bluuebunny/crossref_metadata_2025 huggingface dataset:
Rib cage asymmetry in idiopathic scoliosis
Authors: Stokes Ian A. F. , Dansereau Jean , Moreland Morey S.
Published: February 2005

Seventy‐one patients attending a scoliosis clinic and 10 control subjects were studied by a stereoradiographic three‐dimensional reconstruction of the spine and rib cage. The symmetry of each rib pair (at each anatomic level) was described by measurements of rib arc length, chord length, enclosed area, maximum curvature, and frontal and lateral angulations. Patients were divided into four groups: 19 with a single right thoracic curve, 15 with a single left lumbar or thoracolumbar curve, 22 with double curves, and 15 with a curve with 10° Cobb angle. In the control group and the group with minimal scoliosis, there was no statistically significant rib asymmetry. Among the patients with scoliosis, 11 of 19 patients with right single thoracic curves had rib arc lengths greater on the right side at the curve apex, and nine of 15 patients with left lumbar scoliosis had longer ribs on the left side in the corresponding region of the thoracic spine. Eleven of 22 patients with double curves had symmetrical rib lengths (within ∼3%), the other 11 had ribs longer on the left. These proportions should not have occurred by chance (p < 0.001). The mean rib length difference in patients with single thoracic curves was 1.39% (right longer than left), in single lumbar curves it was 3.57% (left longer than right), and in double curves 3.18% (left longer than right). These differences between the groups of patients and control subjects were statistically significant (p < 0.01). Based on correlations between rib arc length and other measurements of rib size, there was evidence of general rib hypertrophy on the long rib side of patients having length asymmetries.
Biosynthetic response of cartilage explants to dynamic compression
Authors: Sah Robert L.‐Y. , Kim Young‐Jo , Doong Joe‐Yuan H. , Grodzinsky Alan J. , Plass Anna H. K. , Sandy John D.
Published: February 2005

The biosynthetic response of calf articular cartilage explants to dynamic compression was examined over a wide range of amplitudes, waveforms, and frequencies. Glycosaminoglycan synthesis was assessed by 35S‐sulfate incorporation, and amino acid uptake and protein synthesis were assessed by 3H‐proline incorporation. Two culture chambers were designed to allow uniaxial radially unconfined compression and mechanical testing of cartilage disks: one chamber was used inside a standard incubator; the other was used with a mechanical spectrometer and allowed load and displacement to be monitored during compression. Dynamic stiffness measurements of 3‐mm diameter disks identified a characteristic frequency [0.001 Hz (cycles/sec)] that separated low‐ and high‐frequency regimes in which different flow and deformation phenomena predominated; e.g., at 0.0001–0.001 Hz, significant fluid was exuded from cartilage disks, whereas at 0.01–1 Hz, hydrostratic pressure increased within disks. At the higher frequencies, oscillatory strains of only ∼1–5% stimulated 3H‐proline and 35S‐sulfate incorporation by ∼20–40%. In contrast, at the lower frequencies (a) compressions of <5% had no effect, consistent with the dosimetry of biosynthetic inhibition by static compression (∼25% compression caused a ∼20% inhibition of radiolabel incorporation), and (b) higher amplitudes (cycling between disk thicknesses of 1.25 and 0.88–1.00 mm) stimulated 3S‐sulfate incorporation by ∼20–40%, consistent with the kinetics of response to a single 2‐h compression and release. None of the compression protocols was associated with detectable alterations in (e.g., compression‐induced depletion of) total glycosaminoglycan content. This study provides a framework for identifying both the physical and biological mechanisms by which dynamic compression can modulate chondrocyte biosynthesis. In addition, the culture and compression methodology potentially allows in vitro evaluation of clinical strategies of continuous passive motion therapy to stimulate cartilage remodeling.
The effect of low sulfate concentrations on the glycosaminoglycan synthesis in anatomically intact articular cartilage of the mouse
Authors: van der Kraan Peter M. , de Vries Bernard J. , Vitters Elly L. , van den Berg Wim B. , van de Putte Levinus B. A.
Published: February 2005

We have studied the effect of environmental sulfate concentration on the glycosaminoglycan synthesis of anatomically intact patellar cartilage of the mouse in vitro. Incubation of mouse patellae in medium with sulfate concentrations below 0.5 mM resulted in a diminished incorporation of sulfate but in unaltered incorporation of glucosamine. This suggested the synthesis of undersulfated glycosaminoglycans under these conditions. We characterized glycosaminoglycans synthesized at three different sulfate concentrations: a sulfate concentration physiological for the mouse (1.0 mM), a sulfate concentration in the range where sulfate incorporation was strongly diminished (0.1 mM), and an extremely low sulfate concentration (10 nM). Analysis of glycosaminoglycan disaccharides and DEAE anion chromatography of the glycosaminoglycans could not confirm the synthesis of undersulfated glycosaminoglycans at 0.1 mM. The chromatogram of glycosaminoglycans synthesized in medium containing 10 nM showed the presence of a very low sulfated glycosaminoglycan pool not observed at higher medium sulfate concentrations. Intermediately sulfated glycosaminoglycans were also synthesized during incubation with 10 nM sulfate. So, our data indicate that only very low sulfate concentrations in the medium lead to the synthesis of undersulfated glycosaminoglycans and that the sulfation mechanism of murine patellar cartilage chondrocytes does not seem to fit completely in an “all‐or‐nothing” pattern.
Cellular turnover at the chondro‐osseous junction of growth plate cartilage: Analysis by serial sections at the light microscopical level
Authors: Farnum Cornelia E. , Wilsman Norman J.
Published: February 2005

