Ectopic gas in the fibular graft after anterior cervical corpectomy and fusion.

BACKGROUND: Ectopic gas in the graft is occasionally encountered upon follow-up computed tomography (CT) after anterior cervical corpectomy and fusion (ACCF). However, most cases lack inflammatory responses and manifestations of infection. Although the clinical significance of ectopic gas in the graft has not yet been established, to the best of our knowledge, no previous studies have described ectopic gas in the graft after ACCF. This study evaluated ectopic gas in the fibular graft upon follow-up CT after ACCF. METHODS: We reviewed 112 patients who underwent ACCF and follow-up CT, with a minimum follow-up period of 3 years. CT images were retrospectively reviewed to confirm the presence of ectopic gas in the graft and bone fusion. Bone fusion was defined as follows: mobility less than 2 mm between spinous processes on the flection-extension radiograph or a bone bridge on CT images. RESULTS: Of the 112 patients, 30 (27%) patients had ectopic gas in the fibular grafts. Among them, ectopic gas was initially observed 3 months after surgery (early onset) in 23 (77%) patients and 6 months after surgery (late-onset) in the remaining seven (23%) patients. Upon the latest follow-up CT, ectopic gas more frequently remained in late-onset (4/7, 57%) rather than in early-onset (3/23, 13%) cases (p = 0.033). Bone fusion was not observed when CT images exhibited ectopic gas in the graft, whereas ectopic gas was not observed when CT images exhibited bone fusion. CONCLUSION: Ectopic gas in the fibular graft was observed at both early and late-onset after ACCF; late-onset gas remained significantly. The remaining gas was strongly associated with pseudoarthrosis; therefore, pseudoarthrosis should be considered when ectopic gas in the graft is observed on CT images.

Correlation between mutated genes and forearm deformity in patients with multiple osteochondroma.

BACKGROUNDS: Exostosin-1 (EXT1) and exostosin-2 (EXT2) cause multiple osteochondromas (MO). In this study, we investigated the correlation between forearm deformity and mutant EXTs in Japanese families with MO. METHODS: We evaluated 112 patients in 71 families with MO. Genomic DNA was isolated from peripheral blood leucocytes. Of these, 28 patients were selected and underwent radiography for their forearms since they had gross forearm deformities. We measured the radial articular angle (RAA), ulna variance (UV), carpal slip (CS), and percentage of radial bowing (%RB) to compare between patients with mutant EXT1 or EXT2 and those with missense or other mutations using Student's t-test. RESULTS: Twenty-two (78.6%) and 6 (11.4%) out of 28 patients had mutations in EXT1 and EXT2, respectively. Nine (32.1%) and 19 (67.9%) of the 28 patients had missense and other mutations, respectively. The mean age of patients with EXT1 and EXT2 were 25.9 ± 20.3 and 33.5 ± 25.4 years, respectively and those with missense mutation and other mutations were 28.7 ± 27.0 and 24.6 ± 17.0 years, respectively. There were no significant differences in RAA, UV, and RB between patients harbouring mutant EXT1 or EXT2 (RAA, 40.1 ± 8.7 and 31.5 ± 13.9°; UV, -2.7 ± 5.7 and -3.1 ± 3.7 mm; %RB, 8.6 ± 1.5 and 8.3 ± 2.0%). CS was significantly greater in patients with mutant EXT1 than that in those with mutant EXT2 (EXT1, 44.1 ± 16.8%; EXT2, 18.6 ± 14.0%). There were no significant differences in RAA, UV, CS and %RB between patients with missense and other mutations. CONCLUSIONS: Patients with mutant EXT1 displayed greater CS than patients with mutant EXT2, indicating that patients with MO harbouring EXT1 mutations sustain more severe ulnar drift deformities than those with EXT2 mutations.

Bilateral vocal cord palsy after a posterior cervical laminoplasty.

