bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wound healing in the bone chamber 1. Neoosteogenesis during transition from the repair to the regenerative phase in the rabbit tibial cortex
Authors: Winet H. , Albrektsson T. 
Published: February 2005

AbstractThe optical bone chamber technique that includes intravital microscopy is described and is then applied to measuring primary wound healing neoostogenesis in rabbit tibia cortical bone during the period when fibrovascular tissue is being replaced by regenerating osteovascular tissue. The small population of rabbits sampled allowed only tentative conclusions. The quantitative measurements, a direct form of histomorphometry, are applied to determine the consistency of observations, with the hypothesis that healing into the bone chamber slit‐gap follows the pattern of primary bone regeneration established as “characteristic” by other studies. The results supported the hypothesis and showed that bony ingrowth started during the third postoperative‐week (W3) with a maximum linear growth rate of 85.5 μm/day for a bone front. Evidence for remodeling by W6 was also obtained. While the bone chamber environment for tissue ingrowth is artificial, it can generate quantitative data that may provide a statistically valid basis for modeling pathophysiologic processes associated with bone wound healing.
In vitro studies of fretting corrosion of orthopaedic materials
Authors: Brown Stanley A. , Hughes Paula J. , Merritt Katharine 
Published: February 2005

AbstractTwo models were used to study fretting corrosion of surgical alloys. In the first, the amount of load and motion between plates and screws was controlled, and corrosion rates of stainless steel and MP35N were determined by measurements of component weight loss and metal ion concentration in the test solutions. Stainless steel had the higher rate of fretting corrosion. The addition of 10% serum to saline resulted in a significant reduction of the corrosion rate of stainless steel and MP35N. The use of stainless steel screws in a mixed‐metal combination with MP35N and titanium plates showed minimal effects on the performance of the stainless steel screws but an increase in fretting corrosion of the MP35N plates. In the second model, plates were applied to glass fiber‐reinforced plastic tubes as bone analogues and subjected to cyclic axial loads. These results demonstrated a reduction in fretting corrosion rates associated with an increase in screw torque and a decrease in axial load. Corrosion rates were minimal with intact tubes simulating healed fractures and greatest with an oblique‐cut fracture simulation. These models have proven useful for the evaluation of fretting corrosion rates of different alloys and for evaluation of variables such as fracture stability.
A quantitative analysis of donor site morbidity after vascularized fibula transfer
Authors: Youdas James W. , Wood Michael B. , Cahalan Thomas D. , Chao Edmund Y. S. 
Published: February 2005

AbstractEleven patients with free vascularized fibula graft transplants to the upper extremity were studied for donor‐side morbidity effects. Based on their surgical follow‐up times, the patients were divided into either group 1 (5 ± 2 months) or group 2 (21 ± 8 months) to examine the effects of surgical trauma more closely. Gait evaluation was performed using two walkways containing different ground conditions. Knee and ankle‐foot motion was measured using a three‐dimensional electrogoniometer. Basic temporodistance factors and ground reactions were obtained from foot switches, instrumented floor mats, and a force plate. A modified Cybex II isokinetic dynamometer was used to quantitate ankle‐foot strengths. Moderate knee and ankle‐foot motion changes were seen while walking on the level, sideslope, and ramp in patients evaluated less than 10 months after their surgical procedure. Minimal joint motion effects were discovered in patients with follow‐up times longer than 10 months. Muscle strengths were significantly impaired in both groups, especially foot inversion and eversion. An inverse relationship existed between the length of resected fibula and ankle evertor muscle strength. Donor side morbidity does not appear to be caused by surgical soft‐tissue trauma exclusively. These patients need to be studied for several more years to determine the long‐term functional effects of free vascularized fibular graft transfer.
Biomechanics of fascia lata ligament replacements: Early postoperative changes in the goat
Authors: Holden John P. , Grood Edward S. , Butler David L. , Noyes Frank R. , Mendenhall H. Vincent , Van Kampen Craig L. , Neidich Robert L. 
Published: February 2005

