bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanical properties of the anterior cruciate ligament chronically relaxed by elevation of the tibial insertion
Authors: Keira Motoharu , Yasuda Kazunori , Kaneda Kiyoshi , Yamamoto Noritaka , Hayashi Kozaburo 
Published: February 2005

AbstractThe effects of stress deprivation on the mechanical properties of the anterior cruciate ligament were studied in a canine model. Fifty‐eight mature mongrel dogs were divided into two groups. In the relaxed group (n = 30), the tibial insertion of the anterior cruciate ligament in each right knee was surgically elevated proximally 3 mm from the tibia: the elevation was anatomically reduced in the sham group (n = 28). In order to obtain control data, the left knee in each dog was left untreated. A femur‐anterior cruciate ligament‐tibia complex was excised from each knee for biomechanical tests at 6 or 12 weeks after surgery. To simplify data analysis, the treat/nontreat ratio (the ratio of the data obtained from the treated knee to that from the nontreated knee) was used. The cross‐sectional area of the ligament increased significantly in both groups; the area in the relaxed group (average treat/nontreat ratio = 1.37) was significantly larger than that in the sham group (1.16) at 6 weeks but not at 12 weeks. The treat/nontreat ratio of tensile strength in the relaxed group significantly decreased to 0.67 and 0.58 at 6 and 12 weeks, respectively: in the sham group, it significantly decreased to 0.79 at 6 weeks but subsequently increased to 0.87 at 12 weeks. Only at 12 weeks was a significant difference observed between the two groups. This study demonstrated that, in the anterior cruciate ligament, stress deprivation results in a rapid increase in the cross‐sectional area, although this effect disappears by 12 weeks, and in a decrease in mechanical strength, although a relatively long period of more than 6 weeks is required for the deterioration.
Nerve regeneration during patellar tendon autograft remodelling after anterior cruciate ligament reconstruction: An experimental and clinical study
Authors: Aune Arne Kristian , Hukkanen Mika , Madsen Jan Erik , Polak Julia M. , Nordsletten Lars 
Published: February 2005

AbstractThe innervation of the rat and human anterior cruciate ligament, patellar tendon, and patellar tendon autograft after reconstruction of the anterior cruciate ligament was investigated by immunohistochemical and histological methods. A rat model of reconstruction with patellar tendon autograft was evaluated during active graft remodelling (2–16 weeks) and compared with normal ligament and tendon. The knees of 10 patients who had undergone reconstruction with patellar tendon autograft were examined 5–37 months postoperatively (remodelling fully completed) with arthroscopy and biopsy. As a control, biopsies from normal ligament and tendon were obtained from four patients. Nerve fibers were identified using antisera for protein gene product 9.5, a general neural marker. Neuronal regeneration was assessed by the expression of growth‐associated protein 43/B‐50. The sensory type of innervation was characterized by assessing the distribution of nerves containing the sensory neuropeptides calcitonin gene related peptide and substance P. Immunoreactivity for all neural markers was found in both rat and human anterior cruciate ligament and patellar tendon. Two weeks after reconstruction, the rat autograft was acellular and no innervation could be identified. After 4 weeks, the grafts were viable, and immunoreactivity for protein gene product 9.5, growth associated protein 43/B‐50, and calcitonin gene‐related peptide was found until the 16th week postoperatively. Immunoreactivity for substance P was found in rat autografts at 4 weeks postoperatively only. All biopsies of human patellar tendon autograft showed signs of the remodelling process being fully completed, with revascularization and a sinusoidal collagen pattern with fibroblast repopulation. Neuropeptide immunoreactivity, however, was not found. The presence of immunoreactivity to sensory neuropeptides in the anterior cruciate ligament and patellar tendon may indicate a nociceptive and neuromodulatory function of these structures. The expression of sensory neuropeptides in the rat patellar tendon autograft suggests a possible involvement of sensory innervation during healing of the graft.
Intraoperative force‐setting did not improve the mechanical properties of an augmented bone‐tendon‐bone anterior cruciate ligament graft in a goat model
Authors: Smith Joel J. , Lewis Jack L. , Mente Peter L. , Lindquist Conrad M. , Poff Bradley C. , Lew William D. 
Published: February 2005

