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Biomedical subjects

R S Ling

Publications and source records attributed to R S Ling.

At least 19 recordsLinked to original sources
PubMed1992

The Exeter bipolar prosthesis in the active elderly patient: the results at 7 years.

Seventy one Exeter bipolar hemiarthroplasties were reviewed after a mean follow up of 3.2 years (range 1-7 years). Patients with displaced subcapital fractures were selected for operation on the basis of good mobility before the fracture. The operation was well tolerated and the mortality at 1 month and 6 months was 3.7% and 6.5% respectively. Using a newly devised hip scoring system 89% had a good or excellent result and 94% had no or only occasional pain. There was no radiological evidence of acetabular erosion.

Aged↗
PubMed1992

A venous foot pump reduces thrombosis after total hip replacement.

In a prospective, randomised controlled trial, the efficacy of the A-V Impulse System in the prevention of deep-vein thrombosis was investigated in 84 patients who had undergone total hip replacement. The incidence of venographically proven, and clinically significant postoperative deep-vein thrombosis was 40% in the control group and 5% in the treatment group (p less than 0.001). No adverse reactions were recorded.

Assisted Circulation↗
PubMed1992

The use of a collar and precoating on cemented femoral stems is unnecessary and detrimental.

Evidence is presented, largely from clinical sources, that a large collar is not necessary for the transfer of load to the proximal femur in cemented total hip arthroplasty. In fact, the use of a collar may have a number of deleterious side effects that cannot be predicted from theoretical analyses. Concern is also raised over the use of precoated femoral stems.

Arthroplasty↗
PubMed1990

Reduction of post-traumatic swelling and compartment pressure by impulse compression of the foot.

Following the discovery of a powerful venous pump in the foot that is activated by weight-bearing independently of muscular action, a pneumatic impulse device was developed to actuate this pump artificially. In a multicentre international trial the device was shown to reduce post-traumatic and postoperative swelling; pain also was alleviated. Evidence is also presented that dangerously high compartment pressures may be reduced to acceptable levels and fasciotomy avoided. We present an explanation of the clinical effects of activation of the venous footpump, based on recent improved understanding of the physiology of the microcirculation. The hyperaemic response that follows the liberation of endothelial-derived relaxing factor (EDRF) by sudden changes of pressure after weight-bearing or impulse compression is particularly important.

Adolescent↗
PubMed1990

Localised endosteal bone lysis in relation to the femoral components of cemented total hip arthroplasties.

Four cases are described of localised endosteal bone lysis in the femur occurring in association with cemented femoral components that were not obviously 'loose' radiologically. In each, the area of lysis was shown at operation to be related directly to a region in which there was a local defect in the cement mantle surrounding the stem. Via the space between the stem and cement, such defects provide a route through which the contents of the joint cavity may reach the endosteal surface of the femur, subsequently leading to localised bone lysis, and later to frank loosening.

Aged↗
PubMed1988

Experience with the Exeter total hip replacement since 1970.

The satisfactory long-term radiographic appearances with the use of the collarless, smooth, polished, tapered stem encourage its continued use. With the same stem geometry shortly to become available with interchangeable heads, the capacity for the surgeon to change the bearings when polythene wear starts to become marked should address what certainly will emerge as one of the major long-term problems of total hip arthroplasty.

Adult↗
PubMed1987

Cementing technique and the effects of bleeding.

We report the results of simple laboratory experiments which showed that bleeding pressures known to occur at the bone surface during total hip arthroplasty may compromise the integrity of the bone-cement interface and the cement itself. Such undesirable effects can be prevented by maintaining adequate pressure on the cement until its increased viscosity can resist displacement caused by the bleeding pressure.

Blood Pressure↗
PubMed1986

Observations on the fixation of implants to the bony skeleton.

This paper summarizes the now considerable evidence to support the suggestion that the structure of the junctional tissues that separate any skeletal implant from the bone is substantially dependent on mechanical factors, given that the implant itself if basically nonreactive.