AbstractMechanical properties of fascia lata autografts used to replace the anterior cruciate ligament (ACL) in the goat were measured at 0, 2, 4, and 8 weeks after surgery. The ACL was replaced in the right knee of 50 animals divided equally into two groups according to graft fixation technique: (a) two smooth staples at each end, with the tissue pulled back toward the joint over the first staple and (b) reinforced fixation with a spiked bushing placed through the tissue and a 3‐cm‐long flat polypropylene braid sutured to each end of the graft. Eleven unoperated contralateral knees were tested as controls. All statistically significant effects of the reinforced versus staple fixation were observed at 0 weeks, with the reinforced group showing less anteroposterior (AP) translation of the joint and greater maximum force and stiffness of the femurgraft‐tibia units. The reinforced group had increased AP translation and decreased strength and stiffness by 2 weeks after surgery. Increased AP translation resulted primarily from increases in the low‐stiffness region of the forcedisplacement curve (primary AP translation) and to a lesser extent from increased translation in the high‐stiffness region (secondary anterior translation). Failures at 0 weeks with the reinforced fixation occurred at the bushing or end of the reinforcing braid, while all but one of the later failures occurred in the tissue mid‐substance. In the staple group, maximum force was greater at 8 weeks than at 0 weeks, as the failure locations changed from the fixation to the tissue mid‐substance. The failure mechanisms and maximum force values in the reinforced fixation group suggest that the remodeling tissue weakened rapidly after surgery.
Quantitation of glycocalyx production in coagulase‐negative Staphylococcus
Authors: Tsai Ching‐Lin , Schurman David J. , Smith R. Lane 
Published: February 2005

AbstractThe purpose of this study was to develop sensitive and accurate methods of quantitating bacterial glycocalyx. Coagulase‐negative staphylococci were cultured in trypticase soy broth. Quantitation of slime production was evaluated using various methods of fixation and staining. The amount of dye associated with bacterial slime was assessed spectrophotometrically following solubilization of the dye‐biofilm complex by 0.2 M NaOH at 85°C for 1 h. Carnoy's solution was optimal for fixation of the slime, and toluidine blue staining was most reproducible. Fifteen strains of Staphylococcus epidermidis showed a gradation in biofilm production ranging from high, medium, to low that was strain stable. Irrespective of the technique used, high, medium, and low producers of bacterial slime remained in the same category and always showed significantly different optical density reading (p < 0.05). In our experiments, solubilization of a toluidine blue‐bacterial biofilm complex was a direct, simple, and efficient method for reproducibly quantitating glycocalyx. This method provides a useful means of rapid quantitation of biofilm production to assess its role in the infection process and in the response to antibiotic therapy.
A biomechanical assessment of plate fixation, with insufficient bony support
Authors: Beaupré Gary S. , Carter Dennis R. , Dueland Rudolph T. , Caler William E. , Spengler Dan M. 
Published: February 2005

AbstractThe use of an internal fixation plate in the presence of a bone defect was studied using a theoretical model of an idealized long bone having a circular cross section and loaded using a combination of axial and bending loads. The analysis showed that the “bending‐open” loading mode does not occur if, in the normal unplated bone, the line of action of the resultant axial load passes within the outer cortex at the location where the plate is to be applied. In this situation the fracture will deform in a “bending‐closed” mode regardless of whether the plate is attached to the tension or the compression side. If bony contact cannot be achieved, lower plate stress is always encountered when the plate is attached to the compression side instead of the tension side. In vivo verification of the model was addressed in a pilot experiment using instrumented metal plates applied bilaterally to the femora of one dog. Bilateral bone defects were created in the midfemoral canine diaphysis. On one leg the plate was applied to the lateral aspect (“tension” side), and on the other leg the plate was applied to the medial aspect (“compression” side). The plate attached to the lateral aspect deformed plastically in the bending‐closed mode. The contralateral plate that was attached to the medial aspect (compression side) of the femur did not show signs of plastic deformation. Furthermore, the plate strains were lower in the plate attached to the medial aspect than those in the plate attached to the lateral aspect. The results and analysis of this study suggest that when applying plates to diaphyseal fractures where bony stability cannot be achieved, it may be acceptable or even desirable to attach the plate to the compression side of the bone.
Water content and equilibrium water partition in immature cartilage
Authors: Torzilli Peter A. 
Published: February 2005

