Effects of electroacupuncture on a degenerated intervertebral disc using an in-vivo rat-tail model.

Electroacupuncture (EA) has long been used as conservative treatment for low back pain (LBP). Its effect on relief of back pain has been demonstrated in many clinical studies. However, whether it has any effect on the biological properties of an intervertebral disc, which is one of the major causes of LBP, is still unclear. The aim of this study was, therefore, to investigate the effects of EA with different simulation frequencies on an intervertebral disc with simulated degeneration using an in-vivo rat-tail model. In this study, 33 rats were used. Disc degeneration was simulated in the rat caudal 8-9 disc via continuous static compressive loading of 11 N for 2 weeks. EA with a frequency of 2 or 100 Hz was then applied to the degenerated disc for 3 weeks with 3 sessions/week and 20 min/session. The intervertebral disc height was measured before and after compression as well as after EA intervention for 3 weeks. The static compression was found to result in a reduction in the disc height of about 22 per cent. There was no evidence that this change could be reversed after resting or the EA intervention. However, EA at 100 Hz was found to induce a further decrease in disc height, which was not shown for the rats after resting or EA at 2 Hz. The results of this study showed that effects of EA on disc degeneration are frequency dependent and adverse effects could result if EA at a certain frequency was used.

Changes in spinal curvature and proprioception of schoolboys carrying different weights of backpack.

Despite evidence linking backpack carriage and back pain, previous studies to examine the effects of backpack carriage have focused on changes in physical performance rather than the direct effects on the spine itself. Spinal curvature and proprioception (in terms of spinal repositioning consistency) of 15 schoolboys during normal upright stance without a backpack and while carrying a specially adapted backpack loaded at 10, 15 and 20% of their bodyweight were measured and compared using repeated measures ANOVA. A significant flattening of the lumbar lordosis and the upper thoracic kyphosis was found with increasing backpack load, as well as a significant decrease in the thoraco-lumbar and lumbar repositioning consistencies. Carriage of a loaded backpack causes immediate changes in spinal curvature and appears to have a direct effect on the repositioning consistency. Further investigation of the changes in spinal curvature and repositioning consistency over time with prolonged backpack carriage is warranted. Daily carriage of a school backpack on the musculoskeletal health of children and adolescents has become an area of concern due to the association between backpack carriage and back pain. Data regarding the direct effect of backpack carriage on the spine in children are limited.

The feasibility of repositioning ability as a tool for ergonomic evaluation: effects of chair back inclination and fatigue on head repositioning.

Poor posture has been suggested as one of the main factors contributing to the high prevalence of neck pain in video display unit (VDU) users, but no clear association between pain and any particular resting neck posture has been found. Postural awareness of the neck, as indicated by the repositioning accuracy, may therefore be an appropriate measure and potentially useful assessment tool. The objective of this study is to examine whether posture and fatigue affect the head repositioning ability in typical VDU usage. A group of 20 healthy participants reproduced a normal comfortable posture for forward, upright and backward chair back inclinations in random order both before and after fatigue of the upper trapezius muscles. Ten repetitions of the posture were recorded for 2 s each, and the angular and translational deviations from the original head position were measured with regard to the external environment (head in space repositioning) and with regard to the trunk (head on trunk repositioning). Analysis by repeated measures ANOVA showed significant effects and interactions of fatigue and chair back inclination on the repositioning errors in the sagittal plane, which typically showed systematic trends towards certain postures rather than random errors around a mean position. While further work is required to examine the ergonomic impact of impaired repositioning ability, head repositioning is sensitive to ergonomic factors such as seating configuration and fatigue, and may therefore be a useful tool for evaluation of static working postures.

FBN1, TGFBR1, and the Marfan-craniosynostosis/mental retardation disorders revisited.

