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Biomedical subjects

C B Michelsen

Publications and source records attributed to C B Michelsen.

At least 19 recordsLinked to original sources
PubMed1995

Effects of spinal instrumentation on fusion of the lumbosacral spine.

STUDY DESIGN: This study retrospectively, reviewed the effects of pedicle screw fixation on lumbosacral fusion for degenerative conditions. The records and radiographs of a group of patients treated by wide decompression and fusion of the lumbosacral spine and by one surgeon were studied. Two treatment groups were identified by fusion technique; one group received autologous bone graft only, and second group was treated by autologous bone grafting supplemented with pedicle screw fixation. OBJECTIVES: The two study groups were compared to determine the effects of pedicle screw fixation on lumbosacral fusion for degenerative conditions after wide decompression. SUMMARY OF BACKGROUND DATA: The reported success rate of lumbar and lumbosacral fusion in the literature is variable. Although several studies have reported high fusion rates with internal fixation, few controlled studies have been published. A critical review of isolated lumbosacral fusions (for degenerative conditions) and the effects of instrumentation is necessary to determine the effectiveness and complications associated with pedicle screw systems in this setting. METHODS: This study reviewed 215 consecutive patients operated on from 1987 to 1992 for degenerative conditions of the lumbosacral spine. Group 1 included 126 patients who underwent autogenous posterolateral bone graft after decompression. Group 2 included 89 patients treated with Edwards instrumentation and autogenous bone graft. Fusion status was determined via radiographs. Clinical results were based on pain relief after a minimum 2-year follow-up period. RESULTS: In Group 1, an overall fusion rate of 65% was obtained. Clinically, 56% had good or excellent results. Complications included pseudarthroses (35%), dural tears (3.2%), and infection (2.4%). In Group 2, a fusion rate of 91% was achieved. In this group, 89% had a good or excellent clinical result. Complications included pseudarthroses (9%), dural tears (2.2%), and infection (2.2%). CONCLUSIONS: Use of pedicle screw and rod fixation with the Edwards system led to significantly improved results in lumbosacral fusions over autogenous bone graft alone, with a lower complication rate. The use of spinal is a valuable adjunct to achieve lumbosacral fusion in patients who have undergone decompressive surgery for the spine.

Adolescent↗
PubMed1994

Long term followup of thorough debridement and cancellous bone grafting of the femoral head for avascular necrosis.

From 1977 to 1982, 13 patients were diagnosed with avascular necrosis of the femoral head. The diagnoses were made with a combination of clinical exams, radiographs, tomograms, and Tc99 bone scans. One hip was classified as Ficat Stage I, 9 as Stage II, and 5 as Stage III. There were 11 male and 2 female patients with an average age at the time of surgery of 34 years. Idiopathic osteonecrosis was the final diagnosis in 10 patients, while 3 had a significant history of steroid use. The anterior neck was approached via Watson-Jones or Smith-Petersen approach. A window was then made in the femur at the head/neck junction. Drills, burrs and curettes were utilized under image intensification to perform a thorough debridement of all sclerotic bone. Cancellous bone was harvested from the ipsilateral iliac crest and was packed tightly into the femoral head to the subchondral plate. The cortical window was replaced. In 3 patients a gluteus medius pedicle flap was also utilized to augment the blood supply to the bone graft. This approach provided the access necessary to debride all dead and sclerotic bone. Healing and support of the subchondral plate were subsequently augmented with tightly packed cancellous bone graft. The patients were followed for 10-15 years (mean, 12 years). Two (13%) have since gone on to revision with total hip arthroplasty. The others (87%) remain essentially symptom free with minimal progression of osteoarthritis. There were no infections, femoral neck fractures, or thromboembolic events. Two patients with gluteal pedicle flaps developed ectopic calcification. Thorough debridement and cancellous bone grafting in patients with avascular necrosis of the femoral head is an effective procedure in young patients with Stage II or Stage III disease that will delay, if not prevent, the progression of osteoarthrosis and subsequent total hip arthroplasty.

