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Biomedical subjects

R B Willis

Publications and source records attributed to R B Willis.

At least 19 recordsLinked to original sources
PubMed2001

The effect of placing a tensioned graft across open growth plates. A gross and histologic analysis.

BACKGROUND: Midsubstance tears of the anterior cruciate ligament in skeletally immature patients are increasingly common and are a challenging problem. The results of nonoperative treatment are no better in children than they are in adults. Physeal-sparing reconstructive procedures have yielded poor results. Reconstructive procedures that are utilized in adults violate the physis, potentially resulting in growth abnormalities. The objective of this study was to provide a model for reconstruction of the anterior cruciate ligament in skeletally immature patients by evaluating the effects of a tensioned connective-tissue graft placed across the canine physis. METHODS: Twelve ten-week-old beagles underwent reconstruction of the anterior cruciate ligament consisting of placement of fascia lata autograft through drill-holes across the femoral and tibial physes, tensioning of the graft to 80 N, and fixing it with screws and washers. The contralateral limb served as a control. One dog was eliminated from the study secondary to a postoperative infection. Four months postoperatively, the dogs were killed and were inspected grossly, radiographically, and histologically for any evidence of growth disturbance. RESULTS: Significant valgus deformity of the distal part of the femur (p < 0.001) and significant varus deformity of the proximal part of the tibia (p = 0.03) developed in the treated limbs. Neither radiographic nor histologic examination demonstrated any evidence of physeal bar formation. CONCLUSIONS: Significant growth disturbances occur with excessively tensioned transphyseal reconstruction of the anterior cruciate ligament in the canine model. These growth disturbances occur without radiographic or histologic evidence of physeal bar formation.

Animals↗
PubMed1997

Radiological and orthopedic abnormalities in Satoyoshi syndrome.

Satoyoshi syndrome is a rare disorder of unknown etiology characterized by progressive, painful intermittent muscle spasms, severe skeletal abnormalities mimicking a skeletal dysplasia, malabsorption, alopecia, and amenorrhea. We further report on a 20 1/2-year-old Caucasian woman with characteristic manifestations of the syndrome. Since the establishment of the diagnosis 1 year ago, she has been treated with prednisone with good response. However, treatment of the multiple deformities and fractures has been difficult and challenging. The early recognition and treatment of this disorder is of utmost importance, as the skeletal deformities and fractures seem to be secondary to the muscular spasms, as suggested by Satoyoshi.

Adult↗
PubMed1996

Pediatric osteomyelitis masquerading as skeletal neoplasia.

Osteomyelitis has many forms of presentation in the pediatric age group. From neonatal osteomyelitis, with a paucity of clinical symptoms and signs, to the more typical acute hematogenous form or even the subacute or chronic presentations, a high index of suspicion is needed to institute appropriate investigations and treatment.

Bone Neoplasms↗
PubMed1996

Traumatic hip dislocation during childhood. A case report and review of the literature.

Traumatic hip dislocations rarely occur during childhood. Males sustain pediatric hip dislocations four times more often than do females. Posterior hip dislocations comprise 87% of all pediatric hip dislocations. A soft, pliable acetabulum and ligamentous laxity predispose the immature hip joint to a dislocation secondary to minimal trauma. Potential associated injuries include fractures and neurovascular injury, whereas avascular necrosis (AVN) and degenerative joint disease are potential sequelae. Optimal treatment should be prompt reduction of the hip in order to minimize the risk of AVN of the femoral head.

Accidental Falls↗
PubMed1994

Measurement of amorphous ferric phosphate as an assessment of iron bioavailability.

A method for measuring amorphous ferric phosphate in complex salt mixtures and animal diets is described. The procedure uses citrate solutions for extraction of salt mixtures and tartrate solution for extraction of prepared diets. Iron in the solution is then determined colorimetrically. Crystalline ferric phosphate, which has no iron bioavailability, is not extracted by either solution. Thus, the procedure can determine if the amorphous form, which has a high iron bioavailability, is present. The procedure was tested on gypsy moth artificial diet and Wesson salt mixture, which is a salt supplement of the diet.

Animals↗
PubMed1992

Treatment of the missed Monteggia fracture in the child.

Eight children with missed Monteggia fracture-dislocations are described. Seven had reconstructive surgery which included resection of scar tissue from the radiohumeral joint, proximal ulnar osteotomy, reduction of the radial head and reconstruction of the annular ligament. One had excision of the radial head. Excellent results were obtained in patients under ten years of age, up to four years after the initial injury.

Bone Plates↗
PubMed1992

Control of interfragmentary micromotion in Ilizarov distractional osteogenesis.

Growth of the regenerate is affected by various factors during the course of Ilizarov distractional osteogenesis. One of the chief biomechanical factors that influences the quality and rate of bone formation is fixator stiffness. A four-ring Ilizarov apparatus was configured around a synthetic tibia. In a series of trials involving a uniform axial load, different transfixing wire tensions, and the separation of paired proximal and distal rings, fragment displacement was measured. Preliminary results suggest that the effect produced by the distraction of ring pairs on interfragmentary micromotion is as significant as pretensioning of the wires.

Biomechanical Phenomena↗
PubMed1990

Treatment of compartment syndrome in children.