Animals↗
PubMed1985

Acetabular bone destruction related to non-steroidal anti-inflammatory drugs.

In a retrospective investigation of the relation between use of non-steroidal anti-inflammatory drugs (NSAIDs) and acetabular destruction in primary osteoarthritis of the hip, 70 hips were studied in 64 patients. Cranial acetabular migration, a measure of acetabular destruction, was present in 37 hips and absent in 33. Migrators and non-migrators did not differ in age, sex, hip pain score, walking ability score, femoral neck-shaft angle, or distribution of atrophic and hypertrophic types of osteoarthritis. Regular intake of NSAIDs was noted for 31 of the 37 migrating hips and irregular intake for a further 3. Among the 33 non-migrating hips, the corresponding numbers were 7 and 5, respectively. This highly significant association between NSAID use and acetabular destruction gives cause for concern, not least because of the difficulty in achieving satisfactory hip replacements in patients with severely damaged acetabula.

Acetabulum↗
PubMed1981

Improved cementing techniques.

To obtain good-quality cement, one should follow seven steps: 1. Mix with low frequency. 2. Clean bony cavity to avoid contamination of cement. 3. Pressurize cement before insertion. 4. Insert early, at low viscosity. 5. Pressurize cement after insertion. 6. Fully constrain cement. 7. Use no stress risers. To obtain maximum fixation strength, one should follow four steps: 1. Use gouges to expose trabecular bone. 2. Use brush and lavage to clean bone. 3. Insert cement early at low viscosity. 4. Pressurize cement to force it into open trabeculas. It is fortunate that the steps overlap; they are not mutually exclusive. Both require cleanliness. Both require the use of cement at low viscosity. Both require pressurization of the cement. If the steps are followed it is our belief that the best possible fixation with the best possible cement will be obtained.

Bone Cements↗
PubMed1979

Methylmethacrylate metabolism in man. The hydrolysis of methylmethacrylate to methacrylic acid during total hip replacement.

Methylmethacrylate, the monomeric component of the polymethylmethacrylate cement used in orthopedic surgery, has been shown to undergo hydrolysis to methacrylic acid during hip replacement operations. Circulating levels of methacrylic acid were comparable with those of methylmethacrylate. Concentrations of both methylmethacrylate and methacrylic acid normally lay in the range 0--15 micrograms/cc. No correlation could be discerned between changes in the concentrations of methylmethacrylate and methacrylic acid, and changes in blood pressure.

Acetabulum↗
PubMed1978

Some clinically relevant variables affecting the mechanical behaviour of bone cement.

The effects of 12 clinically relevant variables upon the basic mechanical properties of acrylic cement are reported. Attention is drawn to the facts that these variables may at times coexist to lead to serious reductions in the strength of the cement, and that the operating surgeon may exercise a substantial influence on the effective mechanical properties of the cement he is using.

Biomechanical Phenomena↗
PubMed1978

The shear strength of trabecular bone from the femur, and some factors affecting the shear strength of the cement-bone interface.

The shear strength of trabecular bone from the femur has been studied. In general, the strongest trabecular bone is found close to the cortico-cancellous junction, though its shear strength depends also on the relationship of the trabeculae to the plane of shear. Some factors affecting the shear strength of the cement-bone interface have been investigated. In vitro, maximal cement-bone interface shear strength is obtained by exposing and thoroughly cleaning strong trabecular bone, and then forcing onto it under pressure low viscosity cement.

Adhesiveness↗
PubMed1977

The mechanical properties of bone cements.

The mechanical properties of a number of commercially available bone cements have been investigated. Tests were carried out on specimens in compression, in bending and in tension. Using the compression test as a standard, the effects of the following variables were studied: the addition of antibiotics, strain rate, environmental temperature, and age. It was concluded that age, temperature and rate of straining have a marked effect on the strength of the cement, while the addition of small quantities of antibiotics only marginally weakens the cement.

Anti-Bacterial Agents↗