bluuebunny/crossref_metadata_2025_split huggingface dataset:
Determination of bone mineral density by dual X‐ray absorptiometry in patients with uncemented total hip arthroplasty
Authors: Kiratli B. Jenny , Heiner John P. , McBeath Andrew A. , Wilson Michael A. 
Published: February 2005

AbstractBone remodeling is an expected sequela with total hip arthroplasty (THA). Although there are several methods of estimating bone response in THA patients from radiographs, there are no accurate and generally accepted methods for quantitative determinations in vivo. In this study, we describe an application of dual x‐ray absorptiometry (DXA) for measuring bone mineral content and bone mineral density in the proximal femur following THA. DXA is a noninvasive technique with minimal radiation exposure (<5 mrem). Various aspects of measurement error (accuracy and reliability) of this application of DXA were determined in a series of studies reported here. Accuracy error (how similar are the measured and actual values) was <1% determined in bone phantoms of four densities. Precision error (how reproducible are the measurements) was also <1% at all four densities in the phantoms and was only slightly elevated (0.9‐1.5%) in repeated measurements of implanted cadaver femora. Precision error in vivo, determined both from multiple replicates on five patients and from duplicate scans on 30 patients, was further elevated but remained <5%. Contributions to precision error, rotation of the leg, and interoperator variability were assessed; none was found to elevate precision error appreciably. We suggest that DXA is a feasible method for quantifying bone response following THA, and will allow discrimination of small changes (>5%) not previously measurable.
Effects of material properties of femoral hip components on bone remodeling
Authors: Weinans Harrie , Huiskes Rik , Grootenboer Henk J. 
Published: February 2005

AbstractBone loss around femoral hip stems is one of the problems threatening the long‐term fixation of uncemented stems. Many believe that this phenomenon is caused by reduced stresses in the bone (stress shielding). In the present study the mechanical consequences of different femoral stem materials were investigated using adaptive bone remodeling theory in combination with the finite element method. Bone‐remodeling in the femur around the implant and interface stresses between bone and implant were investigated for fully bonded femoral stems. Cemented stems (cobalt‐chrome or titanium alloy) caused less bone resorption and lower interface stresses than uncemented stems made from the same materials. The range of the bone resorption predicted in the simulation models was from 23% in the proximal medial cortex surrounding the cemented titanium alloy stem to 76% in the proximal medial cortex around the uncemented cobalt‐chrome stem. Very little bone resorption was predicted around a flexible, uncemented “iso‐elastic” stem, but the proximal interface stresses increased drastically relative to the stiffer uncemented stems composed of cobalt‐chrome or titanium alloy. However, the proximal interface stress peak was reduced and shifted during the adaptive remodeling process. The latter was found particularly in the stiffer uncemented cobalt‐chrome‐molybdenum implant and less for the flexible isoelastic implant.
Biomechanical effect of a two‐segment anterior cruciate ligament graft with separate femoral attachments and differing levels of prescribed load sharing
Authors: Chao Thomas T. H. , Lew William D. , Lewis Jack L. , Lindquist Conrad , Hong Boyang , Arendt Elizabeth 
Published: February 2005