A compartment syndrome is a symptom complex caused by elevated tissue pressure in a closed osseofascial compartment of a limb. Left unrecognized, it results in permanent damage to muscle and nerve in that compartment. The diagnosis of a compartment syndrome is contingent on the recognition of pain out of proportion with the injury as the most important early symptom. The pain is increased with passive stretching of the muscles in the involved compartment or on palpation of the involved muscles. Once the diagnosis is suspected, prompt treatment by appropriate fasciotomy should result in maintenance of normal limb function.

Adolescent↗
PubMed1981

Fractures Involving the Distal Epiphyseal plate of the femur.

Forty-two fractures involving the distal femoral epiphyseal plate in 41 patients were reviewed. The average age at injury was 11.2 years. The follow up period ranged from one year to 20.3 years, with an average of 6.3 years. The Salter-Harris classification of epiphyseal plate injures proved to be a good indicator of the mechanism of injury and prognosis. Using stringent criteria to classify the end results, 2 out of 3 of the total group and 3 out of 4 of 29 Salter-Harris Type I and Type II injuries had good or excellent results. Type V crushing injuries of the growth plate, open injuries, fractures caused by high velocity motor vehicle accidents with severe displacement or multiple associated fractures, and incompletely reduced epiphyseal injuries gave only poor or fair results. Major problems responsible for poor or fair results were varus or valgus angulation, loss of joint motion and shortening due to premature epiphyseal closure. Orthoradiographs revealed the presence of some degree of shortening in 20 of 29 Salter-Harris Type I and Type II injuries which averaged 1.0 cm, but was of no clinical significance in most patients. These injuries must be reduced accurately. In the Type II epiphyseal separations unsatisfactory results were due to inadequate reduction or to associated injuries.

Adolescent↗
PubMed1976

Tension studies of human knee ligaments. Yield point, ultimate failure, and disruption of the cruciate and tibial collateral ligaments.

Ultimate failure strengths of human tibial collateral and anterior and posterior cruciate ligaments were determined at two different loading rates (12.5 and fifty centimeters per minute) using an Instron Tension Analyzer. The posterior cruciate ligament was significantly stronger than the tibial collateral and anterior cruciate ligaments, which were of equal strength. At ultimate failure the ligaments were intact macroscopically but electron microscopy revealed widespread disruption of the collagen fibrils. Only after further application of stress did actual macroscopic disruption occur, suggesting that microscopic failure of the collagen fibrils in grossly intact ligaments may be a significant cause of clinical instability.

Collagen↗
PubMed1975

Vascular compartment syndromes.

In a 5-year period (1968 to 1973) 33 cases of vascular compartment syndrome were seen. Seven case reports illustrate various etiopathogenetic factors in the development of vascular compartment syndrome. A review of the 33 cases has permitted discussion of the pathophysiology and clinical features of these syndromes, together with introduction of a clinical classification on which treatment is based. Mild cases may be treated by application of ice, elevation, and observation; for severe cases fasciotomy is the treatment of choice. Two techniques of fasciotomy are available: multiple skin incisions with fasciotomy between the incisions for single-compartment sydnromes and extensive skin incisions over the length of the fasciotomy for multicompartment syndromes or severe single-compartment syndromes.

Adolescent↗
PubMedDate not supplied

Strain gauge analysis of knee ligaments.

Mercury strain gauges were sutured onto the tibial collateral anterior and posterior cruciate ligaments to quantitatively determine the relative strain or deformation of each of these ligaments as a function of joint position. The results were obtained on 5 amputation specimens by subjecting them to flexion, extension, rotation, valgus--varus and anteroposterior forces. The tibial collateral ligament is most lax in full flexion and stretches with extension, valgus and external rotation. The cruciate ligaments are most lax at 35 degrees flexion and stretch with both flexion and extension. Internal rotation and varus stretch and anterior cruciate ligament. These principles allow us a better understanding of injury patterns. The most advantageous position for immobilization following acute injuries or reconstructions is better understood knowing that minimal tension on ligamentous fibers occurs as follows: Anterior cruciate, 35 degrees; Posterior cruciate, 35 degrees; Tibial collateral ligament, 45--90 degrees (or as much flexion as the patient will tolerate).

Biomechanical Phenomena↗
PubMedDate not supplied

The in vitro activation of complement by radiologic contrast materials and its inhibition with epsilon-aminocaproic acid.

Radiologic contrast materials activate complement by both the classical and alternative pathways. This activation is time, dose, and temperature dependent and is able to proceed with equal facility in either the presence or absence of Ca++ or Mg++ chelating reagents (EGTA, EDTA). All the components examined (C1, C4, C2, Factor B, C3, and C5) were consumed during complement activation. Immune complexes are produced during interaction of serum with contrast materials. The activation of complement by contrast materials appears to be principally initiated by the activation of plasminogen to plasmin. Inhibition of plasminogen activators by epsilon-aminocaproic acid affects complement activation markedly.

Aminocaproates↗
PubMedDate not supplied

Bilateral lower extremity compartment syndromes secondary to intraosseous fluid resuscitation.

Intraosseous infusions are reserved for use in life-threatening hypovolemic or cardiogenic shock when intravenous (i.v.) access cannot be readily established. Although minor fluid extravasation is a common problem with this technique, a fully established compartment syndrome has never been reported. We describe a child with severe compartment syndromes of both lower extremities complicating the use of intraosseous fluid resuscitation.

Bone and Bones↗