bluuebunny/crossref_metadata_2025 huggingface dataset:
Laser doppler flowmetry for bone blood flow measurement: Correlation with microsphere estimates and evaluation of the effect of intracapsular pressure on femoral head blood flow
Authors: Swiontkowski Marc F. , Tepic S. , Perren S. M. , Moor R. , Ganz R. , Rahn B. A.
Published: February 2005

Laser Doppler flowmetry (LDF) was used to measure bone blood flow in the rabbit femoral head and femoral condyles. To correlate the LDF output signal blood cell flux to in vivo blood flow, simultaneous measurements using LDF and 85Sr‐labeled microspheres were made in an adult rabbit model. There was no correlation between the two methods for blood flow in the femoral condyles and the correlation between the two methods for blood flow in the femoral head does not achieve statistical significance. An LDF signal of 0.4 V was approximately equal to a microsphere measured flow rate of 0.4 ml blood/g bone/min. The strength of the correlation in the latter case may have been affected by (a) large arteriovenous shunts, (b) inadequate mixing of the microspheres with a left ventricular injection, and (c) insufficient numbers of microspheres present in the bone samples with which to satisfy the mathematical requirements of the microsphere method. When LDF was used to evaluate the effect of elevated intracapsular pressure on femoral head blood flow in skeletally mature rabbits, femoral head subchondral bone blood flow declined with increasing intracapsular pressure from a baseline value of 0.343 ± 0.036 to a value of 0.127 ± 0.27 at 120 cm of water pressure. The decline in femoral head blood flow was statistically significant at pressures of 40 cm of water or higher (p < 0.001), and evaluation of sections of the proximal femora made from preterminal disulphine blue injections confirmed these findings. Intracapsular tamponade has an adverse effect on femoral head blood flow beginning well below central venous pressure and should be considered in the pathophysiology of posttraumatic and nontraumatic necrosis of the femoral head. Laser Doppler flowmetry was easy to use and appears to be a reproducible technique for evaluating femoral head blood flow, offering distinct advantages over the microsphere technique for measuring bone blood flow. Further studies of the in vivo calibration of the LDF method for bone blood flow are necessary for the method to have potential for clinical application.
Joint reaction to polyethylene implantation: A method for inducing osteoarthritic change and osteophyte formation in the rabbit knee joint
Authors: Garcia Fernando , Mitrovic Dragoslav R.
Published: February 2005

Joint lesions were induced by implantation of a rigid piece of polyethylene sutured under the patella and quadriceps tendon of the rabbit's right knee. Compared to the left sham‐operated knee, follow‐up studies revealed progressive changes that consisted of early and transient synovial hyperemia and proliferation and late osteoarthritis. By day 7 after surgery, soft synovial‐like tissue proliferated around the implant and the articular margins of the femoral trochlea indicating primitive “osteophytic” protuberances (synovio‐phytes). By day 15 after surgery, the synoviophytes had acquired a more solid consistency and were composed mostly of fibrocartilage covered by a fibro‐cellular synovial lining (chondrophytes). By that time, this tissue was invaded with vascular channels; signs of ossification were already present in the deepest layer adjacent to bone. Between the 2nd and 12th weeks, this fibro‐cartilaginous tissue, except for the surface fibrous or fibrocartilaginous layer, was progressively replaced by immature bone (osteophyte). Secondary bone remodeling started soon after the first lamellae of immature bone were deposited. Complete integration of the osteophyte into the distal femur occurred during the 2nd and 3rd month.
Failure of the rabbit tibial growth plate to respond to the long‐term application of a capacitively‐coupled electrical field
Authors: Armstrong Peter F. , Brighton Carl T.
Published: February 2005

A continuous 5‐V peak‐to‐peak, 60 kHz capacitively‐coupled sine wave signal was applied to the proximal tibial growth plate in fifteen 9‐week‐old male New Zealand white rabbits for 6 weeks. A pair of flexible stainless steel “injectrodes” was held in place medially and laterally on the surface of the proximal hindlimb in each rabbit by means of tape wrappings. The electrodes were connected to a 9‐V battery‐operated power unit carried in a dorsal pouch in a body vest worn by each rabbit. Control animals wore the identical apparatus, only the power unit was inactive. Small Tantalum markers were inserted into the anteromedial aspect of the proximal tibial metaphysis 1 cm distal to the proximal tibial growth plate in all of the animals, control and experimental, 2 weeks prior to the onset of electrical stimulation. The distance between the proximal lateral tibial spine and the Tantalum marker, between the Tantalum marker and the apex of the distal tibial intercondylar notch, and between the proximal tibial spine and the distal notch was measured from roentgenograms made at the time of bone marker insertion, at the time of electrode application to the limb, and at the end of the stimulation period. Results indicate that there was no significant difference in tibial lengths between the stimulated and control groups. There was significantly less total body weight gain in both the experimental and control animals than that which occurred in paired normal animals during the same period of time. This failure to thrive may be responsible for the resultant lack of longitudinal growth stimulation of the capacitive coupling. The observed failure to thrive was thought to be due to encumbrance imposed on the rabbits by the legwraps and the body vest.
Role of internal fixation in infection of open fractures: Studies with Staphylococcus aureus and Proteus mirabilis
Authors: Merritt Katharine , Dowd James D.
Published: February 2005