PURPOSE: To report a patient with bilateral vocal cord palsy following cervical laminoplasty, who survived following a tracheotomy and intensive respiratory care. METHODS: Acute respiratory distress is a fatal complication of cervical spinal surgery. The incidence of bilateral vocal cord palsy after posterior cervical decompression surgery is extremely rare. The authors report a 71-year-old woman who suffered from cervical myelopathy due to ossification of the posterior longitudinal ligament. Open-door laminoplasty from C2 to C6 and laminectomy of C1 were performed. Following surgery, extubation was successfully conducted. Acute-onset dysphagia and stridor had occurred 2 h following extubation. A postoperative fiber optic laryngoscope revealed bilateral vocal cord palsy. After a tracheotomy and intensive respiratory care, she had completely recovered 2 months after surgery. DISCUSSION: One potential cause of this pathology was an intraoperative hyper-flexed neck position, which likely induced mechanical impingement of the larynx, resulting in swelling and edema of the vocal cords and recurrent laryngeal nerve paresis. Direct trauma of the vocal cords during intubation and extubation could have also induced vocal cord paralysis. CONCLUSIONS: We reported a case of bilateral vocal cord palsy associated with posterior cervical laminoplasty. Airway complications following posterior spinal surgery are rare, but they do occur; therefore, spine surgeons should be aware of them and take necessary precautions against intraoperative neck position, intubation technique, even positioning of the intratracheal tube.

Large-scale mutational analysis in the EXT1 and EXT2 genes for Japanese patients with multiple osteochondromas.

BACKGROUND: Multiple osteochondroma (MO) is an autosomal dominant skeletal disorder characterized by the formation of multiple osteochondromas, and exostosin-1 (EXT1) and exostosin-2 (EXT2) are major causative genes in MO. In this study, we evaluated the genetic backgrounds and mutational patterns in Japanese families with MO. RESULTS: We evaluated 112 patients in 71 families with MO. Genomic DNA was isolated from peripheral blood leucocytes. The exons and exon/intron junctions of EXT1 and EXT2 were directly sequenced after PCR amplification. Fifty-two mutations in 47 families with MO in either EXT1 or EXT2, and 42.3% (22/52) of mutations were novel mutations. Twenty-nine families (40.8%) had mutations in EXT1, and 15 families (21.1%) had mutations in EXT2. Interestingly, three families (4.2%) had mutations in both EXT1 and EXT2. Twenty-four families (33.8%) did not exhibit mutations in either EXT1 or EXT2. With regard to the types of mutations identified, 59.6% of mutations were inactivating mutations, and 38.5% of mutations were missense mutations. CONCLUSIONS: We found that the prevalence of EXT1 mutations was greater than that of EXT2 mutations in Japanese MO families. Additionally, we identified 22 novel EXT1 and EXT2 mutations in this Japanese MO cohort. This study represents the variety of genotype in MO.

Morphologic Changes in Contralateral Lumbar Foramen in Unilateral Cantilever Transforaminal Lumbar Interbody Fusion Using Kidney-type Intervertebral Spacers.

STUDY DESIGN: A retrospective study of 58 patients undergoing cantilever transforaminal lumbar interbody fusion (c-TLIF). OBJECTIVES: To evaluate morphologic changes in the intervertebral foramen (IVF) on the side contralateral to spacer insertion in patients undergoing c-TLIF using plain x-ray films and computed tomography scan. SUMMARY OF BACKGROUND DATA: The morphologic changes in the contralateral lumbar foramen in c-TLIF using unilateral insertion of spacers have not been well studied. MATERIALS AND METHODS: Fifty-eight consecutive patients with lumbar dysplastic changes or degenerative disk diseases underwent c-TLIF using 96 kidney-type spacers with local bone grafts. Radiographic findings (sagittal disk angle), computed tomography scan findings (coronal disk angle, disk height, foraminal height (FH), foraminal width, and cross-sectional area of IVF in contralateral lumbar foramen) were compared between preoperative period and 6 months after surgery. The correlations between contralateral lumbar foraminal dimensions and disk height, sagittal disk angle, and coronal disk angle were analyzed. RESULTS: After c-TLIF, sagittal angle, disk height, FH, foraminal width, and cross-sectional area of the IVF were significantly increased. Increase in posterior disk height showed a positive correlation with increases in FH, foraminal width, and cross-sectional area of IVF (r=0.235-0.511). However, the increase in sagittal disk angle showed a negative correlation with changes in foraminal width and cross-sectional area of IVF (r=-0.256 to -0.206). CONCLUSIONS: Lumbar foraminal dimensions on the side contralateral to spacer insertion increased significantly after c-TLIF, suggesting that c-TLIF enables indirect decompression of the contralateral nerve root. Although increase in posterior disk height was shown to be an important factor to increase contralateral foraminal size, segmental lordosis was a risk factor for a decrease in contralateral foraminal size.