Adult↗
PubMed1992

Revision surgery for failed back surgery syndrome.

Results of surgical treatment in 50 failed back surgery patients were retrospectively reviewed to determine what factors influenced surgical outcome. Before surgery, all patients had disabling pain and limited function. Overall significant improvement in pain and function was obtained in 66% of the patients. Thirteen of 16 patients (81%) who had successful fusion of pseudarthrosis had a satisfactory outcome, whereas only 3 of 13 patients (23%) who had failed pseudarthrosis repair had a satisfactory outcome. Successful pseudarthrosis repair is the key to a high clinical success rate in revision surgery for failed back surgery syndrome. Pseudarthrosis repair by conventional posterolateral fusion with postoperative lumbosacral corset immobilization showed a high failure rate. The success rate of reoperation on failed back surgery syndrome patients is low.

Adult↗
PubMed1988

Effects of total hip replacement and bed rest on blood rheology and red cell metabolism.

In order to better understand the pathophysiologic changes in the immediate postoperative period after total hip replacement surgery and to distinguish alterations due to the surgical operation from those due to bed rest, we examined rheologic parameters and red cell metabolism of patients before, 1 day after, and 5 to 6 days after total hip replacement and compared the results to those obtained from normal volunteers placed at bed rest for 5 days. Bed rest in the control group led to increases in hematocrit, mean corpuscular hemoglobin concentration, red cell DPG and ATP levels, and plasma concentrations of total proteins, globulins, and fibrinogen, with attendant increases in whole blood viscosity, plasma viscosity, blood viscosity, relative blood viscosity with hematocrit adjusted to 45%, and viscometric aggregation index, and the viscosity of red cell suspensions in Ringer's solution at 45% hematocrit decreased at low shear rate. The patient group, despite the postoperative lowering of their hematocrit, mean corpuscular hemoglobin concentration, and total plasma proteins and a consequent decrease of whole blood viscosity, revealed disproportionate increases in blood viscosity, relative blood viscosity, and viscometric aggregation index. These rheologic changes, which reflect an enhanced red cell aggregability, may contribute to complications of thrombophlebitis. Enforced inactivity, when superimposed on the effects of trauma, blood loss, transfusion with bank blood, and the low-flow state, would exaggerate these rheologic problems. The results suggest that management of total hip replacement patients should include hemorrheologic considerations (e.g., preoperative intentional hemodilution) and early postoperative activity.

2,3-Diphosphoglycerate↗
PubMed1987

A comparative biomechanical study of spinal fixation using Cotrel-Dubousset instrumentation.

A biomechanical study was performed comparing the stiffness and stability of Cotrel-Dubousset (CD) spinal instrumentation with that of segmentally wired Harrington distraction rods and segmentally wired Luque rods under conditions of single-level instability. The axial and torsional stiffness coefficients of each system were determined on a customized geometric spine simulator fashioned from stainless steel. The relative stability of each instrumentation system was then compared by mounting the fixation systems on bovine thoracic spines from 12-week-old calves, destabilized by anterior vertebrectomy to create simulated two column instability. Thirteen spines were tested. Each specimen was tested under axial and torsional loading conditions while monitoring with a personal computer-based data acquisition system was performed. The stability of first- and second-level CD instrumentation was tested on the bovine specimens. First-level CD instrumentation involved double-hook fixation one level above and below the level of instability. Second-level CD instrumentation involved fixation two levels above and below the level of instability without fixation at the intermediate level. In axial loading, double-level wired Harrington distraction rods, double-level wired Luque rods, and first-level CD rods were 26.5%, 18.4%, and 21.5%, respectively, as stable as second-level CD instrumentation. In torsion, double-level Harrington, double-level Luque, and second-level CD rods were 13%, 64%, and 34%, respectively, as stable as first level CD instrumentation. Locking hooks, double-hook configurations, and stabilizing transverse traction devices of the CD contributed to its greater stability.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Management of plasmacytomas of the spine.

