bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of lower extremity kinematics during level walking
Authors: Kadaba M. P. , Ramakrishnan H. K. , Wootten M. E. 
Published: February 2005

AbstractA simple external marker system and algorithms for computing lower extremity joint angle motion during level walking were developed and implemented on a computer‐aided video motion analysis system (VICON). The concept of embedded axes and Euler rotation angles was used to define the three‐dimensional joint angle motion based on a set of body surface markers. Gait analysis was peformed on 40 normal young adults three times on three different test days at least 1 Week apart using the marker system. Angular motion of the hip, knee, and ankle joints and of the pelvis were obtained throughout a gait cycle utilizing the three‐dimensional trajectories of markers. The effect of uncertainties in defining the embedded axis on joint angles was demonstrated using sensitivity analysis. The errors in the estimation of joint angle motion were quantified with respect to the degree of error in the construction of embedded axes. The limitations of the model and the marker system in evaluating pathologic gait are discussed. The relatively small number of body surface markers used in the system render it easy to implement for use in routine clinical gait evaluations. Additionally, data presented in this paper should be a useful reference for describing and comparing pathologic gait patterns.
The effects of contact pressure elevations and aseptic necrosis on the long‐term outcome of congenital hip dislocation
Authors: Hadley Nancy A. , Brown Thomas D. , Weinstein Stuart L. 
Published: February 2005

AbstractThe relationship between excessive articular contact pressure, aseptic necrosis, and the long‐term outcome with unilateral congenital dislocation of the hip (CDH) was studied in a series of 84 patients treated by closed reduction and followed for an average of 29.2 years. Contact stress was estimated from archived radiographs taken at the time of maturity and at several follow‐up visits. At a recent review, each patient was rated both clinically for pain and function and radiographically for deformity, degeneration, and aseptic necrosis. For each of 431 films, articular contact stress (force/area) was estimated mathematically, based upon a frontal plane equilibrium (force) analysis and a landmark‐based inference of three‐dimensional head surface (area). Good correlation with final deformity (Spearman ρ = 0.78) was obtained when the hips were ranked in terms of a new cumulative overpressure index P̂, defined as a time‐pressure product involving years of pressure exposure beyond a 2 MPa pressure damage level. An unsatisfactory outcome occurred in 90.4% of the hips experiencing P̂ > 10 MPa‐years (most of which had aseptic necrosis involvement), whereas the outcome was satisfactory in 80.9% of hips with P̂ < 10 MPa‐years.
Anterior cruciate ligament replacements: A mechanical study of femoral attachment location, flexion angle at tensioning, and initial tension
Authors: Bylski‐Austrow D. I. , Grood E. S. , Hefzy M. S. , Holden J. P. , Butler D. L. 
Published: February 2005

AbstractWe examined three surgical variables that affect the ability of an anteior cruciate ligament replacement to restore the limit of anterior tibial translation. These were the placement site of the substitute on the femur, the initial tension applied to the replacement, and the flexion angle of the knee at the time of tensioning. An anterior load of 100 N was applied to the tibia. As the knee was flexed, we measured the tensile force in the substitute and the anteroposterior position of the femur relative to the tibia. Placement largely determined whether the force in the replacement increased or decreased with flexion. Placement also largely determined whether the tibia moved anteriorly or posteriorly with flexion compared to its position in the intact knee. The initial tension and the flexion angle at tensioning affected the magnitude of force in the substitute and the magnitude of the change in AP position. They did not affect how force and AP position changed with flexion. Greater increases in force and greater posterior shifts in tibial position were produced by changing the flexion angle at tensioning from 0° to 30° than by increasing the initial tension from 22 to 44 N.
Young's modulus, bending strength, and tissue physical properties of human compact bone
Authors: Keller T. S. , Mao Z. , Spengler D. M. 
Published: February 2005