In the distal hypertrophic cell zone of growth plate cartilage, the penetration of metaphyseal vascular endothelial cells is into the noncalcified territorial and pericellular matrices. Cellular mechanisms that promote metaphyseal vascularization are understood poorly, partly because no study has addressed the question of the time sequence of cellular interactions at the chondro‐osseous junction. The purpose of the present study is to make predictions about the relative and the real time duration of cellular events during vascular invasion, including an analysis of the time sequence of death of the terminal hypertrophic chondrocyte. The data from serial section analysis at the light microscopical level of tetracycline‐labeled growth plates indicate that death of the terminal hypertrophic chondrocyte occurs in discrete morphological stages characterized by rapid cellular condensation followed, within minutes, by endothelial cell penetration into the vacated lacuna. Cellular condensation lasts ∼45 min or 18% of the time a cell spends as a terminal chondrocyte. The data also demonstrate that chondrocytic death occurs prior to invasion by vascular endothelial cells and that the chondrocytic lacuna remains empty for as long as 15 min before an endothelial cell or blood vascular cell fills the space.
Regeneration of growth plate cartilage induced in the neonatal rat hindlimb by reamputation
Authors: Libbin Richard M. , Rivera Maria E.
Published: February 2005

Following primary hindlimb amputations dividing the lower femur or the central tibiofibula, the neonatal rat innately regenerates the distal growth plate(s) with a frequency of about 20–30%. One or two reamputation procedures were performed in an effort to increase the frequency of physeal regeneration, noting that such procedures, and related forms of tissue stimulation, have been repeatedly shown to induce regenerative growth at limb amputation sites of some amphibians that display little innate regenerative capacity. The present reamputation sequences divided the skeletal stump through the cartilaginous mass arising at its distal end. Following first reamputation an approximate three fold increase in the frequency of growth plate cartilage regeneration was observed at transfemoral and transtibiofibular sites. Only after second reamputation, however, did tibiofibular physeal cartlage regeneration equal in frequency that observed after first reamputation through the lower femur. Ectopic growth plate cell architecture was identified in cartilaginous extensions arising from the side of the distal femoral shaft, and also within the regrown secondary cartilage body, which unites the lower tibia and fibula in the shank of the rat. Moreover, among 3 of 11 femoral amputees that had sustained reamputations, regrowth of the distal femoral condylar mass and profile were achieved to varying degrees. It is concluded that a regimen of reamputation, known to induce regenerative growth in the amphibian limb, also induces skeletal regeneration in the mammalian limb, and leads to the appearance of ectopic growth plate cell architecture at adjacent sites.
Effect of hyaluronic acid/chondroitin sulfate on healing of full‐thickness tendon lacerations in rabbits
Authors: Meyers Steven A. , Seaber Anthony V. , Glisson Richard R. , Nunley James A.
Published: February 2005

Viscoat, a high‐molecular‐weight, highly purified hyaluronic acid (HA) and chondroitin sulfate (CS) compound, was instilled around rabbit plantaris tendon following full‐thickness laceration and surgical repair. After 3 weeks of immobilization, no significant difference in adhesion strength or tensile strength of the healing tendons existed between Viscoat‐treated tendons and controls. This contradicts previous studies which suggest that hyaluronic acid reduces postoperative tendon adhesions. Further studies examining tendon adhesions after less severe degrees of tendon injury and using direct, quantitative measurement techniques are warranted to demonstrate whether HA has a beneficial effect on tendon healing.
Effects of intercostal nerve resection on the longitudinal rib growth in the growing rabbit
Authors: Agadir M. , Sevastik B. , Sevastik J. A. , Svensson L.
Published: February 2005

Two, three, or four intercostal nerves with their vasoconstrictive sympathetic fibers were resected on the right side of 15 growing rabbits. Animals submitted to sham operations and intact animals formed two control groups. A scintigraphic study with 99mTc‐methylene diphoshonate, performed on the test group 2 months after the resection, showed a significantly greater uptake of the isotope on the right than on the left costochondral junctions (p < 0.05). Three months later the difference was still larger. There was no such significant difference in the rabbits of the two reference groups. In the rabbits of both these groups, the right and left ribs of each pair were almost equal in length. Of the denervated ribs of the rabbits composing the test group, the right ribs increased in length to a greater extent than the corresponding left ribs. The difference was statistically significant (p < 0.05). As a consequence of this left‐right difference in length, mild thoracic scoliosis convex to the left developed 2 months after the resection. The total weight and volume of the denervated right ribs increased significantly more than those of the corresponding control left ribs (p < 0.05), but their mineral content per unit of weight or volume showed no significant difference.
Temporal biomechanics of posterior cervical spine injuries in vivo in a rabbit model
Authors: Wetzel F. Todd , Panjabi Manohar M. , Pelker Richard R.
Published: February 2005

