The immature goat as an animal model for Legg-Calvé-Perthes disease

Legg-Calvé-Perthes disease (LCPD) results from avascular necrosis of the capital femoral epiphysis in growing children. This disease often yields a significant deformity of the proximal femur, which may result in osteoarthritis. Its cause is unknown, although extensive radiographic, clinical, and histologic evaluations have been performed. Attempts at developing an animal model for LCPD have been unsuccessful. Previous models have been based predominantly on determining the vascular etiology of the disease. There is a need for an animal model that mimics the growth pattern of the proximal femur seen in LCPD. Such a model would allow for the development and testing of new treatments. Thus far, no treatment strategy has been completely successful. A study involving graphic analysis of radiographs found that arrested anterolateral physeal growth with continued or accelerated perichondrial ring and posteromedial epiphyseal growth would account for the most severe morphologic changes observed in the femoral heads of patients with LCPD. A surgical procedure was performed to ablate the capital femoral physis in goat kids in an attempt to mimic the changes noted in this study. The procedure was evaluated with radiographs, gross specimens, and histopathologic slides. Graphic analysis of the radiographs revealed changes in the shape of the operated femoral head compared with the unoperated femoral head. While bone, fibrous, and fibrocartilaginous bridges were histologically observed across the physis, the resultant deformities did not mimic the changes identified in the graphic analysis study, perhaps because of inconsistencies in the surgical ablative techniques, which will require further modification. This study provides the basis for further research to develop a successful model.

Fimbriation, capsulation, and iron-scavenging systems of Klebsiella strains associated with human urinary tract infection

Thirty-two strains of Klebsiella pneumoniae and seven strains of Klebsiella oxytoca isolated from urinary tract infections in elderly adults were analyzed for capsular antigens, iron-scavenging systems, and fimbriation. All strains were capsulated. Twenty-seven different K antigens were identified among the strains, with no particular antigen dominating. All strains produced the iron-scavenging system enterochelin as analyzed by bioassay and DNA hybridization. In contrast, the aerobactin iron-sequestering system was not detected in any of the strains. All strains caused hemagglutination of tannin-treated human erythrocytes and reacted with an anti-type 3 fimbriae antiserum as well as in DNA hybridization with a type 3 fimbria-specific probe, indicating that the Klebsiella strains possessed this fimbrial type. Possession of type 1 fimbriae was analyzed by agglutination tests and by hybridization with DNA probes from two distinct Klebsiella type 1 fimbria gene clusters. Phenotypic expression of the type 1 fimbriae was found in 29 of 32 K. pneumoniae strains, whereas 30 strains reacted with either of the two type 1 fimbrial cluster DNA probes. In K. oxytoca, however, only three of seven strains expressed type 1 fimbriae and reacted with the DNA probes. The type 3 fimbriae were found to bind to a fraction of epithelial cells exfoliated in normal human urine, whereas the type 1 fimbriae bound strongly to urinary slime. No inhibitors of type 3 fimbrial binding were detected in human urine.

Adherence to respiratory epithelia by recombinant Escherichia coli expressing Klebsiella pneumoniae type 3 fimbrial gene products

We examined the role of Klebsiella fimbrial types 1 and 3 in mediating adherence to human buccal and tracheal cells and to lung tissue sections. We found that clinical isolates of Klebsiella pneumoniae producing type 3 fimbriae and Escherichia coli HB101 containing a recombinant plasmid encoding expression of Klebsiella type 3 fimbriae (pFK10) demonstrated increased adherence to tracheal cells, trypsinized buccal cells, and lung tissue sections, in contrast to nonfimbriate and to type 1 fimbriate bacteria. Adherence by type 3 fimbriate bacteria was inhibited by purified type 3 fimbriae and Fab fragments derived from type 3 fimbrial-specific polyclonal immunoglobulin G. Type 3 fimbriae mediated attachment to the basolateral surface of tracheal cells and to the basal epithelial cells and the basement membrane regions of bronchial epithelia. Using an E. coli transformant (pDC17/pFK52), which expresses nonadherent P fimbrial filaments, along with the type 3 fimbrial adhesin (MrkD), we demonstrated that type 3 fimbrial attachment to respiratory cells was attributable to the MrkD adhesin subunit. Subsequent experiments demonstrated that the epithelial target of the type 3 fimbrial adhesin was most likely a peptide molecule rather than a carbohydrate. The results of this study demonstrate that, in vitro, the Klebsiella type 3 fimbrial adhesin mediates adherence to human respiratory tissue.