The recent identification of TGFBR2 mutations in Marfan syndrome II (MFSII) [Mizuguchi et al. (2004); Nat Genet 36:855-860] and of TGFBR1 and TGFBR2 mutations in Loeys-Dietz aortic aneurysm syndrome (LDS) [Loeys et al. (2005); Nat Genet 37:275-281] [OMIM 609192] has provided direct evidence of abnormal signaling in transforming growth factors beta (TGF-beta) in the pathogenesis of Marfan syndrome (MFS). In light of this, we describe the phenotypes and genotypes of five individuals. Patient 1 had MFS and abnormal cranial dura. Patient 2 had severe early onset MFS and an abnormal skull. Patients 3 and 4 had probable Furlong syndrome (FS). Patient 5 had marfanoid (MD) features, mental retardation (MR), and a deletion of chromosome 15q21.1q21.3. All patients had a condition within the MFS, MD-craniosynostosis (CS) or MD-MR spectrum. The names of these entities may become redundant, and instead, come to be considered within the spectrum of TGF-beta signaling pathway disorders. Two recurrent heterozygous FBN1 mutations were found in Patients 1 and 2, and an identical novel heterozygous de novo TGFBR1 mutation was found in Patients 3 and 4, in whom altered fibrillin-1 processing was demonstrated previously [Milewicz et al. (2000); Am J Hum Genet 67:279]. A heterozygous FBN1 deletion was found in Patient 5. These findings support the notion that perturbation of extracellular matrix homeostasis and/or remodeling caused by abnormal TGF-beta signaling is the core pathogenetic mechanism in MFS and related entities including the MD-CS syndromes.

A comparison of deconvolution techniques for stress relaxation.

Stress relaxation (or equivalently creep) allows a large range of the relaxation (retardation) spectrum of materials to be examined, particularly at lower frequencies. However, higher frequency components of the relaxation curves (typically of the order of Hertz) are attenuated due to the finite time taken to strain the specimen. This higher frequency information can be recovered by deconvolution of the stress and strain during the loading period. This paper examines the use of three separate deconvolution techniques: numerical (Fourier) deconvolution, semi-analytical deconvolution using a theoretical form of the strain, and deconvolution by a linear approximation method. Both theoretical data (where the exact form of the relaxation function is known) and experimental data were used to assess the accuracy and applicability of the deconvolution methods. All of the deconvolution techniques produced a consistent improvement in the higher frequency data up to the frequencies of the order of Hertz, with the linear approximation method showing better resolution in high-frequency analysis of the theoretical data. When the different deconvolution techniques were applied to experimental data, similar results were found for all three deconvolution techniques. Deconvolution of the stress and strain during loading is a simple and practical method for the recovery of higher frequency data from stress-relaxation experiments.

Allogeneic bone grafting of calvarial defects: an experimental study in the rabbit.

The purpose of this study was to investigate the incorporation of fresh frozen irradiated membranous allogeneic bone grafts into critical size calvarial defects in the rabbit. Fifteen rabbits had calvarial defects prepared. Twelve rabbits received allogeneic grafts and three received autogenous bone grafts. The rabbits were sacrificed at 9 and 12 months postoperatively, and the specimens were examined radiologically, histopathologically and with fluorescence microscopy. Neovascularization, bone marrow regeneration and new bone formation was evident throughout the grafts however revitalization of the entire graft was incomplete at 12 months. This study revealed that the FFI membranous grafts were well incorporated into rabbit calvarial defects.

Bioactive bone cement as a principal fixture for spinal burst fracture: an in vitro biomechanical and morphologic study.

