PubMed Health⌕ Search

Biomedical subjects

G E Friedlaender

Publications and source records attributed to G E Friedlaender.

At least 37 records · Page 2Linked to original sources
PubMed1989

The effect of radiation on the fracture repair process. A biomechanical evaluation of a closed fracture in a rat model.

The effects of a single dose of irradiation on the biomechanical parameters of the fracture healing process were studied in a rat model. Intramedullary pinning was performed before production of a closed femoral midshaft fracture. The experimental group was exposed to 900 rad 3 days after fracture and was compared with a control group with a similar fracture that received no irradiation. Animals were killed at intervals ranging from 2-16 weeks after surgery and the bones were tested until failure in torsion. In the irradiated groups, a delay of 4 weeks was noted in the biomechanical parameters associated with fracture healing (torque to failure, torsional stiffness, angle to failure, and biomechanical stage). Despite this delay in the normal temporal progression, the staging and stiffness approached normal controls within an 8-week period. However, the torque to failure remained below normal levels at the conclusion of this study. These results differ from a previous study using an open fracture model.

Animals↗
PubMed1989

Allograft incorporation: a biomechanical evaluation in a rat model.

Allogeneic bone from Sprague-Dawley rat femurs was subjected to levels of freezing and/or irradiation that are known to have produced changes in the associated immune responses to these grafts. This bone was transplanted into an experimentally created gap in the femur of Lewis rats. The subsequent healing of the transplants in the Lewis rats was studied at 2, 4, 8, and 16 weeks after transplantation using torsion testing to failure. There was no clear advantageous biologic response in the union of the grafted material accompanying the alterations in immunologic response as measured by biomechanical testing of the proximal osteosynthesis site in torsion. The torsional strength of all of these groups remained lower than that of intact bone. Furthermore, none of the frozen and/or irradiated allografts exceeded the strength of the fresh allograft at a statistically significant level.

Animals↗
PubMed1988

Angiosarcoma associated with foreign body material. A report of three cases.

The production of tumors through solid-state mechanisms has been demonstrated in experimental animals, but foreign body tumorigenesis has not been proven definitively in man. The authors report three patients with angiosarcoma that occurred in intimate association with foreign material retained for prolonged periods. Although several etiologic factors have been defined in angiosarcoma, foreign bodies generally are not appreciated to have this potential. Review of the literature disclosed six cases of angiosarcoma and 40 cases of sarcomas of other histologic types associated with foreign material, with latency periods of from 4 months to 63 years. Implanted foreign material thus should be considered capable of inducing virtually any form of sarcoma in humans.

Abdominal Neoplasms↗
PubMed1988

Organ allocation.

Explore the source record for details and available documents.

Altruism↗
PubMed1987

Immunologic aspects of bone transplantation. A rationale for future studies.

This article presents the hypothesis that bone, like other soft tissue, is rejected in an immunologic fashion. However, because bone is mineralized, it presents unique aspects that are also dealt with by the immune system. The article goes on to review the immunologic considerations of bone allograft reactivity.

Animals↗
PubMed1987

Bone banking. In support of reconstructive surgery of the hip.

Bone banks are now available at local and regional levels that can supply tissues acquired from cadaveric and live donor sources. With appropriate donor selection criteria and banking techniques, these tissues are both safe and efficacious. Understanding the nature of the banking process, particularly the influence of various preservation techniques on biology and biomechanics, as well as knowledge of the incorporation process should lead to selection and an appropriate application of these tissues in reconstructive surgery about the hip. The availability of these allografts has extended our ability to devise salvage procedures and increasingly innovative approaches to numerous reconstructive challenges.

Bone Transplantation↗
PubMed1987

Effects of bone graft and electrical stimulation on the strength of healing bony defects in dogs.