Fimbrial types among respiratory isolates belonging to the family Enterobacteriaceae

Bacterial attachment is believed to be an early step in gram-negative nosocomial pneumonia. The frequency of fimbria-associated adhesins among respiratory pathogens has not been studied in detail. In this study isolates belonging to the family Enterobacteriaceae, prospectively obtained from intensive care unit patients who were suspected of having nosocomial pneumonia, were examined for fimbria-associated adhesins. Type 3, P, type 1, and other fimbrial phenotypes were identified by specific hemagglutination and electron microscopy. The Klebsiella type 3 fimbrial phenotype was further characterized by using a monoclonal antibody. Also, both type 3 and Escherichia coli P fimbrial genotypes were detected by using DNA colony blot assays. The frequencies of genera or species isolated were as follows: Enterobacter (38.6%), Klebsiella (26.8%), Serratia (17.7%), E. coli (13%), and Proteus (5.2%). Isolates of Klebsiella oxytoca, K. pneumoniae, and Enterobacter cloacae most commonly possessed the type 3 fimbrial phenotype and genotype. The phenotype and genotype for E. coli P fimbriae (46.2 and 50%, respectively), a known pathogenic determinant in the urinary tract, were detected more frequently than expected. In addition, a previously unspecified hemagglutinin that was specific for porcine erythrocytes was almost uniformly expressed among isolates of Enterobacter aerogenes. Finally, the expression of the type 1 fimbrial phenotype was widely detected among the isolates tested but notably absent among K. oxytoca and Proteus mirabilis isolates. The frequency of the various fimbrial types identified suggests a role for these bacterial organelles in adherence to respiratory epithelia.

Design and evaluation of a posterior laminar clamp spinal fixation system

A new spinal instrumentation system for posterior applications was designed with the intent of minimizing intrusion of hardware into the neural canal during and postinsertion. Basic biomechanical measurements of posterior pullout strength led to the establishment of a clamp as an effective mechanism for gaining purchase on the vertebral lamina. These experiments defined the appropriate instrumentation size, as well as establishing that there was no loss of strength with the spinous process removed and the posterior laminar cortex compromised. There was no statistically significant difference between the maximum pullout strength achievable, using a band around the lamina as a control, and that produced by the implant system, in the thoracic spine. Comparative testing of a prototype system in flexion, extension, lateral bending, and torsion showed that the system, in general, had stiffness greater than segmental wiring and less than or equal to Cotrel-Dubousset fixation.

Nucleotide sequence and functions of mrk determinants necessary for expression of type 3 fimbriae in Klebsiella pneumoniae

The nucleotide sequence of six genes involved in the expression of type 3 fimbriae of Klebsiella pneumoniae was determined. In addition to the genes that encode the fimbrial subunit (mrkA) and adhesion (mrkD), the mrkB, mrkC, and mrkE genes appear to be involved in assembly of the fimbrial filament and regulation of type 3 fimbrial expression. The mrkF gene product is required to maintain the stability of the fimbrial filament on the cell surface.