AbstractThe Young's modulus, bending strength, apparent density, and ash content of 155 human compact bone bending specimens were determined. Both Young's modulus (E) and bending strength (S) were strongly correlated to tissue dry apparent density (ρa). Based upon the correlation coefficient (R) and the percent deviation of the data from the regression curve (% dev.), these correlations were best described by power law relationships: E∞ ρa1.54 (R2 = 0.79, % dev. = 2.4) and S∞ ρa2.18 (R2 = 0.80, % dev. = 6.4). Bending strength was related to Young's modulus raised to the 1.26 power, implying a nonlinear relationship for these variables. We found a weak correlation between ash content and the mechanical behavior of the compact bone specimens, particularly Young's modulus, but could not statistically justify formulation of a more complex multivariate power model incorporating both density and ash content. Regional variations in strength and stiffness along the femoral shaft and within the cortex were also noted and were attributed primarily to differences in apparent density. The relationships formulated for the mechanical behavior of human compact bone are discussed in terms of the results of previous investigations of the mechanical behavior of nonhuman compact bone and human cancellous bone.
Effects of calcium channel‐blocking agents on platelet–osteogenic sarcoma interaction: Platelet aggregation and electron microscopic findings
Authors: Mehta Paulette , Kimura Arthur , Lawson Daniel 
Published: February 2005

AbstractA variety of tumors stimulate platelet activation. Because platelet activation may, in part, require calcium channel mobilization, we evaluated whether calcium channel blocking agents inhibit osteogenic sarcoma induced platelet aggregation. Platelet rich plasma (PRP) from normal subjects was incubated with one of four calcium channel‐blocking agents: nifedipine, diltiazem, verapamil, or amlodopine, all 0–25 μg/ml, or diluent. Osteogenic sarcoma cells (2 or 4 × 106/ml) were then added. Platelet aggregation was monitored by light transmission through PRP, and residual PRP was processed for electron microscopy. MG63 cells caused aggregation of PRP in most subjects (mean, 36+ 3%). Calcium channel‐blocking agents (nifedipine > diltiazem > amlodopine > verapamil) caused partial inhibition of osteogenic sarcoma‐induced platelet aggregation, at high concentrations only. Electron microscopy showed platelets aggregating to each other and to tumor cell membranes within 1–5 minutes. Changes in pattern of platelet clumping around tumor cells occurred when PRP was incubated with high concentration of diltiazem (50 μg). This study shows that calcium channel‐blocking agents inhibit osteogenic sarcoma‐induced platelet aggregation when used in high doses.
An approach for time‐dependent bone modeling and remodeling—application: A preliminary remodeling simulation
Authors: Beaupré G. S. , Orr T. E. , Carter D. R. 
Published: February 2005

AbstractIn a companion paper, we presented a time‐dependent theory for bone modeling and remodeling in response to a daily loading history. This paper represents a preliminary attempt to use the theory to determine the distribution of bone density within the adult proximal femur under an assumed normal loading history. Subsequent functional adaptation of the internal structure due to changes in the loading history are then determined. Throughout this preliminary study, the external geometry of the proximal femur is considered to be fixed, i.e., changes in the external shape are neither stimulated nor allowed. Linear and trilinear (dead‐zone nonlinearity) rate remodeling laws were compared. Computer emulations using two‐dimensional finite element models were successful in creating a normal‐appearing distribution of bone tissue when remodeling was initiated from a solid structure of homogeneous bone density. Subsequent reduction in the loading history caused regional bone atrophy. Reinstatement of the normal loading history caused a generalized increase in bone mass but resulted in a slightly different bone distribution than was calculated for a constant loading history. These results demonstrate the utility of the remodeling theory and are consistent with the hypothesis that similar stress‐related phenomena are responsible for both normal morphogenesis and functional adaptiation in response to changes in the bone loading.
An in vitro mechanical and histological study of acute stretching on rabbit tibial nerve
Authors: Rydevik Björn L. , Kwan Michael K. , Myers Robert R. , Brown Richard A. , Triggs Kevin J. , Woo Savio L‐Y. , Garfin Steven R. 
Published: February 2005