Epidural plasmacytoma often reflects systemic myelomatous involvement and usually has a poor prognosis. The isolated spinal plasmacytoma, however, is a lesion with the potential for long term remission or even cure in some cases. We report six patients with isolated plasmacytoma of the low thoracic or lumbar region, all of whom presented with pain and minimal neurological deficits. Our approach to such cases included a complete medical work-up and radiographic definition of the lesion with a bone scan, a skeletal survey, myelography, computed tomography, and, in some instances, spinal angiography. All of these patients underwent laminectomy and spinal fusion with autologous bone and Harrington rods. There was no morbidity associated with the procedure, which was designed to prevent possible collapse during subsequent radiotherapy or chemotherapy, with its attendant potential for neurological catastrophe. Several patients have developed systemic involvement necessitating chemotherapy, but in follow-up extending now to 4 years all patients remain ambulatory and pain-free. We are encouraged by the potential for symptomatic relief and neurological improvement of patients with isolated spinal plasmacytomas who are treated with an aggressive medical and surgical approach.

Adult↗
PubMed1982

Effect of postoperative nutrition on muscle high energy phosphates.

This study examines the effect of hypocaloric nutritional regimens on muscle high energy phosphates in normal subjects and patients following total hip replacement. Eighteen patients undergoing total hip replacement and 11 normal subjects on a four-day period of bedrest were studied. The patients were randomly assigned to receive either: (1) 90 gms/day glucose; (2) 70 gms/day amino acids; or (3) 90 gms/day glucose + 70 gms/day amino acids. A percutaneous muscle biopsy was performed before operation and on the morning of the fourth day after operation. Samples were analyzed for adenine triphosphate (ATP), adenine diphosphate (ADP), adenine monophosphate (AMP), phosphocreatine (PC), free creatine (CR), lactate, and pyruvate. Normal subjects were assigned to receive either: (1) 90 gms/day glucose; (2) 70 gms/day amino acids; or (3) no caloric intake. The patients receiving amino acid alone demonstrated a decrease in ATP, ADP, and PC, while AMP and free creatine rose. No significant changes were seen in patients who received 90 gms/day glucose either with, or without, amino acids. There were also no significant changes in any of the normal subjects. These results suggest that a series of metabolic changes occur in skeletal muscle following injury such that small amounts of glucose are important for maintenance of cellular energy levels.

Adenosine Diphosphate↗
PubMed1982

Effect of an anabolic steroid on nitrogen balance and amino acid patterns after total hip replacement.

The effect of an anabolic steroid, nandrolone decanoate, on nitrogen balance and plasma and muscle amino acid concentrations was studied in patients undergoing total hip replacement and receiving daily postoperative infusions of 5% dextrose and 3.5% amino acids. An intramuscular injection of 200 mg immediately after operation resulted in a nitrogen balance of -48 mg N/kg . day for the first 3 days, as compared to 102 mg N/kg . day in noninjected controls. After steroid injection there was also an attenuation of trauma-induced changes in amino acid concentrations in muscle but not in plasma. This suggests that nandrolone decanoate may act directly on muscle to reduce the protein catabolism which follows a major form of operative trauma.

Aged↗
PubMed1981

Influence of injury and nutrition on muscle water electrolytes: effect of elective operation.