Type V collagen as the target for type-3 fimbriae, enterobacterial adherence organelles

Tissue-binding specificity of the type-3 fimbriae of pathogenic enteric bacteria was determined using frozen sections of human kidney. A wild-type Klebsiella sp. strain and the recombinant strain Escherichia coli HB101(pFK12), both expressing type-3 fimbriae, as well as the purified type-3 fimbriae effectively bound to sites at or adjacent to tubular basement membranes, Bowman's capsule, arterial walls, and the interstitial connective tissue. Bacterial adherence to kidney was decreased after collagenase treatment of the tissue sections. Recombinant strains expressing type-3 fimbriae specifically adhered to type V collagen immobilized on glass slides, whereas other collagens, fibronectin or laminin did not support bacterial adherence. In accordance with these findings, specific binding of purified type-3 fimbriae to immobilized type V collagen was demonstrated. Specific adhesion to type V collagen was also seen with the recombinant strain HB101(pFK52/pDC17), which expresses the mrkD gene of the type-3 fimbrial gene cluster in association with the pap-encoded fimbrial filament of E. coli, showing that the observed binding was mediated by the minor lectin (MrkD) protein of the type-3 fimbrial filament. The interaction is highly dependent on the conformation of type V collagen molecules since type V collagen in solution did not react with the fimbriae. Specific binding to type V collagen was also exhibited by type-3 fimbriate strains of Yersinia and Salmonella, showing that the ability to use type V collagen as tissue target is widespread among enteric bacteria.

The effect of local controlled release of sodium fluoride on the stimulation of bone growth

This study was performed to test the feasibility of using a biodegradable delivery system for the local controlled release of sodium fluoride as a mechanism for the stimulation of local bone growth. Sodium fluoride grains were mixed with poly-DL-lactic acid (PLA), and the mixture was then dissolved in acetone. After driving off the solvent, sheets of this material were rolled into rods 3.2 mm in diameter and 28.6 mm long. These were inserted into the intramedullary canals of the right femora of adult New Zealand White rabbits. A sham implant, made the same way but containing no fluoride, was inserted into the contralateral left leg. The effects of three different concentrations of sodium fluoride, 0.125 g NaF/g PLA, 0.250 g NaF/g PLA, and 0.500 g NaF/g PLA, were determined after a 4-week implantation period. In a second set of experiments, the concentration was fixed at 0.500 g NaF/g PLA with implantation durations of 4, 8, and 16 weeks. Expressed in terms of property ratios (experimental/control), bending strengths of the femora were significantly raised in most groups with the notable exception of Group 3 (0.500 g NaF/g PLA, 4 weeks). Cross-sectional area ratios in the distal femora were increased in all groups compared to right/left values for a normal unoperated group (p less than 0.05), with the highest ratio being 1.50 (SD = 0.44) for Group 4 (0.500 g NaF/g PLA, 8 weeks). Only Group 4 animals showed significant (p less than 0.05) increases in midshaft area ratio and none had responses proximally. Growth rates, measured by sequential fluorochrome labeling of bone followed the area ratio data and were only significant for the distal femora.

Effect of personal pain experience on pain assessment

The purpose of this study was to determine the effect of nurses' personal pain experiences on the assessment of their patients' pain. The sample consisted of 134 registered nurses employed in three Midwestern hospitals. In response to a personal pain history questionnaire, pain with headache, menstrual distress and dental events were cited most frequently. Most also reported that a family member had experienced pain in their presence (cancer, surgery, orthopedic injuries). Responses to the Standard Measure of Inferences of Suffering (Davitz & Davitz, 1981) showed significant differences between intensity of pain experienced by the nurse and overall perceived patient psychological distress. Furthermore, the intensity of pain experienced by the nurse was the only variable that predicted significantly perceptions of patients' physical suffering and psychological distress. While additional study is warranted, the findings support the notion that nurses who have experienced intense pain are more sympathetic to the patient in pain.

Identification and characterization of the genes encoding the type 3 and type 1 fimbrial adhesins of Klebsiella pneumoniae

Strains of Klebsiella pneumoniae are known to express two morphologically and functionally distinct filaments, the type 3 and the type 1 fimbriae. The gene (mrkD) encoding the adhesion of K. pneumoniae type 3 fimbriae was identified by transcomplementation analysis with the pap fimbrial gene cluster of Escherichia coli. The nucleotide sequence of the mrkD gene was determined. In addition, the determinant coding for the K. pneumoniae type 1 fimbrial adhesion was identified, and its nucleotide sequence was deduced. The predicted amino acid sequences of the K. pneumoniae adhesion proteins are compared, and similarities with the major fimbrial structural proteins (MrkA and FimA) are discussed.