STUDY DESIGN: An in vitro biomechanical and radiographic study to evaluate the properties of a newly developed bioactive bone cement for stabilization of the fractured spine, suitable for minimally invasive application. OBJECTIVES: To determine the mechanical stability of the fractured spine after injection of the newly developed bioactive bone cement under quasi-static and cyclic loading regimens. SUMMARY OF BACKGROUND DATA: Bone cement injection has been reported as a potentially useful, minimally invasive technique for treating vertebral body fracture or stabilizing osteoporosis. However, potential problems associated with the use of polymethylmethacrylate (PMMA) have prompted the search for alternative solutions. The use of bioactive bone cement as a potential replacement for PMMA has been reported. METHODS: Biomechanical and radiographic analyses were used to test the mechanical stability of the fractured spine. The cement used was formed from hydroxyapatite powder containing strontium and bisphenol A diglycidylether dimethacrylate (D-GMA) resin. Twenty-six fresh porcine spine specimens (T10-L1) were divided into three groups: pilot, intact, and cemented. Spinal stiffness and failure strength were recorded in the intact group with the specimens flexed at 10 degrees. Uniform injuries were created in all specimens of the cemented group, and compressive loading was applied with 10 degrees of flexion until a fracture occurred. The bone cement was injected into the fractured spine, and stiffness was evaluated after 1 hour. Failure strength was also recorded after 3000 and 20,000 fatigue load cycles. Morphology of the specimens was observed and evaluated. RESULTS: Results from a cell biocompatibility test indicated that the new bioactive bone cement was favorable for cell growth. Spinal stiffness significantly decreased after fracture (47.5% of intact condition). Instant stiffness of the spine recovered to 107.8% of the intact condition after bone cement injection. After 3000 and 20,000 cycles of fatigue loading, stiffness of the cemented spine was found to be 93.5% and 94.4% of intact stiffness, respectively (P < 0.05). Average failure strength of the spine was 5056 N (after 3000 cycles) and 5301 N (after 20,000 cycles) after bone cement injection and fatigue loading. Radiographs and cross-sectional observations indicated a good cement-bone bonding and fracture fill. CONCLUSIONS: A new bioactive bone cement without cytotoxic effect has been developed. Results show that minimally invasive techniques to apply this cement to porcine spines results in augmentation of mild burst fractures such that the original stiffness and strength of the vertebra are recovered. This new cement therefore shows potential as an augmentation to traditional instrumentation in the surgical management of vertebral fractures. The potential for further clinical applications is currently under investigation.

Frontoethmoidal encephaloceles: reconstruction and refinements.

Frontoethmoidal encephaloceles are herniations of the intracranial contents through a defect in the skull at the junction of the frontal and ethmoidal bones. They are generally classified as nasofrontal, nasoethmoidal, and naso-orbital, although there may be some overlap or multiplicity. The records of 35 patients treated for frontoethmoidal encephaloceles were examined. Of these, 12 cases with complete and accurate medical records were evaluated in detail. The successful correction of frontoethmoidal encephaloceles was shown to depend on the following: a detailed understanding of the pathological anatomy (such as interorbital hypertelorism rather than true orbital hypertelorism and the presence of secondary trigonocephaly), careful planning of the bone movements to correct these deformities, and attention to detail regarding the placement of scars, positioning of the medial canthi, and the nasal reconstruction. Avoiding the "long-nose" deformity often seen after repair should be a priority. In general, the authors recommend a one-stage repair with both a transcranial and external approach.

Loosening of sacral screw fixation under in vitro fatigue loading.

Sacral screw fixation is frequently used for fusion of the lower lumbar spine, but sacral screws appear to offer less secure fixation than lumbar pedicle screws, and failure due to loosening under fatigue loading is common. The aim of this study was to examine in vitro the stability of medial and lateral bicortical and unicortical sacral screw fixation under a physiologically relevant fatigue-loading pattern. Bone mineral density, screw insertion torque, and screw-fixation stiffness were measured prior to cyclic loading between 40 and 400 N compression at 2 Hz for 20,000 cycles. The screw-fixation stiffness was measured every 500 cycles, and the axial pullout strength of the screws was recorded following loading. All of the lateral insertions loosened under the applied loading, but some of the medial insertions remained stable. Medial insertions proved stiffer and stronger than lateral insertions, and bicortical fixations were stronger than unicortical fixations. Bone mineral density and insertion torque were correlated with screw stiffness and pullout strength, although better correlation was found for insertion torque than bone mineral density. Bone mineral density is a good preoperative indicator of sacral screw-fixation strength, and insertion torque is a good intraoperative indicator. An insertion torque greater than 1.5 Nm is suggested as an indicative value for a stable medial unicortical insertion, whereas an insertion torque greater than 2 Nm suggests a stable medial bicortical insertion. It appears that, apart from the choice of technique (screw orientation and depth), minimizing the load on the screws during the initial part of the fusion process is also critical to maintain stability of the fused section and to obtain a solid fusion mass.

