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Biomedical subjects

S Skjeldal

Publications and source records attributed to S Skjeldal.

14 recordsLinked to original sources
PubMed1995

Periosteal response to transient ischemia. Histological studies on the rat tibia.

Complete arrest of blood flow was induced for 4.5 hours in the left hindlimb of Wistar rats by a tourniquet applied proximally to the thigh. Histologically the periost of the tibial bone after 3 days showed marked hypertrophy and hyperplasia of the periosteal cells with an osteogen differentiation. This response is similar to the initial formation of external callus during fracture healing. Transient ischemia may be an important factor in initiating fracture healing.

Animals↗
PubMed1995

Cardiovascular response to blood loss during high intracranial pressure.

The authors hypothesized that the combination of hemorrhage and increased intracranial pressure (ICP) has deleterious effects on cardiovascular function. The effect of blood loss during normal and increased ICP was studied in eight pigs. The mean arterial pressure (MAP), pulmonary arterial pressure, pulmonary capillary wedge pressure, cardiac output, and cerebrospinal fluid (CSF) pressure were measured. The regional tissue blood flow was determined with radioactive microspheres labeled with four different nuclides. High ICP (80% of MAP) was induced by infusion of artificial CSF into the cisterna magna. The response to rapid arterial bleeding of 25% of blood volume was measured. The decrease in blood flow to the intestine, skeletal muscle, and the kidneys after blood loss was significantly greater during high ICP. The decrease in blood flow to the spleen and pancreas tended to be greater during high ICP, whereas the changes in blood flow to the liver, adrenal glands, and heart muscle showed no such tendency. The fall in cardiac output and heart stroke volume after blood loss were more pronounced when the ICP was high, and the increase in systemic vascular resistance was considerably greater. These observations suggest that during high ICP the physiological protective mechanisms against blood loss are impaired in the systemic circulation, and a loss of 25% of the blood volume, normally well compensated for, may induce a state of shock.

Animals↗
PubMed1992

Slotted versus non-slotted locked intramedullary nailing for femoral shaft fractures.

Experimentally, two slotted nails, the Grosse-Kempf nail and the AO/ASIF universal femoral nail, were compared to the non-slotted Grosse-Kempf nail and control bone using a cadaver femoral osteotomy. The stiffnesses and strengths of the osteotomies fixed with slotted nails in 10-30 degrees torsion were 6-8% and the values of non-slotted nails 40% of control bone. The maximal moments were 14-18% and 48%, respectively. In the "clinical range" of torsion, the implant-bone construct never failed or was deformed. Clinically, 46 femoral shaft fractures were randomized to treatment with Gross-Kempf nails, 24 with slotted nails and 22 with non-slotted nails. Four complications in the slotted nail group and three in the non-slotted nail group were considered to be independent of the choice of nail and did not affect the end result. Three splinterings of the distal fragment, one resulting in a change of the osteosynthesis implant to a condylar plate, were considered to result from the high stiffness of the non-slotted nail. Osteosynthesis of femoral shaft fractures using slotted nails has not resulted in healing disturbances, which could be accounted for by the high torsional elasticity of the nail; there seems to be no indication for high-stiffness nails in femoral fractures.

Adolescent↗
PubMed1992

Protective effect of low-grade hypothermia in experimental skeletal muscle ischemia.

In the present study, a rat hindlimb tourniquet model was used to investigate the effect of moderate hypothermia on ischemic muscle necrosis. Complete circulatory arrest was maintained for 4.5 h. During the ischemic period the animals were kept in an infant incubator at different temperatures. After 72 h survival the percentage of necrosis in the anterior tibial muscle was measured morphometrically on histological slides. At an ambient temperature of 24 degrees C there was 80% necrosis in the anterior tibial muscle. At 22 degrees C the necrosis was reduced to 29%. This reduction corresponds to more than 30 min shortening of the ischemia time. Differences in tissue temperature may explain some of the discrepancies reported in tolerance limits for muscle ischemia. To achieve consistent results in experimental muscle ischemia, it is necessary to control the ambient temperature.

Animals↗
PubMed1992

Healing of cortical bone grafts in athymic rats.