Expression of type 1 fimbriae and mannose-sensitive hemagglutinin by recombinant plasmids

Deletions within the cloned genes (fimA) encoding the type 1 major fimbrial subunits of two isolates of Klebsiella pneumoniae resulted in a nonfimbriate but hemagglutinating phenotype after transformation of Escherichia coli HB101 or ORN103. Phenotypic expression of type 1 fimbriae could be restored by transformation with plasmids containing the fimA genes of the fimbrial gene clusters from different strains. The surface fimbriae expressed were serologically identical to those of the polymerized product of the introduced fimA gene. The fimA gene products of Salmonella typhimurium and Serratia marcescens could utilize the accessory fimbrial genes of K. pneumoniae to produce surface-associated, hemagglutinating fimbriae. The relatedness of the type 1 fimbrial gene clusters from multiple isolates of members of the family Enterobacteriaceae was examined by DNA hybridization techniques. These analyses demonstrated little nucleotide sequence agreement among distinct genera of the enteric bacteria.

Type 3 fimbriae among enterobacteria and the ability of spermidine to inhibit MR/K hemagglutination

The distribution of the gene cluster encoding type 3 fimbriae among various isolates of the family Enterobacteriaceae was investigated by using 112 clinical and nonclinical isolates. Closely related DNA sequences were detected in all Klebsiella strains, in most Enterobacter isolates, in a smaller number of Escherichia coli and Salmonella spp., and in a single isolate each of Yersinia enterocolitica and Serratia liquefaciens but not in isolates of Morganella or Providencia species or Serratia marcescens. Except for E. coli and Salmonella strains, the presence of gene sequences was correlated with the phenotypic expression of either the MR/K hemagglutinin or fimbriae that reacted with specific antibodies. In one isolate of Y. enterocolitica the expression of type 3 fimbriae was plasmid determined. The polyamine spermidine was identified as an inhibitor of MR/K hemagglutinating activity, exhibiting an MIC of 1.2 mM. Spermidine inhibited the hemagglutination of 37 MR/K-positive clinical isolates from various genera. However, one clinical isolate of Enterobacter cloacae and most (four of five) nonclinical Klebsiella isolates were not completely inhibited.

Molecular characterization of the type 3 (MR/K) fimbriae of Klebsiella pneumoniae

The expression of type 3 (MR/K) fimbriae by Klebsiella pneumoniae requires the production of at least four polypeptides with molecular masses of 20.5, 25, 34, and 78 kilodaltons. The genes encoding these polypeptides are located on a gene cluster 5,500 base pairs in length. The nucleotide sequence of the major fimbrial structural gene was determined, and its transcription was shown to initiate in vitro 157 base pairs upstream of the translational start site. The predicted amino acid sequence for the fimbrial subunit comprised 202 residues, including a signal peptide of 22 amino acids. Despite similarities in the organization of the gene cluster, the nucleotide and the amino acid sequence of the major fimbrial subunit revealed little agreement with other known fimbrial subunit sequences.

Biomechanical comparisons of spinal fracture models and the stabilizing effects of posterior instrumentations