Injury is followed by a sequence of metabolic alterations which include fluid and sodium retention. This study used the percutaneous biopsy technique to analyze changes in muscle composition in regions nonadjacent to the area of surgical injury. The effect of nutritional intake on the changes observed in emphasized. Twenty-eight patients undergoing colectomy and 22 patients undergoing total hip replacement were studied. The patients undergoing colectomy resections received total parenteral nutrition with varying nitrogen intake. The patients undergoing hip replacement received either a) 5% dextrose solutions, b) 3.5% amino acid solutions, or c) both. Muscle biopsy procedures were performed preoperatively and postoperatively (day three on the colectomy patients) (day four on the hip replacement patients). The role of inactivity was assessed in eight healthy subjects maintained on strict bedrest for four days. Four subjects received a regular diet, while four received 5% dextrose solution for four days. The tissue samples were analyzed for water, sodium, chloride, potassium, magnesium, and in selected cases glycogen. No significant effects of bedrest with either a regular diet or semistarvation were observed. Surgical injury caused an increase in muscle water, sodium, and chloride while there was a slight reduction in potassium in all groups, with the exception of those colectomy patients who received no amino acids after operation. There was no effect of varying the level of nitrogen intake in the colectomy patients, nor was there an effect of different hypocaloric infusions, in the hip replacement patients. The colectomy patients on admission to the hospital, showed some signs of prior nutritional depletion. After receiving four days of preoperative nutrition, there was a decrease in extracellular water, in sodium and chloride towards normal values. Following injury, there was an increase in muscle water, sodium and chloride, while potassium decreased slightly. In the postoperative period there were only minimal effects of nutritional intake on the observed changes.

Bed Rest↗
PubMed1981

Energy expenditure, nitrogen balance, and norepinephrine excretion after injury.

In this study we examine the effect of different hypocaloric nutritional regimens on nitrogen balance in patients following total hip replacement and compare it to that of normal subjects on strict bed rest. The interrelationship between nitrogen balance, energy expenditure, and urinary free norepinephrine excretion is analyzed with emphasis on the effects of nutrition on these relationships. Amino acid infusions following major elective orthopedic surgery had no nitrogen-sparing effect above that of 5% dextrose. Optimum nitrogen balance was obtained by administration of both 5% dextose and 3.5% amino acids. Patients receiving 5% dextrose showed no increase in resting energy expenditure in postoperative period compared to the preoperative control value. However, patients receiving amino acid infusions showed a 14% rise in energy expenditure postoperatively. Failure to administer 5% dextrose was associated with a high urinary norepinephrine excretion postoperatively. In normal subjects on bed rest either 5% dextrose or total starvation resulted in a marked fall in resting energy expenditure, whereas amino acid infusions isocaloric to the carbohydrate intake prevented any fall in resting energy expenditure. Nitrogen balance was improved with amino acid infusions in normal subjects. This study suggests the effect of amino acid infusions is highly dependent on the metabolic state of the patient.

Adult↗
PubMed1980

Muscle and plasma amino acids after injury: hypocaloric glucose vs. amino acid infusion.

This study examines the effect of three different hypocaloric diets on the patterns of muscle and plasma amino acids in patients undergoing total hip replacement. Group I (seven patients) received 90 g/day of glucose, Group II (seven patients) received 70 g/day of amino acids, Group III (eight patients) received both 90 g of glucose and 70 grams of amino acids per day. Utilizing the percutaneous biopsy technique of Bergström, free amino acid patterns in muscle and plasma were analyzed pre- and postoperatively (day 4). The postoperative pattern of amino acids was characterized by elevated levels in muscle and plasma of the branched chain amino acids, phenylalanine, tyrosine and methionine. There was a marked decrease in muscle glutamine and smaller decreases in the basic amino acids in both muscle and plasma. Muscle:plasma concentration ratios increased for the neutral amino acids, decreased for glutamine and the basic amino acids and were unchanged for the acidic amino acids. The patterns seen after hip replacement are almost identical to those seen after colectomy or accidental injury. There was little effect of diet on amino acid concentrations in muscle. In plasma, concentrations of leucine, isoleucine, valine and proline were higher in Group II in the absence of glucose intake, than in the other groups. Lysine was lower in Group I with no amino acid intake than in the other groups. Thus, there is a unique amino acid pattern associated with operative trauma which is relatively unaffected by hypocaloric, intravenous nutrition.

Amino Acids↗
PubMed1980

Muscle and plasma amino acids following injury. Influence of intercurrent infection.