AbstractThe objective of this study was to analyze the biomechanical effect of varying the level of prescribed load sharing between two segments of an anterior cruciate ligament (ACL) graft, and of separating the femoral attachments of these segments. Total anterior‐posterior (AP) laxity was measured using an instrumented spatial linkage. Forces in graft segments were measured using buckle transducers. The two‐segment graft was formed using the middle third of the patellar tendon with bone blocks and a synthetic augmentation device. Proximal fixation was obtained using a fixture which allowed changing the individual locations of the femoral attachments of the tendon and augmentation segments. Distal fixation was achieved using a force‐setting device which allowed the loads in each segment to be set to prescribed levels. Total graft force, load sharing, and total AP laxity were recorded during the application of 100‐N AP tibial loads at 0°, 30°, 60°, 90°, and 110° flexion, for various combinations of load sharing set at extension and locations of femoral attachment sites. The load sharing, total graft force, and AP laxity during AP loading at the five test flexion angles were not significantly affected by changing the prescribed level of load sharing set at extension for a given femoral attachment configuration. However, varying the separate hole locations of the graft segments for a given level of load sharing significantly affected load sharing, total graft force, and AP laxity. If the tendon graft was located posteriorly (on the medial surface of the lateral femoral condyle) and the augmentation segment proximally, the augmentation carried a greater portion of the total force in flexion. If the augmentation segment was changed to a more posterosuperior location and the tendon posteroinferior, the tendon carried a higher percentage of the total force in flexion. AP laxity in most reconstruction states was significantly greater than in the normal joint with an intact ACL. The nature of the load sharing between the graft segments under AP tibial load over the flexion range can be controlled by the appropriate choice of the segments' femoral attachment locations.
The correlation between anterior‐posterior translation and cross‐sectional area of anterior cruciate ligament reconstructions
Authors: Grood E. S. , Walz‐Hasselfeld K. A. , Holden J. P. , Noyes F. R. , Levy M. S. , Butler D. L. , Jackson D. W. , Drez D. J. 
Published: February 2005

AbstractTotal anterior‐posterior translation is commonly used to assess the integrity of the cruciate ligaments and the success of reconstructive surgery. The purpose of this study was to determine, after surgical reconstruction of the anterior cruciate ligament with a biological graft, if total anterior‐posterior translation correlated with graft length, cross‐sectional area, or mechanical properties. These factors were investigated by analyzing data from three previous studies. These studies involved replacement of the anterior cruciate ligament in cynomolgus monkeys and goats, with free and vascularized patellar tendon autografts and both patellar tendon and anterior cruciate ligament allografts. Data were available at time periods of 6 and 12 months after surgery. We found statistically significant inverse correlations between the amount of anterior‐posterior translation and cross‐sectional area of a graft at the time of sacrifice. The Pearson correlation coefficients ranged from −0.966 (p < 0.002) to −0.830 (p < 0.05). We hypothesize that these correlations result from the following mechanism: the increased anterior translation reflects a slack graft; a slack graft is stress shielded by other structures about the knee; the reduced in vivo stresses on the graft modulate cellular metabolism in a way that over time produces a small cross‐sectional area.
Two processes of bone remodeling in plated intact femora: An experimental study in dogs
Authors: Uhthoff H. K. , Foux A. , Yeadon A. , McAuley J. , Black R. C. 
Published: February 2005

AbstractBone loss is known to occur under plates used for internal fixation. Its exact location and extent and its relationship to the plate‐bone contact area was investigated in 36 adult beagles. Plates with two different contact areas were fixed unilaterally to intact femora for periods of 8 and 24 weeks. After removal, the bones were assessed radiographically, histologically, histomorphometrically, and biomechanically. Two processes that affect the bone after plating became apparent. One is a short‐term process, possibly caused by the interference of the plate with the blood supply to the cortex. This is followed by necrosis, which induces porosis. The second independent process is caused by the tendency of the bone to adapt to the new state of mechanical loads that results from the load sharing by the plate. The first stage of this process is expressed through swift changes in the bone cross‐sectional area under the plate by remodeling in all three envelopes: haversian, periosteal, and endosteal. This stage is followed by a gradual remodeling towards a steady state, in which the final cross‐section of the bone is attained. Both processes affected the bone simultaneously during plate fixation. The process caused by the vascular interference ceases after some time, and only the process due to stress‐shielding prevails for a long period.
Complex balance reactions in different sensory conditions: Adolescents with and without idiopathic scoliosis
Authors: Byl Nancy N. , Gray John M. 
Published: February 2005

