Search PubMed⌕ Search

Biomedical subjects

C L Nelson

Publications and source records attributed to C L Nelson.

At least 145 records · Page 8Linked to original sources
PubMed1981

Condylectomy for temporomandibular joint dysfunction. A survey of seventeen postoperative patients.

Seventeen patients were asked to make a subjective evaluation of their condition after having had a mandibular condylectomy performed. Fourteen of seventeen felt that the surgical procedure had cured their symptoms of pain and limitation of motion. Surgical procedures on the temporomandibular joint are valid when there is organic disease of the temporomandibular joint. However, care must be taken to differentiate between organic disease and the so-called myofascial pain dysfunction syndrome, since surgery is considered inappropriate for the myofascial pain dysfunction syndrome. Even in cases of organic joint disease, care must be taken to identify any existing emotional problems that the patient may have. In cases of organic joint disease with strong psychological overtones, surgical intervention alone may not be enough to relieve the patients of their temporomandibular joint symptoms.

Adult↗
PubMed1981

The role of incompetence of the anterior cruciate and lateral ligaments in anterolateral and anteromedial instability. A biomechanical study of cadaver knees.

UNLABELLED: The anterolateral and anteromedial stability of seventeen fresh frozen cadaver knees was studied in a test apparatus designed to simulate physiological conditions. Statistically significant increases in internal rotation occurred in seven knees when only the anterior cruciate ligament was sectioned, and these increases were enhanced by subsequent sectioning of the posterolateral complex and the lateral collateral ligament, singly or in combination. On the other hand, sectioning of the posterolateral complex and of the lateral collateral ligament, leaving the anterior cruciate intact, did not produce significant increases in internal rotation until the anterior cruciate ligament was sectioned in seven knees. When the entire anterolateral capsule was sectioned as far posterior as the lateral collateral ligament in three knees, no changes in internal or external rotation occurred. Only when the posterolateral complex was sectioned was there a significant increase in external rotation in any of the ligament-sectioning sequences. Thus, it appears that for pathological internal rotation of the tibia on the femur to occur, the anterior cruciate ligament must be incompetent. CLINICAL RELEVANCE: The test apparatus and the results are useful in assessing which ligament structures contribute to clinically noted rotational knee instabilities.

Biomechanical Phenomena↗
PubMed1980

Passive paw anaphylaxis in the rat. Optimum conditions for use in studies on immediate hypersensitivity.

The difficulties involved in quantitating passive cutaneous anaphylaxis led us to examine the rat paw as a site for passive anaphylaxis and to define optimum conditions for passive paw anaphylaxis. Generation of homocytotropic antibodies in a number of different rat strains revealed that female Brown Norway rats were excellent producers of high titre antisera after only a single injection of antigen and Bordetella pertussis. Injection of ratpaws with diluted antisera followed by short (1-2 h) or long (72 h or more) sensitization periods showed that maximum paw swelling occurred 15 min after antigen challenge. Retention of tissue sensitizing capacity in the paw for greater than 35 days but loss of this capacity following heating of antiserum at 56 degrees C, indicated that the rat homocytotropic antibodies involved in passive paw anaphylaxis belong to the IgE class. Experiments using mepyramine, methysergide and diethylcarbamazine showed that 5-hydroxytryptamine is the most important mediator of passive paw anaphylaxis after both a short (2 h) and a long (72 h) sensitization procedure. Passive paw anaphylaxis in the rat is at least as easy to perform as passive cutaneous anaphylaxis, results can be obtained more rapidly and accurate measurement of paw thickness is not difficult. The procedure is a viable alternative to passive cutaneous anaphylaxis and may offer advantages over the latter method especially in the search for, and rapid assessment of, anti-allergic compounds.

Animals↗
PubMed1980

Efficacy of various forms of fixation of transverse fractures of the patella.

