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Biomedical subjects

G R Fernie

Publications and source records attributed to G R Fernie.

At least 19 recordsLinked to original sources
PubMed1995

In vivo measurement of lumbar spinal creep in two seated postures using magnetic resonance imaging.

STUDY DESIGN: A magnetic resonance imaging technique was developed to measure creep in the lumbar spine in different seated postures. Owing to the fixed size and horizontal orientation constraints of the magnetic resonance imaging system bore, gravitational force was simulated in the horizontal plane while the subject assumed each of two near-seated postures: 1) flexed lumbar, and 2) extended lumbar. OBJECTIVES: One experimental subject was used to determine the feasibility of this technique designed to correlate spinal creep with different seated postures. SUMMARY OF BACKGROUND DATA: Although epidemiologic and pathologic studies have linked the seated posture with low back pain and disc degeneration, few in vivo studies have explored the mechanical response of the lumbar spine to seated postures. METHODS: Creep displacement of four lumbar discs (L3-S1) was measured from unloaded and loaded scans separated by 30 minutes of constant loading. Forty-eight images were measured from three trials in each posture, four sagittal slices per trial. RESULTS: Creep while in an extended posture (3.58 mm) was greater than creep while in a flexed posture (2.92 mm). System resolution was 0.78 mm. CONCLUSION: This technique can be used to discern between creep displacements in different postures.

Adult↗
PubMed1994

The impact of new lifting technology in long term care: a pilot study.

1. The researchers conducted a pilot study to test a new lifting system developed with the assistance of nurses. 2. The lift system consists of a portable battery operated power unit that the nurse carries to the bedside and attaches to an overhead track; the ability to share the portable power unit among several track locations is economical. 3. The new lifting system was found to reduce the number of staff necessary to execute patient lifts. This staff saving amounted to 50% of one full time equivalent person per nursing unit. 4. Nurses perceived that less effort was required using the new lifting system compared to a conventional floor model wheeled lifting device.

Adult↗
PubMed1991

Design of an intervertebral disc prosthesis.

This article presents criteria for the design of a lumbar intervertebral disc prosthesis that take into consideration issues of endurance, materials behavior, geometry, kinetics, motion constraints, fixation to bone, and safety. The criteria and design philosophies discussed are generally applicable in the synthesis of any new implant system. Specifications of the design of a disc prosthesis are presented along with an evaluation of the design based on some of the preliminary test data.

Chromium Alloys↗
PubMed1991

Functional biomechanics of the spine.

The exact nature of the mechanisms at work during movement of the human spine are not well understood, nor well defined. The spine supports the torso against loads and allows freedom of motion, within physiologic limits, at the same time. A great deal of information characterizing various attributes of the spine is available. Research has provided values for flexural stiffness, axial compliance, range of motion under various loading modalities, and considerably more. This study will focus not on isolated topics, but rather serve as a broad introduction to the behavior of the spine as a whole.

Biomechanical Phenomena↗
PubMed1990

Aging and postural control. A comparison of spontaneous- and induced-sway balance tests.

Two different balance testing methods were compared: (1) measurement of spontaneous postural sway during quiet standing, and (2) measurement of induced postural sway in response to an applied postural perturbation. Eyes-open tests were performed in 64 healthy young and elderly adults and in five elderly subjects with a history of falling. In both balance tests, the sway was defined in terms of the displacement of the center of pressure on the feet. Spontaneous sway was quantified using a number of different amplitude- and frequency-based parameters. Induced sway was measured in response to anterior-posterior acceleration of a platform on which the subject stood. The induced-sway test was specially designed to be safe and nonthreatening for elderly subjects; thus, the platform perturbation was confined to small accelerations and a gentle pseudorandom motion was used. To derive a measure of postural stability, the data from this test were fitted with a model that was then used to predict the response to sudden (transient) perturbations, thereby simulating the response in actual falls. Although both induced- and spontaneous-sway measures demonstrated significant aging-related decreases in stability, the differences were more pronounced for the induced-sway data. Conversely, some of the spontaneous-sway measures were much more successful in distinguishing the fallers from the nonfallers. There was a significant correlation between induced-sway and certain spontaneous-sway measures in the normal young adults; however, in the elderly normals and fallers, the data from the two types of balance tests either showed no correlation or, for certain spontaneous-sway measures, tended to show an inverse relationship.

Acceleration↗
PubMed1990

An evaluation of computer aided design of below-knee prosthetic sockets.