AbstractWe measured simple and complex balance responses with a force plate stabiliometer in 70 adolescents: 50 with idiopathic scoliosis (IS) and 20 controls. In stable static balance positions, the two groups performed similarly, but when the visual and somatosensory systems were challenged simultaneously, the IS group had a significantly higher mean body sway than the controls. Within the IS group, children with mild, nonprogressive curves that had not been operated on were significantly more likely to maintain their balance when the visual and somatosensory systems were challenged simultaneously than those with curves ≥40°, who had had surgery, and who had more rapid progression of the curve. These findings suggest that adolescents with IS have normal balance in static, stable positions but are not able to perform as well as normal adolescents in sensory‐challenged positions, particularly if they have a severe, progressive curve. Longitudinal studies are needed to determine whether balance dysfunction can be used to predict progression of the curve.
The effects of cisplatin on the incorporation of fresh syngeneic and frozen allogeneic cortical bone grafts
Authors: Zart David J. , Miya Leslie , Wolff David A. , Makley John T. , Stevenson Sharon 
Published: February 2005

AbstractAllograft transplantation with concomitant chemotherapy has proven successful in the treatment of malignant bone tumors. However, these chemotherapeutic agents may delay tissue healing, resulting in clinical complications. To clarify the effects of cisplatin on the healing of bone grafts, we studied the incorporation of stably fixed massive diaphyseal femoral syngeneic and allogeneic grafts in rats treated with cisplatin. These data were compared with those of historical controls from animals that did not receive cisplatin. Rats that were to receive a fresh syngeneic graft or frozen allogeneic graft were given cisplatin every 4 weeks starting 9 weeks preoperatively and continuing until the time of death. The total bone area of the graft in animals that received cisplatin was smaller than that of the graft in untreated control rats that did not receive cisplatin. The area of the frozen allograft did not increase between 2 and 4 months. Revascularization was incomplete in cisplatin‐treated groups at 2 months, but by 4 months, vessel ingrowth in fresh syngeneic grafts approached control values. Frozen allografts remained poorly revascularized at 4 months. Host‐graft union was poor at 2 months in cisplatin‐treated rats compared with controls. In cisplatin‐treated rats, the host‐graft union of the frozen allograft remained inferior at 4 months while that of the syngeneic graft improved. Allogeneic cortical bone grafts are incorporated more slowly and incompletely than syngeneic grafts, and this handicap is exacerbated by the administration of cisplatin.
Healing of cancellous bone osteotomy in rabbits—Part II: Local reversal of arthritis‐induced osteopenia after osteotomy
Authors: Bogoch E. , Gschwend N. , Rahn B. , Moran E. , Perren S. 
Published: February 2005

AbstractWith use of the intravital bone label calcein, we previously identified, by histomorphometry, greatly increased new bone formation and juxtaarticular osteopenia (a high turnover state) in carrageenan‐induced experimental inflammatory arthritis of the knee in rabbits. In Part I of this paper, we showed that a large increase in new bone formation after a stable incomplete distal femoral condylar osteotomy of normal bone in the rabbit does not increase bone volume (BV) in normal tissue adjacent to the osteotomy (zone 1). In this study, we performed an osteotomy of bone made osteopenic by experimental inflammatory arthritis. After 4 weeks of healing, we examined new bone formation and BV in five zones around the osteotomy. In zone 0 (the osteotomy gap), new bone formation filled the gap to normal BV, as we found for the normal/osteotomy group. In zone 1 (adjacent to but excluding the osteotomy gap), we found greatly increased new bone formation and a return to normal BV, increased from the osteopenic level induced by experimental inflammatory arthritis. In this model, osteotomy apparently reversed the bone‐wasting process of inflammatory arthritis. This effect was not observed in other zones: the lateral condyle that had not been operated on, the metaphysis, or the diaphysis.
The proteoglycans of the cartilaginous end‐plate of the human intervertebral disc change after maturity
Authors: Bishop Paul B. , Pearce Richard H. 
Published: February 2005