Comparison of tibial shaft ski fractures in children and adults.

OBJECTIVE: To examine whether child and adult skiers have different risk factors or mechanisms of injury for tibial shaft fractures. DESIGN: Descriptive epidemiological study. SETTING: Prospectively analyzed the epidemiologic factors, injury types, and injury mechanisms at Sumi Memorial Hospital. PATIENTS: This study analyzed information obtained from 276 patients with tibial fractures sustained during skiing between 2004 and 2012. MAIN OUTCOME MEASURES: We focused on 174 ski-related tibial shaft fractures with respect to the following factors: age, gender, laterality of fracture, skill level, mechanism of fracture (fall vs collision), scene of injury (steepness of slope), snow condition, and weather. Fracture pattern was graded according to Arbeitsgemeinschaft für Osteosynthesefragen (AO) classification and mechanical direction [external (ER) or internal rotation (IR)]. RESULTS: Tibial shaft fractures were the most common in both children (89.3%) and adults (47.4%). There were no significant differences in gender, side of fracture, mechanism of fracture, snow condition, or weather between children and adults. Skill levels were significantly lower in children than in adults (P < 0.0001). Type A fractures were more dominant in children (73 cases, 72.3%) than in adults (39 cases, 53.4%). There was significantly more ER in children than in adults (P < 0.0001). Among children, female patients had significantly more IR than ER; in contrast, among adults, women were injured by ER. CONCLUSIONS: We found significant differences in some of these parameters, suggesting that child and adult skiers have different risk factors or mechanisms of injury for tibial shaft fractures.

Increased blood flow in the anterior humeral circumflex artery correlates with night pain in patients with rotator cuff tear.

BACKGROUND: Night pain is a particularly vexing symptom in patients with rotator cuff tear. It disturbs sleep and decreases quality of life, and there is no consensus regarding its etiology. Based on arthroscopic surgical observations of synovitis around the rotator interval or capsule surface in rotator cuff tear, we hypothesized that blood flow from the artery feeding the capsule increases blood supply to the synovium. This study aimed to investigate the relationship between blood flow and night pain using pulse Doppler ultrasonography. METHODS: A series of 47 consecutive patients with rotator cuff tear was evaluated. The peak systolic velocity and resistance index of blood flow in the ascending branch of the anterior humeral circumflex artery were evaluated using pulse Doppler ultrasonography. We also investigated 20 normal shoulders in healthy volunteers. The peak systolic velocity and resistance index were compared between affected and unaffected sides in patients and between dominant and nondominant sides in controls. RESULTS: Anterior humeral circumflex artery peak systolic velocity and resistance index did not differ between sides in control subjects or in patients with rotator cuff tear without night pain. However, anterior humeral circumflex artery peak systolic velocity and resistance index did differ significantly between sides in patients with rotator cuff tear with night pain. CONCLUSIONS: This study revealed anterior humeral circumflex artery hemodynamics in patients with rotator cuff tear and normal subjects using Doppler ultrasonography. Night pain, particularly involving aching, appears to be related to the hemodynamics. These findings suggest that investigating the hemodynamics of patients with rotator cuff tear with night pain may lead to greater understanding of the etiology of this symptom.

Glycosaminoglycans in the blood of hereditary multiple exostoses patients: Half reduction of heparan sulfate to chondroitin sulfate ratio and the possible diagnostic application.