AbstractThe water content, equilibrium water partition, and total thickness for immature bovine articular cartilage were determined and compared to previously determined values for mature tissue. The bulk equilibrium water partition and thickness were significantly greater in immature tissue as compared to mature tissue, while the bulk water content was similar. Spatial differences were noted in each physical parameter.
Effects of polymethylmethacrylate exposure upon macrophages
Authors: Horowitz Stephen M. , Frondoza Carmelita G. , Lennox Dennis W. 
Published: February 2005

AbstractThe effects of polymethylmethacrylate (PMMA) exposure upon macrophage viability and function were studied in an attempt to determine what role these cells play in the loosening of cemented arthroplasties. P388D1 murine macrophage cell line was exposed to PMMA and polystyrene particles of similar size and concentration. DNA synthesis following exposure to PMMA or polystyrene was studied by [3H]thymidine incorporation. Macrophage function was studied by analyzing the ability of activated macrophages to kill mast cell targets following particle exposure. Our results demonstrate that exposure of macrophages to PMMA particles in vitro inhibits DNA synthesis and impairs their cytotoxic ability. Histologic examination revealed that macrophages phagocytose both PMMA and styrene particles, but the former eventually lyse these cells. Our studies suggest that the histologic appearance of macrophages and foreign body giant cells at the bone‐cement interface may be secondary to a repetitive cycle of PMMA particle phagocytosis and cell death, similar to that found in a foreign body granulomatous response.
Cellular events associated with the induction of bone by demineralized bone
Authors: Bernick Sol , Paule Wendelin , Ertl Delia , Nishimoto Satoru K. , Nimni Marcel E. 
Published: February 2005

AbstractImplantation of demineralized bone (DB) in the form of powder or intact segments in extra skeletal sites stimulates new bone formation. Urist and co‐workers presented substantial evidence that there is a noncollagenous protein that has the ability to induce bone formation. One aim of this study was to trace the process of bone formation when DB, in the form of perforated rectangular plates, is implanted subcutaneously in 2‐month‐old rats. A second objective was to determine whether cartilage cells play a role in the formation of bone in this model. Various DB plates with 0.25 mm diameter holes were implanted subcutaneously for 1–4 weeks in rats. One week after implantation, DB plates were covered by vascularized connective tissue that invaded the perforations. Aggregates of chondrocytes were observed within the holes and on periosteal surfaces in only a few specimens. Further cartilage proliferation was not observed, and by the 2nd week there was no evidence of endochondral bone formation. Where these cartilage‐like cells were present, a thin layer of mineral was deposited around them; resorption and fibrous tissue infiltration followed. This aborted form of endochondral calcification was not followed spatially by bone formation. Patent vascularized channels were invaded by alkaline phosphatase‐positive mononuclear cells and fibroblasts, and became enlarged by the enzymatic action of macrophages. The next step involved the calcification of DB plates adjacent to the wide spaces. Osteoclasts now appeared leading to the resorption of this recalcified matrix. The eroded and now enlarged lacunar surfaces were lined by newly formed bone and osteoblasts. This process continued so that, at the end of 4 weeks following implantation, the original DB plates were replaced by trabecular bone. Biochemical data on calcium and alkaline phosphatase levels in the implants paralleled the morphological observations.
Growth hormone stimulates insulin‐like growth factor I actions on adult articular chondrocytes
Authors: Smith R. Lane , Palathumpat Marykutty V. , Ku Christine W. , Hintz Raymond L. 
Published: February 2005

AbstractWe report effects of adding insulin‐like growth factor I (IGF‐I) and methionyl human growth hormone (GH), alone or in combination, to adult bovine articular chondrocytes plated at high density. Purified human and synthetic IGF‐I stimulated chondrocyte DNA and proteoglycan synthesis. GH had no effect on either process. However, GH added in combination with IGF‐I increased proteoglycan, cell‐associated proteoglycan, and keratan sulfate synthesis over levels observed with IGF‐I alone. IGF‐I and GH did not alter the hydrodynamic size of proteoglycans or synthesis of collagen. Our results show that GH and IGF‐I act together to stimulate adult chondrocyte extracellular matrix synthesis.
An ultrastructural study of slipped capital femoral epiphysis: Pathogenetic considerations
Authors: Ippolito E. , Bellocci M. , Farsetti P. , Tudisco C. , Perugia D. 
Published: February 2005

