radiologic findings on the lumbar spine and the clinical symptoms in patients with rheumatoid arthritis (RA). A total of 106 patients who fulfilled the revised criteria of the American Rheumatism Association were subjected. All of the patients were asked to fill out a questionnaire about the existence of low back pain, leg pain, and leg numbness. Radiologic features of the lumbar spine, including scoliosis, spondylolisthesis, disc space narrowing, endplate erosion, osteophyte, and osteoporosis, were checked. Radiographs of the cervical spine were also taken. The clinical background of RA, such as mutilating disease or not, was assessed. Forty-two patients (40%) had the symptoms of low back pain. Abnormal radiologic findings in lumbar spine were detected in 57%. The prevalence of clinical symptoms tended to be higher in the patients with endplate erosion. Forty-two percent of the patients had both lumbar and cervical lesions. The prevalence of lumbar lesion was not high in the mutilating type of RA, except for facet erosion and severe osteoporosis. The patients with pulse steroid therapy revealed a higher prevalence of vertebral fracture. From these results, we concluded that lumbar lesions were frequently observed in patients with RA. The possibility of lumbar lesions as well as the lesions in the cervical spine and peripheral joints should be examined in patients with RA.

Undifferentiated leiomyosarcoma showing various sarcomatous components with incidental B-cell lymphoma after tumor recurrence.

We report a rare case of undifferentiated leiomyosarcoma (LMS) with incidental B-cell lymphoma in a 70-year-old woman. T2-weighted magnetic resonance images revealed a high signal intensity mass measuring 9 x 8 cm in the gluteus muscle. The pathological diagnosis of repeated surgery was undifferentiated LMS that included various sarcomatous components, such as fibrosarcomatous, rhabdomyosarcomatous, and malignant fibrous histiocytoma-like elements. A specimen from a supraclavicular lymph node showed the characteristics of malignant B-cell lymphoma (follicle type). Adjuvant chemotherapy or radiation therapy was not performed because of the patient's advanced age. The patient died from liver metastasis and dysfunction 5 years 8 months after the initial therapy. This is a rare case of LMS with malignant lymphoma. Considerable debate remains whether the B-cell lymphoma developed incidentally.

The association of lumbar disc disease with vitamin-D receptor gene polymorphism.

BACKGROUND: Although the etiology of lumbar disc disease is unknown, it has been suggested that a genetic factor contributes to its development. Recently, some genetic polymorphisms have been found to be related to clinical disorders. We investigated the association between vitamin-D receptor gene and estrogen receptor gene polymorphisms and lumbar disc disease in young adults. METHODS: The participants included 205 young adults (166 women and thirty-nine men) with or without low-back problems. A magnetic resonance imaging scan of the lumbar spine was performed for all subjects, and the grade of disc degeneration was determined, according to the four-grade classification system of Schneiderman et al. The presence or absence of disc herniation was also evaluated. Genomic DNA was extracted from peripheral blood samples. The polymorphisms of the vitamin-D receptor and estrogen receptor genes were detected with use of a polymerase-chain-reaction assay. The restriction fragment length polymorphisms (RFLPs) for the vitamin-D receptor gene were analyzed by TaqI and ApaI restriction enzymes. XbaI and PvuII restriction enzymes were used for the estrogen receptor gene analysis. The distribution of polymorphism in subjects with disc degeneration and/or disc herniation was compared with that in the normal subjects. RESULTS: The allelic frequencies of both vitamin-D receptor gene and estrogen receptor gene polymorphisms were similar to those in previous analyses of Japanese subjects. The allelic variation in the vitamin-D receptor gene was associated with multilevel and severe disc degeneration and disc herniation. The Tt allele was found to be more frequently associated with multilevel disc disease, severe disc degeneration, and disc herniation than was the TT allele. No additional associations were found. CONCLUSIONS: This study revealed that the Tt allele of the vitamin-D receptor gene was more frequently associated with multilevel and severe disc degeneration and disc herniation than was the TT allele, pointing to an increased risk of disc disease at an early age in subjects with the Tt allele in the vitamin-D receptor gene.