AbstractIt has been hypothesized that load affects the mechanical properties of an anterior cruciate ligament graft while it remodels. The goal of this study was to use an existing goat model to evaluate the effect of intraoperative set force on the postoperative mechanical properties of an autograft that had been augmented with a synthetic segment. The following questions were addressed. Do augmented autografts set with a high force intraoperatively have improved structural and material graft properties and lower anterior‐posterior knee laxity at 3 months after surgery, compared with autografts set with a low intraoperative force? How do the structural and material properties of these implanted autografts compare with the mechanical properties of an intact anterior cruciate ligament or an unimplanted control autograft? The anterior cruciate ligament was reconstructed in seven goats with use of a composite graft consisting of a bone‐patellar tendon‐bone autograft and a synthetic augmentation device. A force‐setting technique was used intraoperatively to establish the load‐sharing between the autograft and augmentation segments such that the autograft carried either a high (16.5 N in four animals) or low (1.5 N in three animals) level of force, while the total force in the composite graft remained constant. Tensile testing was performed at 3 months after surgery to determine the material and structural properties of the autograft, the intact anterior cruciate ligament from the normal contralateral knee, and a control bone‐patellar tendon‐bone graft of similar size that was harvested from the contralateral knee at the time of necropsy and had never been implanted in the joint. The structural and material properties of the autografts initially set to high or low loads at surgery were not significantly different after 3 months of implantation. The strength and stiffness of the implanted tendons were an average of 24 and 20% of the strength and stiffness of the normal anterior cruciate ligament and 31 and 62% of the control tendons, respectively. Intraoperative set force in an augmented anterior cruciate ligament graft at the levels chosen in this study did not significantly affect weakening of the autograft at 3 months.
Assessment of donor cell and matrix survival in fresh articular cartilage allografts in a goat model
Authors: Jackson Douglas W. , Halbrecht Jeffery , Proctor Christopher , van Sickle David , Simon Timothy M. 
Published: February 2005

AbstractThe long‐term survival of allografts of articular cartilage has been proposed to be dependent on the survival of the cells that maintain the unique structural and material properties of the allograft. In this study, we assessed cell survival in 24 fresh articular cartilage allografts of the medial plateau in a Spanish‐goat model. A DNA‐probe technique was used to distinguish clearly between DNA from donor (allograft) and host cells. The intraarticular survival of viable allograft chondrocytes in the transplanted articular cartilage started to diminish as early as 3 weeks after transplantation; however, there was considerable variation in the amount of donor cell DNA detected in the allografts at 6 and 12 months following transplantation. This contrasts with our experience with fresh allografts of ligament, tendon, and meniscus, in which no donor DNA was detected 4 weeks after transplantation. DNA from host cells was present in all articular cartilage allografts, as evidenced by detectable unique host DNA patterns. Histological and histochemical assays showed that none of the transplants demonstrated normal structure and composition at 1 year after transplantation. The grafts in which large quantities of donor DNA were present appeared grossly superior to those with no or reduced remaining demonstrable donor DNA.
Effect of capacitive coupled electrical stimulation on regenerate bone
Authors: Pepper John R. , Herbert Morley A. , Anderson J. R. , Bobechko Walter P. 
Published: February 2005