In this study, the authors evaluated the stiffness of motion segments in intact spines in two spine fracture models, and with each of five implant systems used for posterior fixation of thoracolumbar spine fractures. The devices represented a cross-section of types, including those employing sublaminar wires with and without laminar hooks, pedicle screws, plates, and rods. Two spine fracture models, one partially and one totally destabilized, were used in the tests of the instrumentation. Stiffness, or the magnitude of load needed to produce a unit displacement of the construct in the direction of the applied load, was measured in flexion, extension, lateral bending, and torsion in combination with a compressive force. Both horizontal plane shear and angular displacements were measured in the two fracture patterns. All evaluations were made by testing the difference in stiffness for statistical significance among groups. The results showed significant differences in stiffness without instrumentation among intact spines, partly destabilized spines (anterior two-thirds of disk and posterior ligaments removed), and totally destabilized spines (only anterior longitudinal ligament intact). The implant/spine constructs were least stiff relative to the intact spine in torsion, followed in increasing order of stiffness with flexion, lateral bending, and extension. In the Roy-Camille plate with six-screw fixation was found to produce the stiffest construct, followed by wired Harrington rods, C-rods and J-rods, and the Vermont internal fixator.(ABSTRACT TRUNCATED AT 250 WORDS)

A 1988 perspective on the Galveston technique of pelvic fixation

The Galveston technique for pelvic fixation was used in 40 patients who underwent scoliosis surgery with pelvic fixation at The University of Texas Medical Branch from February 1980 through June 1987. Analysis of the outcomes indicates that extension of a scoliosis fusion to the pelvis can be undertaken with excellent chance for success and without the necessity of routine postsurgical casting or bracing. Accurate contouring of the L-rod implant and meticulous fusion technique are essential to success.

The Galveston experience with L-rod instrumentation for adolescent idiopathic scoliosis

Eighty patients were treated with L-rod instrumentation (LRI) for adolescent idiopathic scoliosis at the authors' institution from 1978 through 1985. The percentage correction of Cobb angle, the fusion rate, and the neurologic injury rate were similar to that reported for Harrington instrumentation. Avoidance of postoperative casting or bracing, maintenance of secondary spinal contours, secure pelvic fixation when needed, and anterior thoracoplasty in a majority of patients were achievable goals with LRI.

Considerations in the treatment of cerebral palsy patients with spinal deformities

The natural history of spinal deformities in the cerebral palsy patient is different than that in the idiopathic patient. Consequently, the approach to the patient with cerebral palsy and the surgical decision-making are different from that in the idiopathic patient. The present article gives the UTMB approach to the treatment of the cerebral palsy patient and the unique considerations that must be taken into account when treating these patients. Specific references are made to the use of L-rod instrumentation to stabilize the spinal deformity in the cerebral palsy patient.

The biomechanics of decompressive laminectomy

The biomechanical effect of laminectomy as a means of relieving compression of the spinal cord-meningeal complex by an anterior mass was studied in ten grossly normal human cadaver spines. The basic experimental set-up involved drilling a sagittal plane hole transversely across a vertebral body to provide direct access to the anterior aspect of the neural canal. After securing a probe and linearly variable differential transformer (LVDT) assembly at each site to be tested, the probe was gently pushed into the neural canal; contact force against the tip of the probe as well as the depth of probe penetration was measured and recorded. Laminectomy did not alter the resulting contact force/anterior penetration plots at the fifth cervical, seventh thoracic, 12th thoracic, or third lumbar vertebra. Using the probe/LVDT assembly to measure anterior dural displacement and a cantilever displacement device to measure posterior dural displacement after laminectomy at the 12th thoracic vertebra, the authors found that although the anterior dura underwent gross displacement as the probe was pushed into the neural canal, the posterior dura displaced to a minimal degree. The extent of the laminectomy was not a factor. The study did not demonstrate any possible mechanism by which laminectomy could reduce the pressure exerted on the dura and neural elements by an anterior mass in a spine with otherwise normal neural canal dimensions.

Rib regeneration area as an indicator of fusion area in adolescent idiopathic scoliosis

This retrospective study of 24 patients with adolescent idiopathic scoliosis who underwent L-rod instrumentation, posterior thoracoplasty, and rib-bone grafting analyzed the correlation between the quality of rib regeneration and the host response to the rib-bone grafts. A planimetric technique was used to quantitate the coronal plane area of the resected ribs and of an L1-L2 concave fusion area immediately after surgery and at the end of the first postsurgical year. Using computerized regression analysis, these and other variables such as age, Cobb angle, and grafting technique were studied. Rib regeneration correlated with spinal fusion but not with age or Cobb angle. A better host response with strip vs. morseled graft was suggested, but not statistically proven. The data strongly support the belief that systemic biologic factors are a major variable affecting the quality of the fusion procedure.