The present study was undertaken to determine intracellular amino acid patterns in patients with multiple trauma, whether or not complicated by sepsis and during convalescence. A percutaneous muscle biopsy was performed three to four days following major accidental injury in ten patients and analyzed for muscle free amino acids. Venous blood was drawn at the time of the biopsy and analyzed for plasma free amino acids. Five patients developed sepsis and a repeat biopsy was performed on days 8 to 11. In five of the patients a biopsy was performed during the late convalescent period (anabolic phase). A marked depletion of nonessential amino acids in muscle occurred in both injury and sepsis due to a decrease (50%) in glutamine, which was equally marked in both states. The essential amino acids in muscle increased in injury. During sepsis, a further increase was observed with a return toward normal in the convalescent period. In injury, the most marked rise was in the branched-chain amino acids, phenylalanine, tryosine and methionine. With sepsis, a further rise in muscle branched-chain amino acids, phenylalanine and tryosine occurred, while plasma levels remain unchanged. During convalescence, muscle glutamine, arginine, histidine and plasma branched-chain amino acids were below normal, whereas muscle phenylalanine and methionine were elevated. The muscle free amino acid pattern observed after major trauma was essentially the same as earlier described following elective operation. This suggests a common response of intracellular amino acids irrespective of the degree of injury, and may indicate that the pump settings which regulate amino acid transport follow the "all or none" rule. The high intracellular levels of branched-chain amino acids in sepsis suggest that the energy deficit of this state is due to an impairment of substrate use rather than intracellular availability. The high concentrations of the aromatic amino acids and methionine may be due to altered liver function. During the late convalescent period (anabolic phase) the low levels of certain key amino acids suggests inadequate nutrition. The difficulties in nourishing the injured or septic patient are well recognized. The period following these catabolic states may be an important period for the application of an optimal, aggressive nutritional regimen.

Abdomen, Acute↗
PubMed1980

Increased body temperature secondary to total parenteral nutrition.

Administration of total parenteral nutrition (TPN) (glucose/amino acids), on the 2nd day after surgery, to a 26-year-old male with multiple fractures resulted in a rise in rectal temperature from 37.6 to 39 degrees C. Resting energy expenditure showed a sustained 23% increase when the nutritional intake was changed from 5% dextrose to TPN. This case demonstrates that the increased metabolic rate associated with administration of TPN in acutely injured patients may be associated with an increase in body temperature.

Adult↗
PubMed1979

Changes in metabolism and muscle composition associated with total hip replacement.

Metabolic changes in 10 patients undergoing total hip replacement were studied. Metabolic expenditure postoperatively remained within 5--10% of preoperative values. Net nitrogen loss for the postoperative period was less than 35 gm for the first 4 postoperative days, well below changes seen in major nonsurgical trauma. Fluid balance was positive in all patients for the first 4 postoperative days. Patients not in negative fluid balance by the fourth postoperative day should be closely monitored for complications. Recognition of delayed fluid excretion is essential in order to avoid the complications of further fluid loading in the postoperative period. Muscle composition reveals predictable changes in extracellular water, sodium, and chloride composition following surgery. Our data showed that metabolic changes following total hip replacement are in the order of major general surgical procedures and well below that observed with major trauma.

Adult↗
PubMed1979

Sciatic paralysis. A complication of bleeding following hip surgery.

Of five patients in who sciatic paresis developed as the result of hemorrhage and hematoma following hip surgery, four were receiving prophylactic or therapeutic anticoagulants. The patient who was managed expectantly still had disabling motor and sensory deficity at follow-up. Three patients who had early operative decompression showed more complete return of nerve function. The fifth patient died three weeks after onset with the neuropathy still present. Severe low-back and buttock pain, ecchymosis over these regions, marked swelling in the thigh, sciatic-nerve tenderness, and a distal sciatic neural deficit in the ipsilateral lower limb of a patient who has had hip surgery are evidence of hemorrhage in the vicinity of the sciatic nerve. Early recognition and prompt surgical decompression can prevent irreversible nerve damage.

Adolescent↗