Studies of infections in open fractures are described. The hamster was chosen as the experimental model. Osteotomies of the femur were created with an osteotomy saw. Some osteotomies were left to heal and others were fixed with an 0.9mm K‐wire. The infection rates in fixed and unfixed fractures were compared. The first group of hamsters with fixed and unfixed osteotomies was returned to cages with open wounds. There was no difference in the infection rate at 2 weeks. The second group was deliberately contaminated with Staphylococcus aureus and then returned to cages with open wounds. In this group, the infection rate at 2 weeks was lower in the internally‐fixed fractures than in the unfixed fractures. The third group was deliberately contaminated with the gram negative organism Proteus mirabilis. In these animals, the infection rate was increased in the presence of the internal fixation device. The fourth group was deliberately contaminated with both Staphylococcus aureus and Proteus mirabilis. The infection rate in these animals was very high; Proteus was recovered from those animals with internal fixation and Staphylococcus was recovered from those animals without internal fixation. These studies in the hamster document the usefulness of this animal as an inexpensive and reproducible model for studying infection of open fractures. The hamsters tolerated the procedure well, and wound and fracture healing progressed satisfactorily.
Systemic administration of glycosaminoglycan polysulphate (Arteparon) provides partial protection of articular cartilage from damage produced by meniscectomy in the canine
Authors: Hannan Neil , Ghosh Peter , Bellenger Christopher , Taylor Thomas
Published: February 2005

Bilateral medial meniscectomy was undertaken in 14 mature beagles. Another two underwent arthrotomy (sham‐operated controls). One week after surgery, six of the meniscectomised animals were administered glycosaminoglycan polysulphate (Arteparon) (2 mg/kg) subcutaneously three times a week for 3 weeks, then twice weekly until killed 23 weeks later. Two months before death all animals were given Na235SO4(1.0 mCi/kg) intravenously. At autopsy, articular cartilage (AC) from the medial and lateral compartments, as well as from the femoral trochlear groove and femoral head, was sampled. Proteoglycans (PGs) were isolated by 4.0MGuanidine hydrochloride (GuHCI) extraction of AC and purified by ultracentrifugation. The PG monomers were assayed for hexuronic acid, protein, and hexosamines (galactosamine/glucosamine), and their ability to aggregate. The results indicated that Arteparon provided some protective effect to AC in the menisectomised compartment as demonstrated histologically by reduced surface fibrillation, diminished chondrocyte cloning, and maintence of alcianophilia. The levels of PGs and hexuronate‐protein ratios in medial AC of drug‐treated meniscectomised animals were found to be comparable to sham controls, whereas these parameters in the nondrug‐treated meniscectomized group were depressed.
Force analysis of the patellar mechanism
Authors: Ahmed A. M. , Burke D. L. , Hyder A.
Published: February 2005

The aim of this study is an experimental evaluation of a force analysis of the patellar mechanism based on the assumption that patellofemoral contact is frictionless. At first, the geometric characteristics of contact surfaces, a prior knowledge of which is necessary for quantitative analysis, were measured from radiographs of 42 fresh‐frozen knee specimens in the flexion range 0–120°. The results were then used in the analysis to predict the relations between the forces acting on the patella. For the evaluation of the analysis, the ratio of the tension in the ligamentum patellae and the rectus femoris was measured in ten specimens during simulation of two knee functions: (1)“leg raising” against a resistance; and (2)“static lifiting”. The effect of flexion angle on the ratio is found to be rather complex. With increasing flexion, the ratio increases initially up to 30°, then decreases up to 90°, and finally increases again beyond 90°. The ratio is above unity up to around 45° and below that in the remaining flexion range. The analysis has been found to predict not only the characteristic variation of the ratio but also its magnitude with reasonable accuracy. It has been concluded that for an accurate prediction of the patellofemoral joint reaction, the force analysis needs to be based on the geometry of the contact surfaces. This implies that the mechanical consequences of surgical procedures involving tibial tubercle relocation cannot be inferred simply on the basis of their effect on the patellar mechanism angle, but that they also require consideration of their effect on the contact geometry.
Femoral anteversion: Assessment based on function axes
Authors: Yoshioka Yuki , Cooke T. Derek V.
Published: February 2005

This study describes a clinically oriented anatomical assessment of anteversion on 32 cadavers ranging from 61 to 89 years. The method used a three‐dimensional reference system based on functional axes of the femur. Each soft tissue‐free femur was mounted on an osteometric table and aligned to its functional axes. The long axes were defined as passing from the centre of the femoral head to the femoral attachment of the posterior cruciate ligament (PCL). A line that ran through the PCL attachment (equal distal origin of this system) and was parallel to a transepicondylar line served as a transverse axis. Anteversion of the femur was defined as an angle formed to the transverse axis by a line running through the centre of the femoral head through the midpoint of the narrowest segment of the femoral neck. The measurement mean for anteversion among these specimens was 7.4° with a range from −10.8° (retroversion) to 22.1°. There was no statistical difference in mean values (p<0.05) between sexes or between right and left sides of the group; however there were large variations for anteversions when each side in the same individual was compared (although there was no dominant side). Retroversions were observed in four of 32 femurs (12.5%). No correlation was found between the anteversion in these femurs and rotational geometry at the knee. We compared our data with those obtained by conventional techniques, by which anteversion for each femur was measured after the bone had been placed on a flat surface. The anteversion so defined was 13.1°, i.e., an average of 5.7° more external rotation induced by condylar disproportion. Such data indicate the influence of condylar disproportion on the measurement of anteversion and reveal the potential errors in measurements of anteversion that may be imposed by variations in condylar dimensions. The measurement method may be applied to computer tomographic radiographs of femora in vivo.
The use of laser doppler flowmetry to evaluate anterior cruciate blood flow
Authors: Schlehr Frank J. , Limbird Thomas A. , Swiontkowki Marc F. , Keller Tony S.
Published: February 2005