Computer-assisted instruction in orthopedic biomechanics

A computer-aided instructional (CAI) course in biomechanics was developed at the University of Texas Medical Branch in Galveston. This was used by our residents in preparation for the 1984 OITE. The course was developed on a 256K IBM personal computer with a color graphics board and color monitor. The course requires about 6 hours of user time to complete. The program was written in the Basic computer language and consists of a master and teaching program. The master program keeps track of the name of the user and his or her progress. The teaching program contains the chapters of biomechanical concepts with a quiz after each chapter. The chapters present the basic concepts of biomechanics with interactive color graphics. The quizzes contain about 20 board-type questions. Six residents voluntarily used the CAI and nine residents chose not to use the CAI. There was no difference in the two groups' outside reading of biomechanical texts or other methods of study. There was no statistical difference between the two groups 1983 OITE biomechanics score. There was also no statistical change in the nonusers' score from 1983 to 1984. The users, however, showed a statistically significant improvement (p less than .05) from the previous year. We conclude that with the wide use of properly developed CAI is an effective and efficient method to provide education for orthopedists.

An algorithm for the treatment of unstable thoracolumbar fractures

This article describes a fracture classification used at the University of Texas Medical Branch that takes into account the fracture mechanics and attempts to match the requirements of the fracture to the strong points of a particular spinal implant. The present algorithm for the treatment of thoracolumbar fractures is presented, and its efficacy is demonstrated by comparing it with an evolutionary group of spinal fractures cases

Neurologic injuries with the Galveston technique of L-rod instrumentation for scoliosis

A group of surgeons who used the Galveston technique for L-rod instrumentation (LRI) were surveyed to learn their experience with associated neurologic injuries. Among 507 LRIs for scoliosis there were two partial cord syndromes (0.4%), 13 "nerve root hyperesthesias" (2.6%), and two other nerve injuries (0.4%). All patients, except one with mild residuals after a partial cord injury, fully recovered from their neurologic problem. Experience in spinal surgery, education about LRI strategies and techniques, hands-on technical instruction, and use of an established process for LRI are believed to be the factors that enabled these surgeons to perform this complex procedure with relative safety.

Topics of interest in pediatric orthopedics

This two-in-one article presents an overview of septic arthritis of the hip and school screening for adolescent idiopathic scoliosis--two problems commonly shared by the pediatrician and the pediatric orthopedic surgeon. The importance of aggressive diagnostic measures and treatment for the septic hip is emphasized and the basis for the rationale is given. In the section on scoliosis, the reader is introduced to the "scoliometer," and a rationale for management of most of these children by the primary physician is given.

A biomechanical study of thoracolumbar spine fractures with bone in the canal. Part III. Mechanical properties of the dura and its tethering ligaments

Experiments were performed to determine some mechanical properties of the spinal cord-meningeal (SCM) complex and its tethering elements with reference to factors contributing to contact pressure of an anterior mass on the SCM complex with spinal fracture and the development of some means to relieve the pressure. Measurements were made using a combined microload cell and displacement transducer that was passed posteriorly through a hole drilled in vertebra T12 through the interpedicular space and contacted the cord. Loss of nerve roots and anterior ligaments as dural tethers in the lumbar region permitted the SCM complex to fall out of the lordosis of the canal and fail to resist transverse loading. Head and neck flexion increased contact force for a given depth of penetration, particularly in the cervical region. This was consistent with measurements of strain along the dura that was greatest in the cervical region. The dura was found to be elastic, having a failure strain averaging 34% but was uniform in thickness, stiffness, and elastic modulus along its length. The study did not delineate any surgical manipulation other than removal of the anterior mass that would be beneficial when there is anterior compression of the spinal cord.