AbstractLumbar spines collected postmortem were assigned to one of two groups: group 1—three spines with healthy discs, or group 2—three spines with severely degenerated discs. The proteoglycans (PGs) of the cartilaginous end‐plate (CEP) were extracted with 4 M guanidinium chloride containing protease inhibitors and were purified by caesium chloride density gradient ultracentrifugation. On Sepharose CL‐2B chromatography, the most dense 20% of the gradient (the A1 fraction) showed two subfractions, one eluting near the void volume and one partitioned by the gel. Both fractions resembled those of the nucleus pulposus and the anulus fibrosus in the number of components seen on agarose‐polyacrylamide gel electrophoresis. Both fractions changed with ageing/degeneration; the ratio of keratan sulphate to chondroitin sulphate, which was about 1 in group 1, increased to about 3 in group 2; the hydrodynamic volumes fell; the electrophoretically distinguishable component of lowest mobility disappeared while new, highly mobile components appeared; and the water content decreased slightly. Clearly, the PGs of the CEP of degenerated intervertebral discs differed from those of healthy discs; this supports the view that the CEP participates in the process of ageing/degeneration in the disc.
The effect of position of immobilisation on resting length, resting stiffness, and weight of the soleus muscle of the rabbit
Authors: Herbert Robert D. , Balnave Ronald J. 
Published: February 2005

AbstractThe extent of immobilisation‐induced adaptations of muscle length and muscle weight is known to be profoundly influenced by the position (or length) at which the muscle is immobilised. However, the effect of the full range of positions of immobilisation on subsequent adaptations of muscle length and weight has not yet been investigated. To examine further the effect of position of immobilisation, we used cast‐immobilisation of the hind limbs of 23 rabbits, in various positions between full plantar flexion and full dorsi‐flexion. Six muscles from non‐immobilised rabbits were used as the controls. After 10 days of immobilisation, the wet weight of the soleus muscle and the resting length and resting stiffness of the soleus muscle‐tendon unit were determined. Immobilisation in a shortened position was associated with a significantly greater decrease in length and weight than was immobilisation in a lengthened position. In addition, immobilisation produced significant increases in the resting stiffness of muscle‐tendon units, although there was no evidence of a position‐dependent increase in stiffness. Muscle weight was influenced by the position of immobilisation in a nonlinear way. The data support the views that the pre‐immobilisation resting length of the muscle represents a threshold length and that immobilisation at lengths longer than this retards immobilisation‐induced atrophy.
Cellular shape and pressure may mediate mechanical control of tissue composition in tendons
Authors: Giori N. J. , Beaupré G. S. , Carter D. R. 
Published: February 2005

AbstractIn vivo studies have suggested that mechanical factors are involved in the regulation of the morphology and biochemical composition of tendons that wrap around bones. In these tendons fibrocartilage is found in the segment wrapped around the bone, and tendon far from the bone displays normal tendon histomorphology. Recent in vitro studies have shown that intermittently loaded connective tissue cells are sensitive to changes in cellular shape and hydrostatic pressure: stretching and distortion of the cells enhances production of fibrous matrix and hydrostatic pressure enhances production of cartilaginous matrix. We used finite‐element analysis to determine whether the regions of increased development of cartilaginous matrix in tendons that wrap around bones correspond to regions in which tendon cells are subjected to higher pressures, and whether the maintenance and rearrangement of fibrous extracellular matrix in these tendons is associated with regions of stretching and distortion of cells. We found that regions of cartilaginous matrix and fibrous matrix formation and turnover correlate well with patterns of hydrostatic compressive stress and distortional strain in the tendon. Although further experiments clearly are needed to establish the predictive value of our approach, hydrostatic stress and distortional strain history—parameters intimately related to changes in cellular pressure and shape, respectively—appear to be important tissue‐level mechanical stimuli that regulate cartilaginous and fibrous matrix composition of connective tissues.
In vitro biomechanical analysis of suture methods for flexor tendon repair
Authors: Noguchi Masahiko , Seiler John G. , Gelberman Richard H. , Sofranko Richard A. , Woo Savio L‐Y. 
Published: February 2005