There are numerous clinical and biomechanical criteria for determination of acute spinal instability. No data, however, exist on the biomechanical behavior of the injured, untreated spine during the healing period. Using a rabbit model, this study was designed to quantify changes in the mechanical properties of the injured spine over time. Sixteen rabbits were assigned to four injury groups: Injury 1 (C4–5 supra/intraspinous ligament transection), Injury 2 (C4 laminectomy), or Injury 3 (C4 laminectomy, plus bilateral facet capsular ligament transection). The fourth injury group was Sham (posterior exposure of C4–5, no spinal injury). Preinjury range of motion was determined by standardized flexion‐extension radiographs on all animals. Postinjury flexion–extension radiographs were taken at 4, 8, and 12 weeks. At the end of 12 weeks, animals were killed. Mean range of motion at C4–5 for all injury groups decreased from preinjury values. The greatest decrease was for the most severe injury. At 8 weeks, the range of motion for this injury was less than half of the preinjury level and increased to 62% of the preinjury level at 12 weeks.
The effect of surface and internal electrodes on the gait of children with cerebral palsy, spastic diplegic type
Authors: Young Craig C. , Rose Sven E. , Biden Edmund N. , Wyatt Marilynn P. , Sutherland David H.
Published: February 2005

The purpose of this study was to determine whether surface and internal fine‐wire electromyography electrodes had an effect on gait. The subjects for the experiments were 38 children with the spastic diplegic type of cerebral palsy. The children were filmed using the high‐speed cinematographic technique while they walked (a) with no electrodes (unencumbered), (b) with only surface electrodes, and (c) with internal electrodes. Single stance time, step length, cadence, and walking velocity were compared with analysis of variance and Bonferroni t tests. The results included a significant decrease in cadence (−6.3% of unencumbered walking; p < 0.05) when comparing walking with surface electrodes with walking without any electrodes. The internal electrodes caused significant decreases from normal walking in the following parameters: step length for both the measured leg ( −18.6%; p < 0.005) and the nonmeasured leg ( −18.0%; p < 0.005), cadence ( −7.9%; p < 0.02), and walking velocity ( −23.5%; p < 0.005). Internal electrodes caused significant decreases as compared with surface electrodes in the step length for both the measured leg (15.7%; p < 0.01) and the nonmeasured leg (15.6%; p < 0.005) and walking velocity (19.7%; p < 0.005). Single stance phase did not change significantly in any of the comparisons. It appears that the addition of the surface electrode apparatus does change the normal gait of a subject, causing a large decrease in cadence. The measurement of gait with internal electrodes causes further change in gait, resulting in large decreases in step length and walking velocity. While these tests provide important and useful clinical data, physicians and researchers must realize that the gait being measured with these techniques is different from a normal gait pattern.
Density changes at the proximal tibia after medial meniscectomy
Authors: Odgaard Anders , Pedersen Claus M. , Bentzen Søren M. , Jørgensen Jørgen , Hvid Ivan
Published: February 2005

Trabecular bone density changes at the proximal tibia were studied after total and partial meniscectomy using quantitative computerized tomography. Thirty‐seven medially meniscectomized patients (5‐and 10‐year followup) and 10 control persons were included. In the partially and the totally meniscectomized knees, the area of maximal density in the medial tibial condyle was displaced ∼4 mm in a posteromedial direction relative to the position in the intact knees. In both partially and totally meniscectomized knees, the density in the region of tibiofemoral contact in the medial tibial condyle was higher compared with the density in the same region in the contralateral intact knees. This difference was of the same order in the 5‐ and 10‐year follow‐up groups. The density difference between the meniscectomized and the intact knees in the region of tibiofemoral contact in the medial condyle was significantly higher in totally than in partially meniscectomized patients. It is concluded that not only total but also partial medial meniscectomy is followed by density changes, occurring within the first 5 years after meniscectomy. The results emphasize the importance of the utmost conservatism in surgery on the meniscus.
Effects of elevation on nerve function in an acute upper extremity nerve compression model
Authors: Chidgey Larry K. , Szabo Robert M. , Kolack Barbara
Published: February 2005

External compression was applied to the palmar surface of the wrist over the carpal tunnel in eight healthy volunteer subjects. With the arm in the maximum elevated position, the carpal tunnel pressure was elevated to 50 mm Hg, being continuously monitored by a slit catheter inserted into the carpal canal. Sensory and motor latencies and amplitudes were evaluated at 1‐min intervals. When the sensory amplitude decreased by 50% (correlating with subjective sensory changes), the hand was lowered to heart level, still maintaining the carpal tunnel pressure at 50 mm Hg. Nerve conduction velocity and amplitude monitoring continued at 30‐s intervals until complete sensory block. Four subjects demonstrated a transient reversal in the sensory amplitude decline with lowering of the hand to heart level, but soon progressed to a complete sensory block. The remaining four subjects demonstrated no change in the sensory amplitude decline with lowering of the hand to heart level. Our results suggest that with moderately elevated carpal tunnel pressures, once the sensory amplitude drops by 50% and the patient starts experiencing subjective sensory changes, lowering the hand to heart level may not change the local tissue blood flow sufficiently to maintain a sustained reversal in the declining nerve function and impending nerve damage.
Neutral protein‐degrading enzymes in experimental fracture callus: A preliminary report
Authors: Einhorn Thomas A. , Hirschman Albert , Kaplan Charles , Nashed Rafat , Devlin Vincent J. , Warman Jeffrey
Published: February 2005