To determine whether any of the commonly used wiring techniques are rigid enough to allow early motion in the treatment of transverse fracture of the patella, the patellae of twenty-five fresh cadaver knees were fractured transversely and fixed using the following techniques: circumferential wiring, tension-band wiring, Magnusson wiring, and a modification of tension-band wiring. The knees were mounted in a machine capable of measuring quadriceps force, flexion angle, and fracture separation simultaneously. The knees were extended from 90 to zero degrees by applying tension to the quadriceps tendon with the force of gravity as the only resistance, and separation of the fracture fragments was measured first with the retinaculum unrepaired and then again with the retinaculum repaired. Separation of the fracture fragments was much less with the Magnusson wiring and modified tension-band wiring than with circumferential wiring or standard tension-band wiring. The retinacular repair was found to contribute to stability; however, this seemed most important in the less rigid repairs. We concluded that if early motion is to be used in treating transverse fractures of the patella, techniques in which the wire is anchored directly in bone should be used and the retinaculum should be repaired.

Cadaver↗
PubMed1980

Device and method for controlling cement thickness.

The ideal thickness of cement between the prosthesis and bone has not been accurately determined, but there is general agreement that the surgeon should be able to provide and accurately produce a certain thickness of cement between the prosthesis and the bone. Conventional cementing technique could allow the surgeon to ovepush the cup into direct contact with the bone producing a very thin cement coat or a void. We have developed a simple method of achieving a predictable thickness. We insert small spacers made of methylmethacrylate, which can be placed between the bone of the acetabulum and the acetabular component, preventing voids or thin areas in the cement coat. The device has been used in over 50 patients and has proven to be a simple and reliable method of allowing the surgeon to produce a predictable thickness of cement surrounding a joint replacement component. An additional benefit obtained from the use of these spacers is the ability to rigidly hold the acetabular component during polymerization of the acrylic without fear of overpushing. This allows better packing of the bone cement and prevents imperfections caused by the cup contacting the bone.

Acetabulum↗
PubMed1979

Environmental bacteriology in the unidirectional (horizontal) operating room.

The continuing attempts to reduce bacterial contamination through clean air systems have been of special interest to surgeons dealing in joint replacement surgery. Although the definitive relationship between airborne contamination and surgical infections is not universally agreed on, there is little question that clean air systems reduce bacterial contamination of the surgical wound at the time of operation. This report reviews the history of surgical infections, presents statistical data that show the reduction of bacterial contamination by a clear air system, and suggests a pragmatic attitude regarding airborne bacterial contamination of surgical wounds.

Air↗
PubMed1979

Experimental reaming of the proximal femur and acrylic cement implantation: vascular and histologic effects.

The technique of microangiography and correlated histology was used, in experiments on the proximal femora of mature mongrel dogs, to study the effects of simple medullary reaming and of reaming followed by insertion of acrylic cement. The hip joints were not disturbed. A segment of Steinmann pin, representing the stem of a hip prosthesis, was inserted into the cement as it was polymerizing. The most significant results, after reaming alone, were devascularization and apparent necrosis of large areas of the cortex of the subtrochanteric femoral diaphysis. Full recovery was observed in 6 months. However, when acrylic cement was introduced following the reaming, extensive necrosis of the inner layers of the diaphyseal cortex was still present after a year, when the observations were terminated. The presence of necrosis of bone was judged by the lack of visible osteocytes in the lacunae. After the devascularization caused by filling the diaphyseal medulla with acrylic cement, the apparently necrotic cortex was revitalized without osteoclasia. That is in contrast to the results in another study in which osteoclasia and osteoneogenesis were required to restore cortex with empty cell lacunae. This raises the question of dormant osteonecrosis in contrast to total osteonecrosis. These studies show, in thin histologic preparations, acrylic bone cement in situ in the tissues. A fibrous membrane was found at the cement-bone interface in most areas. It was thicker in the diaphysis than in the metaphysis. The physiologic effects of acrylic cement implantation are considered to be likely factors in the loosening which is observed clinically when the femoral components of hip prostheses are under protracted stress.

