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Biomedical subjects

W G Kernohan

Publications and source records attributed to W G Kernohan.

49 records · Page 3Linked to original sources
PubMed1989

The effect of ultrasonically induced cavitation on articular cartilage.

Cavitation, the term used to describe bubble activity in fluids, is a destructive phenomenon encountered in fluid systems. The effect of cavitation on articular cartilage was investigated by ultrasonically inducing bubble activity on the surface of bovine specimens. Distinctive pits and craters, not present on control specimens, were observed using scanning electron microscopy on the damaged surface. Human osteoarthrotic articular cartilage specimens were removed during arthroplasty and examined using scanning electron microscopy. Craters and pits observed on the osteoarthrotic specimens were similar in appearance to those on the cavitated specimens. The mechanism of cavitation bubble collapse could be responsible for damage in vivo, thus providing articular cartilage with a degenerative pathway toward osteoarthrosis.

Animals↗
PubMed1989

Impedance plethysmography. A noninvasive screening method to detect deep-vein thrombosis.

Impedance plethysmography (IPG) is a useful noninvasive detection of proximal segment thrombosis. Seven hundred patients treated with total hip arthroplasty were examined preoperatively and several times postoperatively using this technique. Twenty-one abnormal IPG results were obtained, and venography confirmed that 12 of these patients had proximal segment thrombi and five had evidence of calf thrombi. Four venograms were completely clear, demonstrating a false-positive rate of 1.3% (including calf thrombi). Six patients with normal IPG results had calf thrombi. All positive venograms indicating a thrombus in the proximal venous segment were indicated with a positive IPG result, giving a sensitivity of 100%. The standardization of the procedure involving constant leg elevation has assisted in the accuracy of this screening system.

Hip Prosthesis↗
PubMed1988

Fourier analysis of ventricular fibrillation and synchronization of DC countershocks in defibrillation.

Spectral analysis of the first 40 seconds of ventricular fibrillation confirmed the presence of a large periodic component in fibrillation, with a dominant frequency of 9.9 +/- 0.7 Hz and a narrow bandwidth. To determine whether less energy was required for defibrillation at any particular phase of the ventricular fibrillation cycle, the authors studied the effect of synchronization of the countershock to the peaks and troughs of the ventricular fibrillation waveform in 12 dogs anesthetized with sodium pentobarbitone (35 mg/kg iv). There was no significant difference in threshold-delivered energy or threshold-delivered current between shocks synchronized to the peaks of ventricular fibrillation, shocks synchronized to the troughs of ventricular fibrillation, and unsynchronized shocks.

Animals↗
PubMed1987

Vibration arthrography as a diagnostic aid in diseases of the knee. A preliminary report.

The detection and recording of vibration emission from human joints, a technique which we have termed "vibration arthrography", is a sensitive, non-invasive method for the objective study of the locomotor system. Using vibration sensors attached to bony prominences around the knee, we studied the joints of both normal and symptomatic subjects. Normal subjects produced three signal types--physiological patellofemoral crepitus, patellar clicks, and the lateral band signal. In symptomatic subjects we identified and categorised many signal types and related them to pathology. Lesions of the menisci produced distinctive signals, and it was possible not only to lateralise the tear, but in many cases to determine the type of meniscal injury present. Vibration arthrography promises to be a useful tool in the non-invasive diagnosis of knee disorders.

Auscultation↗
PubMed1986

The diagnostic potential of vibration arthrography.

The detection and interpretation of vibration emission from the locomotor system is a sensitive, noninvasive method for the objective study of human joints. The projects reviewed here aimed to identify and categorize vibration signals from various joints, chiefly the neonatal hip and the adult knee. Using a vibration detection and computerized analysis system, various studies have suggested that vibration arthrography will be a potentially valuable diagnostic service for the orthopedic surgeon of the 1990s.

Auscultation↗
PubMedDate not supplied

[Current trends in phonoarthrography].

