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Biomedical subjects

P F Armstrong

Publications and source records attributed to P F Armstrong.

At least 19 recordsLinked to original sources
PubMed1997

Proposed curriculum model for resident education in pediatric orthopaedic surgery.

A curriculum developed for pediatric orthopaedic residency training is described. The curriculum is practice based, emphasizing those components thought to be necessary for orthopaedic practice. Highly technical or esoteric topics are deemphasized, because they are not relevant to practice capabilities at the end of residency training. The curriculum is designed to serve as a guide for educational direction in pediatric orthopaedic residency training, and not as a description of competency. Resource materials are being developed to provide the educator with relevant clinical material, objectives, and bibliography. The advantages of a practice based curriculum warrant further development of this model for other orthopaedic subspecialties.

Clinical Competence↗
PubMed1993

Complications of use of the Ilizarov technique in the correction of limb deformities in children.

We reviewed the records of the first forty patients who had been managed at our institution with the Ilizarov technique for the correction of limb deformities, including limb-length inequality, to delineate the complications of this method of treatment. The duration of follow-up ranged from two and one-half to four years. A complication was defined as any untoward occurrence to a patient either during the course of treatment or after removal of the fixator. A major complication was considered one that necessitated an additional operative procedure; caused lasting sequelae, such as malunion, deformation of new bone, joint contracture or stiffness, or nerve palsy; or prolonged the treatment. A minor complication was regarded as one that responded to non-operative treatment and did not cause lasting sequelae, such as transient decreased motion of the joint, paresthesia, or pin-track infection. There were eighty-eight complications--thirty-eight, major, and the remaining fifty, minor--in the sixty-one segments of the limb that were treated; this represented an average of almost one and one-half complications for each segment. Twenty-nine unplanned operative procedures were performed either during treatment with the Ilizarov technique or after removal of the fixator. As anticipated, the prevalence of major complications was highest in the patients who had had more complex and prolonged treatment. Such complications were encountered less often as the surgeons gained experience with the procedure, but the rate of minor complications remained relatively constant, despite the increased experience.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

High synovial immunoglobulin E levels in eosinophilic synovitis.

Eosinophilic synovitis occurred in a 7-year-old boy. Synovial fluid leukocytes were mostly eosinophils; the peripheral blood showed only mild eosinophilia. The level of eosinophil-derived neurotoxin in the synovial fluid was higher than that in the serum, suggesting intraarticular eosinophil degranulation. The IgE level was also elevated in the synovial fluid (3854 ng/ml) but normal in the serum (408 ng/ml), suggesting a localized immediate hypersensitivity immune response.

Child↗
PubMed1992

The morbid anatomy of congenital deficiency of the tibia and its relevance to treatment.

Two specimens obtained from a 5-month-old boy with bilateral type 1a congenital tibial deficiency were dissected to describe their morbid anatomy. Examination revealed a rigid equinovarus deformity, absence of a tibial remnant, an abnormal saddle-shaped talus, and several tarsal coalitions. Observation of the arterial pattern during surgery supported the previously reported finding that persistence of an immature arterial structure is inherent in this condition. Knowledge of potential structural anomalies is essential during the planning of an amputation or of a knee or an ankle reconstruction. Anatomic abnormalities may affect the design of soft-tissue flaps in an amputation and plantigrade positioning and foot biomechanics in reconstructive procedures.

Abnormalities, Multiple↗
PubMed1992

Pediatric applications of the Ilizarov method.

Since mid-1987, more than 250 applications of the Ilizarov technique have been successful in treating a variety of pediatric orthopedic problems. The principles of the method are the same in adults and children. Careful preoperative planning and close follow-up evaluation during distraction are important to success. Complication rates are high but improving as experience is gained with the technique. Most complications can be managed such that the ultimate success is not jeopardized. The Ilizarov technique has wide application in the treatment of difficult deformities. The method is useful for treatment of limb-length discrepancy projected to be greater than 5 cm and in limb-length discrepancy combined with angular deformity. The method is applicable to angular deformities such as in adolescent Blount's disease and congenital tibial pseudarthrosis, especially conditions where bone transport may be needed to gain length. In resistant or recurrent clubfeet, the Ilizarov technique is useful as an alternative to osteotomy of the mid- and hindfoot or both. The method may even be indicated for lengthening limbs in selected patients with short stature.

Adolescent↗
PubMed1990

Force and stiffness changes during Ilizarov leg lengthening.