AbstractTwo normal proximal femoral growth plates and core biopsies from six patients with slipped capital femoral epiphysis (SCFE) were studied by electron microscopy. In these SCFE patients, chondrocytes from all the zones of the plate were frequently smaller than normal, more irregular in shape, and many of them were degenerating, with formation of matrix vesicles and cellular debris. Floccular electron‐dense material, most likely abnormal proteoglycan, was present in the hypertrophic rough‐surfaced endoplasmic reticulum and Golgi apparatus as well as in the extracellular matrix, intermingled with collagen fibrils thinner than normal and lossely arranged. Mineralization of the abnormal matrix of the longitudinal septa of the degenerating zone was either scanty or absent, with scanty formation of irregular and thin bone trabeculae. The‐abnormalities observed in SCFE seem to be caused by a change in chondrocyte metabolism with consequent altered synthesis and/or extracellular aggregation of both collagen and proteoglycan, and scanty mineralization of the abnormal cartilage matrix.
Altered structural and functional properties of myosins, from platelets of idiopathic scoliosis patients
Authors: Peleg Itzhak , Eldor Amiram , Kahane Itzhak , Muhlrad Andras , Liebergall Meir , Floman Yizhar 
Published: February 2005

AbstractPlatelets of patients with idiopathic scoliosis (IS) have been shown to have decreased capacity to aggregate and secrete in response to certain agonists. Similarities between the contractile protein system of platelets and muscle have made the platelets a popular model for muscle disease. We attempted to characterize the function and structure of myosin in platelets of IS patients. Blood was obtained from seven IS patients and seven matched nonscoliotic healthy controls. The mean Cobb angle measurement of the IS patients was 35.4° with a mean Risser sign of 2.2. Washed platelets were isolated from the blood, and the contractile proteins from the membrane and the cytosol compartments were isolated and analyzed by two‐dimensional peptide mapping. As previously reported (J Biol Chem 258:9290, 1983), peptide maps of normal platelets revealed that the heavy chain of myosin located in the platelet membrane lacks one major spot relative to the cytoplasmic myosin. In IS patients the cytoplasmic myosin lacks the same peptide that is missing in the membrane myosin of normal individuals. In addition, the ATPase specific activity of the cytoplasmic myosin from IS platelets was significantly lower compared with the activity of the cytoplasmic myosin from normal platelets. These results suggest the presence of a fundamental abnormality of IS platelet contractile proteins.
The influence of chair height on lower limb mechanics during rising
Authors: Rodosky Mark W. , Andriacchi Thomas P. , Andersson Gunnar B. J. 
Published: February 2005

AbstractThe mechanics of the lower limb were analyzed in young, adult normal subjects when rising from a seated position. Limb mechanics were described in terms of flexion–extension motion and moments at the hip, knee and ankle while rising from four seat heights corresponding to 65, 80, 100, and 115% of the subject's knee joint height. The results indicate that the maximum moment tending to flex the hip joint was higher than that occurring at the knee or ankle. The magnitude of the maximum flexion moment at the hip was not substantially influenced by chair height, changing by < 12% between the highest and lowest chair heights. Conversely, the maximum knee flexion moments were found to be highly dependent on chair height and nearly doubled from the highest to the lowest position. The magnitude of the moments at the ankle did not change with chair height and were significantly lower than the magnitude of the moments found during normal walking. The magnitude of motion and moments at the hip were greater during chair‐rising than during stair‐climbing or walking. The range of motion required at the knee for the lower chair heights was also greater than was reported during stair‐climbing studies. Thus, the combination of moments in joint angles during chair‐rising are unique among common activities of daily living and should be considered in chair selection as well as in the guidelines for prosthetic devices.
Biochemical changes in articular cartilage after joint immobilization by casting or external fixation
Authors: Behrens Fred , Kraft Ellen L. , Oegema Theodore R. 
Published: February 2005