Forty-eight below-knee amputees compared sockets designed using CANFIT computer aided design (CAD) software with sockets designed using conventional methods. Each subject was fitted by one prosthetist who used conventional techniques and one who used the CANFIT system to design the socket. Prosthetists alternated design methods for each new subject. The prosthetist using the conventional techniques was allowed up to 2 design attempts and the prosthetist using the CANFIT system was allowed up to 5 design attempts. After 2 design attempts with each method 21% of the subjects preferred the CANFIT design socket. Following up to 5 attempts 54% preferred the CANFIT designed socket. A jury of experts made an assessment of the CANFIT system and of CAD in prosthetics. The jury did not think that the version of the system tested was cost effective but that at the rate that it was improving it would become such within 3 to 5 years. The jury noted that, as well as monetary benefits, CAD presents the possibility of benefits in other areas such as research and teaching. A number of specific suggestions regarding the use and development of CAD in prosthetics were also made.

Artificial Limbs↗
PubMed1990

Computer-aided design and computer-aided manufacturing (CAD/CAM) in prosthetics.

Computer-aided design and computer-aided manufacturing (CAD/CAM) systems for the design and manufacture of limb prostheses have recently become commercially available. However, rigorous evaluations of these systems have not been performed to determine whether they produce sockets that fit as well as or better than sockets made using conventional design methods. A controlled evaluation protocol, in which computer-designed sockets are compared with conventionally designed sockets, has been developed and pilot tested at the authors' facility. A full trial of one of the commercially available systems for transtibial sockets is currently in progress. In preliminary findings, the CAD/CAM socket was preferred by one-half of the first 20 subjects. During the course of this trial, it was noted that the CAD/CAM technique seems to be better suited to some prosthetists than others.

Adult↗
PubMed1989

Oxybutynin chloride for geriatric urinary dysfunction: a double-blind placebo-controlled study.

Twenty-four incontinent elderly institutionalized subjects with detrusor instability participated in a double-blind placebo-controlled trial of oxybutynin chloride. Patients were randomly assigned to oral oxybutynin 5 mg or placebo twice daily. Administration continued for 8 days; a 6-day washout period was followed by the alternative treatment. Incontinence was recorded using a bedside electronic monitor. Four subjects withdrew because of side-effects before completing the trial. There were no clinically significant differences between the oxybutynin and placebo treatments. Both groups experienced side-effects, of which dry mouth was the commonest. Thus, oxybutynin does not appear to be more effective than placebo for the treatment of incontinence in the presence of detrusor instability in elderly institutionalized people.

Aged↗
PubMed1987

Production of a reproducible spinal burst fracture for use in biomechanical testing.

We have developed a technique to create a reproducible spinal burst fracture of the 12th vertebral body using 6-8-week-old calf spines with ribs, muscles, and vessels resected. We used the entire thoracolumbar segment of 20 calf spines with a standardized 5-mm-deep slice placed onto the body of T12 and the T11-12 disc. We then delivered a proximal-axial impact to the vertically mounted spine, preflexed to 15 degrees of forward flexion, by dropping a 32-kg weight, guided by a 1.55-m steel rod (potential energy = 487 J). Motion was limited to anterior flexion only, at the T12-13 disc, by splinting the rest of the spinal segments. Fractures were documented with the use of radiographs and computed tomography (CT) scans. We noted disruption of the vertebral column and end plates, fracture of the posterior body wall, fracture of the pedicles, and retropulsion of bony fragments into the neural canal. With the production of a reproducible spinal burst fracture model, various spinal fixation devices can be applied and tested.

Animals↗
PubMed1987

Extent of artificial limb use following rehabilitation.

The extent of prosthesis use is reported for 104 lower limb amputees from the onset of gait training up to 2 years later. Subjects were divided into groups according to age (greater than or equal to 65 years or less than 65 years) and amputation level. An analysis of variance including the factors of age and level of amputation was done. Unilateral trans-tibial (UTT) amputees progressed more quickly during the inpatient gait training program that did unilateral trans-femoral (UTF) subjects (p less than 0.05). UTT subjects also walked more than UTF subjects just prior to discharge (p less than 0.05), during the first year after discharge (p less than 0.01), and during the second year after discharge (p less than 0.01). Similarly, younger patients progressed more quickly in gait training (p less than 0.05) and walked more than older subjects throughout the study period (p less than 0.05). There were no significant interactions between age and amputation. The extent of walking of these amputees is compared with the minimal levels required for them to function in different living environments. At the time of discharge from the inpatient gait training program, older unilateral amputees and trans-femoral amputees were not able to walk the 600 steps a day necessary to manage with a moderate level of support in a one-level apartment or home. The declining number of steps taken in the follow-up period indicated that the UTF subjects might benefit from some special attention paid to their community support needs. These findings are also viewed in the context of limited data available on the extent of walking of non-amputees.