The purpose of this study was to quantitate the blood flow of the anterior cruciate ligament in vivo. Functional flow was evaluated using laser Doppler flowmetry (LDF), for which the output signal, blood cell flux (BCF), is expressed in terms of volts. Ten patients undergoing routine arthroscopic surgery with clinically intact anterior cruciate ligaments were selected at random for participation in the study. Under arthroscopic visualization, a 2.2‐mm probe was placed through a trocar sleeve into the anterior cruciate ligament after the arthroscopic procedure. Pulsatile flow within the ligament was observed in all patients. The mean maximum BCF value ranged from 101 to 274 mV; SD range was + 3–9 mV. The mean minimum BCF ranged from 75 to 197 mV; SD range was + 0 to 9 mV. Laser Doppler flowmetry offers significant promise as a method for measurement of in vivo anterior cruciate and cruciate substitution blood flow.
Degeneration and the chemical composition of the human lumbar intervertebral disc
Authors: Pearce Richard H. , Grimmer Beverley J. , Adams Mark E.
Published: February 2005

Fifteen lumbar spines were collected postmortem. The intervertebral discs were assigned morphological grades and were analyzed for water, collagen, and proteoglycan. In order of increasing degeneration, five grade 0, four grade 1, 45 grade 2, 12 grade 3A, and nine grade 3B discs were identified. The proteoglycan concentration fell progressively with increasing grade, although the concentrations of each component overlapped extensively among the grades. Grade 2 discs showed no consistent differences from adjacent grade 3A or 3B discs and all discs in three spines with no grade 3A or 3B discs had proteoglycan concentrations below 52 mg/g fresh weight. Four of five spines with at least one disc of proteoglycan concentration above this value contained no grade 3A or 3B discs. These observations support the hypothesis that low proteoglycan concentrations in all the discs of a spine precede degeneration.
Effect of electric currents on DNA synthesis in rat osteosarcoma cells: Dependence on conditions that influence cell growth
Authors: Noda Masaki , Johnson David E. , Chiabrera Allesandro , Rodan Gideon A.
Published: February 2005

Effects of sinusoidal 60‐Hz electric currents on DNA synthesis in rat osteosarcoma cell (ROS 17/2.8) in culture were investigated using agar electrodes. This exposure system eliminates electrochemical effects at electrode surfaces, minimizes the contribution of magnetic fields and produces no detectable temperature changes (< t 0. l°C) at current densities of up to 1,500 pA r.m.s. (root mean square)/cm2. Thirty‐four hours exposure to electric current at intensities of 300–400 pA r.m.s./cm2 enhanced DNA synthesis by 20% relative to controls. The effect depended on serum concentration, cell seeding density, and the age of the cell population at the time of seeding: effects were seen at 0.2% fetal bovine serum, in cells seeded 4 days after previous passage, at 20,000 cells/cm2. These findings indicate that sinusoidal electric currents can mildly enhance DNA synthesis in these cells under growth‐limiting conditions.
Platelet pathology in minimal curve idiopathic scoliosis: An attempt to predict curve progression
Authors: Meyer S. , More R. , Yarom R.
Published: February 2005

Platelets from adolescents with minimal curve scoliosis (mcs) (7–18?) and healthy control subjects were examined for morphometry under the electron microscope and tested for calcium content and surface negative charge. These parameters have previously been found to be abnormal in severe idiopathic scoliosis (is) patients. Significantly more patients than control subjects showed deviations from normal in all tests. Two tests in particular, the average number of dense bodies per cell and an increased surface negative charge, were the most frequent abnormalities. In an attempt to assess the possibility of using platelet tests for prediction of curve progression, statistical comparisons were made and discriminant scores were generated for each patient. The results were compared with the clinical findings after a 2‐to 3.5‐year follow‐up. The predictions proved to be incorrect although each of the five patients who had curve progression had some platelet abnormality. It is concluded that although platelet pathology does occur in early idiopathic scoliosis, it cannot be used as a prognostic indicator of curve progression.
The effect of proximally and fully porous‐coated canine hip stem design on bone modeling
Authors: Bobyn J. D. , Pilliar R. M. , Binnington A. G. , Szivek J. A.
Published: February 2005

