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Biomedical subjects

L W Anson

Publications and source records attributed to L W Anson.

8 recordsLinked to original sources
PubMed1994

Limited internal fixation of the tibia with external fixation: an in vivo canine study.

This study reports the results of the healing of canine tibial osteotomies with external fixation alone or in combination with a single lag screw. Twelve dogs had a midshaft tibial osteotomy performed at a 45 degree obliquity. Half of the dogs had a six-pin, unilateral, medial, external half-frame applied after the osteotomy. The remaining six had an identical frame plus a lag screw placed perpendicular to the osteotomy site. When compared with their contralateral controls, the fixator-alone group had a 16.3% (p < 0.05) decrease in bone density, whereas no significant density change was seen in the group with the additional lag screw. Torsional stiffness was 29% higher in the osteotomies treated, and tested, with the lag screw, but this did not achieve statistical significance. Computed tomography scanning revealed that the surface area was increased by an average of 30-40% in both groups, relative to contralateral controls, but there was no difference between the two treatment groups. Three tibias in the group with external fixation alone, and two tibias in the screw group showed primary bone healing without evidence of callus formation. The combination of a semirigid external fixation construct with a lag screw resulted in increased torsional stiffness but healing equal to that seen with external fixation alone.

Animals↗
PubMed1991

Malunions.

The decision to attempt surgical correction of a malunion must be based on a careful preoperative assessment of the patient. The animal's gait must be observed. An animal that is not clinically affected by the malunion usually is not a candidate for surgery. Joint function and the condition of the bone, cartilage, and soft tissues must be noted. If the joints and soft tissues are irreversibly altered, surgical correction should not be performed. Accurate planning of any corrective osteotomy requires careful evaluation of the bony deformities that are present. Angular and rotational deformities may be present. Shortening of the limb also may be observed. Integration of these findings enables the surgeon to select the osteotomy technique best suited for a patient. External fixators or bone plates are most commonly used to stabilize the corrective osteotomy. When contemplating surgical correction of a malunion, critical preoperative assessment and planning are essential to achieving the desired goals. These goals are achieving normal limb function and preventing further damage to the joints of the limb.

Animals↗
PubMed1989

Ultrasonic propagation in mammalian cell suspensions based on a shell model.

The interaction of ultrasonic waves with individual cells has been modelled on the basis that the cells can be represented by viscous liquid spheres surrounded by a viscoelastic shell (the membrane) immersed in a viscous fluid. The computational model includes thermal waves and requires 22 input parameters. Many of the parameters are not available in the literature and a detailed discussion is given on the procedures by which the values used in the model calculations were chosen. In spite of the arbitrariness of the choice of many of the parameter values, the computations show surprisingly good agreement with experimental measurements of ultrasonic attenuation in animal cell suspensions. The model has been used here to investigate different aspects of the interaction of ultrasound with the cells. It is found that the membrane is important only between 0.5 and 30 MHz and contributes less than 15% to the attenuation. Absorption is shown to be an important feature to include, while the scattering contribution to the attenuation is less than 1% at 3 MHz. The thermal effects are important at frequencies below 1 MHz and contribute some 65% to the attenuation at 100 MHz.

Animals↗
PubMed1987

Fatal air embolism during anesthesia for laparoscopy in a dog.

A 13-year-old dog went into cardiopulmonary arrest after insufflation of the abdominal cavity with nitrogen for laparoscopy. Resuscitation was unsuccessful. Necropsy findings included a punctured spleen and confirmed the development of air embolism.

Anesthesia, General↗
PubMed1985

Idiopathic hyperaldosteronism in a dog.

Idiopathic hyperaldosteronism was diagnosed in an 8-year-old castrated male Yorkshire Terrier, based on increased concentration of plasma aldosterone, hypertension, hypernatremia, decreased natriuresis, hypokalemia, and hyperkaluria. Unilateral adrenalectomy was performed after visualization of a nodule on the right adrenal gland. Hyperplasia of the zona glomerulosa and increased postoperative aldosterone concentrations supported the diagnosis of idiopathic hyperaldosteronism.

Adrenal Glands↗
PubMedDate not supplied

A retrospective evaluation of the rectal pull-through technique. Procedure and postoperative complications.

Ten animals (8 dogs and 2 cats) with distal rectal lesions were treated by surgically resecting the affected segment of the rectum by the rectal pull-through technique. There were four malignant tumors, three benign tumors, two inflammatory lesions, and one malignant tumor that extended histologically to the margins of a previous surgical excision. Postoperative complications were tenesmus (7 animals), fecal incontinence (4 animals), rectal bleeding (4 animals), and abscess formation (1 animal). Dehiscence and stricture were not observed. The four animals with malignant tumors survived less than 12 months after surgery. One of the four animals still living has persistent fecal incontinence. The rectal pull-through technique is described and illustrated.

Animals↗
PubMedDate not supplied

Clinical evaluation of canine acetabular fractures stabilized with an acetabular plate.

A retrospective study of 14 dogs with one or more acetabular fractures stabilized with an acetabular plate was conducted. Twelve of the 14 dogs had additional orthopedic injuries. Follow-up was longer than 6 months. Eleven dogs were evaluated by assessment of radiographs, lameness, mid-thigh circumference, coxofemoral joint range of motion, crepitus, and pain. Varying degrees of osteoarthrosis were noted radiographically at follow-up. Ten of 12 dogs examined had occasional or no clinical lameness. In 10 of 12 dogs, mid-thigh circumference was less on the limb that sustained the acetabular fracture. Nonunion was diagnosed in one plated acetabulum in which two screws had broken. A return to normal or nearly normal function was observed when there were no more than two orthopedic injuries.

Acetabulum↗