AbstractPeripheral nerves are often mechanically stretched in association with trauma to extremities, resulting in varying degrees of impairment of nerve function. However, little is known about the biomechanical properties of peripheral nerves and limits of stretching that the nerve may undergo before structural changes occur. Also, the injury pattern of nerves under stretching is poorly understood. In the present study, fresh rabbit tibial nerves (n = 18) were harvested. Nine nerves were stretched to failure in an INSTRON materials testing machine at a rate of 1 cm/min (strain rate of 0.5%/s). Loaddeformation and stress‐strain curves were determined. Histological examination by light microscopy of the stretched nerves as well as six normal control nerves and three clamped nonstretched control nerves was performed. The results show that the rabbit tibial nerves have an in situ strain of 11.0 + 1.5% and exhibit a nonlinear stress‐strain relationship. After 20% strain, the curve becomes linear up to failure. The ultimate strain and tensile strength of the nerves were 38.5 + 2.0% and 11.7 + 0.7 MPa, respectively. At failure, the load dropped suddenly, but the specimens remained grossly intact. Histological analysis of the stretched nerves showed multiple ruptures of perineurial sheaths when compared to controls.
Method for setting total graft force and load sharing in augmented ACL grafts
Authors: Lew William D. , Engebretsen Lars , Lewis Jack L. , Hunter Robert E. , Kowalczyk Curtis 
Published: February 2005

AbstractThe objective of this study was to develop a method for obtaining a controllable and reproducible immediate postoperative mechanical state in a knee with an anterior cruciate ligament (ACL) reconstruction. This method, called the force‐setting technique, was demonstrated using a composite graft consisting of the middle third of the patellar tendon with bone blocks (PT) and the ligament augmentation device (LAD). The total graft force was set to match the force in the intact ACL at 30° flexion with the knee under the same standardized external load, while at the same time the load sharing between the biologic and augmentation components was controlled. The total graft force was set to match the ACL force three separate times in each knee, with ratios of load sharing set at the following levels: 50% PT‐50% LAD, 25% PT‐75% LAD, and 75% PT‐25% LAD. ACL, PT, LAD, and collateral forces were measured using buckle transducers, and three‐dimensional knee motion was measured using an instrumented spatial linkage as 90 N anteriorly directed tibial loads were applied to eigth specimens at 0°, 30°, 60°, and 90° flexion with an intact ACL, an excised ACL, and the three load‐sharing reconstruction states. The total graft force could be consistently set to within an average of 2% of the intact ACL force at 30° flexion, and load sharing between the graft segments could be set to within an average of 5.1% of the desired ratio at 30°. The load sharing was maintained at the other flexion angles except 90° when the PT was to have carried 25 and 50% of the total graft force, and extension when the PT was to have carried 75% of the graft force. When averaged over all specimens and flexion angles, the total graft force was 15% greater than the force in the ACL, and this was not statistically significant.
Glucosaminidase, galactosaminidase, and glucuronidase in the growth plate
Authors: Gamble James G. , Haimson Robert , Smith R. Lane 
Published: February 2005

AbstractThe activities of glucosaminidase, galactosaminidase, and glucuronidase were determined in fractions of bovine growth plate cartilage. Glucosaminidase and galactosaminidase activities were lowest in the area corresponding to the reserve cartilage and increased from the upper to the lower portions of the hypertrophic zones of the growth plate, reaching a maximum in the calcifying cartilage. Glucuronidase activity showed a distinct spike of activity in the calcifying cartilage. The spatial distribution of these activities suggests a role in calcification and in the dissolution of the extracellular matrix at the chondro‐osseous junction of the growth plate.
A study of fracture callus material properties: Relationship to the torsional strength of bone
Authors: Markel Mark D. , Wikenheiser Mark A. , Chao Edmund Y. S. 
Published: February 2005

AbstractThis study was designed to quantitate the local material properties of fracture callus during gap healing and to relate these local properties to the torsional strength of bone in a canine model under external fixation. Bilateral tibial transverse osteotomies were performed in 32 dogs and stabilized using unilateral external skeletal fixators with a 2‐mm gap. Dogs were divided into four equal groups and euthanized at either 2, 4, 8, or 12 weeks. The torsional properties of one bone of each pair were determined. In both bones of each pair, the indentation stiffness, calcium content, and histomorphometric properties of six sites of periosteal callus, six sites of endosteal callus, four sites of cortical bone, and two sites of gap tissue were determined. Each of the four types of tissue had a specific structural or material property change during the study period. The indentation stiffness of periosteal callus increased up to 8 weeks and then plateaued. Endosteal callus stiffness peaked at 8 weeks and then decreased by 12 weeks. Gap tissue stiffness increased linearly over time. Cortical bone stiffness decreased over time. Indentation stiffness was significantly associated with the calcium content of periosteal callus (R2 = 0.50, p < 0.0001) and gap tissue (R2 = 0.66, p < 0.0001). The local stiffnesses of gap tissue and periosteal callus were significantly associated with the maximum torque (gap, R2 = 0.50, p < 0.0001; periosteal, R2 = 0.34, p < 0.05) and the torsional stiffness (gap, R2 = 0.44, p < 0.0001; periosteal, R2 = 0.65, p < 0.0001) of the bone. Changes in local material properties corresponded to histologic changes in new bone formation and porosity of the four tissues.
An animal model for the study of neuromuscular injury induced beneath and distal to a pneumatic tourniquet
Authors: Pedowitz Robert A. , Rydevik Bjorn L. , Gershuni David H. , Hargens Alan R. 
Published: February 2005