Tuberous breast deformity: principles and practice.

The tuberous breast deformity is one of the most challenging congenital breast anomalies. The nomenclature, classification, and treatment of this pathological condition have varied considerably. In this study, 16 patients with 23 tuberous breast deformities are evaluated. The breast deformities are classified according to the three-tier classification system used at the authors' institution. The treatment pattern is evaluated and a flexible algorithm is discussed for the treatment of the tuberous breast deformity.

Delayed presentation of transorbital intracranial pen.

A 13 year old Fijian boy sustained a stab wound to the left orbit 3 years ago. It was not appreciated by the treating physicians in Fiji that the plastic pen had crossed from the left orbit, through the nose, right orbit and right optic nerve, into the right middle cranial fossa and lodged in the right temporal lobe and that the pen remained in situ for the past 3 years. The boy presented to Australia with a discharge from the entry wound in his left lower eyelid. The retained foreign body was not detected on computed tomography imaging, but was detected on subsequent magnetic resonance image. A combined neurosurgery/plastic surgery craniofacial approach was undertaken with successful complete removal of the retained pen, and preservation of vision in his only seeing eye.

The effects of cyclic loading on pull-out strength of sacral screw fixation: an in vitro biomechanical study.

STUDY DESIGN: The pull-out strength of sacral screw fixation after cyclic loading was tested using young human cadaveric specimens. OBJECTIVES: To evaluate the effects of fatigue loading on the pull-out strength of medial and lateral unicortical and bicortical sacral screws and to correlate the pull-out strength with sacral bone density and the screw insertion torque. SUMMARY OF BACKGROUND DATA: The immediate biomechanical effects of depth of penetration, screw orientation, and bone density on sacral screw fixation have been studied in aged cadaveric specimens. The effect of cyclic loading on the pull-out strength of sacral screw fixation is unknown, however, and data from young specimens is rare. METHODS: Eleven fresh specimens of human sacrum were used in this study. Bone mineral density at the vertebral body and the ala were determined by peripheral quantitative computed tomography. Seven-millimeter compact Cotrel-Dubousset sacral screws were inserted into the sacrum anteromedially and anterolaterally, both unicortically and bicortically, and the insertion torque for each screw was measured. Cyclic loading from 40 to 400 N was applied to each screw at a frequency of 2 Hz up to 20,000 cycles. Pull-out tests were conducted after completion of the fatigue tests. RESULTS: The average bone density was 0.38 +/- 0.08 g/mL at the S1 body and 0.24 +/- 0.05 g/mL at the S1 ala. The insertion torque and average pull-out force after cyclic loading were significantly higher for bicortical fixation than for unicortical fixation for a particular screw alignment. The pull-out strength and insertion torque of medially oriented fixation was always higher than that for lateral fixation, however, regardless of whether the insertion was unicortical or bicortical. The pull-out force of unicortical and bicortical medial screw fixations after cyclic loading showed significant linear correlations with both the insertion torque and the bone mineral density of the S1 body. CONCLUSIONS: In a young population, screw orientation (anterolateral or anteromedial) was more important in determining pull-out strength than screw depth (unicortical or bicortical) after fatigue loading, anteromedially directed screws being significantly stronger than laterallyplaced screws. Bone mineral density of the S1 body andinsertion torque were good preoperative and intraoperative indicators of screw pull-out strength.

Biomechanical properties of thin skin flap after basic fibroblast growth factor (bFGF) administration.