Autogenous cancellous bone graft alone or in combination with electrical stimulation is commonly employed yet there exists no conclusive data that the strength of the healing defect is actually modified. The authors examined three groups of paired canine femurs that were torsion tested to failure. Group I (in vitro): an intact femur was compared to a standard defect; Group II (in vivo): a defect alone was compared to a defect plus graft killed at eight weeks; Group III (in vivo): a defect plus graft was compared to a defect graft plus Osteostim (BGS Medical Corp., Milwaukee, Wisconsin) implantable stimulator killed at eight weeks. In Group I the defect decreased the average strength 45% (p = 0.005); in Group II the grafted defect decreased the strength 20% (p = 0.121); in Group III the defect graft plus electrical stimulation increased strength 4% (p = 0.669). At eight weeks, bone grafting, alone or with electrical stimulation did not statistically increase the torsional strength of the healing bony defect.

Animals↗
PubMed1987

Methods of banking bone and cartilage for allograft transplantation.

Storage of bone for use as allograft has become an important endeavor because banked bone is becoming increasingly useful and popular as a substitute for, or as a supplement to, autograft bone. Methods have been developed for safe and reliable bone banking, including standard criteria for acceptable donors, proven techniques of retrieval of tissue, and appropriate storage facilities and conditions. In contrast, cartilage banking is still an investigative procedure, but current research may provide more effective approaches to maintaining viable cells during freezer storage of osteochondral allografts.

Animals↗
PubMed1987

Allogeneic bone in the treatment of tumors, trauma, and congenital anomalies of the hand.

Because autogenous bone grafts are histocompatible by definition and because the hand does not require massive bone grafts, one may question the indications for using allogeneic bone in the hand. Although humans have been shown to develop donorgraft specific antibodies following large osteochondral allografts, these antibodies have not yet been noted after smaller bone grafts nor is the clinical significance of these antibodies clear. The use of allogeneic bone better satisfies the architectural and strength requirements for reconstruction when there is a need for osteochondral grafts, strong cortical grafts to allow secure fixation and early motion, and small tubular grafts that meet the demands of minimizing bulk in the hand. For the repair of osteochondral defects, autogenous grafts (ie, fibular head or metatarsal head) impose donor site deficits that can be clinically significant. In addition, grafts such as the fibular head do not provide reconstruction of a congruent joint surface. Strong cortical bone is an asset in metacarpal reconstruction; it enhances the quality of internal fixation, which in turn allows hand therapy to be started early, an essential treatment following hand injuries. A stiff hand after reconstruction will result despite excellent bony reconstruction if the fixation does not allow early motion. Autogenous cortical grafts donor sites (eg, ulna or tibia) can cause donor site morbidity, including fracture of weakened bone. The need for small tubular grafts is especially important in pediatric patients. Strong autogenous corticocancellous grafts are difficult to obtain in children, and these grafts are bulky and difficult to insert. In addition, for adults and children, the lack of a donor site means a much shorter hospital stay.

Adult↗
PubMed1987

Biomechanical aspects of bone autografts and allografts.

The structural requirements of skeletal reconstruction should be included in the consideration of an appropriate type of bone graft, whether autogenous or allogeneic tissues are chosen. This analysis should include the nature of any fixation devices to be used, as well as characteristics of the host and donor bone. The mechanical properties and biomechanical response of the graft must be balanced against the type and magnitude of the load to which the graft will be subject. For example, the information presented here suggests that, from a biomechanical perspective, frozen bone would be better suited than freeze-dried bone when the graft is subject to large torsional loads or else the graft must be appropriately protected during incorporation by adequate internal fixation or external bracing. In a situation that is primarily subjected to compressive loads, however, freeze-dried grafts would be just as biomechanically sound. Thus, an understanding of the normal biomechanics of the anatomic region to be reconstructed is crucial. The mechanical properties of the graft are affected by preservation, storage, and sterilization. Incorporation and remodeling of the graft further alter its properties. These properties are, in turn, influenced by the host immune response as well as the local biomechanical environment. The influence of each of these factors is predictable. Obviously, there are numerous considerations in choosing approaches to skeletal reconstruction other than the mechanical issues discussed here. However, an understanding of the mechanical properties involved will help in optimizing the clinical success of these choices.

