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Biomedical subjects

J B Richardson

Publications and source records attributed to J B Richardson.

At least 19 recordsLinked to original sources
PubMed1995

Dynamisation of tibial fractures.

We studied the effect of 'dynamisation' on tibial fractures in six patients treated by the Dynamic Axial Fixator. In the early stages, peak cyclic movement at two to four weeks averaged 0.75 mm (0.19 to 1.02) on the medial side of the bone and 0.86 mm (0.21 to 1.25) on the lateral side. The amount of movement correlated with the applied load and the fracture stiffness. After unlocking the fixator column at six weeks, progressive closure of the gap averaged 1.3 mm (0.1 to 3.5). Cyclic movement is produced by early weight-bearing with the fixator column locked. Progressive closure occurs after unlocking the column, and is often associated with a reduction in cyclic movements. The effects of dynamisation on movement at the fracture site should be defined separately, in terms of cyclic movement and of progressive closure.

Adult↗
PubMed1994

Outcome of carotid endarterectomy performed at a community medical center.

From 1990 to 1992 there was a 43% increase in the number of carotid endarterectomies (CEAs) performed at our institution. Not coincidentally the North American Symptomatic Carotid Endarterectomy Trial study was published in August 1991. To determine whether CEAs could be performed safely at community medical centers, records of 181 consecutive CEAs performed during a 30-month period at a suburban community medical center were reviewed. CEAs were performed by 14 surgeons: six vascular, three thoracic, and five general surgeons. Among all patients 87% had lesions with > or = 70% stenosis. Seventy percent of CEAs were performed on symptomatic patients, 84% of whom had stenoses > or = 70%. Among asymptomatic patients 96% had stenoses > or = 70%. There were five instances of neurologic complications in the perioperative period--two transient ischemic attacks, two reversible ischemic neurologic deficits, and one permanent neurologic deficit. One patient died. The mortality rate was 0.6%, the combined major stroke/mortality rate was 1.2%, and the any stroke/mortality rate was 2.2%. There were five patients with nonfatal major complications--one with myocardial infarction, one with pulmonary edema, one with congestive heart failure, and two with postoperative arrhythmia. Thirteen minor complications included eight cases of cranial nerve dysfunction. These data demonstrate that CEAs can be performed safely at community medical centers.

Aged↗
PubMed1994

Measuring stiffness can define healing of tibial fractures.

We measured fracture stiffness in 212 patients with tibial fractures treated by external fixation. In the first 117 patients (group 1) the decision to remove the fixator and allow independent weight-bearing was made on clinical grounds. In the other 95 patients (group 2) the frames were removed when the fracture stiffness had reached 15 Nm/degree. In group 1 there were eight refractures and in group 2 there was none (p = 0.02, Fisher's exact test). The time to independent weight-bearing was longer in group 1 (median 24 weeks) than in group 2 (21.7 weeks, p = 0.02). The greater precision of our objective measurement was associated with a reduction in refracture rate and in the time taken to achieve independent weight-bearing. We consider that a stiffness of 15 Nm/degree in the sagittal plane provides a useful definition of union of tibial fractures.

Biomechanical Phenomena↗
PubMed1991

Axial movement and tibial fractures. A controlled randomised trial of treatment.

Diaphyseal fractures of the tibia in 80 patients were treated by external skeletal fixation using a unilateral frame, either in a fixed mode or in a mode which allowed the application of a small amount of predominantly axial micromovement. Patients were allocated to each regime by random selection. Fracture healing was assessed clinically, radiologically and by measurement of the mechanical stiffness of the fracture. Both clinical and mechanical healing were enhanced in the group subjected to micromovement, compared to those treated with frames in a fixed mode possessing an overall stiffness similar to that of others in common clinical use. The differences in healing time were statistically significant and independently related to the treatment method. There was no difference in complication rates between treatment groups.

Adolescent↗
PubMed1991

Clinical, serologic, and immunogenetic studies in patients with dermatomyositis.

Dermatomyositis is a disease of unknown etiology characterized by progressive, symmetrical, proximal muscle weakness with accompanying compatible cutaneous findings. Thirty-nine patients with dermatomyositis from the Louisville, Kentucky area were enrolled in this study. Patients were grouped into those with or without a malignancy. Ten patients (26%) either had or have had a malignancy. Twenty-five Caucasian patients were HLA typed for the A, B, DR and DQ locus antigens, of whom 5 had an associated malignancy and 20 did not have a malignancy. We found that no single antigen had a significantly increased or decreased frequency as compared with our control population for the entire group, or for any clinical subset we examined. Serologic testing revealed 4 patients with anti-Mi-2 antibodies and 1 patient with anti-PM-SCL antibodies. No patient had a positive anti-Jo-1 antibody in this group. The results of serologic tests in this group did not correlate with any clinical subset or HLA antigen. Our findings were in agreement with the previous reports in which approximately 25% of patients with DM have an associated malignancy. Our findings also support the notion that untargeted malignancy searches are not warranted. Contrary to previous reports we did not observe an inverse relationship between cancer and pulmonary disease in the dermatomyositis patient. This study does not indicate that there are any HLA associations or clinical associations, other than age, that distinguish patients with dermatomyositis as running a greater risk of developing malignancy.

Dermatomyositis↗
PubMed1990

Comparison of audible sound transmission with ultrasound in screening for congenital dislocation of the hip.

In a comparative study ultrasound and the sound transmission test were used to seek congenital dislocation of the hip in 102 babies referred to a paediatric orthopaedic clinic. The sound transmission test correctly identified all those hips considered normal or dislocated on ultrasound. 17 babies underwent repeated ultrasound examination for hips considered abnormal but not dislocated. 12 improved and 5 required treatment. With a cut-off decibel difference between the hips of 5.8 dB the sound transmission test correctly identified the dislocated hips but did not detect some of the hips that needed treatment. A cut-off of 5.6 dB reduced the likelihood of a false-negative result while maintaining the sensitivity of the test.