Porous coated canine femoral hip replacement implants were evaluated for biological fixation by bone ingrowth and the effect of the extent of porous coating on bone modeling. The Co‐Cr alloy implants were either fully porous coated or coated only on the proximal 40% of the stem. Two implants of each type were studied 9, 16, and 36 months after surgery. Implant fixation and bone modeling were assessed radiographically throughout the implant periods and histologically after the test animals were killed. All 12 implants appeared stably fixed within the femur and were bone‐ingrown in the porous region. Radiographic features such as proximal medial and anterior cortical thinning, proximal cancellous bone hypertrophy, and new endosteal bone formation near the stem tip were noted within the first postoperative year, with no appreciable change thereafter. The extent of proximal cortical thinning varied from virtually none to as much as 40%, being more prominent with the proximally coated implants at 16 months and with the fully coated implants at 36 months. Of consistent note was cancellous hypertrophy at the junction of porous and smooth implant surfaces with proximally coated implants and new endosteal bone formation and ingrowth at the stem tip of fully coated implants. These results indicate that the proximally porous‐coated implant design causes increased proximal stress transfer, but this does not necessarily preclude proximal cortical resorption.
Increased transsynovial transport with continuous passive motion
Authors: Danzig Larry A. , Hargens Alan R. , Gershuni David H. , Skyhar Michael J. , Sfakianos Peter N. , Akeson Wayne H.
Published: February 2005

Thirteen freshly killed immature rabbits were used to study the effect of continuous passive motion (CPM) on regional nutritional pathways of the medial and lateral menisci and the transport of a solute from synovial fluid to the patellar tendon. A bolus of 35SO4 was injected into each knee joint cavity. The right knee underwent CPM for 1 h, whereas the left knee was immobilized (rest extremity). Both knees were then rapidly resected and immediately frozen. The medial and lateral menisci were removed and sectioned into anterior, middle, and posterior thirds for Group 1 animals; in Group 2 animals a portion of patellar tendon was harvested. Radioactivity as counts per minute per milligram of tissue was counted in a scintillation counter. The posterior portion of the lateral meniscus in the rest extremity had significantly higher uptake than the extremity that underwent CPM (p < 0.001). In the extremity at rest, the posterior third of the lateral meniscus had a significantly higher uptake than that of the middle third (p = 0.04). In Group 2 rabbits, the patellar tendon of the knee undergoing CPM had significantly higher uptake as compared with the patellar tendon of the knee at rest (p = 0.02). These results indicate that diffusion from synovial fluid to meniscal cells is an important mechanism of transport for low‐molecular‐weight nutrients such as sulfate; CPM does not facilitate this mechanism. However, even with a decreased amount of 35SO4 left in the CPM‐treated joint, the amount taken up by these menisci was still roughly the same as that in the rested knee that had a higher concentration of 35SO4 available in the synovial cavity. Regional differences are small for the 1‐h period examined in this study. Transarticular transport of sulfate from the joint space to an extraarticular tissue (patellar tendo) is facilitated by convective flow induced by CPM.
Torsion and bending analysis of internal fixation techniques for femoral neck fractures: The role of implant design and bone density
Authors: Swiontkowski Marc F. , Harrington Richard M. , Keller Tony S. , Van Patten Peter K.
Published: February 2005

To evaluate pin/screw/plate fixation for management of femoral neck fractures, 39 proximal femora were tested in both torsion and flexion under physiological loading conditions. Three, four, or five implants of six commonly used multiple‐fixation devices, and a sliding hip screw with and without an additional 6.5‐mm cancellous screw were examined in paired femora. The intact and postfixation femora were initially subjected to a single applied moment, and the torsion and bending stiffness were determined from the load‐deformation data. Postfixation femora were also subjected to cyclic loading in flexion at three load ranges, and fixation was judged successful if no failure occurred on or before 1,500 cycles of 667 to 2,000 N of a combined compressive force and moment. Anterior‐posterior and lateral radiographs of each specimen were taken after fixation in order to evaluate Singh's index of bone density, fracture reduction, implant placement, and cross‐sectional diameter of the femoral neck. Bone density was also evaluated by computed tomography (CT) and physical measurement of core samples obtained from the femoral head. The results indicate that there appears to be no justification for the use of more than three pin/screw implants for management of femoral neck fractures. Bone density was found to correlate with fracture stability and may be a useful predictor of fixation success.
Osteonal remodeling in response to screw implantation in in canine femora
Authors: Martin R. B.
Published: February 2005

We examined the patterns of osteonal remodeling associated with the implantation of a screw in the femoral diaphysis of four mongrel dogs. The dogs were killed at intervals ranging from 11 to 93 days after implantation, and resorption spaces and tetracycline‐labeled osteons were counted as functions of postimplant time and distance from the screw. The contralateral femur was used as a control. We found that implantation of the screw initiated a sequence of remodeling activity at the screw site; numerous resorption spaces were observed after 3 weeks, followed by numerous refilling osteons at 7 weeks. When sequential sections along the shaft adjacent to the screw were examined, it appeared that the increased resorption and refilling activity subsequently migrated away from the screw site, both proximally and distally. Also, both the implanted and control femurs exhibited occasional zones along the shaft within which the numbers of labeled osteons were sharply reduced. These “extinction zones” were found to be asscoiated with local maxima in resorption space density. We further noted that the ratio of singly to doubly labeled osteons in the experimental control femurs was high as compared with that in humans, but similar to that previously observed in the canine iliac crest.
Cross the borders
Authors: Nachemson Alf L.
Published: February 2005