We studied healing of allogeneic and syngeneic cortical tibial segment grafts in athymic and normal rats. After 3, 6, and 12 weeks, the weight, circulation, and mineralization rate of the healing segment, and mechanical strength and stiffness of the healing tibia were measured. There were no differences between allogeneic and syngeneic grafts in athymic and normal animals at 3 or 6 weeks. After 12 weeks, the vascularization and mineralization of the grafts, but not of the surrounding callus, were smaller in the allogeneic grafts in the normal recipients than in the other groups. Also after 12 weeks, the stiffness of the healing tibiae was less in allogeneic grafts in normal recipients than in the other groups. The strength of the allogeneic grafts was less than the strength of the syngeneic grafts in both athymic and normal recipients. This suggests that T-cell-mediated rejection is responsible for decreased vascularization and mineralization of allogeneic bone and that the difference in strength between allogeneic and syngeneic grafts is not due to T-lymphocyte graft rejection.

Animals↗
PubMed1991

Model for skeletal muscle ischemia in rat hindlimb: evaluation of reperfusion and necrosis.

In this study we describe a technique for complete arrest of blood flow in rat hindlimbs. After graded periods of ischemia, immediate reperfusion in the leg was demonstrated by direct microscopy and scintigraphy. Laser Doppler flowmetry indicated microvascular hypoperfusion in the anterior tibial muscle during the first 2 h of reperfusion. The extent and distribution of necrosis in the middle part of the anterior tibial muscle of the legs were determined histologically 3 days after the ischemic insult. We found a reproducible degree of necrosis under constant experimental conditions. The necrosis was most pronounced in the central part of the muscle, leaving the subfascial fibers undamaged. After 4.0 h of ischemia, 46% of the cross-section area was necrotic. After 4.5 h, the necrosis increased to 70%. This difference was significant. Two types of necrotic zones were detected. One type was characterized by numerous macrophages and partial resorption of the muscle fibers, the other by a lack of macrophages and no resorption. Most cases with little damage had only the first type of necrosis, while most cases with extensive damage had both types. The areas that had no signs of resorption and therefore had been without circulation during most of the postischemic period, measured 8% after 4.0 h of ischemia and 22% after 4.5 h.

Animals↗
PubMed1990

Plethysmographic screening for deep venous thrombosis following total hip replacement.

A series of 97 lower limbs examined with venography and plethysmography after total hip replacement surgery is presented. No patients had clinical signs of deep venous thrombosis (DVT). Venography revealed distal DVT in 26 limbs. Plethysmography was negative in 25 of these cases. A low sensitivity for plethysmographic detection of calf thrombi is described in previous publications. In this study, however, we found a complete lack of correlation between positive plethysmography and venography in limbs with distal, symptomfree thrombosis.

Aged↗
PubMed1989

Mechanical effects of intramedullary reaming in pinned osteotomies in rats.

The biomechanical effects of intramedullary reaming on the healing of femoral osteotomies were studied. In rats, transverse osteotomies at the midshaft of both femurs were made. On the left side only, reaming of the medullary cavity was performed, and the osteotomies were then stabilized by intramedullary pinning. At 15, 30, 60, and 90 days after osteotomy, the production of callus, the bending moment, and the bending rigidity were evaluated. There were no significant differences in these biomechanical parameters between the right unreamed and the left reamed femurs during the experimental period. The results indicate that reaming of the medullary cavity of diaphyseal bone does not significantly impair or improve the healing of pinned osteotomies in rats.

Animals↗
PubMed1988

Coracoid process transfer for acromioclavicular dislocation.

Seventeen patients with complete separation of the acromioclavicular joint were operated on acutely with transposition of the coracoid tip to the clavicle. All the patients were examined after a mean follow-up time of 7.5 years. Twelve patients had good function, 3 had slight pain in extreme positions, and 2 had poor function with pain at rest. Eleven patients had the screw removed, 2 of them because of deep infection. In 3 patients the coracoid tip fragmented during the operation. Two patients had an unsatisfying cosmetic result. As long as nonoperative treatment gives equal or better long-term functional results, we do not recommend this operation in acute dislocations.

Acromioclavicular Joint↗
PubMed1987

Interlocking medullary nails--radiation doses in distal targeting.

Distal interlocking of intramedullary nails involves the use of a fluoroscope and a targeting device. A specially designed awl makes the interlocking procedure simple and efficient. The 30-cm-long side arm of this awl protects the surgeon's hand from direct radiation, and measurements of X-ray exposure show that the protection against radiation is sufficient.

Bone Nails↗