Biomechanical considerations of limb lengthening procedures are fundamental to their clinical outcome. The purpose of this study was to determine the relationships among force, stiffness, and distracted length in a patient whose leg was lengthened 50 mm with the Ilizarov procedure. A modified Ilizarov apparatus with force transducers in its three columns was surgically applied to the left tibia of an 11-year-old female patient after corticotomy of the proximal metaphysis. The leg was distracted 0.25 mm four times daily for 50 days, commencing six days after surgery. At approximately weekly intervals, forces at rest were recorded before and after distraction. Resting predistractional force magnitudes increased almost linearly during the first three weeks of lengthening, from 49 N to 223 N. The rate of increase slowed markedly thereafter with a further force increase of 11 N in the next three weeks. The stiffness of the limb, derived from the change in force accompanying the 0.25-mm change in length, increased by approximately 3.9%/mm of distracted length with 95% confidence limits of 6.8% and 0.9%. These results show marked differences from the nonlinearly increasing force-displacement relationship during in vitro limb distraction.

Biomechanical Phenomena↗
PubMed1990

Amputation stump lengthening with the Ilizarov technique. A case report.

It is often difficult to create a functional stump from a traumatic amputation, especially in a child. A case is described of a traumatic, high, below-knee amputation in a five-year-old child. The resulting stump was too short to allow a conventional below-knee prosthesis, decreasing gait efficiency. The Ilizarov technique was used to increase tibial length. Bony lengthening was very successful, but several problems were encountered with the soft-tissue reconstruction. This technique of stump reconstruction holds promise only if the soft-tissue problems are anticipated. The suggestions for future stump-lengthening procedures are preparatory plastic surgery for skin requirements including infection prevention measures.

Amputation Stumps↗
PubMed1989

Functional outcome in pediatric trauma.

Two hundred fifty consecutive children hospitalized with severe injuries (at least one injury with an Abbreviated Injury Score [AIS] greater than or equal to 4 or two or more injuries with AIS scores greater than or equal to 2) were studied to determine their functional status at discharge and 6 months later using questions from the RAND Health Insurance Study (HIS) and the Glasgow Outcome Scale (GOS). Of the 217 surviving patients, 190 (88%) had one or more functional limitations by the HIS scale at discharge. Ten (5%) were in a vegetative state, 40 (18%) severely disabled, 97 (45%) moderately disabled, and 70 (32%) healthy by the GOS. Six-month followup was complete for 156 patients. Of these, 84 (54%) had one or more functional limitations by the HIS scale. Seven (4%) were in a vegetative state, 17 (11%) severely disabled, 50 (32%) moderately disabled, and 82 (53%) healthy by the GOS. A substantial proportion of the whole group of children hospitalized for the treatment of severe injuries had ongoing physical disabilities that limited their participation in normal activities 6 months after they were discharged. This suggests a need for greater emphasis on the rehabilitation of pediatric trauma patients.

Activities of Daily Living↗
PubMed1988

Capacitively coupled electrical stimulation of bovine growth plate chondrocytes grown in pellet form.

Pellets formed from isolated bovine growth plate chondrocytes were grown in various capacitively coupled electrical fields. The signals chosen were 0, 10, 100, 250, 500, 750, 1,000, and 1,500 V peak-to-peak, 60 kHz. The effect on cell proliferation and matrix production of these different voltages was determined by [3H]thymidine and [35S]sulfate uptake, respectively, Cyclic AMP assays were done to determine if increases in either thymidine or sulfate uptake were associated with changes in cAMP levels. Significantly increased cell proliferation occurred at 500, 750, and 1,000 V peak to peak. The calculated electric fields were 1.5 to 3.0 x 10(-2) V/cm. Proliferation was significantly inhibited at 1,500 V peak-to-peak with a calculated field of 4.5 x 10(-2) V/cm. Little if any change was seen in cAMP levels at 30 or 60 min following application of the appropriate electric signals.

Animals↗
PubMed1988

Evaluating a pediatric trauma program: effectiveness versus preventable death rate.

We compared effectiveness (E), the proportion of severely injured patients who were salvageable and survived, to the preventable death rate (PDR) over three consecutive 1-year periods. Severely injured patients were those with at least one injury with an Abbreviated Injury Score (AIS) of greater than or equal to 4. Those with one fatal injury (AIS greater than or equal to 6), a critical head injury (AIS greater than or equal to 5) apart from acute epidural hematoma, or massive multiple injuries (Injury Severity Score greater than 59) were considered nonsalvageable; the remainder were considered salvageable. In the first year, six of 74 salvageable patients died, in the second year five of 76, and in the third year one of 69. The PDR rates were 0.32 (6/19), 0.23 (5/22), and 0.06 (1/17), respectively. There was no significant difference in the E of our trauma program over the 3 years. The apparent improvement in PDR in the second and third years resulted from an increased number of deaths among nonsalvageable patients and fewer deaths among salvageable patients. This finding demonstrates that PDR is sensitive to case mix and not just quality of care, and confirms the superiority of E over PDR for assessing a trauma program.

Child↗
PubMed1987

Cytosolic calcium concentration in bovine growth plate chondrocytes.