The orthopaedic scientists of today, whether a clinician or a basic scientist, must cross both interdisciplinary and national borders to advance the field. Examples derived from the author's own experience of such border crossing are given, mainly as they relate to research in spinal disorders.
Obesity and decreased femoral anteversion in adolescence
Authors: Galbraith Robert T. , Gelberman Richar H. , Hajek Paul C. , Baker Lori A. , Sartoris David J. , Rab George T. , Cohen Mark S. , Griffin Paul P.
Published: February 2005

The degree of femoral anteversion in a group of obese adolescent children and a group of adolescent children of normal weight was determined by either magnetic resonance imaging or computerized axial tomography. Compared with the children of normal weight, the obese children showed a significantly reduced angle of femoral anteversion. Increased biomechanical forces generated across the hip joint of obese children leads to increased remodeling of the femoral neck. This may account for the association of slipped capital femoral epiphysis, reduced femoral anteversion, and obesity in the adolescent population.
Extent of artificial limb use following rehabilitation
Authors: Holden Jean M. , Fernie Geoffrey R.
Published: February 2005

The extent of prosthesis use is reported for 104 lower limb amputees from the onset of gait training up to 2 years later. Subjects were divided into groups according to age (265 years or < 65 years) and amputation level. An analysis of variance including the factors of age and level of amputation was done. Unilateral trans‐tibial (UTT) amputees progressed more quickly during the inpatient gait training program that did unilateral trans‐femoral (UTF) subjects (p < 0.05). UTT subjects also walked more than UTF subjects just prior to discharge (p < 0.05), during the first year after discharge (p < 0.01), and during the second year after discharge (p < 0.01). Similarly, younger patients progressed more quickly in gait training (p < 0.05) and walked more than older subjects throughout the study period (p < 0.05). There were no significant interactions between age and amputation. The extent of walking of these amputees is compared with the minimal levels required for them to function in different living environments. At the time of discharge from the inpatient gait training program, older unilateral amputees and trans‐femoral amputees were not able to walk the 600 steps a day necessary to manage with a moderate level of support in a one‐level apartment or home. The declining number of steps taken in the follow‐up period indicated that the UTF subjects might benefit from some special attention paid to their community support needs. These findings are also viewed in the context of limited data available on the extent of walking of non‐amputees.
Changes in bone marrow blood flow with aging
Authors: Kita Kiyoshi , Kawai Kazuo , Hirohata Kazushi
Published: February 2005

We investigated changes in bone marrow blood flow and histology with aging in rabbits. Bone marrow blood flow was measured by the hydrogen washout method, which was performed in the proximal tibia of Japanese white rabbits, 3–42 months of age. Bone marrow blood flow was found to decrease with age. Histological observations of the proximal tibia identified a decrease in the number of osteoblasts and hematopoietic cells, an increase of the number of empty lacunae, a reduction in bone formation rate, and a degeneration of marrow fat with aging. These results suggest that the decrease of bone marrow blood flow is related to histological changes found with aging.
Acute staphylococcal septic arthritis: The effect of cloxacillin therpy in an avian model
Authors: Patel Harjit , Nade Sydney
Published: February 2005

An experimental model of acute staphylococcal septic arthritis in chickens was used to study the effect of different therapeutic regimens of the antibiotic cloxacillin on the natural history of the disease. Three different theapeutic regimens were used in order to assess the effect of increasing the frequency and of delaying the commencement of administration. The results were assessed by measurement of animal growth rate, clinical condition, bacterial and leukocyte counts in synovial fluid, and histological appearance. An inadequate dosage regimen (a single daily dose) prevented spread of bacteria but did not control abscesses. Delay in commencing treatment permitted persistence and spread of abscesses with destruction of the secondary (epiphyseal) ossification center and even transphyseal spread into metaphyseal bone. Repair by fibroblasts was mainly seen in articular and epiphyseal cartilage but was not seen in the epiphyseal ossification center during the duration of the experiments (up to 18 days). Synovial fluid sampling with measurement of leukocyte and bacterial concentrations appears to be a useful guide to the effectiveness of treatment, because the numbers of cells correlate with the pathological process.
Cell populations of tendon: A simplified method for isolation of synovial cells and internal fibroblasts: Confirmation of origin and biologic properties
Authors: Banes Albert J. , Donlon Kathy , Link G. William , Gillespie Yancy , Bevin A. Griswald , Peterson Hugh D. , Bynum Donald , Watts Susan , Dahners Laurence
Published: February 2005