Hereditary multiple exostoses (HME) is an autosomal dominant skeletal disorder with wide variation in clinical phenotype and is caused by heterogeneous germline mutations in two of the Ext genes, EXT-1 and EXT-2, which encode ubiquitously expressed glycosyltransferases involved in the polymerization of heparan sulfate (HS) chains. To examine whether the Ext mutation could affect HS structures and amounts in HME patients being heterozygous for the Ext genes, we collected blood from patients and healthy individuals, separated it into plasma and cellular fractions and then isolated glycosaminoglycans (GAGs) from those fractions. A newly established method consisting of a combination of selective ethanol precipitation of GAGs, digestion of GAGs recovered on the filter-cup by direct addition of heparitinase or chondroitinase reaction solution and subsequent high-performance liquid chromatography of the unsaturated disaccharide products enabled the analysis using the least amount of blood (200 µL). We found that HS structures of HME patients were almost similar to those of controls in both plasma and cellular fractions. However, interestingly, although both the amounts of HS and chondroitin sulfate (CS) varied depending on the different individuals, the amounts of HS in both the plasma and cellular fractions of HME patient samples were decreased and the ratios of HS to CS (HS/CS) of HME patient samples were almost half those of healthy individuals. The results suggest that HME patients' blood exhibited reduced HS amounts and HS/CS ratios, which could be used as a diagnostic biomarker for HME.

Pathogenesis of Morquio A syndrome: an autopsied case reveals systemic storage disorder.

Mucopolysaccharidosis IVA (MPS IVA; Morquio A syndrome) is a lysosomal storage disorder caused by deficiency of N-acetylgalactosamine-6-sulfate sulfatase, which results in systemic accumulation of glycosaminoglycans (GAGs), keratan sulfate and chondroitin-6-sulfate. Accumulation of these GAGs causes characteristic features as disproportionate dwarfism associated with skeletal deformities, genu valgum, pigeon chest, joint laxity, and kyphoscoliosis. However, the pathological mechanism of systemic skeletal dysplasia and involvement of other tissues remain unanswered in the paucity of availability of an autopsied case and successive systemic analyses of multiple tissues. We report here a 20-year-old male autopsied case with MPS IVA, who developed characteristic skeletal features by the age of 1.5 years and died of acute respiratory distress syndrome five days later after occipito-C1-C2 cervical fusion. We pathohistologically analyzed postmortem tissues including trachea, lung, thyroid, humerus, aorta, heart, liver, spleen, kidney, testes, bone marrow, and lumbar vertebrae. The postmortem tissues relevant with clinical findings demonstrated 1) systemic storage materials in multiple tissues beyond cartilage, 2) severely vacuolated and ballooned chondrocytes in trachea, humerus, vertebrae, and thyroid cartilage with disorganized extracellular matrix and poor ossification, 3) appearance of foam cells and macrophages in lung, aorta, heart valves, heart muscle, trachea, visceral organs, and bone marrow, and 4) storage of chondrotin-6-sulfate in aorta. This is the first autopsied case with MPS IVA whose multiple tissues have been analyzed pathohistologically and these pathological findings should provide a new insight into pathogenesis of MPS IVA.

Alterations in axial curvature of the cervical spine with a combination of rotation and extension in the conventional anterior cervical approach.

PURPOSE: Alterations of three-dimensional cervical curvature in conventional anterior cervical approach position are not well understood. The purpose of this study was to evaluate alignment changes of the cervical spine in the position. In addition, simulated corpectomy was evaluated with regard to sufficiency of decompression and perforation of the vertebral artery canal. METHODS: Fifty patients with cervical spinal disorders participated. Cervical CT scanning was performed in the neutral and supine position (N-position) and in extension and right rotation simulating the conventional anterior approach position (ER-position). Rotation at each vertebral level was measured. With simulation of anterior corpectomy in a vertical direction with a width of 17 mm, decompression width at the posterior wall of the vertebrae and the distance from each foramen of the vertebral artery (VA) were measured. RESULTS: In the ER-position, the cervical spine was rotated rightward by 37.2° ± 6.2° between the occipital bone and C7. While the cervical spine was mainly rotated at C1/2, the subaxial vertebrae were also rotated by several degrees. Due to the subaxial rotation, the simulated corpectomy resulted in smaller decompression width on the left side and came closer to the VA canal on the right side. CONCLUSIONS: In the ER-position, the degrees of right rotation of subaxial vertebrae were small but significant. Therefore, preoperative understanding of this alteration of cervical alignment is essential for performing safe and sufficient anterior corpectomy of the cervical spine.