AbstractAn in vivo study was carried out to determine if capacitive coupled electrical stimulation increased the rate of recovery of strength of regenerate bone produced as a result of lengthening by the Ilizarov technique. Thirty‐four adult male beagles underwent a right tibial mid‐diaphyseal corticotomy, followed by a 5‐day delay, and then 21 days of lengthening (1 mm/day). At the start of the post‐distraction period (day 27), stimulation (3–6.3 V peak to peak, 5–10 mA root‐mean‐square at 60 kHz) was applied for 28 days to one group. The nonstimulated group (n = 17) underwent a 28‐day period with no stimulation. From each group, four tibiae were prepared for histology; both ends of the remaining bones were embedded in polymethylmethacrylate and tested in torsion (internal rotation at 4.7°/sec) until failure. Statistically significant changes included a 37% lower maximum torque capacity and a 40% decrease in strain energy to failure in the stimulated group compared with the nonstimulated group. The findings are supported by measured trends to a lower modulus of rigidity (37% decrease) and a smaller percentage of active osteoid perimeter (20% decrease) for the stimulated group. The experimental data suggest that when this dose of capacitive coupled electrical stimulation is applied to the regenerating bone created during distraction osteogenesis, it delays the recovery of bone strength compared with an untreated control.
Basic fibroblast growth factor enhances bone‐graft incorporation: Dose and time dependence in rats
Authors: Wang Jian‐Sheng , Aspenberg Per 
Published: February 2005

AbstractIn a previous study, we found that basic fibroblast growth factor could stimulate bone‐graft incorporation. In the present study, the effects of different doses and implantation times were further studied, using the bone conduction chamber, in rats. Inside the chamber, the graft is isolated from the surrounding tissues except at one end, where small openings embedded in host bone allow ingrowth of tissue. The distance that new tissues had reached from the openings into the graft was measured on histological slides. Bone grafts were obtained from the proximal tibiae of donor rats, frozen at −70°C, and lipid‐extracted. Before implantation, they were soaked overnight in a hyaluronate gel with or without basic fibroblast growth factor and then were fitted into the chambers, which were implanted in the proximal tibiae of recipient rats. In a doseresponse experiment, grafts containing 0.3, 8, 40, 200, or 1,000 ng of basic fibroblast growth factor were compared with grafts treated with carrier gel only, after an implantation time of 6 weeks. Fibrous tissue always penetrated the grafts further than the ingrown bone; the distance that it reached from the ingrowth openings (total ingrowth distance) was increased by all of the doses except 0.3 ng per implant. The distance of bone ingrowth was increased by 8, 40, and 200 ng. The increased total ingrowth with 1,000 ng was due to an increased amount of fibrous tissue ahead of the bone, whereas with the lower doses the increase was due to more bone. Thus, the dose had an effect on the type of ingrown tissue found in the graft. In a time‐effect study, grafts treated with 40 ng of basic fibroblast growth factor had a higher uptake of [99mTc]MDP at 2 and 4 weeks and an increased bone ingrowth distance at 10 weeks. The radioactivity from [125I]basic fibroblast growth factor declined with a half‐life of 17 hours. The results suggest that basic fibroblast growth factor may be beneficial for the incorporation of contained bone grafts; studies using more clinically relevant models are required.
Differential effects of insulin‐like growth factor‐I on matrix and DNA synthesis in various regions and types of rabbit tendons
Authors: Abrahamsson Sven‐Olof , Lohmander Stefan 
Published: February 2005

AbstractTendon healing and integration of tendon grafts may be site or donor specific. To determine if differences exist in sensitivity to growth factors that have the potential to influence tendon repair, we compared the effects of recombinant human insulin‐like growth factor‐I on various types of tendon segments. The dose response effects on proteoglycan, collagen, noncollagen protein, and DNA synthesis were investigated in short‐term explant cultures of intrasynovial intermediate and proximal segments of deep flexor tendons, extrasynovial segments of deep flexor tendons, and Achilles tendons of rabbits. The four different types of tendon segments cultured in media without recombinant human insulin‐like growth factor‐I synthesized similar amounts of each of the matrix components. Intrasynovial proximal segments synthesized 15 times less DNA than other tendon segments. Recombinant human insulin‐like growth factor‐I stimulated matrix and DNA synthesis of all tendon segments in a dose‐dependent manner in intervals from 10 to 1,000 ng/ml. The potency (LogED50) of the stimulation did not differ between the segments. The estimated maximal stimulation (Emax) of proteoglycan synthesis by recombinant human insulin‐like growth factor‐I was higher, and of collagen and noncollagen protein synthesis was lower, in intrasynovial proximal segments as compared with that of the other types of segments. In contrast, the estimated maximal stimulation of DNA synthesis by recombinant human insulin‐like growth factor‐I was 6‐fold higher than controls in all types of tendons. These findings demonstrate differences in mitotic capacity between anatomical regions of tendons during culture without recombinant human insulin‐like growth factor‐I and in matrix synthesis after stimulation with it.
Distribution of cellular repopulation and collagen synthesis in a canine anterior cruciate ligament autograft
Authors: Spindler Kurt P. , Andrish Jack T. , Miller Raymond R. , Tsujimoto Kazuo , Diz Debra I. 
Published: February 2005

