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Biomedical subjects

J H Calhoun

Publications and source records attributed to J H Calhoun.

At least 55 records · Page 3Linked to original sources
PubMed1992

Techniques for the management of burn contractures with the Ilizarov Fixator.

The Ilizarov fixator was used to correct chronic burn deformities of the foot and ankle. These contractures can be classified as "simple" or "complex" based on associated deformities and musculoskeletal function. The simple, undirectional deformities of equinus, cavus, rockerbottom, and toe dislocations are fairly easy to correct and maintain. Correction and maintenance of complex deformities with varus or valgus angulation, bone abnormality, or muscle loss are more difficult.

Burns↗
PubMed1992

Biomechanics of the Ilizarov fixator for fracture fixation.

Compression, distraction, and torsion stiffness of the Ilizarov external fixator was measured in two fracture models in autopsy specimens of tibia and fibula. A transverse model was tested in six frame constructions with the osteotomy site preloaded in four different positions. An oblique model was tested in four frame constructions also with four preloaded positions. Stiffness was more dependent on bone preload than wire number, wire type, or frame design. High stiffness was achieved by bone preloading, by compressing the rings together, by increasing the number of wires, and by using olive wires. The stiffness can be decreased (dynamization) by separating the rings and by removing wires. This data is helpful for frame design of the Ilizarov fixator.

Biomechanical Phenomena↗
PubMed1991

The Ilizarov technique in the treatment of osteomyelitis.

Seventy-five patients with bone infection have been treated at The University of Texas Medical Branch at Galveston (UTMB) with the Ilizarov external fixator. Multiple deformities were present in many patients. Thirty-four patients had infected nonunions, 22 were short, 18 were angulated, 15 needed joint fusions, 12 had open fractures, 10 had segmental defects, 5 had knee problems and equinus deformities, 4 had rotational problems, 2 had hip problems, and 1 had a translational problem. The average number of deformities per patient was 1.71. Problems with the device include length of therapy (6.8 months average time in device), pin tract infection (superficial, 41.3%; deep, 2.7%), pain (narcotic use, 2.7 months average), and device adjustment. Successful results were obtained in a high percentage of cases. The infection was arrested in 92.0% of the patients and the deformities were corrected in 85.1%. We found that the Ilizarov fixator was effective in the reconstruction of difficult deformities that result from osteomyelitis.

Adult↗
PubMed1991

Does hyperbaric oxygen have a place in the treatment of osteomyelitis?

There are several specific mechanisms by which HBO restores normal cellular processes that are compromised by hypoxia, or by which HBO augments bactericidal events. All of these are potentially applicable to, and beneficial for, the osteomyelitis patient. At the University of Texas Medical Branch, we find that early osteomyelitis is usually amenable to appropriate medical and surgical therapy. Adjunctive HBO is generally reserved for treatment of advanced stages of osteomyelitis (3B and 4B). In addition, HBO is occasionally used when patient circumstances dictate suppression of osteomyelitis rather than definitive treatment. Our clinical impression is that HBO has a beneficial effect on treatment outcome in these selected patients. Fault-free clinical studies are difficult to perform in this complex and varied patient population. Several studies have suggested a beneficial effect with the addition of adjunctive hyperbaric oxygen to usual osteomyelitis treatment regimens, whereas other clinical studies have failed to demonstrate such a benefit. No study has shown any harmful effect of adjunctive HBO on the outcome of osteomyelitis treatment. We hope that clinical researchers will continue to address this question, despite the research design problems inherent in the osteomyelitis population.

Clinical Trials as Topic↗
PubMed1990

Treatment of manifest latent nystagmus.

Eight patients with manifest latent nystagmus, as noted by ocular movement recordings, were examined for nystagmus reduction after surgical or optical treatment. Seven of the patients had strabismus. Five patients underwent strabismus surgery, had no tropia postoperatively, and the manifest latent nystagmus converted to latent nystagmus. Four of these five patients subsequently showed improvement in binocular visual acuity. Three patients received optical treatment; one had accommodative esotropia and, with appropriate spectacle correction, the manifest latent nystagmus was converted to latent nystagmus with improved vision. In the other two patients the manifest latent nystagmus lessened after correction with appropriate spectacles; binocular visual acuity of one of these patients improved. The possibility of converting manifest latent nystagmus to latent nystagmus by strabismus surgery is a reasonable surgical goal. In patients with manifest latent nystagmus and strabismus, surgical or optical alignment of the eyes decreases the nystagmus intensity and may also improve binocular visual acuity.