The detection of sounds from the human body for diagnostic purposes has a long history. In the respiratory and circulatory systems such auscultation is a precise science yielding much useful information. The detection and interpretation of joint sounds, however, has been much less successful in its development. In this paper we outline the history of joint auscultation, of phonoarthrography, and of their modern equivalent: vibration arthrography. The relative merits of acoustic and vibration based systems are discussed and these are illustrated with data from simultaneous recordings of several joint phenomena. Finally, we concluded that the future of phonoarthrography as a clinical test is based on its further development using accelerometers rather than microphones as detectors.

Auscultation↗
PubMedDate not supplied

[Vibration arthrography in the diagnosis of knee joint diseases].

In this paper, the principles of vibration arthrography are briefly described and the analysis of the resulting signals is explained. Using such a system, localisation of signals from within the joint is possible. Finally, the development of a vibration-based arthrographic system is proposed as a safe, relatively inexpensive, and totally non-invasive aid to the diagnosis of internal disease of the knee.

Arthroscopy↗
PubMedDate not supplied

[Meniscus signals in vibration arthrography].

The technique of vibration arthrography (VAG) permits the non-invasive evaluation of internal derangements of the knee. Using the computer-assisted recording and analysis equipment which has previously been described, a major survey was conducted into the signal patterns present in subjects with symptomatic knee joints. Two hundred and forty-seven patients were examined, and all of these subsequently underwent arthroscopy. One hundred and seventy-two patients were demonstrated arthroscopically to have a meniscal lesion and 150 of these gave characteristic meniscal signals. This paper discusses the vibration signal patterns associated with the various types of meniscal tear and the effect of surgery on the meniscal signal. The overall accuracy of vibration arthrography in the diagnosis of meniscal pathology was 86%. In many cases, not only could the site of a meniscal tear be determined, but the type of tear could be diagnosed with reasonable accuracy.

Arthrography↗
PubMedDate not supplied

Lasers in medicine--a review.

Laser systems permit very high energy radiation of a single wavelength to be focused on a tiny spot, and have found application in many areas of engineering. They are also currently used in many branches of medicine. The fields reviewed here are ophthalmology, gynaecology, dermatology, otolaryngology, gastroenterology and physiotherapy. Lasers which are in wide use for medical applications include argon, YAG and carbon dioxide types. In many areas, lasers have been found to be more effective than conventional treatment methods with advantages including less blood loss, more accurate removal of unwanted tissue, shorter operating time and less postoperative pain. It is expected that the next decade will see the laser as an everyday tool in many more medical applications.

Gastroenterology↗
PubMedDate not supplied

Towards computer assisted evaluation of plagiocephaly.

Plagiocephaly is a common asymmetry of the skull giving the impression that the subject, usually a neonate, has suffered a compressive force acting unilaterally. Normally innocuous, it is a postural deformity that can be suggestive of other significant abnormalities, e.g. joint dysplasia. Although intuitive measurements of plagiocephaly appear in the literature there is little evidence of analytical evaluation. This paper describes a measurement methodology based on black and white photography. A flat-bed scanner and a personal computer facilitated the transformation of the prepared photograph to standard tagged image file format at 256 grey scale. A utility was used to convert the file scan to a monochrome bitmap image which was displayed on the screen and subjected to an algorithm to compute the centroid of the cranial profile. Radials that emerge from the centroid to the cranial circumference at five degree intervals map to a signal display that represents the plagiocephaly.

Cephalometry↗
PubMedDate not supplied

They cannot sit properly or move around: seating and mobility during treatment for developmental dysplasia of the hip in children.

Children diagnosed with Developmental Dysplasia of the Hip (0.2% of live births) are often treated by splintage to hold the head of the femur in the acetabulum during early joint development. Whilst clinically effective, this can create difficulties for the parents in handling the child and affects the mobility of the family, which subsequently creates emotional and social difficulty resulting from the disruption of the family routine. To identify these problems and their order of priority, a survey of 113 recently affected families was carried out in England and Northern Ireland. Parents identified mobility, emotional and social problems. Splintage size and shape was the fundamental problem from which the other difficulties arose. Solutions to the basic difficulties of transporting and seating a child in splintage would largely alleviate the feelings of frustration felt by the families and enable more normal activities of daily living.

Activities of Daily Living↗