AbstractWhether the central core of an anterior cruciate ligament autograft reconstruction is nutritionally compromised at a time when revascularization is known to be complete has not been determined by methods that detect matrix synthesis. In a canine model of anterior cruciate ligament reconstruction with patellar tendon autograft, the adequacy of the supply of metabolites for cellular matrix synthesis was determined by autoradiographic analysis. Total collagen synthesis and cellularity were also quantified. Total collagen synthesis was found to be significantly elevated (p = 0.014 by analysis of variance) in the ligament reconstructions as compared with normal anterior cruciate ligaments or patellar tendons, but cellularity was not (p = 0.13 by analysis of variance). Autoradiography demonstrated even distribution of [3H]proline incorporation throughout the graft and normal tissue. When revascularization was complete, there was an adequate supply of metabolites for cellular synthesis of protein macromolecules within all regions of the ligament reconstruction. At 3 months after reconstruction, the grafts were found to be actively remodeling their collagen matrix. Since the long‐term function of an anterior cruciate ligament autograft is dependent on viable fibroblasts to maintain the collagen matrix, the canine anterior cruciate ligament reconstruction contains living cells that are able to remodel the matrix under appropriate conditions.
Swelling and fibronectin accumulation in articular cartilage explants after cyclical impact
Authors: Farquhar T. , Xia Y. , Mann K. , Bertram J. , Burton‐Wurster N. , Jelinski L. , Lust G. 
Published: February 2005

AbstractThe objective of this study was to determine if repeated impact could damage living cartilage and lead to osteoarthritis‐like changes in its biology. Canine cartilage explants were subjected to impacts of as much as 50 MPa once every 5 seconds for 30 minutes. On each impact cycle, the loading rate was 100 MPa/sec to the assigned peak stress, which was held for 1 second. After impact testing, the cartilage was kept in defined culture for as long as 10 days. Radiosulfate incorporation in the region that received direct impact varied with load 0–4 hours after impact, but it did not vary with load at 20–24 hours after impact. Even so, most explants were visibly damaged by 20 or 50 MPa, and there was subtle evidence of damage from impacts of 5 or 10 MPa. For example, ion‐induced swelling in 0.01MNaCl was increased, suggesting that the physical integrity of the matrix was reduced relative to controls. Self‐diffusion of water, measured by proton magnetic resonance imaging, was also increased in the deeper zones of the explant, consistent with changes in structure at the molecular level. Ten days after impact, the water content and the fibronectin content of the loaded region of the explant were both increased. In combination, these osteoarthritis‐like changes suggested that the physical strength of normal cartilage limits its ability to withstand cyclical impact.
Influence of biomaterial surface texture on bone ingrowth in the rabbit femur
Authors: Friedman Richard J. , An Yuehuei H. , Ming Jing , Draughn Robert A. , Bauer Thomas W. 
Published: February 2005