Tendons transmit the force of muscle contraction to bone to effect limb movement. Special structural and biological properties of tendon have developed to facilitate force transmission. The tendon has a complex organization of cells surrounding the collagen bundles inside tendon as well as at the tendon surface. Internal cells may act to maintain the bulk of the collagen in tendon. External cells in the epitenon may provide lubrication for tendon gliding. To develop better understanding of these processes and the roles the cell populations play, we isolated cells from the surface and interior of tendon and studied them in vitro. Flexor tendons from 8‐week‐old white Leghorn chickens were separated into two distinct cell populations: the outer synovial cells and the fibroblasts more internal in tendon. These cell populations were discernible by their locations in the intact tendon, determined by sequential enzymatic and physical release from their substrata. Initially, some cells eluted in Hanks' salt solution (HSS) (population 1); then synovial cells were released after a 2‐min treatment with 0.5% collagenase (population 2). Next, a population of synovial cells was released in high yield by treatment with 0.25% trypsin (step III, population 3). Step III, population 3 cells were used as synovial cells (SCs). Next, a population of SCs and fibroblasts were released by scraping with a rubber policeman (population 4). Subsequently, fibroblasts were released after incubation with 0.5% collagenase (population 5). A more direct procedure (procedure 2) to isolate the synovial and internal tendon cells involved treatment in 0.5% collagenase followed by sedimentation at 900 g. Cells that sedimented were largely fibroblasts, whereas the cells that remained at the top of the tube were largely SCs. Cells designated as SCs, isolated by procedure 2, most likely contained surface cells from epitenon and internal interfascicular cells from endotenon and paratenon. Surface tendon cells separated by sequential enzymatic and physical release from their substrata (by procedure 1) had all the following characteristics: distinct subpopulations of cells based on morphology; presence of cytoplasmic, lipid‐containing vesicles; decreased sensitivity to trypsin; and reduced generation time as compared with that of internal fibroblasts. Conversely, the internal fibroblasts (IFs) appeared to represent a more uniform population based on morphological characteristics.
Spinal deformity and back surface asymmetry in idiopathic scoliosis
Authors: Stokes Ian A. F. , Armstrong John G. , Moreland Morey S.
Published: February 2005

Stereo radiography and stereotopography were used to record simultaneously the three‐dimensional spinal and back surface shape of 141 patients with a clinical diagnosis of adolescent onset idiopathic scoliosis. Radiography confirmed 80 patients with single lateral curves (Cobb angle 5–87°); 59 with double curves (Cobb angle 5–61°). and two patients with triple curves. Orientation of each vertebra was measured by the lateral deviation from the spinal axis and the axial rotation. For each curve detected, the Cobb angle, the maximum deviation, the maximum axial rotation, and the sagittal plane curvature was measured. Topographic data were used to generate a profile of a cross‐section through the back of each vertebral level. This section was characterized by its axial rotation, deviation of its midpoint from the spinal axis, and area symmetry about the midpoint. Maximum values of these measurements in the region of each radiographic scoliosis curve were noted. Regression and correlation analysis showed (for each curve) a high correlation of apical vertebral lateral deviation with back surface axial rotation (r = 0.79) and with vertebral axial rotation (r = 0.79). The back surface rotation was less than vertebral rotation in magnitude, however, by a mean factor of 0.55. The measurement of the back surface asymmetry that gave the highest correlation with the skeletal deformity was the axial rotation. Relationships between skeletal and surface measures were similar for curves in thoracic and lumber regions and for patients with single and double curves. There is potential for clinical application of surface measurement techniques to prescription of orthoses and monitoring of changes due to progression or treatment.
Mechanical stresses and endochondral ossification in the chondroepiphysis
Authors: Carter Dennis R. , Wong Marcy
Published: February 2005

In 1911, Gebhardt used a photoelastic model to relate mechanical stresses to the ossification pattern of the chondroepiphysis. Pauwels later conducted a photoelastic study using the same model geometry to develop a theory that the secondary ossific nucleus originates at a position of high‐magnitude hydrostatic pressure where the shear stresses are zero. We conducted two‐dimensional finite element analyses of the model used by Gebhardt and Pauwels. We demonstrate that Pauwels's photoelastic results are correct but are based on the imposition of incorrect boundary conditions. When more realistic boundary conditions were used, the finite element results changed dramatically. These results suggest that (a) the ossific nucleus appears in an area of high shear (deviatoric) stresses; (b) the edge of the advancing ossification front (zone of Ranvier or ossification grove) also experiences high shear stresses; and (c) the joint surface, where articular cartilage forms, is exposed to high‐magnitude hydrostatic compression. These findings support the theory proposed by Carter and associates that intermittently applied shear stresses (or strain energy) promote endochondral ossification and that intermittently applied hydrostatic compression inhibits or prevents cartilage degeneration and ossification.
Effects of ankle taping on the motion and loading pattern of the foot for walking subjects
Authors: Carmines David V. , Nunley James A. , McElhaney James H.
Published: February 2005

Gait analysis was used to compare the ground reaction forces, ankle and foot rotations in the sagittal plane, and the center of pressure pattern beneath the right feet of seven normal subjects walking barefoot, with and without their right ankles taped in the neutral position. Instrumentation included a force plate, ankle goniometer, and two accelerometers mounted on top of the foot. The ground reaction forces showéd no change between the same ankle, taped and untaped. Taping served to reduce the range of ankle rotations in the sagittal plane by ∼20%, with a subsequent increase in the rotation about the metatarsal heads during heel‐up. Hell‐up occurred earlier in stance when the ankle was taped than with no taping. The vertical force graph was integrated over time when the center of pressure was located beneath the heel and the ball, resulting in two impulse measurements. The heel impulse decreased for each of the 7 subjects and 6 of the 7 subjects displayed an increase in the ball impulse due to taping, indicating that taping served to shift the load‐time history away from the heel and toward the ball. The results of this study may apply to fused ankle patients, who may suffer forefoot abnormalities subsequent to ankle fusion surgery.
Capacitively coupled electrical stimulation of bovine growth plate chondrocytes grown in pellet form
Authors: Armstrong Peter F. , Brighton Carl T. , Star Andrew M.
Published: February 2005