Radiographic classification of L5 isthmic spondylolisthesis as adolescent or adult vertebral slip.

STUDY DESIGN: A radiographic and morphologic study was conducted to investigate low-grade spondylolisthesis in cases with preexisting isthmic spondylolysis of L5. OBJECTIVE: To distinguish radiographically between vertebral slips before and after skeletal maturity as determined by deformities of the sacral endplate. SUMMARY AND BACKGROUND DATA: Very few reports have shown that spondylolisthesis with preexisting isthmic defects of L5 develops frequently in adulthood. The prognostic factors of the vertebral slip have remained unclear. It is hard to determine the onset time of low-grade spondylolisthesis. METHODS: This study examined plain radiographs of 367 adult patients with pars defects of L5 (213 without slippage and 154 with Grade 1 or 2 spondylolisthesis) and 310 control subjects, ages 20 to 59 years at the first visit. The following parameters were measured and analyzed for each age decade: the sacral table index (anteroposterior width of the sacral endplate expressed as a percentage of the anteroposterior diameter of the upper L5 endplate), the sacral table angle (formed by the sacral endplate with the posterior wall of S1), the relative thickness of the L5 transverse process, and the iliac crest height. RESULTS: The prevalence of patients with slippage who met deformity criteria (sacral table index > 102% [the mean plus 2 standard deviations of the controls] and sacral table angle /=89 degrees [mean minus 2 standard deviations of the controls]) was 0% in the third decade, but increased remarkably in the fifth and sixth decades. Of the 213 patients without slippage, 8 patients in whom new slippage developed during long-term follow-up evaluation all had a normally-shaped sacral table. The prevalence of patients without slippage decreased gradually with age, and elderly patients had relatively broader transverse processes and a higher iliac crest line. CONCLUSIONS: The authors considered that the slips with and those without deformities of the sacral table had developed in adolescence and adulthood, respectively. Using new radiographic parameters that indicate widening and tilting of the sacral table, low-grade isthmic spondylolis thesis can be categorized into "adolescent and adult vertebral slips."

Computer-assisted Magerl's transarticular screw fixation for atlantoaxial subluxation.

We report two patients with rheumatoid arthritis in whom posterior atlantoaxial fixation was carried out using transarticular screws with computer assistance. Two bilateral transarticular screws were inserted in one patient; however, in the other patient, only a unilateral screw was used, because computerized images showed that the vertebral artery at the other side was placed too medially to allow insertion of the screw. Neither of these patients had any neurovascular complications after surgery. Computer-assisted surgery is useful for avoiding neurovascular complications with transarticular screw fixation of C1-2.

[Regional shifts in the vertebral column of inbred mice treated with X-rays or FCdR]. / über die Verschiebungen der Wirbelsulengrenzen, induziert durch Röntgenstrahlen und 5-Fluor-2'-desoxycytidin (FCdR) bei Muse-Inzuchtstmmen.

In three inbred-strains of mice (C57 BL/6, C57 BL/10 and C57 BL/Ks) 5-fluoro2'-deoxycytidine (FCdR) and X-rays have been applied at several stages of pregnancy. The shiftings of the regions of the vertebral column in the offspring have been examined. 1. There are several critical periods concerning differentiation of the cervical ribs. 2. Critical periods for differentiation of lumbar ribs are at stages day VIII and day IX of pregnancy. 3. X-rays and FCdR, applied at stage day IX, inhibit the formation of cervical ribs; in the controls they were found in a high percentage rate. 4. The appearance of the 13th ribs is inhibited by X-rays at stage day X+20 h of pregnancy. 5. The appearance of the 13th ribs is inhibited by FCdR at stage day IX; lumbar ribs have their critical period at the same time. 6. First ribs were never absent in the control and experimental series. 7. At stage day IX+20 h X-rays induced at a third time cervical ribs. This shows the importance of a broadly timed experiment. 8. The border between the lumbar and the sacral region is very sensitive to exogeneous influences; in the controls asymmetrical vertebrae fixed at the pelvic girdle are rather frequent.