Adolescent↗
PubMed1990

Signs distinguishing spasmus nutans (with and without central nervous system lesions) from infantile nystagmus.

Clinical findings as well as eye and head movement recordings were analyzed from 23 patients with spasmus nutans without central nervous system (CNS) changes, 10 patients with spasmus nutans-like disease (head nodding, intermittent nystagmus associated with intracranial anomalies or visual pathway disorders), and 25 patients with infantile nystagmus. Ten diagnostic signs were established to differentiate between the patient groups. Although they were helpful in separating patients with infantile nystagmus from those with spasmus nutans, no difference was found between the patients with spasmus nutans with and without CNS lesions. This study indicates that eye and head movement recordings do not allow differentiation between benign spasmus nutans and spasmus nutans-like disease. The differentiation must be made on the basis of neuroimaging.

Child↗
PubMed1990

Hyperbaric oxygen as adjunctive therapy for osteomyelitis.

Mechanistically, hyperbaric oxygen (HBO) appears useful for the treatment of osteomyelitis. HBO increases the oxygen tension in infected tissue, including bone. An adequate oxygen tension is necessary for oxygen-dependent killing of organisms by the polymorphonuclear leukocytes and for fibroblast activity leading to angiogenesis and wound healing. HBO has a direct bacteriocidal or bacteriostatic effect on anaerobic organisms. In addition, HBO augments the killing of Pseudomonas aeruginosa by the aminoglycoside--tobramycin. At the University of Texas Medical Branch at Galveston, adjunctive HBO is used for the Cierny Mader stage 3B and 4B osteomyelitis.

Animals↗
PubMed1989

The effect of local controlled release of sodium fluoride on the stimulation of bone growth.

This study was performed to test the feasibility of using a biodegradable delivery system for the local controlled release of sodium fluoride as a mechanism for the stimulation of local bone growth. Sodium fluoride grains were mixed with poly-DL-lactic acid (PLA), and the mixture was then dissolved in acetone. After driving off the solvent, sheets of this material were rolled into rods 3.2 mm in diameter and 28.6 mm long. These were inserted into the intramedullary canals of the right femora of adult New Zealand White rabbits. A sham implant, made the same way but containing no fluoride, was inserted into the contralateral left leg. The effects of three different concentrations of sodium fluoride, 0.125 g NaF/g PLA, 0.250 g NaF/g PLA, and 0.500 g NaF/g PLA, were determined after a 4-week implantation period. In a second set of experiments, the concentration was fixed at 0.500 g NaF/g PLA with implantation durations of 4, 8, and 16 weeks. Expressed in terms of property ratios (experimental/control), bending strengths of the femora were significantly raised in most groups with the notable exception of Group 3 (0.500 g NaF/g PLA, 4 weeks). Cross-sectional area ratios in the distal femora were increased in all groups compared to right/left values for a normal unoperated group (p less than 0.05), with the highest ratio being 1.50 (SD = 0.44) for Group 4 (0.500 g NaF/g PLA, 8 weeks). Only Group 4 animals showed significant (p less than 0.05) increases in midshaft area ratio and none had responses proximally. Growth rates, measured by sequential fluorochrome labeling of bone followed the area ratio data and were only significant for the distal femora.

Animals↗
PubMed1989

Dynamic axial fixation for immobilization of cross-leg flaps in chronic osteomyelitis.

Free flaps are usually the first choice for soft tissue coverage in the distal leg. There continue to be, however, some clinical situations in which a cross-leg flap is the best choice. Use of the cross-leg flap has previously been limited by the difficulty of immobilizing both legs during the early healing stage (2 to 3 weeks). The traditional plaster immobilization or multibar external fixator system is time consuming to apply, difficult to adjust, cumbersome for nursing care, and uncomfortable for the patient. We have used the Orthofix external fixator to immobilize a cross-leg flap in 3 patients with refractory distal tibial osteomyelitis. The Orthofix dynamic axial fixator (DAF) is a single frame external fixator which, when used in a cross-leg fashion, is quick and easy to apply. It provides the necessary strength for immobilization and overhead suspension. It has few parts and is therefore lighter and less awkward both for the patient and nursing personnel and is easy to adjust on the ward or in the clinic. The DAF has two modes: locked (static) and released (dynamic). The locked mode can be easily adjusted to alter tension on the healing flap. As the flap matures the dynamic mode allows the frame to slide, decreasing muscle spasms and increasing flap movement. The DAF also provides better soft tissue access for flap observation and nursing care. Few transfixation pins are needed, decreasing the chance of pin tract infection. When a cross-leg flap is required, use of the DAF for immobilization circumvents many of the previous problems with both-leg immobilization.