Pellets formed from isolated bovine growth plate chondrocytes were grown in various capacitively coupled electrical fields. The signals chosen were 0, 10, 100, 250, 500, 750, 1,000, and 1,500 V peak‐to‐peak, 60 kHZ. The effect on cell proliferation and matrix production of these different voltages was determined by [3H]thymidine and [35S]sulfate uptake, respectively. Cyclic AMP assays were done to determine if increases in either thymidine or sulfate uptake were associated with changes in cAMP levels. Significantly increased cell proliferation occurred at 500, 750, and 1,000 V peak to peak. The calculated electric fields were 1.5 to 3.0 × 10−2 V/cm. Proliferation was significantly inhibited at 1,500 V peak‐to‐peak with a calculated field of 4.5 × 10−2 V/cm. Little if any change was seen in cAMP levels at 30 or 60 min following application of the appropriate electric signals.
Comparative evaluation of the diffusion of tobramycin and cefotaxime out of antibiotic‐impregnated polymethylmethacrylate beads
Authors: Wilson Katharine J. , Cierny George , Adams Kenneth R. , Mader Jon T.
Published: February 2005

Both tobramycin and cefotaxime diffuse from antibiotic‐impregnated polymethylmethacrylate (PMMA) beads in quantities sufficient to inhibit the growth of bacteria on agar lawns or in broth cultures over a 28‐day period. Extraction of antibiotic from tobramycin or cefotaxime‐impregnated PMMA beads revealed that substantial amounts of both antibiotics remained within the beads despite 28 days of diffusion. Diffusion of antibiotic from the PMMA beads during the initial 3–5 days is much greater than occurs for the remainder of the 4‐week period. The results of the study suggest that perhaps tobramycin or cefotaxime‐impregnated PMMA beads would produce local levels of antibiotic high enough to sterilize a given dead space for a period of 28 days.
Streaming potentials in chemically modified bone
Authors: Otter Mark , Goheen Susanna , Williams Wendell S.
Published: February 2005

Direct streaming experiments with no significant mechanical deformation have been performed to determine the constituent or constituents of bovine tibia mainly responsible for the production of streaming potentials. Following the approach of Frank and Grodzinsky (5), selective removal of either main constituent—collagen or hydroxyapatite—of the tissue was performed by chemical means, and the streaming potential was remeasured. Demineralized samples were prepared by soaking in formic acid/sodium citrate, and anorganic samples were prepared by boiling and also by sodium hypochlorite treatment. Demineralized samples demonstrated ζ potentials close to those of whole bone samples, whereas anorganic samples had much smaller ζ potentials. Collagen rather than hydroxyapatite mineral is therefore implicated as the constituent of whole bone dominating the streaming potential, in agreement with the observation that collagenous tissues containing no mineral phase, i.e., tendon and cartilage, also exhibit streaming potentials. No sign change was observed in whole bone at high NaCI concentration in solutions containing calcium or at low pH. Although the sign of the signal for anorganic bone could be reversed by the addition of Ca2+ or PO43+ to the test solutions, the sign of the signal in neither whole bone nor demineralized bone could be so affected. Sign changes in whole bone were observed only with solutions containing basic organic molecules, e.g., protamine sulphates.
Transient synovitis of the hip in the child: Increased levels of proteoglycan fragments in joint fluid
Authors: Lohmander L. S. , Wingstrand H. , Heinegård D.
Published: February 2005

The levels of proteoglycan antigen were measured in joint aspirates from the hip of children with transient synovitis, septic arthritis, Legg‐Calvé‐Perthes' disease and congenital and traumatic dislocation. Significantly increased levles were found in children with transient synovitis and septic arthritis as compared with other conditions. We propose that the proteoglycan antigens in the joint fluid were released from the articular cartilage in a partially degraded form as a result of an increased rate of proteolytic degradation. In transient synovitis, the source of proteolytic activity may be chondrocytes activated by factors released by synovial cells. The release of joint proteoglycan may cause a temporary increase in deformability of the hip cartilage of the child that could be an important pathogenetic mechanism in some of the sequelac of these diseases.
Effects of ingrowth, geometry, and material on stress transfer under porous‐coated hip surface replacements
Authors: Fyhrie D. P. , Carter D. R. , Schurman D. J.
Published: February 2005

Three different interface geometries for porous ingrowth surface replacements of the hip were examined using two‐dimensional linear and non‐linear contact finite element analyses. The results indicate that incorporation of a nearly flat prosthesis interface between the surface replacement and the underlying cancellous bone may reduce stress shielding and improve stress transfer from the component. For all designs analyzed, the bone stress shielding was insensitive to component material stiffness when the elastic modulus was >30 MPa. The use of titanium instead of cobalt‐chrome (Co–Cr) as the prosthesis material therefore had a negligible effect on stress shielding.
Biomechanics of the craniocervical region: The alar and transverse ligaments
Authors: Dvorak Jiri , Schneider Erich , Saldinger Pierre , Rahn Berton
Published: February 2005