Analysis of Variance↗
PubMed1989

Dermatomyositis and malignancy.

In summary, it can be stated that: 1. Dermatomyositis is probably associated with an increased incidence of malignancy. 2. Tumor types found seem to roughly approximate the frequencies of those found in the general population. 3. If present, the malignancy can precede, occur concurrently with, or follow the diagnosis of dermatomyositis. 4. Treatment of associated malignancy may or may not have an effect on myositic or cutaneous disease. 5. Dermatomyositis and associated malignancy may share a common pathogenesis resulting from abnormal immune function. 6. Search for malignancy should be carried out on the basis of abnormal findings on history and physical examination or screening laboratory.

Dermatomyositis↗
PubMed1989

A mechanical assessment of applied compression and healing in knee arthrodesis.

The applied compression and stiffness of a knee arthrodesis treated with unilateral external fixation can be mechanically assessed. Of ten patients in whom arthrodesis bending stiffness measurements were obtained during healing, nine had a minimum bending stiffness of 5 Nm/degree and sound clinical fusion. In seven of these nine patients, a bending stiffness of at least 10 Nm/degree was obtained, suggesting that this stiffness value is a safe and reliable indicator for successful arthrodesis. Arthrodesis compression declined rapidly; daily adjustments were required to maintain a compression of 500 Newtons. A small but significant loss of length was associated with this high value of compression. On reduction of the compression to 200 Newtons, the rate of decrease of compression and the loss of length across the arthrodesis were simultaneously reduced.

Arthrodesis↗
PubMed1988

Radiographs in shoulder trauma.

It is difficult to establish the diagnosis of an injured shoulder if only one radiographic projection is used. We have compared two lateral projections, the Neer trans-scapular and the apical oblique in 80 patients; the radiographs were presented randomly to 10 casualty officers and nine radiologists. The apical oblique view was found to permit more accurate diagnosis of fractures and of dislocation by both groups.

Diagnostic Errors↗
PubMed1986

Effect of controlled axial micromovement on healing of tibial fractures.

The preliminary results are presented from a study in which 85 serious tibial fractures were treated with external skeletal fixation. In group I patients were treated with highly rigid fixation. In group II the same fixation was used but axial micromovement was applied across the fracture site for 30 min per day, starting 1-3 weeks after injury and continuing until partial weight-bearing, which leads to self-induced movement. The overall mean time to independent weight-bearing was longer in group I than group II (p = 0.02); delayed union occurred in more group I patients. Objective measurement of fracture stiffness was made by means of strain gauges placed on the fixation frame for 49 fractures treated consecutively. The time to reach stiffness levels equivalent to clinical union was significantly longer in group I than in group II. The fractures in the treatment groups were of comparable severity. It seems that the fracture healing process is susceptible to small changes in mechanical environment.

Fracture Fixation↗
PubMed1986

A temporary arteriovenous shunt (Scribner) in the management of traumatic venous injuries of the lower extremity.

The use of a temporary arteriovenous shunt distal to the repair of a traumatic venous injury of the lower extremity in eight patients is reported. Three patients sustained injury to the superficial femoral vein, three had common femoral vein injuries, one had a through-and-through injury of common iliac vein, and one had a popliteal venous injury. Seven patients had associated arterial injuries. Venous repairs included four vein patches, two end-to-end anastomoses, a single venography, and one autogenous vein interposition graft. At the end of each operation, a distal A-V shunt utilizing the posterior tibial artery and vein was constructed. In two patients the shunt clotted within hours after insertion and could not be reopened. In the remaining six patients, the temporary A-V shunt was left in place an average of 10 days (range, 3-15). Followup venograms obtained 2 to 15 days postoperatively revealed patent venous repairs in all patients whose shunt remained functional for 72 hours or more. Noninvasive Doppler studies were obtained in four patients 3 to 8 months post repair and revealed no evidence of deep venous obstruction. No patient with a functioning distal A-V shunt had significant limb edema following repair. This technique appears to improve patency rates of venous repairs and has several distinct advantages over previously described A-V anastomotic fistulas.

Adult↗
PubMed1983

Recent progress in pulmonary innervation.

Recent additions to the understanding of the innervation of the lung have included a detailed description of the pattern in the canine airways, confirmation of the two pathways in the human, the demonstration of nonadrenergic inhibition in vivo, and studies that raise the question as to whether or not the distal airways are innervated. The inhibitory contribution of the nonadrenergic inhibitory system in the guinea pig has been shown to be less than that of the adrenergic system, and the role of the nonadrenergic system in airway smooth muscle control remains unclear. The ganglia of the human lung resemble those in the gastrointestinal tract, but their function in the lung remains speculative. Many features of the innervation in a variety of species are unexplained, and some features, such as the dominant inhibitory pattern in several birds, are completely opposite to that in mammals; the purpose of this is not understood.

Animals↗
PubMed1982

A three-year experience with phleborheography: a noninvasive technique for the diagnosis of deep venous thrombosis.

The need for a reliable noninvasive method to detect deep venous thrombosis (DVT) is apparent from its prevalence, the fallibility of its clinical diagnosis, and the several drawbacks of phlebography. Experience with phleborheography (a plethysmographic technique for detecting DVT) over three years is presented. Phleborheography (PRG) is found to have an overall accuracy of 93% compared to phlebography. It is recommended that treatment decisions can be based on unequivocal PRG results, and PRG should be used to screen high risk patients. The medical, economic, and social benefits of PRG are described.

Anticoagulants↗