The process of endochondral fracture healing is biochemically similar to growth plate calcification. Recent studies have identified potentially important roles for proteoglycan‐degrading enzymes in the growth plate. The purpose of the study described herein was to identify, in healing fractures, neutral enzyme activities capable of degrading proteoglycans and other matrix proteins. Two sets of 60 male Sprague‐Dawley rats underwent the production of closed femoral fractures. Calluses were retrieved at timed intervals, and cell and matrix vesicle fractions were prepared for electron microscopy, neutral peptidase, and alkaline phosphatase assays. In another group of 10 animals, fractions were prepared from 14‐day calluses and examined for proteoglycanase activity. In the cell fractions, alkaline phosphatase, alanyl‐β‐naphthylamidase, aminopeptidase, and endopeptidase activities showed somewhat parallel distributions peaking at ∼14–17 days. In the matrix vesicle fractions, similar relative distributions were observed for alkaline phosphatase and endopeptidase. However, here the peak activities occurred up to 3 days later than they did in the cell fractions. Significant proteoglycanase activity was confirmed in both cell and matrix vesicle fractions. These findings are consistent with the hypotheses that (a) neutral peptidases, by virtue of their temporal expression in parallel with alkaline phosphatase, may be involved in preparing fracture callus matrix for calcification; and (b) matrix vesicles may convey certain of these enzymes to sites of both matrix degradation and calcification, since the same activities found in cells are found in matrix vesicles a few days later. The possibility that some of these enzymes are involved in growth factor activation remains to be investigated.
Structural consequences of endosteal metastatic lesions in long bones
Authors: Hipp J. A. , McBroom R. J. , Cheal E. J. , Hayes W. C.
Published: February 2005

Lytic metastatic lesions from breast, prostate, and other cancers often develop on the endosteal surface of a long bone without penetrating the cortical wall. Current clinical guidelines for determining the fracture risk associated with these endosteal defects do not account for the structural consequences of the lesion. We undertook a combined experimental and analytical study of the structural consequences of the lesions with the ultimate goal of providing improved fracture risk guidelines. Endosteal defects of variable length and involving a variable amount of the cortical wall were created with an expanding reamer in canine femurs. The contralateral femur served as a control. The femurs were tested to failure in four point bending. The geometry of the experimental defects was determined from radiographs and CT. Finite element models of the canine femurs were then used to examine geometric and material parameters in both four point bending and in torsion. The experimental data demonstrate a linear relation between bone strength and amount of cortical wall remaining: % intact strength = 99.6 × remaining wall thickness −2.0, R2 = 0.769, standard deviation of regression = 11.57. Four of five data points from the linear finite element models were within the 95% confidence intervals for the experimental data. Experimental and finite element data suggest that the minimum wall thickness is the most critical geometric parameter for predicting the structural consequences of endosteal defects. The length of the defect along the bones' long axis has little effect on bone strength. The length of the defect along the bones' long axis has little effect on bone strength. The anelastic behavior of bone does not need to be represented in finite element models of simple endosteal defects because the defects do not cause significant stress concentrations. However, reduction in the modulus of bone along the border of a defect (due to osteolytic changes) can significantly reduce bone strength. These results indicate that the minimum wall thickness should be determined when clinically evaluating an endosteal defect. The results also suggest that information on bone porosity around metastatic lesions should be considered when making estimates of bone strength.
Cancellous bone material properties in osteoarthritic and rheumatoid total knee patients
Authors: Wixson Richard L. , Elasky Neal , Lewis Jack
Published: February 2005

One hundred and thirty‐four cancellous bone biopsy specimens were takne from the proximal tibias and distal femurs of 55 patients undergoing total knee replacement for analysis of their area fraction and mechanical testing to determine their strength and stiffness. The purpose of the study was to measure the material properties of cancellous bone taken from arthritic patients and compare these with bone from normal subjects. The results showed a wide variation of strength (0.5–18.1 MPa, mean 5.6 MPa) and stiffness (11–504 MPa, mean 152 MPa). These values are in the same range or less than those reported for bone from normal tibias.
Bone ingrowth into the tibial component of a canine total condylar knee replacement prosthesis
Authors: Turner Thomas M. , Urban Robert M. , Sumner Dale R. , Skipor Anastasia K. , Galante Jorge O.
Published: February 2005