In vivo measurement of lumbar foramen during axial loading using a compression device and computed tomography.

STUDY DESIGN: In vivo measurement of lumbar foramen using computed tomography and an axial loading device in healthy young subjects. OBJECTIVE: To investigate the effects of axial loading on the morphology of the lumbar foramen in vivo. SUMMARY OF BACKGROUND DATA: In vitro studies have shown morphologic changes in the lumbar foramen in response to axial loading. The effects of axial loading on foraminal dimensions in vivo, however, are poorly understood. MATERIALS AND METHODS: The study population consisted of 12 asymptomatic healthy young volunteers [6 men and 6 women; age range, 22-34 y (mean, 27 y)]. Lumbar computed tomography images were compared with and without axial loading using a compression device (DynaWell), and differences in disk height (DH), foraminal height (FH), foraminal width (FW), and the cross-sectional area (CSA) of the intervertebral foramen (IVF) were determined. RESULTS: During axial loading, the FHs at L1/L2, L2/L3, L3/L4, and L4/L5 each decreased significantly (P<0.01 each), by 4.0%, 6.6%, 6.6%, and 5.1%, respectively. Maximum FW decreased significantly (P<0.05 each) at L2/L3 (7.2%) and L3/L4 (5.7%), and increased significantly (P<0.05) at L5/S1 (8.9%). The CSAs of the IVF decreased significantly (P<0.01 each) at L2/L3 (10.8%) and L3/L4 (10.7%) and increased significantly (P<0.01) at L5/S1 (23.3%). Changes in FH, maximum and minimum FW, and CSA of the IVF significantly (P<0.01) correlated with change in posterior DH. CONCLUSIONS: FH, FW, and CSA of the IVF, except for L5/S1, decreased significantly during axial loading. Changes in posterior DH correlated well with the changes in foraminal dimensions.

Primary total hip arthroplasty with a spongy metal surface acetabular component for hip dysplasia.

We evaluated the clinical and radiographic results of primary total hip arthroplasty for 81 dysplastic hips (71 patients) using cementless Spongiosa Metal II cups (ESKA Implants, Lübeck, Germany). The mean follow-up period was 6.4 years (minimum 5 years), and the preoperative mean Japanese Orthopaedic Association hip score had improved from 45.2 to 87.4 points at the latest follow-up. The radiographic outcome was no aseptic loosening in all 81 hips. The hip center was located significantly more superior than in the contralateral normal hip in 45 patients, but the difference was less than 10 mm; however, there was no significant difference in the lateral position of the hip center. The use of a Spongiosa Metal II cup for dysplastic hips provided satisfactory 5- to 10-year clinical and radiographic results.

Lumbar corsets can decrease lumbar motion in golf swing.

Swinging a golf club includes the rotation and extension of the lumbar spine. Golf-related low back pain has been associated with degeneration of the lumbar facet and intervertebral discs, and with spondylolysis. Reflective markers were placed directly onto the skin of 11young male amateur golfers without a previous history of back pain. Using a VICON system (Oxford Metrics, U.K.), full golf swings were monitored without a corset (WOC), with a soft corset (SC), and with a hard corset (HC), with each subject taking 3 swings. Changes in the angle between the pelvis and the thorax (maximum range of motion and angular velocity) in 3 dimensions (lumbar rotation, flexion-extension, and lateral tilt) were analyzed, as was rotation of the hip joint. Peak changes in lumbar extension and rotation occurred just after impact with the ball. The extension angle of the lumbar spine at finish was significantly lower under SC (38°) or HC (28°) than under WOC (44°) conditions (p < 0.05). The maximum angular velocity after impact was significantly smaller under HC (94°/sec) than under SC (177°/sec) and WOC (191° /sec) conditions, as were the lumbar rotation angles at top and finish. In contrast, right hip rotation angles at top showed a compensatory increase under HC conditions. Wearing a lumbar corset while swinging a golf club can effectively decrease lumbar extension and rotation angles from impact until the end of the swing. These effects were significantly enhanced while wearing an HC. Key pointsRotational and extension forces on the lumbar spine may cause golf-related low back painWearing lumbar corsets during a golf swing can effectively decrease lumbar extension and rotation angles and angular velocity.Wearing lumbar corsets increased the rotational motion of the hip joint while reducing the rotation of the lumbar spine.