The cytosolic free calcium ion concentration for mammalian cell systems is believed to be maintained within a narrow range compatible with cellular homeostasis. Growth plate chondrocytes have been shown to accumulate large quantities of calcium within their mitochondria, but the cytosolic free calcium concentration has not been determined. This study measures the cytosolic free ionic calcium concentration in growth plate chondrocytes using two variations of the Quin II fluorescence technique. The results indicate that in isolated growth plate chondrocytes, the cytosolic free ionic calcium concentration is similar to other nonmineralizing mammalian cell types (106-137 mM).

Animals↗
PubMed1987

Injury scoring systems in children.

Injury scoring systems are used to describe groups or individuals for purposes of epidemiologic studies, quality assurance or triage. The two most widely used methods are the injury severity score (ISS) and the trauma score (TS). In this paper, the authors describe their experience with these two methods in a group of 175 severely injured children. They found both to be reliable and valid but found the ISS the more useful of the two for various practical reasons.

Child↗
PubMed1987

The pediatric passenger: trends in seatbelt use and injury patterns.

Injury patterns and use of passenger restraints were studied in 91 children injured while riding in motor vehicles and admitted to The Hospital for Sick Children, Toronto, from June 1984 through December 1985. Of theses, 44 had used restraints and 38 had not. Nine were excluded from the study because restraint use could not be determined. Age and sex distributions were closely matched in both study groups. The no-restraint group had more massive head injuries, thoracic injuries, and liver and spleen injuries than the restraint group. Classic "seatbelt syndrome" injuries were seen in the seatbelt group. The overall Injury Severity Scores were not significantly different between the groups. Despite mandatory legislation, many children do not use restraints, and many who do still suffer severe or fatal injuries. We conclude that better compliance with existing passenger restraint laws and more effective restraint systems are needed.

Accidents, Traffic↗
PubMed1986

Failure of the rabbit tibial growth plate to respond to the long-term application of a capacitively-coupled electrical field.

A continuous 5-V peak-to-peak, 60 kHz capacitively-coupled sine wave signal was applied to the proximal tibial growth plate in fifteen 9-week-old male New Zealand white rabbits for 6 weeks. A pair of flexible stainless steel "injectrodes" was held in place medially and laterally on the surface of the proximal hindlimb in each rabbit by means of tape wrappings. The electrodes were connected to a 9-V battery-operated power unit carried in a dorsal pouch in a body vest worn by each rabbit. Control animals wore the identical apparatus, only the power unit was inactive. Small Tantalum markers were inserted into the anteromedial aspect of the proximal tibial metaphysis 1 cm distal to the proximal tibial growth plate in all of the animals, control and experimental, 2 weeks prior to the onset of electrical stimulation. The distance between the proximal lateral tibial spine and the Tantalum marker, between the Tantalum marker and the apex of the distal tibial intercondylar notch, and between the proximal tibial spine and the distal notch was measured from roentgenograms made at the time of bone marker insertion, at the time of electrode application to the limb, and at the end of the stimulation period. Results indicate that there was no significant difference in tibial lengths between the stimulated and control groups. There was significantly less total body weight gain in both the experimental and control animals than that which occurred in paired normal animals during the same period of time. This failure to thrive may be responsible for the resultant lack of longitudinal growth stimulation of the capacitive coupling.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Use of a short wavelength filter in an operating microscope.

There is growing concern over the potential phototoxic effect on the patient's retina from the coaxial illumination of the operating microscope. By replacing the existing red-free filter in the body of a Zeiss operating microscope, with a 470-nm filter, the ultraviolet and low wavelength blue light can be easily and effectively filtered from the transmitted white light. In this location, the filter can be quickly and safely rotated into or out of line with the transmitted light depending on the preference of the ophthalmologist.

Filtration↗
PubMedDate not supplied

Results of tibial lengthening with the Ilizarov technique.

Between June 1987 and June 1992, 62 tibiae in 52 patients underwent lengthening by using the Ilizarov technique. Follow-up was from 18 months to 5 years. The mean age at surgery was 12.9 years (range, 5-19). The etiology of limb shortening was congenital in 53 and acquired in nine tibiae. Thirty-five tibiae had bifocal and 27 had unifocal treatment. Twenty-two of the 62 limbs had simultaneous treatment of other associated problems, including rotational or angular deformity or foot deformity. The average lengthening was 7.5 cm (range, 3.5-12), which was equivalent to a 32% average overall increase in limb-segment length (range, 6-96%). Complications required 28 (22%) unplanned procedures in the 62 tibiae, including nine osteotomies for iatrogenic malunion or deformation of regenerate bone (31%). Three tendo Achilles lengthenings and posterior ankle capsulotomies were required for persistent equinus contractures. Bony complications declined as experience with the technique increased. This technique allows simultaneous lengthening correction with control of the adjacent foot when required.

Adolescent↗