AbstractThis study was designed to compare five different suture methods that are used clinically for tendon repair. The flexor digitorum profundus tendons from the digits of adult mongrel dogs and adult human cadavers were used as models. The tendons in zone II of the hand, defined as the region from the distal palmar crease to the insertion of the flexor digitorum superficialis tendon at the middle phalanx, were transected and then were repaired by one of the suture methods developed by Kessler, Tsuge, Tajima, Savage, or Lee. The gliding function and tensile properties of the repaired tendons were evaluated biomechanically at time zero. The Tajima and Savage methods produced better gliding function than the other techniques. In the canine specimens that had been repaired by one of these two methods, the rotation of the distal interphalangeal joint was more than 60% of the rotation of the canine control specimens; only the Savage technique produced a rotation 124% that of the human control specimens. After the Tajima repair, the rotation of the proximal interphalangeal joint was 113% that of the canine control specimens and 157% that of the human controls. In the canine specimens that had had the Tajima or Savage repair, excursion of the tendon was greater than 55% that of the controls. The tendons repaired by the Savage method tolerated a significantly higher ultimate load to failure (14 and 25% that of the canine and human control specimens, respectively) than the other methods. Of the suture methods that were tested, the Savage technique provides sufficiently satisfactory gliding function and has enough initial stiffness and strength that it may be able to withstand early active mobilization following primary repair of flexor tendons.
Method to determine collagen density distributions in fibrous tissues
Authors: Mommersteeg T. J. A. , Kauer J. M. G. , Huiskes R. , Blankevoort L. 
Published: February 2005

AbstractWe present a method for the measurement of hydroxyproline density distributions, as an estimate for collagen density distributions, in fibrous tissues such as ligments and tendons. To evaluate this method, a single flexor tendon of a human hand was divided into seven tissue locations. Triplicate determinations of the dry weight tissue mass, volume, and hydroxyproline mass were made at each location: two samples were analyzed at the same time (a and b) and one was analyzed later (c). The intralocation variation is an estimate for the measurement error variance, which indicates both the precision (a compared with b) and the repeatability (b compared with c) of the technique for determination of volume, dry weight tissue mass, hydroxyproline concentration, and hydroxyproline density. The precision was about 5% for all variables, and the repeatability ranged from 1.5–4.3%. In comparison with the interlocation variations, the error variances were small, except for collagen concentration. This indicates that despite the measurement errors, differences in hydroxyproline density can be detected within fibrous tissues with the proposed method. The use of only a single tendon is adequate to evaluate the measurement error of the method, but more tendons should be measured to generalize the absolute values of the variables.
Enhancement of bone growth into metal screws implanted in the medullary canal of the femur in rats
Authors: Hazan R. , Oron U. 
Published: February 2005

AbstractThe kinetics of growth of bone into control (nontreated) and heat‐treated screws made of stainless steel (type 316L) and Ti‐6Al‐4V, implanted in the medullary canal of the femur in rats, were studied by mechanical, histological, and biochemical methods. A progressive and significant increase in the ingrowth of bone, as reflected by interfacial shear strengths of the screws, was measured with time after implantation. At all time intervals for as long as 35 days after implantation, the shear strength of the heat‐treated Ti‐6Al‐4V and stainless‐steel screws was significantly higher than (1.6–3.4 times) that of the control screws. The specific activity of alkaline phosphatase in extracts of tissue from around the implanted screws peaked 6 days after insertion, with significantly higher values at 5, 6, and 7 days postoperatively for the heat‐treated screws than for the controls. The extent of calcification also was higher at all time intervals for the heat‐treated screws than for the controls. The histological evaluation of formation of bone between the ridges of the implanted screw corroborated the mechanical and biochemical measurements. At each time interval, a more mature bone was noted around the heat‐treated screws than around the controls. It was concluded that the heat treatment of metal implants before insertion can result in augmentation of osseous ingrowth 1.6–5.3 times that into control implants in an in vivo experimental model.