Adolescent↗
PubMed1986

Three-dimensional load-displacement curves due to forces on the cervical spine.

Load-displacement curves were measured for six types of pure force loading of the cervical spine specimens obtained from fresh human cadavers. A new measuring and mounting technique was developed that yielded data for all of the functional spinal units for each specimen tested. All five of the coupled, as well as the main, load-displacement curves were studied. For anterior and posterior shear loadings, the main resulting motions were translation in that direction (1.6 +/- 0.3 and 1.9 +/- 0.3 mm), and the major coupled motions were flexion and extension (3.6 degrees +/- 1.2 degrees and 6.3 degrees +/- 1.2 degrees). The main motions with right and left lateral shear loadings were translations laterally (1.4 +/- 0.3 and 1.6 +/- 0.3 mm), and the major coupled motions were axial rotations (1.5 degrees +/- 0.6 degrees and 2.3 degrees +/- 0.6 degrees) and not lateral bending. For compression and distraction loadings, the main motions were translations in that direction (0.7 +/- 0.3 and 1.1 +/- 0.3 mm), and the major coupled motions were flexion and extension (2.0 degrees +/- 1.0 degrees and 2.8 degrees +/- 1.0 degrees) and lateral bending (1.4 degrees +/- 0.3 degrees and 1.9 degrees +/- 0.3 degrees). The neutral zones for anterior and posterior shear forces were 1.6 +/- 0.2 mm of translation and 5.8 degrees +/- 1.3 degrees of rotation, for lateral shear force 1.4 +/- 0.3 mm and 2.0 degrees +/- 0.5 degrees, and for compression/distraction 0.6 +/- 0.1 mm and 2.8 degrees +/- 0.9 degrees.

Aged↗
PubMed1985

Chemotherapy-induced alterations in the biomechanics of rat bone.

The effects of methotrexate and doxorubicin (Adriamycin) on intact and fractured bone were studied in a rat model. Methotrexate, 0.1 mg/kg i.p., was administered five times a week, or doxorubicin, 1 mg/kg i.v., was given once a week. Animals were killed and evaluated at 4, 8, 12, and 16 weeks after surgical production of a unilateral femoral osteotomy and initiation of the chemotherapeutic program. Both intact and fractured bones were tested to failure in rapid torsion, and the torque, angular deformation, stiffness, and energy were measured. There was a significant alteration in the strength of the healing osteotomies in doxorubicin- and methotrexate-treated animals compared with the control group. The torsional strength of intact bone was not significantly altered by either drug protocol over the period of this observation.

Animals↗
PubMed1985

Effects of short-term cyclosporin-A on biomechanical properties of intact and fractured bone in the rat.

Cyclosporin-A is a new immunosuppressant drug being used widely for solid organ transplantation. The systemic effects of Cyclosporin-A on the skeletal system have not previously been defined. This study examined the effects of Cyclosporin-A on biomechanical properties of intact bone and fracture repair in a rat model. Closed midshaft femoral fractures were produced over a preplaced intramedullary pin. Cyclosporin-A, dissolved in olive oil and administered by gavage, was begun the day following surgery and continued for 14 consecutive days at a dose known to prolong solid organ allograft survival in rats (7 mg/kg/day), and a second group of control animals received comparable volumes of plain olive oil under identical circumstances. Groups of both experimental and control animals were killed at 4, 8, 12, or 16 weeks following fracture, after which both intact and fractured femurs were tested to failure in torsion. As judged by torque, angular deformation, stiffness, and energy absorption, Cyclosporin-A did not significantly alter the biomechanical properties of fracture repair or intact bone turnover. Based on current biomechanical data, we can find no reason to discourage the short-term clinical use of Cyclosporin-A in patients with or without fractures. Histomorphometric studies are required to accurately assess the biologic effects of this drug on bone biology and to complete the analysis of skeletal toxicity.

Animals↗