The purpose of this study was to evaluate the occurrence of bone ingrowth in a porous coated tibial component of a canine total condylar design knee replacement model. The entire undersurface of the tibial prosthesis was covered by a titanium fiber metal porous composite pad. Projecting from this surface were three short, cylindrical, fiber metal coated pegs that along with a posterior screw provided initial stabilization of the device. Left total knee replacements were performed on six dogs using alignment and cutting jigs to prepare the bony surfaces. The dogs were killed 6 months following surgery. Extensive bone ingrowth was present in all pegs of every tibial component. Bone ingrowth was present in 12% of the pad area of one component, 22.7 to 41.6% in four components, and 81.1% in another. The void spaces in other areas were filled with fibrous tissue or in the periphery of the device with fibrocartilage. Bone ingrowth in the pad was consistent in the vicinity of the pegs and was variable in regions not adjacent to the pegs, suggesting that the pegs exerted a strong influence on the pattern of bone ingrowth into the pad.
Tissue fluid pressures: From basic research tools to clinical applications
Authors: Hargens Alan R. , Akeson Wayne H. , Mubarak Scott J. , Owen Charles A. , Gershuni David H. , Garfin Steven R. , Lieber Richard L. , Danzig Larry A. , Botte Michael J. , Gelberman Richard H.
Published: February 2005

The two basic research tools developed to measure tissue fluid pressure (wick catheter) and osmotic pressure (colloid osmometer) have undergone extensive validation and refinement over the past 20 years. Using these techniques, basic science investigations were undertaken of edema in Amazon reptiles, pressure‐volume relations in animals and plants, adaptive physiology of Antarctic penguins and fishes, edema in spawning salmon, tissue fluid balance in humans under normal conditions and during simulated weightlessness, and orthostatic adaptation in a mammal with high and variable blood pressures—the giraffe. Following and sometimes paralleling this basic research have been several clinical applications related to use of our colloid osmometer and wick technique. Applications of the osmometer have included insights into (a) reduced osmotic pressure of sickle‐cell hemoglobin with deoxygenation and (b) reduced swelling pressure of human nucleus pulposus with hydration or certain enzymes. Clinical uses of the wick technique have included (a) improvement of diagnosis and treatment of acute and chronic compartment syndromes, (b) elucidation of tissue pressure thresholds for neuromuscular dysfunction, and (c) development of a better tourniquet design for orthopaedics. This article demonstrates that basic research tools open up areas of basic, applied, and clinical research.
The interrelation of fiber bundles in the anterior cruciate ligament
Authors: Clark John M. , Sidles John A.
Published: February 2005

The anterior cruciate ligaments (ACL) of dogs, humans, and rabbits were studied by light and scanning electron microscopy after fixation in situ. In all species, the ACL was composed of multiple 20 μm‐wide collagen fiber bundles separated by columns of cells in fibrous capsules. These bundles were in turn grouped into fascioles of varied size. The fascicles were surrounded by thin membranous sheets that ran through the ligament forming single or multiple layers between fascicles. Splaying of the ACL at insertion was created by increased volume in the cellular intervals. Bending of the fiber bundles occurred in this region—which corresponds to the fibrocartilaginous zone. We propose that the cell layers accommodate compressive forces and the membranes allow slipping among fascicles without compromising blood supply.
Effect of donor age on the growth in vitro of cells obtained from human trabecular bone
Authors: Evans Carol E. , Galasko Charles S. B. , Ward Carol
Published: February 2005

The proliferation of human bone‐derived cells (BDCs) was assessed in vitro, using [3H]thymidine incorporation and cell counting in a haemacytometer. The cells were cultured from human trabecular bone from 87 patients aged 2–88 years. The in vitro growth of these cells was unaffected by the chronological age of the donor. However, the cell number at confluence was shown to decrease with increasing donor age, this trend being most marked after 60 years of age. Other assays of the metabolic efficiency of the BDCs, namely, total protein, osteocalcin, and alkaline phosphatase synthesis, did not show any change with increasing donor age. These results suggest that while the ability of individual cells to divide and to perform specific synthetic activities is unimpaired with increasing age, other subtler changes may occur, leading to a decrease in the bone's osteogenic capacity.
Dynamic electromyography. II. Normal patterns during gait
Authors: Wootten M. E. , Kadaba M. P. , Cochran G. V. B.
Published: February 2005

Human gait is a complex phenomenon. Many descriptors are needed to completely describe gait in terms of the biomechanics involved. The descriptors, when expressed as a function of the gait cycle, are complex waveforms. For each of these variables, a single “normal” pattern with bands of deviation has generally been accepted as a reference in clinical/research use to explain the abnormalities in a patient's walking pattern. In fact, one observes many “normal” patterns, and a body of research has been devoted to explaining the differences between these patterns in terms of walking speed, age, cadence, sex, etc. It would be simpler in one sense to start with the fact that different people walk with different patterns, not one pattern with bands of deviation. Numerical representation of the waveforms simplifies the analysis and interpretation of waveform data and facilitates comparison between subjects or groups of subjects. When combined with pattern recognition techniques, it also is useful for identifying subpatterns within a group. In this article, the numerical representation of electromyographic data by Karhunen‐Loeve expansion are combined with cluster analysis to obtain patterns of dynamic phasic activity of 10 muscles of the lower extremity. From the 35 normal subjects walking at self‐selected speed, two to four patterns are developed for each of the muscles and the physiological significance of the patterns are discussed.
Pulsing direct current‐induced repair of articular cartilage in rabbit osteochondral defects
Authors: Lippiello Louis , Chakkalakal Dennis , Connolly John F.
Published: February 2005

