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Biomedical subjects

C N Cornell

Publications and source records attributed to C N Cornell.

At least 37 records · Page 2Linked to original sources
PubMed1991

Multicenter trial of Collagraft as bone graft substitute.

Collagraft (Zimmer and Collagen Corporation) consists of a mixture of porous beads composed of 60% hydroxyapatite and 40% tricalcium phosphate ceramic and fibrillar collagen. When mixed with autogenous bone marrow, it serves as an effective bone graft substitute. Since September 1986, this material has been used in a multiclinic prospective trial, randomized against cancellous iliac crest autografts in the treatment of long bone fractures. To date, 267 patients have entered this study with 128 patients receiving cancellous autograft and 139 patients receiving Collagraft. At 6- and 12-month follow-ups, Collagraft appears to function as well as autogenous graft when used in the treatment of acute long bone fractures.

Adolescent↗
PubMed1990

Management of fractures in patients with osteoporosis.

The treatment of the most common osteoporotic fractures has been reviewed. In general, early functional treatment is used to allow early restoration of function and weight bearing. Fracture treatment should always be accompanied by an investigation of the bone mass in these patients. Nutritional support and calcium and vitamin supplementation should be provided during the healing phase.

Aged↗
PubMed1988

Quantification of osteopenia in hip fracture patients.

Osteopenia was assessed in 56 consecutive hip fracture patients by using dual photon absorptiometry of the lumbar spine and uninjured, contralateral femoral neck and by performing iliac crest biopsy. Of the 56 patients, 47 were female and 9 were male. The mean age was 78 years. There were 31 femoral neck and 25 intertrochanteric fractures. Two comparison populations were also studied. Population 1 consisted of 269 postmenopausal females older than 60 years of age with no history of fracture who were referred for dual photon absorptiometry of the lumbar spine as screening for osteoporosis. Population 2 included 94 patients with vertebral compression fractures who underwent transilial biopsy to evaluate osteoporosis. All transilial biopsies were assessed with the use of quantitative histomorphometry. Dual photon absorptiometry of the lumbar spine indicated that 76.9% of the hip fracture patients had severe bone loss (less than 1 gm/cm2). Nevertheless, no difference in spinal bone density was found when the hip fracture patients were compared to population 1. No difference in density of the lumbar spine or femoral neck was found in patients in the hip fracture group when intertrochanteric and femoral neck fractures were compared. No difference in histomorphometric measurements of total bone, cortical bone, and cancellous bone volume was noted between the hip fracture patients and population 2. There was no difference noted when the intertrochanteric and femoral neck fracture patients were compared. No evidence of osteomalacia was noted in any group.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Long-term follow-up of total hip replacement in patients with avascular necrosis.

Long-term studies show that patients with osteonecrosis who undergo total hip replacement experience an overall failure rate four times greater than those with osteoarthritis. Different etiologic factors associated with osteonecrosis appear to carry different prognoses for the durability of total hip replacements. Important factors, in addition to discouraging total hip replacement in patients under 30 to 40 years of age and making all possible efforts to decrease the patient's weight and activity level, include improvements in bone quality, surgical and cementing techniques, prosthetic design, and materials that will prolong the durability of total hip replacements. Despite the inferior long-term results of total hip replacement performed for advanced osteonecrosis, we feel the procedure should not be abandoned for patients in their fifth decade of life or older because it provides a painless, functional hip more consistently than does any other form of arthroplasty. These patients should be informed about the importance of protecting the hip replacement by avoiding strenuous activities, impact, and obesity, and about the possibilities of future mechanical failure that may require revision surgery. Although significant improvements have been made in regard to the technology of total hip replacement, future research in the bone biology of osteonecrosis is necessary.

Adult↗
PubMed1987

Osteoporosis: the structural and reparative consequences for the skeleton.

We have discussed the biomechanical and biomaterial properties of bone with emphasis on the microenvironment. The microdensity of bone tissues determines the resistance to compressive forces (strength = density2). The structural orientation of bone determines the ability of bone to withstand torsion and bending forces. Highly remodeled bone is brittle and fractures easily because of the multiple reversal planes within the bone plates. Conversely, augmentation of bone on the periphery by modeling leads to increased material microstrength and structural macrostrength. Consequently, appositional modeling augments whereas remodeling diminishes bone strength. Hip fractures, spinal fractures, Colles' fractures, and pelvic fractures have been discussed in terms of their pathophysiology and treatment. An algorithm (Fig. 4-7) has been presented for the differential diagnosis of patients with recently discovered spinal compression fractures. Lastly, a discussion of exercise demonstrated its beneficial role, especially in the retention of bone mass.