AbstractKnees of mature dogs were immobilized for 6 weeks by long‐leg casts allowing 8°–15° of motion, a model studied by others, or with external fixators, a new, more severe model that kept the joints rigid. Some animals were allowed to recover for 1 week after the immobilization period. Articular cartilage was examined histologically and biochemically. After 6 weeks of immobilization, water increased 7% in both casted and fixator‐immobilized joints compared with normal knee cartilage, while hexuronic acid was 23 and 28% lower, respectively. The limited motion permitted by the casts resulted in a smaller depression of proteoglycan synthesis and less proteoglycan loss during immobilization than occurred in the rigid external fixator group. The protective effect of limited motion was shown clearly during the recovery period: as measured by hexuronic acid content. cartilage from the casted joints had almost recovered within 1 week, whereas the external fixator group experienced little or no recovery during the week after treatment. In contrast to previous studies by others with casted joints, both newly synthesized [35S]sulfate‐labeled and accumulated unlabeled proteoglycans from both casted and fixator‐immobilized cartilages were able to form complexes with exogenous hyaluronic acid to the same extent as those from control cartilage. Thus, in immobilized cartilage, failure of the newly synthesized proteoglycan to bind to hyaluronate is not a mechanism of accelerated proteoglycan loss. The accelerated proteoglycan turnover appears to be caused by a combination of decreased synthesis and increased proteolysis of the secreted proteoglycans. Clinically external fixators used to immobilize joint injuries should be applied for the shortest time possible and if possible should be mechanically modified to allow up to 10° of joint motion.
Neuropathology with spinal instrumentation
Authors: Coe Jeffrey D. , Becker P. Scott , McAfee Paul C. , Gurr Kevin R. 
Published: February 2005

AbstractNeurohistologic examination of the spinal cord and cauda equina were compared for 28 beagles undergoing anterior and posterior spinal destabilization procedures—Group I (n = 7), destabilized operative controls; Group II (n = 7), posterolateral bone grafting; Group III (n = 7), Harrington distraction instrumentation and posterolateral fusion; and Group IV (n = 7), Luque rectangular instrumentation and posterolateral fusion. All dogs had appeared neurologically intact upon repeated examinations prior to death. Neurohistological abnormalities (Wallerian degeneration of the dorsal columns, corticospinal tracts, and nerve roots, focal cystic degeneration, and intraspinal central cavitation) occurred in only 1 of the 14 animals (7%) in Groups I and II (noninstrumented) and in 9 of the 14 animals (64%) in Groups III and IV (instrumented). This result is statistically significant (p < 0.001). Transient sensory disturbances and radicular paresthesias have been described in clinical reports of spinal instrumentation. It is probable that subclinical neurologic injuries, such as intraspinal and nerve root infarction in posterior neural tissue, can occur with the use of sublaminar hooks or wires. The chondrodystrophic beagle spinal model in this study should be considered a “worst case situation,” and the clinical incidence of neurohistologic changes is expected to be lower.
Recovery of the dog quadriceps after 10 weeks of immobilization followed by 4 weeks of remobilization
Authors: Lieber Richard L. , McKee‐Woodburn Thalia , Gershuni David H. 
Published: February 2005

AbstractSkeletal muscle fiber areas were measured in three heads of the dog quadriceps after 10 weeks of immobilization followed by 4 weeks of remobilization. Two‐way analysis of variance demonstrated a significant decrease in both type 1 (p < 0.005) and type 2 (p < 0.001) fiber area. However, there was no significant difference among the three heads of the quadriceps (p > 0.2). Although muscle fiber areas had not returned to control levels following remobilization, the area fraction of perimysial and epimysial connective tissue was not significantly different from control values (p > 0.15). These data suggest that although the degree of muscle atrophy following 10 weeks of immobilization is severe and muscle specific, following 4 weeks of remobilization, muscles uniformly recover to about 70% of control values.