In the treatment of spine fractures and fracture‐dislocations, stability of the spine is one of the major objectives. In the craniocervical joint, the alar and transverse ligaments provide much of the stability of the healthy spine. Because the anatomy appears well described, the contribution of each of these structures so far has received little attention. The alar ligament restrains rotation of the upper cervical spine, whereas the transverse ligament restricts flexion as well as anterior displacement of the atlas. A lesion in one or both structures can produce damage to the neural structures and/or cause pain. To investigate the possible role of each of these ligaments, a mechanical and histologic study of the upper cervical spine was made. The bone‐ligament‐bone complex of the alar and transverse ligaments was subjected to unlaxial mechanical testing in seven specimens. The alar ligaments had an in vitro strength of 200 N, and the transverse ligaments had an in vitro strength of 350 N. Histologic analysis revealed a mainly collagenous nature of these ligaments. Clinical evidence (broken odontoid processes) suggests that the transverse ligament is strong enough to withstand physiologic loads. The alar ligament, on the other hand, due to its lower strength and its axial direction of loading, might be prone to injury and therefore require stabilization of the appropriate vertebra more often than normally is assumed.
Synovial membrane and cartilage changes in experimental osteoarthrosis
Authors: Lukoschek M. , Schaffler M. B. , Burr D. B. , Boyd R. D. , Radin E. L.
Published: February 2005

The Hulth instability model was performed on 25 rabbit knee joints. Electron‐microscopic, light‐microscopic, and histomorphometric data demonstrated consistent chondrocyte alterations and cartilage destruction. The comparison between operated, sham, and control knees shows that surgical intervention without surgically induced instability is followed by changes in the synovial membrane and cartilage. The cartilage destruction is preceded by a synovial reaction, suggesting that the inflammatory response has an important role in the onset of cartilage damage in this model. The damage was more severe in the experimental knees, suggesting that mechanical instability is also a factor in cartilge destruction.
Loading‐related reorientation of bone proteoglycan in vivo. Strain memory in bone tissue?
Authors: Skerry T. M. , Bitensky L. , Chayen J. , Lanyon L. E.
Published: February 2005

The load‐carrying capacity of the skeleton is achieved and maintained as the result of a continued functional stimulus to the cell populations responsible for bone remodeling. Although some bone cells have been assumed to be influenced by the load‐induced changes in strain throughout the matrix, no evidence is available to indicate which cells are susceptible to such strain change or how such transient events provide a sustained influence on cell behaviour. In the present study, we showed that a short period of dynamic loading in vivo affects the orientation of proteoglycan within bone tissue. This reorientation declines only slowly, thus providing a persistent record of the tissue's recent strain history. Such a record has the ability not only to “capture” strain transients but also to “update” and “average” them. In this way, the bone cells could be presented with a sustained and coherent stimulus directly related to dynamic strain transients. These transients are the tissue's principal function variable.
Increased cAMP production after short‐term capacitively coupled stimulation in bovine growth plate chondrocytes
Authors: Brighton Carl T. , Townsend Peter F.
Published: February 2005

Growth plate chondrocytes from newborn calf costochondral junctions grown in monolayer were subjected to a capacitive AC signal of 500 V peak to peak (P‐P) at 60 kHz for 48 h and were analyzed for [3H]thymidine uptake. The stimulated chondrocytes showed a 130% greater uptake over unstimulated controls. Other newborn calf growth plate chondrocytes were stimulated at 500 V P‐P at 60 kHz for 2.5, 5.0, 10.0, and 20.0 min and were analyzed for cAMP. Chondrocytes stimulated for 2.5 and 5.0 min showed a 142.8% (p < 0.05) and 394.5% (p < 0.01) increase over controls, respectively. The chondrocytes stimulated for 10.0 and 20.0 min showed no significant difference from the controls. It is concluded that short‐term exposure of growth plate chondrocytes to an appropriate capacitively coupled field stimulates cAMP production, but longer‐term application of the electrical field is ineffective.
Calcium incorporation in cultured chondroblasts perturbed by an electromagnetic field
Authors: Norton Louis A. , Rovetti Leslie A.
Published: February 2005

We tested the hypothesis that electric perturbation influences 45Ca incorporation in extracellular matrix (ECM) of cartilage in vitro. Hypertrophic chondroblasts of tibial epiphyses (HC), sternum (SC), and skin fibroblasts (F) were cultured from chick embryos. HC, SC, and F cells were micromass seeded three times per week and maintained at 37.5°C with 5% CO2 for two weeks. Cultures were randomly designated control (C) or exposed (E) to a pulsed electromagnetic field (PEMF). A time course experiment of calcium incorporation for all cultured groups showed that 24 h of exposure produced the largest biological response in chondroblasts. Calcium incorporation required supplemental phosphate. Autoradiography data indicated that the calcium incorporation into macromolecules largely occurred in the ECM. 45Ca steady‐state perturbation was enhanced by Streptomyces hyaluronidase (SH) but not by testicular hyaluronidase (TH). 45Ca incorporation experiments tested the effects of phosphate, SH, TH, and PEMF alone and in various combinations on these cultures. Only PEMF or SH plus PEMF with phosphate enhanced 45Ca incorporation. Other experiments examined the effect of rotenone or freeze‐thawing on cells exposed to PEMF. PEMF plus freeze‐thaw enhanced calcium incorporation in HC only. PEMF appeared to cause disruption of the ECM, enhancing the probability of matrix calcification.