摘要:

AbstractThe role of histocompatibility matching in bone allografting was studied in two canine bone graft models. In a cancellous ulnar segmental replacement model, frozen bone allografts exchanged between closely matched dogs were significantly better incorporated by radiographic and histologic criteria than were strongly incompatible grafts. Frozen allograts from disparate donors in recipients receiving immunosuppression appeared indistinguishable 6 months later from those in the untreated closely matched groups and from fresh autografts. Fresh vascularized orthotopically placed fibular bone grafts were evaluated by quantitative blood flow assessment, microangiography, and fluorochrome histomorphometry. Revascularized grafts exchanged between untreated closely matched dogs demonstrated preservation of blood flow and a pattern of repair that was delayed by not otherwise different than vascularized autografts. These results suggest that fresh vascularized grafts in the Judiciously matched or immunosuppressed recipient offer attractive clinical possibilities.

ISSN:0736-0266    

DOI:10.1002/jor.1100030401

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractBone biopsy is the definitive method for bone tumor diagnosis. Unfortunately, the procedure is not without risk and may substantially increase the rate and extent of tumor cell metastasis. This study used radioactive microspheres (15 μm diameter) to explore the spread of cell‐sized particles from the distal femur into the lymphatic system, venous drainage, and local tissue following a simulated biopsy in the canine model procedure. In the initial group of test animals the microspheres rapidly moved from the femur through the venous system to the lungs. There was no movement from the femur into the lymphatic system within 4 days. The lungs effectively filtered the 15μm microspheres, thus preventing arterial dissemination. Additional groups were used to explore the movement of the cell‐sized particles from the soft tissue surrounding the bone. At the end of the 4 day experimental period, microspheres were found in the iliac lymph nodes in two of nine animals. Microspheres were not detected in the lungs of any of these nine animals. These results suggest that tumor cell‐sized particles can move rapidly from the bone venous system to the lungs following a bone biopsy. It appears that the lymphatic system does not contribute to this rapid dissemination. However, the role of lymphatics in a more chronic process remains

ISSN:0736-0266    

DOI:10.1002/jor.1100030402

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractCircumferential wires were placed around both midshaft femora of six immature dogs. On one side the wires were placed under the periosteum and on the other side the wires were placed over the periosteum. All wires were tightened to an equivalent tension. A diffuse growth of periosteal new bone occurred in those femora in which wires were placed under the periosteum but not in those over the periosteum. Corresponding microangiographs at 3 weeks in those femora in which wires were placed under the periosteum revealed dramatically increased medullary and periosteal vascularity coupled with histologic active trabecular bone formation. In those femora in which the wires were placed over the periosteum, even though the placement of the wires should supposedly have been the most detrimental, vascularity was not restricted. There were perfused vessels within the cortex directly under the wires. At 8 weeks the wires in both preparations were becoming encased in the growing cortical bone. Cerclage did not devitalize immature bone nor did it restrict adjacent appositional bone growth.

ISSN:0736-0266    

DOI:10.1002/jor.1100030403

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractEvaluation of tibiofibular motion in vivo has been possible only by invasive methods. A new nonivasive method has been developed that uses computed tomography (CT). A special device was constructed for use on the CT table to study fibular motion with load placed across the ankle. From dorsal to plantar flexion the fibula moved 1.1 ± 0.4 mm medially with an accompanying nonsignificant ventral shift and medial rotation. Application of load across the ankle did not significantly alter these findings. In a subgroup of predominantly females, plantar flexion of the ankle provoked a dorsal fibular motion of 0.7 ± 0.8 mm. In this subgroup application of load across the ankle reduced the medial and dorsal motion during the accompanying plantar flexion. The mechanism of these different movements can be deduced from the morphology of the ankle joint and its ligamentous and muscular guidance mechanism. The variable axis of joint movement and the insertion of the lateral ligament forced the fibula anterior in plantar flexion. When external talar rotation is present, the normal fibular motion is prevented unless load is applied across the ankle. The new investigative procedure permits study of the sequelae of traumatic and iatrogenic injuries to the fibul

ISSN:0736-0266    

DOI:10.1002/jor.1100030404

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractWe generated three‐dimensional finite element models of the proximal tibia with an implanted tibial component. The component features a cobalt‐chromium tray with four short vertical posts and a porous‐coated surface for improved fixation to polymethylmethacrylate (PMMA). We examined the stresses after varying: (a) the structural rigidity of the metaphyseal cortical shell; (b) the surface area of the cobalt‐chromium tray; and (c) the depth of pressure‐injected PMMA bone cement. Our results indicate that previous finite element models of prosthetic tibial components have overestimated the structural contribution of the metaphyseal cortical shell by a factor of approximately 6. A standard size tray, in contrast to a tray that extends to the cortical shell, does not significantly alter the axial load distribution but could result in bone resorption beyond the tray periphery. An important consequence of the component peg locations is that they direct the compressive stresses into dense regions of trabeculae that run from the subchondral articular surface to the metaphyseal‐diaphyseal junction. The use of a modified von Mises failure criterion suggests that at excessive load levels the most likely location of material failure is at the bone cement–trabecular bone interface immediately distal to the fixation posts. Due to its added rigidity, injection of cement beyond the fixation posts results in slightly increased stresses in this region, but these stress increases are compensated for by an increased strength of the cementb