Atlantoaxial Instability after Treatment of Atlantoaxial Rotatory Fixation: A Case Report.

Introduction: We encountered a case of atlantoaxial subluxation (AAS) after treatment of atlantoaxial rotatory fixation (AARF). Reports of developing AAS after AARF are extremely rare. Case Report: An 8-year-old male who feels neck pain was diagnosed with AARF type II according to the Fielding classification. Computed tomography (CT) showed that the atlas was rotated 32° to the right relative to the axis. Neck collar, Glisson traction, and reduction under anesthesia were performed. Five months after the onset of AARF, the patient was diagnosed with AAS due to dilatation of atlantodental interval (ADI) and underwent posterior cervical fusion. Conclusion: AARF treatments, such as long-term Glisson traction and reduction under general anesthesia, which exert a stress on the cervical spine, may damage the alar ligaments, apical ligaments, lower longitudinal band, and Gruber's ligament. Transverse ligament damage can also occur during the treatment of AARF, especially if AARF is refractory or requires long-term treatment. In addition, knowledge of the pathophysiology of atlantoaxial instability after AARF treatment is important.

TRPV4-pathy manifesting both skeletal dysplasia and peripheral neuropathy: a report of three patients.

Heterozygous missense mutations of transient receptor potential vanilloid 4 channel (TRPV4) cause a spectrum of skeletal disorders, including brachyolmia, spondylometaphyseal dysplasia Kozlowski type, metatropic dysplasia, parastremmatic dysplasia, and spondyloepimetaphyseal dysplasia Maroteaux type. Similarly, heterozygous missense mutations of TRPV4 cause a spectrum of peripheral neuropathy, including hereditary motor and sensory neuropathy type IIC, congenital spinal muscular atrophy, and scapuloperoneal spinal muscular atrophy. There are no apparent differences in the amino acid positions affected or type of change predicted by the TRPV4 mutations responsible for the two disease spectrums; nevertheless, no fundamental phenotypic overlap has been shown between the two spectrums. Here, we report on three patients who had both skeletal dysplasia and peripheral neuropathy caused by heterozygous TRPV4 missense mutations. The skeletal and neurologic phenotypes of these patients covered the wide spectrum of reported TRPV4-pathies (disease caused by TRPV4 mutations). The molecular data are complementary, proving that "neuropathic" mutations can cause skeletal dysplasia but also the "skeletopathic" mutations can lead to neuropathies. Our findings suggest that pathogenic mechanisms of TRPV4-pathies in skeletal and nervous systems are not always mutually exclusive and provide further evidence that there is no clear genotype-phenotype correlation for either spectrum. Co-occurrence of skeletal dysplasia and degenerative neuropathy should be kept in mind in clinical practice including diagnostic testing, surgical evaluation, and genetic counseling.

Does 20-min arm crank ergometer exercise increase plasma interleukin-6 in individuals with cervical spinal cord injury?