Acrylic Resins↗
PubMed1978

Concentration of antibiotics in normal bone after intravenous injection.

The concentrations in serum, cancellous bone, and cortical bone of three antibiotics--nafcillin, cefazolin, and gentamicin--were measured in eleven normal dogs. All antibiotics rapidly penetrated into bone. The peak concentration in serum was reached within twenty minutes of intravenous injections, and the concentration in bone generally paralleled that in serum. Cancellous bone had higher concentrations than did cortical bone because of the admixture of blood.

Animals↗
PubMed1977

Current status of total knee replacement.

Correction of deformity and relief of pain in advanced arthritis of the knee joint can be obtained by implantation of a total knee prosthesis. For the painful, mildly damaged knee, the Charnley prosthesis may be used, while in the more moderately damaged knee, the geometric prosthesis may be indicated. For the unstable, severely damaged knee, a constrained prosthesis may be implanted. These knee prostheses can be used to treat knees which previously were not amenable to surgical correction, except by arthrodesis.

Humans↗
PubMed1977

Supracondylar fractures of the humerus: the role of dynamic factors in prevention of deformity.

In a retrospective survey of eighty-two children with supracondylar fractures of the humerus, forty were found to have sufficient clinical and roentgenographic data to classify the fractures as varus or valgus, and to determine the carrying angles at end result. The initial displacement (varus or valgus) of the distal fragment correlated with the final carrying angle, but the use of internal fixation, the adequacy of reduction achieved and the duration of traction or immobilization did not. The sixteen varus supracondylar fractures immobilized with the forearm in supination had a mean varus deformity of about 16 degrees, whereas the eight immobilized in pronation had a varus deformity of only 3 degrees. The findings in the few valgus fractures suggested that the valgus angulation was less at follow-up if they had been immobilized in supination. Dissection of eight cadaver limbs and electromyographic studies of one normal limb suggested that the position of the forearm affects the result by altering muscle tension.

Adolescent↗
PubMed1976

Mechanical strength of acrylic bone cements impregnated with antibiotics.

Admixing of several antibiotic powders which were insoluble in methyl methacrylate did not decrease the compressive and diametral tensile strengths of two acrylic bone cements when tested after setting for 1 day and after leaching 40 days in water at 37 degrees C. When antibiotics were added as water solutions, the included water resulted in a significant decrease in these bulk mechanical properties. Storage in water for 40 days caused surface irregularities only on specimens of the set antibiotic admixtures. Approximately 0.5% of the admixed dosage of these water-soluble antibiotics could be leached from the set cements. The observed surface channels, presumably left by the loss of antibiotic, suggest further study of surface-sensitive mechanical properties may be needed. The bulk mechanical strengths presented here are conclusive only for the particular combinations of antibiotics and cements investigated, and should not be generalized at this time to any or all antibiotic admixtures or other mechanical properties.

Anti-Bacterial Agents↗
PubMed1976

Antibiotic-impregnated acrylic bone cement.

In vitro and in vivo experiments were performed to study the antibacterial and mechanical properties of Simplex and Palacos acrylic bone cements utilized for the production of acrylic cement-antibiotic composites. Acrylic cement without antibiotic had no bacteriostatic effect on Staphylococcus aureus, Escherichia coli, and Pseudomonas. Oxacillin, cefazolin, and gentamicin are stable in acrylic cement and are released in a microbiologically active form. The three antibiotics diffused from the Palacos in larger amounts daily and for a significantly longer time than from the Simplex. Mechanical tests demonstrated that admixture of antibiotics and acrylic cement had no influence on the compressive and diametral tension strengths of the cement. Bacteriostatic concentrations of oxacillin in wound hematomas were measured for fourteen days after implantation of an oxacillin-Simplex composite in dogs. High bactericidal concentrations of the antibiotic were measured in the surrounding bone for twenty-one days after implantation.

Animals↗