ISSN:0736-0266    

DOI:10.1002/jor.1100030405

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractTwo‐dimensional finite element analyses were conducted of the normal hip using contact elements at the joint surface. The models studied were constructed for a slice through the pubis, acetabulum, and ilium. In the analyses the proximal femur was pressed into the acetabulum and intraarticular pressures and principal stresses in the joint region were determined for different load magnitudes and directions and various boundary conditions. Three sets of boundary conditions were examined: (a) deformable pubic symphysis, (b) rigid pubic symphysis, and (c) simulations of experimental studies. In the deformable model the pubic symphysis was free to displace in the sagittal plane and rotate. In the rigid model the pubic symphysis was rigidly fixed. Superoposterior loading resulted in high‐contact pressures at the acetabular dome for all sets of boundary conditions. For the deformable model subject to a more medially directed load the acetabulum closed in such a manner as to squeeze the head of the femur creating high‐contact pressures superiorly and inferiorly. This resulted in significant compressive stresses in the superior dome cancellous bone and inferior cancellous bone. The cumulative effect of this squeezing action with normal biological remodeling may cause elongation of the femoral head resulting in asphericity and incongruity of the unloaded hip joint articular surfaces. Rigidly fixing the pubic symphysis stiffened the model and resulted in principal stress patterns that did not reflect trabecular density or orientations as well as those of the deformable pubic symphysis model. Finite element simulations of previous experimental studies modeled the close proximity of the fixation to the fixation to the excised acetablulum. These boundary conditions prevented the squeezing caused by pelvis deformations. The resulting contact areas, pressure distributions, and bone stresses were very different from those of more anatomic, deformable pubic symphysis model. These findings demonstrate the sensitivity of hip contact pressures and stresses to imposed boundary conditions and indicate that care should be taken to simulate anatomic conditions in experimental and theoretical st

ISSN:0736-0266    

DOI:10.1002/jor.1100030406

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe objective of this study was to experimentally determine the optimal length of a femoral component in revision total hip arthroplasty (THA). Embalmed cadaveric femurs were loaded in a physiologic manner, and strains on the lateral cortex were measured. Two kinds of defects were tested to simulate THA after removal of a nail plate and after removal of a loose femoral stem. A drill hole was made in the lateral cortex of the femur to simulate the removal of a nail plate. A reaming defect was made, using flexible reamers to thin the cortex from the lesser trochanter distally to a site corresponding to the tip of a standard femoral component, to simulate THA after removal of a previously inserted femoral stem. Femurs were tested intact, with the defects, and after insertion of femoral components with stem lengths of 100 to 250 mm. The strain increased with the creation of a defect and decreased with the insertion of an implant. For a femur with a defect, the strain was minimized when the stem length extended 1.5 femoral diameters past the defect.

ISSN:0736-0266    

DOI:10.1002/jor.1100030407

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThis study reports a new technique for the measurements of bone mineral content (BMC) in live rats. A single photon absorptiometric instrument has been adapted for rapid, reproducible measurement of BMC. Four bone sites were selected for use, based on ease of positioning and reproducibility of measurement; these were as follows: proximal femur, midfemur, proximal seventh caudal vertebra, and midseventh caudal vertebra. Significant increases were detected when BMC was measured at biweekly intervals from weaning to 18 weeks of age in normal male rats. Comparison of body growth and changes in BMC of male and female rats with age showed that body weight gain of female rats slowed earlier than that of male rats whereas BMC increased at similar rates in both sexes. Vitamin D deprivation from day 24 of life resulted in decreased BMC at all four measurement sites compared with such measurements in normal control rats. Differences were detectable after 8 weeks of age and occurred despite the maintenance of serum calcium levels within normal range and only slight reduction in body weights of vitamin D deprived rats. These studies demonstrate that single photon absorptiometry can be used to mointor changes in BMC in live rats on a routine basis without harm to the animals. Changes in BMC such as those due to growth or vitamin D deprivation can easily be quantitated using this technique.

ISSN:0736-0266    

DOI:10.1002/jor.1100030408

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe longitudinal compressive strength of trabecular bone from the human proximal tibial epiphysis was investigated in 12 autopsy specimens using multiple penetration tests with a small diameter indentor. Strength profiles were visualized by three‐dimensional computerized reconstruction as a function of location on the resection surfaces. There were large variations of the maximal values between individuals, but the patterns obtained were remarkably uniform. The medial condyle showed the highest peak value in all but one knee with a mean medial‐to‐lateral peak value‐ratio of 1.7. At the medial condyle the high strength area was relatively large with peak values being obtained centrally and anteriorly; the lateral condyle showed a more restricted, posteriorly localized area a high strength. Beneath the menisci, bone strength gradually decreased toward the margins of the condyles; likewise, bone strength decreased to reach very low values at the intercondylar region. There was a significant reduction of bone strength with the distance from the subchondral resection surface. This reduction was most pronounced at the high strengt

ISSN:0736-0266    

DOI:10.1002/jor.1100030409

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe spatial and bulk water equilibrium partition and fluid content were determined for normal adult bovine articular cartilage as a function of pH, temperature, and geometric confinement. Water partition averaged 60 ± 7% at neutral pH and 37°C and increased with decreasing pH and increasing temperature without a concomitant change in fluid content. The variation in water partition appeared to be a result of local conformation changes in the collagen fibril ultrastructure causing a transfer between free and trapped water volume. Removal of the lateral and subchondral bone geometric constraints caused an increase in both the water partition and fluid content. However, this partiton variation could be accounted for solely from a change in free fluid volume. These results suggest that in articular cartilage the proteoglycan‐collagen interaction may be an important mechanism for controlling the partition of water between a freely exchangeable space and a space allowing no fluid excha

ISSN:0736-0266    

DOI:10.1002/jor.1100030410

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY