Search PubMed⌕ Search

Biomedical subjects

D I Rowley

Publications and source records attributed to D I Rowley.

At least 19 recordsLinked to original sources
PubMed1998

Mechanical performance of an axially mobile plate for fracture fixation.

BACKGROUND: Emphasis of the advantages of secondary bone healing over primary bone healing has led to a trend of moving from rigid fixation to less-rigid fixation. A reduction in axial stiffness of fixators has been shown to be beneficial to bone healing, and many external fixators have been designed that incorporate axial dynamization. METHODS AND RESULTS: A new axially mobile plate has been designed for long-bone fracture fixation, to give the bone fragments a degree of axial mobility while maintaining bending and torsional stability after fixation. Mechanical bending and torsion tests have been conducted on the axially mobile plate and also on the conventional dynamic compression plate and the limited-contact dynamic compression plate. The results have shown that the new plate is stiffer and stronger in both bending and torsion than at least one of these conventional plates. CONCLUSION: The axially mobile plate has adequate mechanical properties and can be taken forward to clinical trails.

Biomechanical Phenomena↗
PubMed1998

Meniscal regeneration in the long-term after total meniscectomy?

A cohort of 39 patients (28 male, 11 female) that had undergone total meniscectomy as adolescents (mean age 16 years) underwent FISP 3D Magnetic Resonance Imaging at a mean follow up of 30 years. The presence of meniscal tissue was assessed by two independent observers blinded to the operation details. The volume of any meniscal tissue present was calculated. A posterior horn remnant was seen in 57% of medial and 45% of lateral meniscectomy cases. The mean volume of an operated medial meniscal remnant was 0.29 mL compared with a mean volume of 1.15 mL for an intact medial meniscus. The mean volume of an operated lateral meniscal remnant was 0.30 mL compared with 1.07 mL for an intact lateral meniscus. We have shown that the incidence of incomplete excision of the posterior horn is more common after total medial meniscectomy, and that at a mean follow up of 30 years there is no convincing in vivo MRI evidence of long-term meniscal regeneration.

Adolescent↗
PubMed1997

Further development of hybrid functional electrical stimulation orthoses.

In this study two aspects of hybrid functional electrical stimulation (FES) orthoses were investigated: joint motion constraints and FES control strategies. First, the effects of joint motion constraints on the gait of normal subjects were investigated using modern motion analysis systems, including electromyogram (EMG) and heart rate measurements. An orthosis was developed to impose joint motion constraints; the knee and ankle could be fixed or free, and the hip joint could rotate independently or coupled, according to a preset flexion-extension coupling ratio (FECR). Compared with a 1:1 hip FECR, a 2:1 hip FECR was associated with a reduced energy cost and increased speed and step length. The knee flexion during swing significantly reduced energy cost and increased walking speed. Ankle plantar flexion reduced the knee flexing moment during the early stance phase. Second, trials on 3 paraplegic subjects were conducted to implement some of these findings. It appeared that the 2:1 FECR encouraged hip flexion and made leg swing easier. A simple FES strategy increased walking speed and step length and reduced crutch force impulse using fixed orthotic joints.

Ankle↗
PubMed1997

Evaluation of cancellous structure in the distal radius using spectral analysis.

A preliminary study was conducted to analyze trabecular patterns in digitized wrist radiographic images from 68 patients (31 males and 37 females), aged from 7 to 93 years. The fast Fourier transform was used to perform the spectral analysis of the distal radius. Three indices were defined to permit quantification of the cancellous structure in terms of the spacing and orientation of bone trabeculae (periodicity): a spectral trabecular index, a longitudinal trabecular index, and a transverse trabecular index. The spectral trabecular index reflects the periodicity of the trabeculae (spacing and orientation), while the other 2 selectively reflect the periodicity of longitudinally and transversely oriented ones. The ratio of the longitudinal and transverse trabecular indices was also studied. The shape of the high magnitude frequencies in the spectrum was crosslike for all patients, implying a preferentially orthogonal 2-dimensional structure for the cancellous bone in the distal end of the radius. The variation of the defined trabecular bone indices with age corresponded with the formation of bone through infancy and adolescence, reaching a peak in adulthood and gradual loss thereafter. This quantification detects structural changes that occur with aging and may therefore be useful in the study of osteoporosis.

Adolescent↗
PubMed1996

Effects of joint motion constraints on the gait of normal subjects and their implications on the further development of hybrid FES orthosis for paraplegic persons.

In this study the effects of angular motion constraints of the lower limbs on the gait of normal subjects were investigated. An assessment orthosis was developed with a new hip coupling mechanism which allows its ratio of reciprocal flexion to extension to be altered. The knee and ankle joints of the orthosis could also be set to be free or locked in specific directions of angular motion in the sagittal plane. A total of 12 different orthosis configurations was tested on three normal subjects. The kinematic, kinetic and electromyographic (EMG) data were collected using the VICON system, two Kistler forceplates, foot switches and an eight channel EMG system. The physiological cost index of walking was assessed by measuring the heart rate and walking speed. It was found that (1) a higher hip flexion-extension ratio was associated with lower energy cost and faster walking; (2) allowing the knee to flex significantly reduced the energy cost and increased the walking speed; (3) allowing the ankle to plantarflex during early stance phase reduced the knee flexing moment. The implications of these effects on the further development of hybrid functional electrical stimulation orthotic systems are discussed.