Biomechanical Phenomena↗
PubMed1986

A clinical and radiographic analysis of loosening of total knee arthroplasty components using a bilateral model.

Patients undergoing bilateral, simultaneous total knee replacement provide a unique opportunity to study the role of operative techniques in the development of radiolucent lines because variables such as age, sex, weight, diagnosis, and bone quality are internally matched when the result on one side is compared with that of the other. This allows more conclusive examination of operative factors, such as component alignment, level of tibial bone resection, and cement handling. With this as the objective, the clinical and radiographic results of the first 50 bilateral total knee replacements performed by the senior author were studied. Postoperative alignment was found to influence significantly the incidence of tibial radiolucent lines. Use of cement to reconstruct defects in the proximal tibia resulting from preoperative deformity consistently led to the development of radiolucent lines in the area of the defect. There was also indirect evidence that failure to achieve an intimate microinterlock at the bone-cement interface may play a major role in the development of tibial radiolucent lines.

Adult↗
PubMed1986

The impact of modern cement techniques on acetabular fixation in cemented total hip replacement.

A radiographic study was performed to assess acetabular fixation in 78 total hip replacements performed between 1971 and 1980. In 1979, the technique of acetabular component insertion was modified to include water-pik lavage, preservation of subchondral bone of the acetabulum during reaming, multiple fixation holes in the pubis ischium and ilium, and devices that improve pressurization of the cement into the cancellous bone surfaces. The impact of these techniques was studied. A cumulative radiolucency score was calculated for each acetabulum from 5-year follow-up radiographs, and the mean cup radiolucency scores for two chronologic groups were compared using the t-test for independent samples. No significant differences in patient age, weight, or sex, type of prosthesis, or approach used was found between groups. The acetabular components inserted between 1979 and 1980 had significantly lower cup radiolucency scores than those inserted between 1971 and 1978, at 5-year follow-up evaluation. Modern cement technique may be responsible for significantly enhanced durability of acetabular fixation in cemented total hip replacement.

Acetabulum↗
PubMed1986

Survivorship analysis of total hip replacements. Results in a series of active patients who were less than fifty-five years old.

Between 1971 and 1980, the senior one of us (C.S.R.) performed 101 primary total hip replacements in eighty-five consecutive patients who were less than fifty-five years old. All of the patients had degenerative joint disease. Survivorship analysis was used to calculate a predicted cumulative rate of success for this series of total hip replacements over ten years of follow-up. This method of analysis of the data was chosen because it provides a prediction of the expected durability of a total hip arthroplasty in any individual patient. The need for revision because of loosening or infection or else radiographic evidence of migration of a component was the criterion for failure. Two revisions were performed for aseptic loosening of the acetabular component. One infection necessitated revision, and radiographic evidence of loss of fixation was seen in one additional acetabular component and one femoral stem. Life-table calculations predicted that the survivorship of all of the total hip replacements in this series would be 87.6 per cent at ten years of follow-up. Based on the results of the application of this method of analysis to the current series, we concluded that a primary cemented total hip replacement, when performed for coxarthrosis, can be expected to function durably in an active middle-aged patient.

Actuarial Analysis↗
PubMed1985

Healing of ischemic colonic anastomoses in the rat: role of antibiotic preparation.

In this study we evaluated the relative effects of ischemia with and without antibiotic bowel preparation on colonic wound healing. Thirty-two Sprague-Dawley rats (185 to 300 gm) were divided into five study groups: Groups I and II (n = 14) had no colonic ischemia, half receiving antibiotic bowel preparation before colocolostomy. Groups III, IV, and V (n = 18) had colonic ischemia induced by division of the marginal artery and ligation of the arteries to the splenic flexure and pelvic colon, assuring that all blood supply to the left side of the colon was intramural. Enteral (neomycin and erythromycin) antibiotic preparation was given in group III, no antibiotics were given in group IV, and parenteral (clindamycin and gentamicin) preparation was given in group V. The mid-left side of the colon was transected and an everting anastomosis was constructed with continuous 6.0 silk sutures. All animals were killed on the seventh postoperative day. Anastomotic healing in unprepared, ischemic rat colon was severely impaired, with an 83% dehiscence rate. In the colon prepared with enteral antibiotics, no adverse effect of ischemia was found. No animal had dehiscence, proximal dilation of the colon, or intra-abdominal abscess. This study may have clinical relevance in patients with ischemic intestinal disorders.