AbstractA well‐controlled animal model is presented for the study of neuromuscular injury induced by a pneumatic tourniquet. This model comprises a curved tourniquet surrounded by a stiff exterior shell, both of which were specifically designed to fit the conical and oblong shape of the rabbit hindlimb. Computed tomographic imaging was used to assess transverse tissue displacement induced by tourniquet compression. The curved tourniquet/shell configuration occluded the distal arterial blood flow to the extremity at a significantly lower cuff inflation pressure than a straight tourniquet of equal width. The magnitude and distribution of tissue pressures in the subcutaneous and deep tissues beneath the tourniquet were similar to those recorded in previous human cadaver studies of tourniquet compression. This animal model will facilitate the quantitation and analysis of tissue injury induced beneath and distal to a pneumatic tourniquet. Such data can help define the critical pressure and time limits for the safe use of pneumatic tourniquets in extremity surgery.
Rerouting peripheral nerves for spinal cord lesions
Authors: Romano Victor M. , Blair Sidney J. , Wurster Robert D. 
Published: February 2005

AbstractTo provide control of paralyzed limb muscles following spinal cord lesions, peripheral nerves containing motor axons from motoneurons located above a spinal cord lesion could potentially be rerouted to nerves containing motor axons located below the spinal cord lesion. To test this hypothesis in rats, the distal end of a cut tibial nerve, innervted by the L4–6 spinal level, was anastomosed or rerouted to the central end of the cut femoral nerve, innervated by the L3–4 spinal level. Appropriate controls were used. Recovery of lower hind limb motor function was followed at regular intervals, measuring the twitch tension of toe flexion (innervated by the tibial nerve) induced by transcutaneous stimulation of nerve rootlets exiting the spinal cord. After 4–6 months, 54% of motor function returned in the experimental group. Retrograde transport of horseradish peroxidase from the gastrocnemius muscles to spinal motoneuron cell bodies confirmed that the innervation of this group was at a higher level. Furthermore, after an L4 spinal transection, twitch tension responses to spinal cord outlet stimulation remained only in the experimental group. Therefore, a peripheral nerve containing motor axons from above the lesion was rerouted to a distal peripheral nerve to control muscles that would have otherwise been denervated.
Role of interfragmentary strain in fracture healing: Ovine model of a healing osteotomy
Authors: Cheal E. J. , Mansmann K. A. , Digioia A. M. , Hayes W. C. , Perren S. M. 
Published: February 2005

AbstractIt has been hypothesized that the histological pattern of fracture healing is controlled at least in part by the local mechanical strains in the interfragmentary region. To test this “interfragmentary strain hypothesis,” we applied cyclic bending deformations to tibial osteotomies in 11 sheep. An instrumented flexible plate spanning a 1‐mm osteotomy gap was deformed to create a gradient of tissue elongation from 10% under the plate to 100% at the opposite cortex. The cyclic deformations were applied three times per minute, 24 h per day, for 1–5 weeks. However, as a result of tissue differentiation, the bone‐plate complex increased in stiffness with healing time, resulting in a marked reduction of the gap deformation at approximately 4 weeks. Fracture healing was evaluated using vascular injection of India ink and conventional histology. A nonlinear three‐dimensional finite element model of the interfragmentary tissue at the initial stage of healing was used to predict the complex tissue strains. The ingrowth of vascularized soft tissue into the interfragmentary gap, as well as the subsequent differentiation of this tissue, occurred earlier and to a greater degree in regions of lower strain. In contrast, the proliferation of callus tissue was greatest at the periosteal and endosteal surfaces of the cortex opposite the plate. Direct comparison of the finite element predictions with the histology demonstrated that the spatial distribution of bone resorption at the fracture fragment ends directly corresponded to the locations of elevated tissue strain and stress. However, there was no consistent numerical relationship between the magnitude of these local peak strains and the corresponding volume of cortical bone resorption over the bone cross section.
Effect of circumferential bands on cortical vascularity and viability
Authors: Kirby Barbara M. , Wilson James W. 
Published: February 2005