Osteochondral defects in the distal femoral condyles of rabbits exposed to a pulsing direct current exhibits an enhanced quality of repair. The signal, with a peak value of 2 μA repeating at 100 Hz, imposed an electric field in the tissue of 20–60 mV/cm2. Maximum efficacy was seen with a shorter period of exposure (40 vs. 160h) initiated 48 h after surgery for 4 h/day. Repair tissue originated primarily from metaplasia of subchondral elements although hyperplasia of pre‐existing chondrocytes at the margins of the defect could be detected. Defects in treated joints contained Safranin O staining material that was histologically similar to a disorganized hyaline cartilage. Central areas of the defects in control animals contained Safranin O‐negative material that generally extruded over the surface as a pannus. The edges of nontreated defects also had characteristics of cartilaginous healing, stressing the importance of using serial sectioning techniques in this model of cartilage repair.
Effect of low frequency pulsing electromagnetic fields on skin ulcers of venous origin in humans: A double‐blind study
Authors: Ieran M. , Zaffuto S. , Bagnacani M. , Annovi M. , Moratti A. , Cadossi R.
Published: February 2005

The effect of an electromagnetic field on the healing of skin ulcers of venous origin in humans has been investigated in a double‐blind study. Forty‐four patients have been admitted to the study; one‐half were exposed to active stimulators (experimental group) and the remaining to dummy stimulators (control group). The stimulation was scheduled to last a maximum of 90 days. The success rate was significantly higher in the experimental group both at day 90 (p < 0.02) and in the follow‐up period (p < 0.005). The data suggest that the effect of the electromagnetic field lasts even when the stimulation is over. No ulcers worsened in the experimental group, while four worsened in the control group. Twenty‐five percent of the patients in the experimental group and 50% in the control group experienced recurrence of the ulcer. It is concluded that stimulation with an electromagnetic field is a useful adjunctive therapy in the management of these patients.
Vascular changes in the chest wall after unilateral resection of the intercostal nerves in the growing rabbit
Authors: Agadir M. , Sevastik B. , Reinholt F. P. , Perbeck L. , Sevastik J.
Published: February 2005

In young, growing white New Zealand rabbits the third, fourth, and fifth intercostal nerves were resected anteriorly on the right side. Six months later the animals developed structural left convex scoliosis, with a Cobb angle ranging from 15 to 31°. The vascular structure changes of the anterior chest wall were evaluated by measuring surface temperature and fluorescein intensity of the pectoral muscles, and the capillary density of the pectoral and intercostal muscle and periosteal parts of the ribs after angiography. In five normal control rabbits there was neither scoliotic deformity nor significant differences in the examined vascular variables between the right and left sides. In the animals undergoing resection, the temperature of the pectoral muscle on the side of the denervation—the right side—was significantly increased (p < 0.05), but the difference was not correlated to the degree of scoliosis. The fluorescence index was significantly greater (p < 0.05) on the right than on the left side, this difference being fairly strongly correlated to the degree of scoliosis. The capillary densities of the costal periosteum and the intercostal and the pectoral muscle were significantly greater (p < 0.05) on the right than on the left side, and the difference was positively correlated to the degree of scoliosis. The volume density of the periosteum of the ribs was likewise significantly greater on the right. These results demonstrate that unilateral resection of the intercostal nerves significantly increase the vascularity of the structures on the denervated side of the thorax. This development may account for the greater longitudinal growth of the ribs on this side and for the development of the scoliosis observed in earlier studies.
The potential of adult human perichondrium to form hyalin cartilage in vitro
Authors: Bulstra Sjoerd K. , Homminga George N. , Buurman Wim A. , Terwindt‐Rouwenhorst E. , van der Linden Anton J.
Published: February 2005

The usefulness of adult human perichondrium for the restoration of articular cartilage defects depends on the potential to form hyalin cartilage. In order to evaluate the capacity of adult human perichondrium to form hyalin cartilage in vitro, perichondrium of the rib of eight adult human beings was cultured in vitro. After removal of residual cartilage, perichondrial explants were cultured for 7 or 10 days. The explants were histologically examined using specific stains to prove the presence of glycosaminoglycans (GAGs) normal for hyalin cartilage. Clear differentiation of perichondrial cells towards chondrocytes was noted. The chondrocytes synthesized new matrix substances normally present in hyalin cartilage. This investigation supports the usefulness of adult human rib perichondrium for the restoration of cartilage defects. Due to the enormous potential of the rib perichondrium to from hyalin cartilage in vitro, even defects in joints with a rather thick cartilage layer might be restored using this biological material.
Cathepsin B and cysteine protease inhibitors in human osteoarthritis
Authors: Martel‐Pelletier J. , Cloutier J. M. , Pelletier J. P.
Published: February 2005