AbstractThe purpose of this study was to examine both the histologic and the mechanical characteristics of bone apposition to an experimental surface, arc‐deposited titanium, in a rabbit model and to compare them with those of four previously studied surfaces: one layer of cobalt‐chromium beads, three layers of cobalt‐chromium beads, plasma‐sprayed cobalt‐chromium, and uncoated titanium alloy. Bilateral cylindrical implants were press‐fit into the lateral femoral condyles of 70 adult New Zealand White rabbits, which were allowed unrestricted activity and then killed at 6 or 12 weeks. The distal femora were harvested, radiographed, and prepared for either mechanical or histologic evaluation. All of the implants with coated surfaces had significantly greater shear strength than the implants of grit‐blasted titanium alloy after both 6 and 12 weeks. After 6 weeks, maximum bone apposition occurred in the beaded surfaces. After 12 weeks, the shear strengths and bone apposition of implants of arc‐deposited titanium and of one and three layers of cobalt‐chromium beads were significantly greater than those of implants of plasma‐sprayed cobalt‐chromium and grit‐blasted titanium alloy. The histologic studies correlated with the mechanical results. After 12 weeks, the bone apposition and mechanical stability of arc‐deposited titanium were similar to those of a single layer of beads. There appeared to be no advantage to multiple layers of beads, and the plasma‐sprayed cobalt‐chromium and gritblasted titanium surfaces showed lower shear strength and bone apposition than the other groups.
Bone formation and bone resorption in failed total joint arthroplasties: Histomorphometric analysis with histochemical and immunohistochemical technique
Authors: Kadoya Y. , Revell P. A. , Al‐Saffar N. , Kobayashi A. , Scott G. , Freeman M. A. R. 
Published: February 2005

AbstractTo elucidate the reactions of bone around aseptically loosened total joint arthroplasties, 24 interface tissues with adjacent bone were obtained in 17 revision operations (11 hips and six knees). The morphology of the bone surface next to the interface membrane was investigated with histochemical and immunohistochemical techniques and then histomorphometrically analysed. One‐third of the total bone surface, 32.69 ± 5.16% (mean ± SE) (n = 24), showed positive alkaline phosphatase activity. The bone surface in contact with the cells positive for CD11b (a macrophage marker) amounted to 19.33 ± 5.16% (n = 24). The proportion of the osteoclastic bone resorption estimated by vitronectin receptor expression was 7.67 ± 1.82% (n = 21). Tissues retrieved from the sites where radiographic evidence of osteolysis was present (n = 12) had a significantly larger extent of the bone surface in contact with CD11b‐positive cells than did the tissues from areas without osteolysis (n = 12, p = 0.0067, Mann‐Whitney U test), whereas no significant difference was observed in the extent of osteoclastic bone resorption. These data demonstrate that active bone formation, regarded as a repair process, is the most common feature even in revised cases. They also highlight the role played by macrophages, not as cells producing inflammatory mediators that could activate osteoclasts, but as cells primarily responsible for the bone loss in osteolytic lesions.
Curved beam model of the proximal femur for estimating stress using dual‐energy x‐ray absorptiometry derived structural geometry
Authors: Mourtada Firas A. , Beck Thomas J. , Hauser Diana L. , Ruff Christopher B. , Bao Gang 
Published: February 2005

AbstractThe investigation of individual differences in hip strength requires a method to measure structural geometry in vivo and a valid analytical approach to calculate mechanical stress. We developed a method for deriving structural geometry of the femur from the proximal shaft through the femoral neck, using data from dual energy x‐ray absorptiometry. The geometric properties are employed in a two‐dimensional curved beam model of the proximal femur to estimate stresses on the lateral and medial bone surfaces. Stresses calculated by this method are compared with those from the conventional flexure formula and with results produced from a cadaver femur with use of three‐dimensional finite element analysis of computed tomography data. Loading conditions simulating a one‐legged stance and a fall on the greater trochanter are employed. Stresses calculated by curved beam theory are in much better agreement with three‐dimensional finite element analysis than are those for which the conventional straight beam formula was used. In simulation of a fall on the greater trochanter, all three methods show peaks of stress at the femoral neck but only the curved beam and finite element analysis methods show an additional peak at the medial intertrochanteric margin. Both neck and trochanter regions correspond to common failure sites for hip fractures in the elderly. The curved beam treatment of hip structure derived from dual‐energy x‐ray absorptiometry provides an approach for the in vivo engineering analysis of hip structure that is not practical by other methods.