This study is designed to examine the effects of basic fibroblast growth factor (bFGF) administration on the biomechanical properties of thin skin flap healing. A total of 42 rats were used in this study, and skin flaps 10 cm long by 3 cm wide were raised in 28 rats. One injection of bFGF was applied at three different times (immediately postoperatively, and 24 h and 48 h postoperatively) between the flap and wound bed of 14 rats (the bFGF treated group), while the other 14 rats with flaps had the same tissue culture medium treatment but without bFGF (the untreated group). The remaining 14 rats without flaps constituted the control group (normal group). The rats were killed 10 days postoperatively, and 1. 0 cm x 6.0 cm sections of the skin flap taken for mechanical and histological testing. The load, deformation and tensile strength at failure were recorded. The average flap survival area in the bFGF treated group was 27 cm(2), significantly higher (P< 0.001) than that seen in the untreated group. The average elastic stiffness of the skin flap in the bFGF treated group was also observed to be higher than in the untreated group although this difference was not significant. The mean tensile strength of the bFGF treated group (61 N) was significantly higher than the untreated group (38 N, P< 0.01) however. Despite this, the tensile strengths at failure of both of these groups were found to be significantly lower than that of normal skin (101 N, P< 0.01). A relaxation in load of about 8% was seen in specimens from the normal group and the bFGF treated group, while the untreated group showed a relaxation of about 15%.

Comparison of the API Candida system with the AUXACOLOR system for identification of common yeast pathogens.

Two commercial systems for the identification of yeasts were evaluated by using 159 clinical isolates that had also been identified by conventional biochemical and morphological methods. The API Candida system correctly identified 146 isolates (91.8%), and the AUXACOLOR system correctly identified 145 isolates (91.2%). However, of the 146 isolates identified by the API Candida system, 23 required supplemental biochemical tests or morphological assessment to obtain the correct identification. The AUXACOLOR system gave no identification in 13 cases (8.2%), while the API Candida system gave an unreadable profile in only one case. Incorrect identifications were more common with the API Candida system (12 isolates; 7.5%) than with the AUXACOLOR system (1 isolate; 0.6%).

Juvenile ossifying fibroma of the midface.

Juvenile ossifying fibroma is an unusual maxillofacial fibro-osseous lesion characterized by cell-rich osteoid strands. A 7-year-old girl presenting with a massive juvenile ossifying fibroma of the maxilla resulting in facial deformity, orbital displacement, and extension into the anterior skull base is discussed. The importance of combining clinical, radiographic, and histopathological findings for the diagnosis and management of the tumor is discussed.

In-vitro susceptibility of Cryptococcus neoformans isolates to fluconazole and itraconazole.

The in-vitro susceptibilities of 143 isolates of Cryptococcus neoformans, collected from British patients between 1994 and 1996, to fluconazole and itraconazole were compared with those of 36 isolates collected between 1971 and 1985, 41 isolates collected between 1986 and 1989, and 43 Ugandan isolates collected in 1996. Testing was done with a broth microdilution method in YNB medium supplemented with glucose, incubation at 30 degrees C for 72 h, and an endpoint of 50% inhibition. The results showed that the MIC ranges, MIC50s and MIC90s of fluconazole and itraconazole for C. neoformans isolates from the UK have remained unchanged despite the recent widespread use of triazoles for long-term maintenance of patients with AIDS-associated cryptococcal meningitis. The MIC ranges, MIC50s and MIC90s of the 43 isolates from untreated Ugandan patients with AIDS were similar to those of the British isolates. Examination of our records for 1994-96 revealed six cases in which a four-fold or greater rise in the MIC of fluconazole was associated with relapsed cryptococcal meningitis.

Comparative evaluation of FUNGITEST and broth microdilution methods for antifungal drug susceptibility testing of Candida species and Cryptococcus neoformans.