Adolescent↗
PubMed1987

Migration, attachment, and orientation of human gingival fibroblasts to root slices, naked and porous-surfaced titanium alloy discs, and Zircalloy 2 discs in vitro.

Cell migration, attachment, and orientation of cultured human gingival fibroblasts (HGF) were measured in relation to four types of specimens: Ti-6Al-4V alloy discs with either ground surfaces or porous structured surfaces, and Zr alloy discs (Zircalloy 2) with either ground surfaces or surfaces modified by being heated to form a thicker oxide cover. Surface-demineralized and non-demineralized root slices were used as controls. Initial cell attachment was measured by means of a 51Cr assay, and cell attachment and orientation following migration by an assay that measures development of the resulting refractile material in relation to the specimen. No significant difference between initial cell attachment to Ti alloy and control demineralized root slices could be detected after one hr using the 51Cr assay. However, with the second assay, cell attachment and orientation at three, seven, 10, and 14 days were significantly higher in relation to surface-demineralized root slices than to all of the metal discs and the non-demineralized root slices. While cell attachment to the surface-ground Ti alloy discs appeared to be higher than that to the porous-surfaced Ti alloy discs at three days and seven days, cell orientation to the porous-surfaced Ti alloy discs and the non-demineralized root slices at days 7, 10, and 14 was greater than that to all of the other metal discs. These data suggest that surface geometry could affect attachment and orientation of cells in vitro.

Alloys↗
PubMed1986

An anatomical comparison of the human and bovine thoracolumbar spine.

The bovine spine has been frequently selected as the model for in vitro mechanical studies. A comparative anatomical study has been presented describing important differences and similarities between selected areas in the adult human and calf thoracolumbar spinal segment. Differences in column length and curvature were observed. The total length of the adult bovine vertebral column was found to be on average 209 cm longer than the adult human spine. Equivalent thoracolumbar lengths were obtained by selecting 6-8 week-old dairy calves, which because of their young age had the benefit of consistent bone density. The bovine spine was found to have only a single cervical lordotic curve and a single thoracolumbar kyphotic curve (2). A quantitative comparison of selected dimensions of vertebrae T6, T12, and L3 was performed, and significant findings are discussed. The bovine spinous processes were found to be on average 111% greater in length at level T6, which contributed to a 56% greater total anterior/posterior length at this level in comparison to the vertebrae of an adult male. A 23% greater bovine intertransverse length at level L3 was also shown. The orientation of the human and bovine superior facets, while being in the same general plane and direction, varied as much as 10.5 and 107% at vertebral level L3 on the two axes measured. These significantly different measurements were considered important factors that can influence experimental results when using the bovine spine as a model.

Anatomy, Comparative↗
PubMed1986

Results of the pilot phase of a clinical evaluation of computer aided design of trans-tibial prosthesis sockets.

This study served as a pilot to develop the methodology for a larger number of clinical trials. Ten trans-tibial amputees compared sockets made by conventional methods with sockets made using computer aided socket design (CASD). Prosthetists, paired for experience, fitted each subject with one prosthesis using each method. A preferred socket was selected by the subject on the basis of comfort without knowledge of the method by which the socket was designed. Prosthetists also evaluated the sockets. Three subjects preferred sockets built using CASD and one subject preferred the conventional socket only slightly more than the CASD socket. Six subjects clearly preferred the conventional fitting.

Aged↗
PubMed1986

Biomechanical study of full-contact karate contrasted with boxing.

It is known that boxers suffer a characteristic cumulative brain injury from repeated blows to the head that correlates well with the number of bouts fought. Much less is known about full-contact karate (kickboxing), which is relatively new. In full-contact karate, punches and kicks are actually landed, rather than being focused to culminate just short of an opponent, as practiced in traditional karate. Although a combatant can win on points, the surest means of victory is a knockout. Consequently, fighters strive to land blows to the head. To investigate the relative force of kicks and punches, a dummy head was mounted 175 cm above the floor (to simulate a 50th-percentile man standing erect) and 125 cm above the floor (to simulate the man in a crouched position) on a universal joint permitting motion about three axes. The mechanism was contrived to provide constant rotational stiffness, and springs provided constant restorative moments about the three axes. The texture of soft tissue was simulated by a mask of visco-elastic foamed materials. Fourteen karate experts punched and kicked the dummy. Accelerometer measurements in the 90- to 120-G range indicated that safety-chops (hand protectors) and safety-kicks (foot padding) did not reduce acceleration of the dummy. Ten-ounce boxing gloves mitigated peak acceleration to some extent. Kicks and punches produced accelerations in the same range. Violent acceleration of the head by any means produces injury. The authors conclude that, if full-contact karate is widely practiced, cases of kickboxer's encephalopathy will soon be reported.

Acceleration↗