Accidents, Traffic↗
PubMed1989

Complex fracture-dislocation of a fifth metacarpophalangeal joint: case report and literature review.

An uncommon complex fracture-dislocation of the fifth metacarpophalangeal joint with an unusually important fracture component is presented. The injury was successfully treated by a combination of open reduction exposing the entrapping structures and percutaneous pin fixation. The case demonstrated the classic pathomechanics as described by Kaplan in 1957. The widened joint space and interposed sesamoid as described by Nutter in 1940 were seen on radiographs.

Adult↗
PubMed1989

Treatment of high-pressure water gun injection injury of the foot with adjunctive hyperbaric oxygen: a case report.

High-pressure injection injuries are reported often in the hand and occasionally in the foot. Injection with water and air causes minimal tissue damage but nevertheless requires irrigation, minimal debridement, administration of antibiotics, and concern for development of compartment syndrome. The outcome for patients injected with water and air should be excellent. Adjunctive hyperbaric oxygen causes immediate resolution of subcutaneous emphysema, edema, and pain for more rapid rehabilitation.

Adult↗
PubMed1989

Long bone osteomyelitis. An overview.

Osteomyelitis has always been a difficult disease to classify, diagnose, and treat. Its etiology and course are not fully understood. A review of the traditional aspects of osteomyelitis is presented along with the discussion of a more recent classification system.

Humans↗
PubMed1989

Characteristics of successful and unsuccessful applicants to orthopedic residency training programs.

In 1985 there were 288 applicants for the ten postgraduate Year 1 orthopedic residency positions in Galveston and San Antonio, of which 119 (41%) applicants successfully obtained a residency position in one of 76 orthopedic programs approved by the Accreditation Council for Graduate Medical Education. Successful applicants were younger and had higher Medical College Admissions Test scores, National Board of Medical Examiners, Part I (NBME-I) scores, and medical school grade point averages than unsuccessful applicants. Variables that increased acceptance rates were medical student status, an NBME-I score above 500, class rank in the top 40%, and membership in Alpha Omega Alpha honor society. Foreign citizenship and prior residency experience in a different specialty strongly decreased acceptance rates. Variables that did not affect acceptance rates were: gender, military experience, marital status, graduate degree, research, publications, or NBME-II scores.

Adult↗
PubMed1988

Osteomyelitis of the mandible.

The presenting characteristics and clinical courses of 60 patients with mandibular bone infections are described. Fifteen of the patients had posttraumatic osteomyelitis, 13 had odontogenic osteomyelitis, and 28 had osteoradionecrosis. Most infections (93%) were polymicrobial, and anaerobes played an important role. Types of surgical procedures and use of adjunctive hyperbaric oxygen are described. There were minimal differences in presentation or response to treatment between these four different groups. A clinical staging system for mandibular bone infections is proposed and results of treatment are retrospectively analyzed by stage. The results support the concept that initial treatment planning can be safely and successfully based on the stage of the disease.

Anti-Bacterial Agents↗
PubMed1988

Extended-wear contact lenses for the treatment of pediatric aphakia.

The practicality of extended-wear contact lenses in the refractive correction of pediatric aphakia was assessed with 240 eyes in 184 patients. Patient ages at the time of contact lens fitting ranged from 18 days to 9.8 years. One hundred forty-one eyes were fit from 1 day to 55 months postoperatively and then followed for 6 months to 5.7 years (average, 29 months). Only five patients lost more than five lenses. The overall loss rate was less than one lens per year of follow-up. No patient had contact lens-related complications with permanent visual sequelae. Only 14% of patients had contact lens problems or factors related to parental inability to care for the lens which resulted in discontinuation of contact lens therapy. The authors were unable to identify any subset of patients who should be considered for primary surgical optical correction of their aphakia.

Aphakia, Postcataract↗
PubMed1988

Removal of the acetabular component minimizing destruction of the bone bed.

Removal of a well-fixed acetabular component can be difficult and may produce destruction of the acetabular bone bed. The authors describe a technique for removal of such a component with minimal bone destruction that involves the use of an offset punch and breaking the fixation interface in tension. This technique obviates the need for prying at the interface and fracturing the bone bed.

Acetabulum↗