The FUNGITEST method (Sanofi Diagnostics Pasteur, Paris, France) is a microplate-based procedure for the breakpoint testing of six antifungal agents (amphotericin B, flucytosine, fluconazole, itraconazole, ketoconazole, and miconazole). We compared the FUNGITEST method with a broth microdilution test, performed according to National Committee for Clinical Laboratory Standards document M27-A guidelines, for determining the in vitro susceptibilities of 180 isolates of Candida spp. (50 C. albicans, 50 C. glabrata, 10 C. kefyr, 20 C. krusei, 10 C. lusitaniae, 20 C. parapsilosis, and 20 C. tropicalis isolates) and 20 isolates of Cryptococcus neoformans. Overall, there was 100% agreement between the methods for amphotericin B, 95% agreement for flucytosine, 84% agreement for miconazole, 83% agreement for itraconazole, 77% agreement for ketoconazole, and 76% agreement for fluconazole. The overall agreement between the methods exceeded 80% for all species tested with the exception of C. glabrata (71% agreement). The poorest agreement between the results for individual agents was seen with C. glabrata (38% for fluconazole, 44% for ketoconazole, and 56% for itraconazole) and C. tropicalis (50% for miconazole). The FUNGITEST method misclassified as susceptible 2 of 12 (16.6%) fluconazole-resistant isolates, 2 of 10 (20%) itraconazole-resistant isolates, and 4 of 8 (50%) ketoconazole-resistant isolates of several Candida spp. Further development of the FUNGITEST procedure will be required before it can be recommended as an alternative method for the susceptibility testing of Candida spp. or C. neoformans.

The surgical management of osseous cranial base tumours in children.

BACKGROUND: Osseous cranial base tumours in children present as a diverse collection of both benign and malignant pathologies. Concerns raised by the difficulty in accurate diagnosis and local recurrence of benign lesions and by the long-term sequelae of radiotherapy for malignant cranial tumours (marked local growth disturbances, pituitary dysfunction, visual disturbances, late new tumour induction) prompted an evaluation of surgical resection of cranial base tumours in children, with specific regard to safety, efficacy and aesthetic result. METHODS: A retrospective review was performed of 10 consecutive children presenting with tumours either arising from or eroding into bone of the cranial base who were managed by surgical resection in a 10-year period from 1986 to 1996. The patients demonstrated a great variation in both presentation and pathology. All underwent surgical resection of tumour with reconstruction where indicated. RESULTS: There were no postoperative complications or mortality. All patients remained clinically free of disease at follow-up, which ranged from 17 months to 9 years (mean 6 years and 4 months). CONCLUSION: The aggressive surgical resection and craniofacial reconstruction of cranial base tumours in the paediatric population offers a safe and efficacious mode of treatment that obviates problems of diagnosis and local recurrence for benign lesions and of the long-term sequelae of radiotherapy for malignant lesions.

Analysis of load-relaxation in compressed segments of lumbar spine.

Load-relaxation was measured in 12 segments of human cadaveric lumbar spine. Each segment consisted of an intact intervertebral disc attached to half of its adjacent vertebrae with the posterior elements removed. Six specimens were each compressed at six different strains (corresponding to initial loads of 0.5-2.5 kN) and, for each strain, the load-relaxation was measured for a period of 20 min at room temperature. These load-relaxation curves were used to plot three isochrones for each specimen. All isochrones were linear (r values in the range 0.95-0.99). This result indicated that a linear model could be used to represent load-relaxation. Four specimens were tested at a single strain (corresponding to an initial load of about 2 kN) at 37 degrees C for a period of 4-6 h. Load was plotted against the logarithm of time. The resulting plots did not show any peaks, indicating that relaxation effects did not predominate at any particular times during load-relaxation. However, it was possible to model the load-relaxation as a simple linear system which can be represented as two Maxwell elements in parallel. These elements were characterized by relaxation times of 16 +/- 8 min and 4.6 +/- 0.8 h. Fourier transformation of the load-relaxation curves showed a gradual increase in the storage modulus and a gradual decrease in the loss modulus for frequencies of about 1 Hz and above. At these frequencies, the spine cannot function as a shock-absorber in pure compression.