Interleukin-6 (IL-6) is produced by contracting skeletal muscles and then released into the circulation and considered to mediate the health benefits of exercise against chronic diseases. Individuals with spinal cord injury (SCI) are reported to be at higher risk of developing metabolic diseases. We investigated the IL-6 responses to 20-min arm crank ergometer exercise at 60% of maximum oxygen consumption in eight trained individuals with cervical SCI (CSCI) between C6 and C7, and eight able-bodied trained healthy subjects. The plasma concentrations of IL-6, adrenaline, prostaglandin E(2) and cortisol were measured before, immediately after the exercise, 1 and 2 h after exercise. At rest, the plasma adrenaline concentration was significantly lower in individuals with CSCI than in able-bodied subjects (P < 0.01). On the other hand, the concentration of IL-6 was significantly higher at rest in individuals with CSCI (2.18 ± 0.44 pg/ml, mean ± SEM) than the control (1.02 ± 0.22 pg/ml, P < 0.05). In able-bodied subjects, the plasma adrenaline concentration increased significantly immediately after the exercise (P < 0.01) and returned to the baseline level at 1 h after exercise, and the plasma IL-6 level increased significantly at 1 h after exercise (1.91 ± 0.28 pg/ml, P < 0.05) and returned to the baseline level at 2 h after exercise. In contrast, adrenaline and IL-6 levels were steady throughout the study in individuals with CSCI. The lack of exercise-related IL-6 response in individuals with CSCI could be due to muscle atrophy and sympathetic nervous system dysfunction.

Hip pads reduce the overall risk of injuries in recreational snowboarders.

OBJECTIVE: The purpose is to determine common injuries in recreational snowboarding as targets of preventive strategy and protective gear that reduces the overall risk of these injuries. METHODS: The subjects comprised 5561 injured recreational snowboarders. On the basis of patients' self-reporting form, 'the common snowboarding injuries' (cut-off point >2.0% in prevalence) were decided, and all injured snowboarders were categorised into two groups: common injuries and the other injuries (control). Several factors such as age, gender, self-reported skill level, experienced seasons, experienced days, previous snowboarding school attendance and the use of protective gears (helmet, elbow pads, wrist guards, backbone guard, hip pads and knee pads) were recorded. Multiple logistic regression analysis was conducted to investigate which type of protective gear reduced the overall risk of the common injuries. RESULTS: The common snowboarding injuries consisted of eight types, in which distal radial fracture was the most common (17.7%), followed by head injury (9.4%) and clavicle fracture (6.5%). In univariate regression analysis, skill level, experienced seasons, experienced days and the use of hip pads and knee pads were manifested potential risk factors on the common injuries. In subsequent multivariate regression analysis, the use of hip pads was related with a lower overall risk of these common injuries (OR, 0.84; 95% CI, 0.75 to 0.95), specifically that of distal radial fracture and glenohumeral dislocation. CONCLUSIONS: The use of hip pads is recommended for snowboarders as it reduces the overall risk of common snowboarding injuries.

Lower incidence of adjacent segment degeneration after anterior cervical fusion found with those fusing C5-6 and C6-7 than those leaving C5-6 or C6-7 as an adjacent level.

STUDY DESIGN: Retrospective analysis of adjacent disc degeneration (ADD) after anterior cervical decompression and fusion (ADF). OBJECTIVES: To elucidate the influence of the number of levels fused in ADF on the incidence of ADD. SUMMARY OF BACKGROUND DATA: ADD is known as a complication associated with ADF. However, how the number of levels fused affects the incidence of ADD is not well understood. METHODS: One hundred and two patients with cervical degenerative disease, who underwent ADF and were followed for more than 24 months, were retrospectively analyzed. They were classified into 2 groups, a long group (L group) consisting of 50 cases with ADF of 4 or more disc levels, and a short group (S group) consisting of 52 cases with ADF of 3 or fewer disc levels. Furthermore, the patients were also divided into 2 groups according to inclusion or exclusion of C5-6 and C6-7 (C group: including both, NC group: not including both). The incidence of ADD, and that of symptomatic ADD (sADD), was compared between the 2 classifications. RESULTS: In the L group, there were 13 cases of ADD (26.0%), including 1 case of sADD (2.0%), whereas in the S group, there were 22 cases of ADD (42.3%), including 11 cases of sADD (21.2%). The incidence of sADD was significantly lesser in the L group (P=0.024). Three cases with sADD in the S group required revision surgery, whereas no additional surgery related to ADD was performed on patients in the L group. In addition, in the C group, ADD occurred in 20 of 71 cases (28.2%) and sADD occurred in 4 of 71 cases (5.6%), whereas in the NC group, ADD occurred in 15 of 31 cases (48.4%) and sADD occurred in 8 of 31 cases (25.8%). The incidence of ADD and sADD were significantly lesser in the C group (P=0.048). CONCLUSIONS: ADD occurs less frequently among patients in whom C5-6 and C6-7 are fused than among those in whom C5-6 or C6-7 is left at an adjacent level, irrespective of the length of the fusion.