Adult↗
PubMed1996

Further development of hybrid functional electrical stimulation orthoses.

It is recognised that, in paraplegic walking with reciprocating gait orthoses, inadequate hip flexion angles may contribute to the low walking speed and high energy cost. In this study a new orthotic hip joint was developed which had a 2:1 flexion extension coupling ratio. Experiments on paraplegic subjects were conducted to evaluate this orthotic hip joint. It was found that the new hip joint was associated with a reduced energy cost and increased step length. A simple application of FES assisted hip flexion further increased walking speed and step length and reduced energy cost and crutch force impulse.

Adult↗
PubMed1996

The management of war wounds involving bone.

Over 200 high-velocity missile injuries treated in a low-technology environment were audited under the aegis of the International Committee of the Red Cross Hospitals in Afghanistan and Northern Kenya. Femoral fractures were treated either by traction or external fixation using a uniaxial frame. The results showed that patients treated by external fixation remained in hospital longer than those treated on traction. The positional outcome was identical in both groups. In tibial fractures the external fixator was only of extra benefit in those of the lower third when compared with simple plaster slabs unless more complex procedures such as flaps or vascular repair were to be performed. In complex humeral fractures, external fixation resulted in long stays in hospital and a large number of interventions when compared with simple treatment in a sling. We conclude therefore that in an environment where facilities are limited and surgeons have only general experience very careful initial wound excision is the most important factor determining outcome. The application of complex holding techniques was generally inappropriate.

Afghanistan↗
PubMed1995

Subspecies discrimination of staphylococci from revision arthroplasties by ribotyping.

Sixty-six cultures of Staphylococcus spp. were obtained from bone and tissue samples collected from 37 patients during revision arthroplasties and were speciated and ribotyped to assess strain diversity in each species. There were 10 ribotypes among 51 isolates of S. epidermidis, three among three isolates of S. capitis, two among four isolates of S. aureus and two among two isolates of S. simulans. One ribotype was found among each of: two isolates of S. warneri; two isolates of S. haemolyticus and single isolates of S. cohnii and S. saprophyticus. Low molecular weight bands of ribotype patterns characterized one or two related species whereas high molecular weight bands were useful for distinguishing types within species. Specimens from 17 patients yielded more than one isolate of Staphylococcus spp. In 13 of these patients the isolates were representatives of a single species but in only eight did ribotyping show the isolates to be identical. The findings of multiple species and ribotypes from samples taken from the same patient may have implications for understanding the nature of infection in revision arthroplasty and for antibiotic therapy.

Bacterial Typing Techniques↗
PubMed1994

A 5-10 year follow-up of the Sheehan total knee endoprosthesis in Tayside.

The Sheehan total knee endoprosthesis has been widely used since 1971. It takes the form of a semi-constrained hinge with intramedullary stems cemented into the femur and tibia for fixation. In Tayside the prosthesis has been in use since 1980. The clinical impression was that the prosthesis was not performing well and formal assessment of surviving prostheses was therefore carried out using the Hospital for Special Surgery (HSS) scoring system. Thirty-seven patients were available for follow-up, 15.6% of whom had good results while 40% had poor results according to this assessment. At review, 31% of patients had undergone revision surgery or were awaiting such surgery. This compares poorly with reported results of surface joint replacements. In the light of these results the authors feel that the Sheehan knee replacement is now obsolete.

Aged↗
PubMed1993

The physiological benefits of paraplegic orthotically aided walking.

A group of first-time paraplegic users of a particular ambulatory orthosis was studied to assess the physiological benefits of changing from a wholly sedentary lifestyle to one which included regular periods of upright weight-bearing and walking. Little clinically apparent benefit was noted in respiratory mechanics. There was a subjective reduction in urinary tract infections, but without a corresponding reduction in the level of bacteria. A possible improvement in bone density was noted in a small subgroup. It is concluded that, at least in the shorter term, the physiological benefits to paraplegics of using walking orthoses are not as great as has generally been claimed in the literature.

Adolescent↗
PubMed1992

Energetics of paraplegic walking.

A group of 35 paraplegic subjects using reciprocating walking orthoses have been examined in order to gain an insight into the potential functional benefits of using such devices. Measurements have been made of walking speeds and of the energy costs of ambulation using an established technique based on heart rate recordings. It was found that orthotically aided walking for paraplegics was slow and energy costly compared with both normal walking and wheelchair propulsion and, as it additionally requires the use of a walking aid in both hands, cannot be considered to confer the functional benefits frequently claimed for it. Nevertheless, the majority of the subjects studied liked their orthosis and did well in it, with many subjectively reporting improvements in mobility and independence.

Adolescent↗
PubMed1992

Surgeons and HIV.

Explore the source record for details and available documents.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Fixation is fun.

Explore the source record for details and available documents.

Fracture Fixation↗