The aim of this study was to determine the involvement of cathepsin B and its inhibitors in the proteolytic degradation of human osteoarthritic (OA) tissue. The characteristics of the cathepsin B found in both normal and OA cartilage and synovium were similar to those of the lysosomal cathepsin B. Two inhibitors of cysteine proteases were found with a molecular weight of 67,000 and 16,000 Da. The cartilage cathepsin B level of OA specimens (54.8 ± 7.3 units/μg of DNA) was greater than the controls (39.8 ± 3.2 units/μg of DNA). Mild‐moderate graded samples (78.1 ± 12.0 units/μg of DNA) had significantly higher levels of enzyme activity than the severely graded ones (31.4 ± 3.9 units/μg of DNA, p < 0.001) and controls (p < 0.01). Compared to controls (2.3 ± 0.4 units/mg of tissue w.w.), cysteine protease inhibitory activity in OA cartilage was decreased in specimens with severe lesions (1.5 ± 0.2 units/mg of tissue). This was particularly noted in patients who had not received steroid injections (1.2 ± 0.3 units/mg of tissue, p < 0.05). In OA synovia, the cathepsin B level was greater (40.7 ± 7.4 units/mg of tissue w.w., p < 0.02) than in the controls (13.6 ± 3.7 units/mg of tissue). The cysteine protease inhibitory activity was similar in OA synovium (1.7 ± 0.2 units/mg of tissue w.w.) and in controls (1.5 ± 0.3 units/mg of tissue). This data demonstrated an imbalance between the levels of cathepsin B and cysteine protease inhibitors in OA tissue. A decrease of specific inhibitors could be an important contributing factor, particularly in more severe lesions.
The development morphology of a “periosteal” ligament insertion: Growth and maturation of the tibial insertion of the rabbit medial collateral ligament
Authors: Matyas J. R. , Bodie D. , Andersen M. , Frank C. B.
Published: February 2005

The structural properties of ligament insertions change dramatically during growth and maturation, but little is known about their developmental anatomy. This study describes and quantifies changes in the gross and microscopic anatomy of the tibial insertion of the rabbit medial collateral ligament (MCL) during development and at skeletal maturity. Eighty animals were used for growth and descriptive studies. From this group, 27 animals, ranging in age from 1 to 24 months, were injected with fluorescent bone markers and their tibial insertions were processed undecalcified for histology. Sections were examined by polarized light and fluorescence microscopy to identify matrix and cells and to quantify mineral formation. Results showed that animals achieved histological skeletal maturity between 9 and 12 months of age. Body weights were a poor index of skeletal maturity. The tibial insertion was composed of five tissue layers, which changed proportions during growth and maturation. In immature animals, MCL fibers entered the periosteum; in older animals, MCL fibers were cemented to the tibia by advancing mineral. The tibial attachment of the MCL was thus transferred from the periosteum to the cortex during growth, suggesting that the term “periosteal insertion” is imprecise in adults. The hypothesis is put forward that these structural changes account for the reported increase in tensile failure of this insertion near skeletal maturity.
The early effect of high molecular weight hyaluronan (hyaluronic acid) on anterior cruciate ligament healing: An experimental study in rabbits
Authors: Wiig Monica E. , Amiel David , Vandeberg Jerry , Kitabayashi Linda , Harwood Fred L. , Arfors Karl E.
Published: February 2005

The purpose of this study was to assess, morphologically and biochemically, the effect of hyaluronan (HA) on the early repair process of the anterior cruciate ligament (ACL). Following partial bilateral laceration in the midsubstance of the cruciate ligament, a single dose of HA (MW of 3.6 × 106) was injected in one knee and saline in the contralateral knee. Postsurgery, the rabbits were allowed normal (nonimmobilized) cage activity, and were killed after 4 (n = 11) and 12 (n = 10) weeks. The ligaments were evaluated by gross morphology and graded according to the degree of repair. We used grades 1, 2, and 3 for uncovered, partially covered, and totally covered lacerations, respectively. Five of the HA‐treated ligaments at each time studied were completely covered, compared to 0 at 4 weeks, and 1 at 12 weeks in the saline group. Paired evaluations of the lacerated ACLs showed that the HA‐treated ligaments received a healing grade higher than the ligaments exposed to saline in 14 of the 21 animals. In the remaining animals, there was no difference between the sides. The repaired tissue of the ACLs was also examined by light and electron microscopy. When compared qualitatively with saline controls, HA‐treated ligaments exhibited a more pronounced repair, with an increased angiogenesis and less inflammatory response. Biochemical analysis demonstrated a mean higher value of type III collagen in the HA‐treated injured ACL than in saline‐treated injured ACL (13.4 ± 1.1% and 11.0 ± 0.8%, respectively). This increased synthesis of type III collagen in the HA‐treated injured ACL was statistically higher (p < 0.05) when compared to the saline‐treated injured ACL.
Dynamic stress response of the implant/cement interface: An axisymmetric analysis of a knee tibial component
Authors: Ahemd A. M. , Tissakht M. , Shrivastava S. C. , Chan K.
Published: February 2005