A Rare Case of Cervical Myelopathy Caused by an Anomaly of the Axis: A Case Report and a Review of Current Comprehensive Literature.

Introduction: Cervical myelopathy due to anomalies of the posterior elements of the axis is rare, and limited cases have been reported. This study reports such a unique case of congenital anomaly of the laminae of the axis, which is treated by partial removal of the anomalous bony structure surgically, and provides a comprehensive review of the present literature on this pathological condition. Case Presentation: A 65-year-old man presented with a 3-year history of numbness in both arms with a sensory change in the right arm. Six months before admission, he noticed weakness in his right upper extremities and stiffness of the right lower extremity. Magnetic resonance imaging (MRI) showed a bilaterally compressed spinal cord with an anomalous bony structure at the C2-3 level. Computed tomography (CT) showed an invaginated abnormal bony structure at the C2-3 level and an abnormal lateral mass on the right side at the C2-3 level. The patient underwent posterior decompression surgery using the conventional open approach. One year after surgery, his myelopathy partially ameliorated, with his cervical radiograph showing no signs of the secondary instability and MRI showing sufficient decompression of the spinal cord. The age of onset, symptoms, and surgical treatment in our case was similar to those in the 14 previously reported cases; however, the morphology of the anomaly had variations. Conclusion: This is a report of a rare anomaly in the laminae of the axis. MRI and reconstructed CT scans were useful for the treatment of this case. Partial surgical removal was an appropriate treatment for this patient, resulting in a satisfactory outcome.

Chondroitin sulfate synthase-2/chondroitin polymerizing factor has two variants with distinct function.

Chondroitin sulfate (CS) is a polysaccharide consisting of repeating disaccharide units of N-acetyl-D-galactosamine and d-glucuronic acid residues, modified with sulfated residues at various positions. To date six glycosyltransferases for chondroitin synthesis have been identified, and the complex of chondroitin sulfate synthase-1 (CSS1)/chondroitin synthase-1 (ChSy-1) and chondroitin sulfate synthase-2 (CSS2)/chondroitin polymerizing factor is assumed to play a major role in CS biosynthesis. We found an alternative splice variant of mouse CSS2 in a data base that lacks the N-terminal transmembrane domain, contrasting to the original CSS2. Here, we investigated the roles of CSS2 variants. Both the original enzyme and the splice variant, designated CSS2A and CSS2B, respectively, were expressed at different levels and ratios in tissues. Western blot analysis of cultured mouse embryonic fibroblasts confirmed that both enzymes were actually synthesized as proteins and were localized in both the endoplasmic reticulum and the Golgi apparatus. Pulldown assays revealed that either of CSS2A, CSS2B, and CSS1/ChSy-1 heterogeneously and homogeneously interacts with each other, suggesting that they form a complex of multimers. In vitro glycosyltransferase assays demonstrated a reduced glucuronyltransferase activity in CSS2B and no polymerizing activity in CSS2B co-expressed with CSS1, in contrast to CSS2A co-expressed with CSS1. Radiolabeling analysis of cultured COS-7 cells overexpressing each variant revealed that, whereas CSS2A facilitated CS biosynthesis, CSS2B inhibited it. Molecular modeling of CSS2A and CSS2B provided support for their properties. These findings, implicating regulation of CS chain polymerization by CSS2 variants, provide insight in elucidating the mechanisms of CS biosynthesis.