AbstractWire cerclage devices do not restrict cortical vascularity; however, bands, because they are flat and wide, have been implicated as the cause of fracture nonunion by disruption of cortical vascularity. This experiment evaluated the effect of cerclage bands on the cortical vascularity of bones that had not been fractured. Stainless‐stell bands of four sizes (2.5, 5.0, 7.5, and 10.0 mm wide) and nylon bands of five sizes (2.5, 3.6, 4.8, 7.6, and 9.0 mm wide) were applied 1 cm apart to both femoral diaphyses of four mature dogs. In two additional dogs, 18‐gauge cerclage wires were applied 5 mm apart on one femur and nylon bands were applied immediately adjacent to one another on the other femur to cover 3 cm of the length of each femoral diaphysis. These six dogs were euthanatized and perfused 7 days postoperatively and specimens were studied by microangiography and correlated histology. Two additional dogs were studied 4 and 15 weeks after application of nylon and metal bands. There was no evidence of complete cortical devascularization under any size or type of cerclage appliance at any time interval. Numerous examples of vessels traversing the cortex directly beneath all the cerclage appliances were observed. Cerclage devices, even when flat and wide, do not restrict cortical vascularity when applied to intact bones.
Hemiepiphyseal reconstruction using tissue donated from fetal limbs in a murine model
Authors: Wolohan Michael J. , Zaleske David J. 
Published: February 2005

AbstractEpiphyseal reconstruction in the immature skeleton could have great clinical significance. Hemiepiphyseal reconstruction was performed in a murine model by transplanting fetal tissue to surgically created defects in postnatal mice. Reconstruction is facilitated by the existence of inbred strains. While the reconstruction as performed here did not completely restore the growth characteristics of the epiphysis, the model represents a potentially fruitful interface between basic and clinical biology.
Radiographic assessment of longitudinal growth of the rabbit femoral physes
Authors: Thomsen Erik , Drummond Denis S. , Robertson William W. , Christofersen Mark R. 
Published: February 2005

AbstractUsing surgically implanted metal markers, serial radiographs of 17 immature femurs were evaluated for growth of the entire femur and of the distal femoral physis in rabbits 20 to 100 days of age. From these data the rate of longitudinal growth was plotted. The most rapid growth during the study period was from 20 to 40 days. Growth rates reached a plateau at 100 days of age. The increases in length for unit of time were compared for the entire femur and the distal physis. The distal physis was responsible for ∼65–70% of the femoral growth for the study period. As an internal control of reproducibility of measurement two means of determining distal femoral growth rates were compared. Their best fit curves proved to be almost identical. The model of evaluation of femoral growth is reproducible and can serve as a control against which variables in growth can be compared.
Large compressive preloads decrease lumbar motion segment flexibility
Authors: Janevic J. , Ashton‐Miller J. A. , Schultz A. B. 
Published: February 2005

AbstractThe bending, shear, and torsion flexibilities of 13 intact adult lumbar motion segments (from 11 men, two women, 48–83 years of age) were compared under three different compressive preloads, 0, 2,200, and 4,400 N. Test forces and moments up to 160 N and 16 Nm were applied at the center of the upper end plate of the intact disc. A compressive preload of 2,200 N resulted in a significant decrease in motion segment flexibilities in all seven test directions (p < 0.06) when compared with results obtained with no preload; the preload decreased flexibility 2.6, 4.5, and 6.1 times in bending, axial torsion, and shear, respectively. These results suggest that studies of internal trunk load‐sharing between active and passive tissues during strenuous tasks, which engender large spine compressive loads, should take these changes in spine passive resistance into consideration.