To determine the adverse effects on the implant/cement interface stresses caused by a dynamic load on the implant, an axisymmetric dynamic finite element analysis was performed for an idealized knee tibial component assuming perfect bonding at the interface. The component, consisting of a metal plate with a central stem, was subjected to a compressive load that varied with time as a terminated ramp function. At first, the reliability of the interface stress predictions was assessed by computing the effects of a number of method‐related parameters, viz., the finite element mesh density, the assumed bone properties. Analysis was then performed considering the stem length, cement mantle thickness, and the type of implant metal as design variables. The analysis predicts high‐frequency (600 Hz) stress oscillations of significant amplitude at those locations of the interface that are also subjected to high static stresses: near the stem‐plate junction and the stem tip for normal stress, and at the stem tip for shear stress. However, the predicted stress amplitude has been found to be particularly sensitive to the assumed rise time of the input load function. With a rise time of 2.0 ms, an input condition considered to be severe enough to represent the most vigorous dynamic activity, the maximum stress augmentation, because of stress oscillations, is predicted to be less than 25%. In general, the design variables have been found to affect the static stresses much more than the dynamic ones. It has been concluded that for the cases studied, dynamic effects are relatively small and a static analysis is sufficient to characterize the interface stress condition.
A new “transducer‐tipped” fiber optic catheter for measuring intramuscular pressures
Authors: Crenshaw Albert G. , Styf Jorma R. , Mubarak Scott J. , Hargens Alan R.
Published: February 2005

Laboratory and clinical tests were used to determine the efficacy of a new fiber optic “transducer‐tipped” catheter for measuring intramuscular pressures. When pressures ranging from 0 to 250 mm Hg were applied by a mercury manometer, the fiber optic system accurtely recorded the pressures. In addition, the fiber optic system showed long‐term stability by accurately recording the manometer pressure over a 3 day period. The Slit system showed a higher magnitude of hydrostatic pressure artifacts with catheter tip movement as compared to the fiber optic system. The two catheters showed no difference when measuring pressures in pig muscle at rest or when being compressed throughout a range of 0 to 250 mm Hg. In human volunteers, both catheters measured essentially equal pressures at rest, during venous stasis, and during a combination of venous stasis and compression. For long‐term assessment, the Slit system required as many as three saline flushes, whereas the fiber optic system measured pressures continuously without manipulation. We conclude that the fiber optic system is as accurate as the Slit catheter for measuring tissue fluid pressures at rest. In addition, the fiber optic system offers distinct advantages over conventional fluid‐filled systems for measuring intramuscular pressures due to a lack of hydrostatic pressure artifacts caused by limb position and to the lack of flushing for long‐term measurements.
The effect of anaesthesia on the bone blood flow of the rabbit
Authors: Davis T. R. C. , Holloway I. , Pooley J.
Published: February 2005

The effect of anaesthesia on the rate of bone blood flow in the rabbit was studied. Two estimates of bone blood flow were performed, using 15 μm radioactively labelled microspheres, in three groups of rabbits. The first group was anaesthetised and the interval between the two estimates was 5 min. The second group was also anaesthetised but the interval between estimates was 60 min. The third group of rabbits was conscious and the interval between the two estimates was 4 h. In the first group, small uniform falls in whole bone blood flow were observed (mean change = −5%). In the second group, larger and less predictable reductions were observed (mean change = −24%). In the third group (conscious), little change was observed in whole bone blood flow during the 4‐h experiment (mean change = + 7%). It is concluded that substantial falls can occur in bone blood flow in the rabbit during a 1‐h anaesthetic. If bone blood flow is to be monitored under anaesthesia, then the effect of the anaesthetic on bone blood flow must be accurately defined. In conscious rabbits, estimates of whole bone blood flow performed at an interval of 4 h under control conditions will give reproducable results.
Chronic achilles paratenonitis with tendinosis: An experimental model in the rabbit
Authors: Backman Clas , Boquist Lennart , Fridén Jan , Lorentzon Ronny , Toolanen Göran
Published: February 2005

An experimental model for inducing chronic Achilles paratenonitis with tendinosis in the rabbit is presented. Thirteen rabbits were exercised in a kicking machine producing passive flexions and extensions of the ankle joint. Active contractions of the triceps surae muscles were induced by electric stimulation via surface electrodes. The animals were exercised for 5 to 6 weeks, with a rate of 150 flexions and extensions per minute for 2 h, three times a week. Light microscopic examination showed degenerative changes of the tendon, and increased number of capillaries, infiltrates of inflammatory cells, edema, and fibrosis in the paratenon. We conclude that chronic Achilles paratenonitis with tendinosis can be experimentally induced in a standardized manner in rabbits.
Acute hemarthrosis: A histological, biochemical, and biomechanical correlation of early effects on the anterior cruciate ligament in a rabbit model
Authors: Ishizue Kenneth K. , Lyon Roger M. , Amiel David , Woo Savio L‐Y.
Published: February 2005

The early histological, biochemical, and biomechanical characteristics of the anterior cruciate ligament (ACL) were determined in a rabbit model of acute hemarthrosis. The ACLs of 19 rabbits were given seven consecutive daily knee injections of 2 ml of fresh autologous blood, and then compared to contralateral ACLs from control knees injected with 2 ml of lactated Ringer's solution daily for 7 days. The rabbits were then sacrificed. Synovial proliferation with iron deposition within synoviocytes was observed; however, the architecture of the ACL was maintained. Additionally, the total collagen content, collagenase activity, and biomechanical properties of the ACL were unaltered.