Biomedical subjects

T Tasker

Publications and source records attributed to T Tasker.

6 recordsLinked to original sources

PubMed2006

ACL graft constructs: In-vitro fatigue testing highlights the occurrence of irrecoverable lengthening and the need for adequate (pre)conditioning to avert the recurrence of knee instability.

The performance of ACL grafts in both the short and long term is only as good as the condition of the graft at the time of surgery. If the graft lengthens under load at the two fixation ends incorporation will take longer to occur. Previous studies have shown that the various grafts currently used are strong enough. However, data on strength came primarily from quasistatic single pull to failure tests with, in some cases, modest cycling to precondition the grafts. The present study examined the in-vitro biomechanical behaviour of model ACL grafts, which have been fatigue cycled to failure over a wide range of loads in physiological ambient conditions. Load/deformation curves and the stretch of the grafts was continuously recorded until final rupture. The grafts demonstrated typical creep-rupture like behaviour with elongation (non-recoverable stretch) and loss of stiffness leading to gradual failure. Some of the graft designs were consistently shown to elongate up to 20 mm in length within the first 2000 cycles at moderate physiological loads and a further 10 mm of elongation occurred between the initial preconditioned state and just prior to complete rupture. Not enough attention has been paid previously to the likely long term elongation patterns of ACL grafts post-surgery and even after the usual empirical preconditioning has been performed by the surgeon. Increased graft dimensions may result in recurrent knee instability and may also lead to failure of the graft to incorporate. Preconditioning in-vitro may still be a way to remove some slack and prepare the graft for its operational environment by stiffening in particular the tissue/fixation interface for those grafts that use soft polymer fixation ends.

Animals↗

PubMed1993

Risk profiles for genital infection in women.

OBJECTIVE: To determine independent risks with predictive value for specific sexually transmitted diseases in women. DESIGN: A prospective study of reported sexual behaviour in patients who presented for screening and diagnosis of sexually transmitted diseases. SETTING: A genitourinary medicine clinic at the West London Hospital. SUBJECTS: 1025 consecutive newly attending patients who completed a sexual behaviour questionnaire between February and June 1982. MAIN OUTCOME MEASURES: Sexual behaviour reported by standardised self-administered questionnaire and sexually transmitted diseases diagnosed by routine clinical and laboratory methods. RESULTS: Independent risks for gonorrhoea were teenage (RR 2.0), black race (RR 2.0), more than two partners in the past year (RR 2.2) and previous pregnancy (RR 2.1). Trichomoniasis (RR 2.5), chlamydial infection (RR 1.8) and pelvic inflammatory disease (RR 4.8) also had significant predictive value. Conversely, gonorrhoea proved a risk for chlamydial infection (RR 2.1) together with age under 25 years (RR 2.3) and more than five partners in the previous year (RR 2.2). Ano-genital herpes was predicted by a total of more than 10 sexual partners (RR 2.6) and by both anal (RR 2.2) and oral intercourse (RR 2.9). Age under 25 years was the only independent risk for ano-genital warts (RR 2.0). We found no evidence that either vaginal candidosis or bacterial vaginosis were sexually transmitted. The risk for any genital infection was increased by more than one sexual partner in the preceding year (RR 1.7) and black race (RR 2.0). CONCLUSIONS: Sexually transmitted diseases show both similarities and differences in the risk factors associated with their transmission. These risk profiles facilitate the targeting of health education measures for those sections of the community at greatest risk and form a baseline for the future assessment of the effects of condom protected sexual intercourse and other safer sexual practices.

Adolescent↗

PubMed1993

A comparison of sexual behaviour and risk behaviour for HIV infection between women in three clinical settings.

OBJECTIVE: To compare sexual behaviour and HIV risk behaviour between women in three clinical settings and to investigate the effect of socio-economic status and ethnic origin upon these behaviours. SUBJECTS AND METHODS: A questionnaire was administered to 1,950 women attending clinics for genitourinary medicine (GUM) family planning and termination of pregnancy (TOP), all in inner London. RESULTS: A quarter of women attending the GUM and TOP clinics were not using any regular form of contraception. Differences in the median numbers of sexual partners in the past year (1-2) and over lifetime (4-6) between the three groups were slight. Amongst the women in all three groups: more than half (54.8-64.9%) had had a non-regular partner in the preceding twelve months; fewer than one-fifth (10.4-17.1%) reported always using condoms with their regular partners, and fewer than two-fifths (31.3-39.7%) always used them with their non-regular partners; approximately one in five women (18.6-23.9%) reported one or more major HIV risk behaviours. Some parameters of sexual behaviour were found to be influenced by socio-economic status and/or ethnic origin. CONCLUSIONS: The behaviour of women attending these three clinics is very similar. Women attending clinics for family planning or termination of pregnancy need advice on sexually transmitted diseases and HIV infection, and women attending genitourinary medicine or termination clinics need advice on contraception. Closer integration between disciplines is required to provide a comprehensive sexual health service for women.

Abortion, Legal↗

PubMed1988

Discitis following lumbar surgery.

Although well described in the orthopaedic literature and some orthopaedic textbooks, postoperative discitis is regularly missed or diagnosed late. Six cases of discitis were studied in detail with special reference to the clinical presentation. All patients with discitis had an erythrocyte sedimentation rate (ESR) greater than 50 at 2 or more weeks after surgery. A prospective study of 26 patients undergoing uncomplicated discectomy or fusion was made. ESRs were measured preoperatively and at 1,2, and 6 weeks after operation. Any patient with increasing back pain and an ESR greater than 52 or more weeks after surgery should be considered to have discitis until proven otherwise. If the ESR is measured routinely preoperatively and at 2 weeks postoperatively, this condition should not be missed.

Blood Sedimentation↗

PubMed1982

Articular changes associated with internal derangement of the knee.

A prospective study was made of 100 knees which had been operated on for various kinds of internal derangement. An observer, who did not know the clinical condition of the knee, recorded whether or not there were articular lesions of the femoral condyles. Lesions were found to be localised to a triangular area on the medial condyle and to a strip on the lateral condyle. Similar lesions have been described in association with flexion deformities in rheumatoid and osteoarthritic knees. Lesions were found in 49 out of 50 knees which had been locked for more than three days. They were also found in 29 knees in which there appeared to be full extension before operation, but where there was either a torn meniscus with a history of intermittent locking or serious anterolateral instability. In these cases it was considered that the final "screw-home" mechanism of full extension had been lost. Lesions were not present in 10 knees which appeared locked, but in nine of these the interval between injury and operation was less than three days. Lesions were not found in eight knees where there was full extension and no history of locking or instability. In four knees with a plica syndrome similar lesions were present.

Adolescent↗

PubMed1980

Pitfalls in double contrast knee arthrography.

Two hundred and forty-two patients investigated by double-contrast knee arthrography between 1973 and 1977 have reviewed. Of these 134 have come to arthrotomy and an initial arthrographic accuracy of 85% is reported. An attempt to explain the disparities between arthrography and arthrotomy has revealed that in half the cases (ten patients) there were simple reporting errors on the arthrograms. These are shown all to be false negative reports. The other group of ten patients comprised presumed errors in arthrotomy interpretation in four and arthrographic interpretation or technical failure in six. The causes and implications of those errors are analysed and discussed.

Adolescent↗