Administration, Oral↗
PubMed1985

Long-term follow-up of total hip replacement in patients with osteonecrosis.

Patients with osteonecrosis who undergo total hip replacement experience an overall failure rate four times greater than that of patients with osteoarthritis who undergo the procedure. Different etiologic factors associated with osteonecrosis appear to carry different prognoses for the durability of total hip replacements. In addition to discouraging total hip replacement in patients under 30 to 40 years of age and making all possible efforts at reduction of the patient's weight and activity, improvement of bone quality, surgical and cementing techniques, prosthetic design, and materials will prolong the durability of total hip replacement. Despite the inferior long-term results of total hip replacement performed for advanced osteonecrosis, we believe the procedure should not be abandoned for patients in their fifth decade or older because it provides a painless, functional hip more consistently than any other form of arthroplasty. These patients should be informed about the importance of protecting the hip replacement by avoiding strenuous activities, impact, and obesity and about the possibilities of future mechanical failure, requiring revision surgery.

Adult↗
PubMed1979

Videothermometry for assay of fescue foot in cattle.

Surface temperatures of hoofs of calves given toxic anion fractions of tall fescue were measured with an infrared sensitive camera. These changes expressed in terms of a weighted average coronary band temperature relate to clinical signs of fescue foot. The weighted average coronary band temperature values for control calves given saline solution were 27 to 31 C; those values of test calves given anion fractions of tall fescue were as low as 22 +/- 1 C. Videothermometry provides an independent, permanent, objective measure that is useful in assessing fescue-foot potential of tall fescue fractions by intraperitoneal injection. Videothermometry may also serve as a clinical means for determining progression of the total fescue foot syndrome.

Animals↗
PubMed1978

Spin-label studies of the sulfhydryl environment in bovine plasma albumin. 1. The N--F transition and acid expansion.

The environment of the sulfhydryl group in plasma albumin was previously characterized by employing spin-labels of varying chain lengths (Hull, H. H., Chang, R., & Kaplan, L. J. (1975) Biochim. Biophys. Acta 400, 132). It was established that the sulfhydryl is in a crevice approximately 10 A deep but this crevice was not identified further. We now report the results of titrating albumin through the acidic conformational transitions while monitoring the electron-spin resonance of the bound nitroxide. With short spin-labels a general change is observed as the pH is lowered but the N--F transition is not discernible. However, with a spin label previously shown to project to the lip on the crevice a clear N--F transition as well as the subsequent acid expansion are observed. These results indicate that the sulfhydryl is in the crevice, formed by the domains of albumin, which opens during the N--F transition. Further results indicate that bound fatty acids do not influence the integrity of the sulfhydryl environment at neutral pH.

Chemical Phenomena↗
PubMed1978

Spin-label studies on the sulfhydryl environment in bovine plasma albumin. 2. The neutral transition and the A isomer.

Since we were able to demonstrate that the sulfhydryl group is located in the crevice which opens during the N--F transition (Cornell, C. N., & Kaplan, L. J. (1978) Biochemistry 17 (preceding paper in this issue), the investigation was extended by characterizing the environment during the N--B transition and in the A isomer. The results indicate that the N--B and N--F transitions are very similar in that the sulfhydryl group moves from a restricted to unhindered environment during both. The use of molecular dipstick technique further demonstrated the similarity between the F and A forms. However, since A is a covalently stabilized form of albumin after a pH dependent transition, it retains its properties during subsequent pH changes rather than reverting to the N form. We were thus able to titrate spin-labeled A through the pH range of the acidic transitions without detecting the N--F transition. Isoelectric focusing analysis of A generated during alkaline aging and purified by SP-Sephadex chromatography indicates that it is a mixture of a small number of albumin forms rather than the large number of components once thought to be formed during aging.

Chemical Phenomena↗