Biomedical subjects

P A Fleming

Publications and source records attributed to P A Fleming.

At least 19 recordsLinked to original sources

PubMed2006

The angle-bore acetabular component and dislocation after revision of a failed total hip replacement.

We reviewed 1039 revision total hip replacements where an angle-bore acetabular component was used. After a mean follow-up of nine years (0 to 20.6), the incidence of revision for dislocation was 2.1% (22 revisions), a success rate of 97.9%. In 974 revisions, where the indication was other than dislocation, the success rate was 98.5%. Of the 65 revisions for dislocation, 58 (89.2%) were successful after the first revision and a further five after the second revision, an overall success of 96.9%. Two patients elected to have their implants removed. Dislocation after revision of failed total hip replacement is a complex issue. There is often no single cause and no simple solution. The angle-bore acetabular component, in combination with a 22.225-mm diameter femoral head, offers a high level of success.

Acetabulum↗

PubMed2006

The Charnley hip replacement -- 43 years of clinical success.

The Charnley low-frictional torque arthroplasty of the hip with 22.225 mm diameter head and thick ultra high molecular weigh polyethylene cup, both components grouted with cold curing acrylic cement, has reached 43 years of clinical success. Follow-up past 30 years is now available. Over 96% of patients are satisfied with the result. Post operative activity level is a reflection of patient selection. The neuropathic nature of the new joint does not reflect the mechanical state of the arthroplasty: regular follow-up with good quality radiographs is essential. Revisions may have to be undertaken for asymptomatic radiographic changes: a principle that must be understood and accepted before the primary procedure. The long-term problems are wear and cup loosening and strain shielding of the proximal femur. Long-term success will be further extended by understanding and practical application of the principles at the primary procedure and use of low wear materials for the articulation. The operation of total hip arthroplasty marks the beginning and not the end of treatment.

Arthroplasty, Replacement, Hip↗

PubMed2005

Low-friction arthroplasty of the hip using alumina ceramic and cross-linked polyethylene. A 17-year follow-up report.

We report the results of our continued review of 11 total hip arthroplasties using 22.225 mm alumina ceramic femoral heads on a Charnley flanged stem, articulating with chemically cross-linked polyethylene. There was an initial bedding-in of up to 0.41 mm at the articular surface in the first two years. This had not progressed further, at a minimum follow-up of 15 years. Radiographically no femoral or acetabular component showed loosening or osteolysis.

Adult↗

PubMed2004

Circadian rhythm of water balance and aldosterone excretion in the whitebellied sunbird Nectarinia talatala.

Nectarivorous whitebellied sunbirds, Nectarinia talatala, demonstrate distinct circadian patterns in osmoregulatory parameters. We recorded intake of a 1 mol/l sucrose solution which enabled calculation of total water gain, and collected cloacal fluid for measurements of volume, osmolality and aldosterone concentration. These variables were assessed hourly over 12 h of photophase, and averaged over the 12-h scotophase period. Overnight, when sunbirds were in negative water balance, aldosterone concentrations and outputs were significantly higher than diurnal levels, reflecting a shut-down of cloacal fluid production. Early morning was marked by a high rate of osmotic excretion, disproportionate to water gain or cloacal fluid output, followed by steady intake and cloacal fluid output during the morning and early afternoon. Reduced water flux (decreased feeding and cloacal fluid output) during mid-afternoon was accompanied by a paradoxical decline in osmotic excretion, whilst a significant increase in the discrepancy between water intake and output was recorded as the birds effectively stored water before the scotophase. These patterns of intake and excretion may be informative in explaining drinking and foraging behaviour in the field.

Aldosterone↗

PubMed2004

Osmoregulatory response to acute diet change in an avian nectarivore: rapid rehydration following water shortage.

Nectarivores may be required to switch between water conservation and water excretion as rapidly as they change food plants in nature. We examined the rehydration response in Whitebellied Sunbirds (Nectarinia talatala) that had been fed a concentrated sucrose diet (2.5 mol/l) for 2 days and then were switched to a diet 10 x less concentrated (0.25 mol/l) on the morning of the third day. We measured water gain as well as cloacal fluid (CF) volume hourly over 12 h, and analysed CF osmolality and calculated osmotic excretion. CF was also assayed for the osmoregulatory hormone aldosterone (ALDO). As in most water-deprived birds, whitebellied sunbirds cope with water shortage when fed a concentrated sugar diet by almost completely ceasing to void CF. Although osmolality of CF is high, volumes are not sufficient to maintain a steady rate of excretion and the birds retain osmolytes. Immediately upon switching to dilute diet, sunbirds produce copious volumes of CF and osmotic excretion is elevated and maintained at high levels over the first 6 h of rehydration. This stabilises by the afternoon at levels expected for hydrated birds. Some 2-3 h after peak osmotic excretion, there is a peak in the discrepancy between water intake and output, mirrored in an increase in ALDO output. These data suggest that excretion of retained osmolytes is undertaken as soon as water is available, with changes in the body fluid composition occurring subsequently. This study vindicates the use of CF to obtain repeated measurements of changes in the osmoregulatory steroid ALDO in small birds.

Aldosterone↗

PubMed2004

Dietary intake effects on arginine vasotocin and aldosterone in cloacal fluid of whitebellied sunbirds (Nectarinia talatala).

The main objective of this study was to determine whether or not the renal outputs of the osmoregulatory hormones arginine vasotocin (AVT) and aldosterone (ALDO) reflect the osmotic status of whitebellied sunbirds (Nectarinia talatala). The birds were fed a range of sucrose concentrations (from 0.07 to 2.5 mol/l, with osmolalities of 70 to approximately 5,800 mosM/kg), and adjusted their intakes so that they drank large volumes of dilute diets and small volumes of concentrated diets. Renal fluid outputs were appropriately regulated so that large volumes of cloacal fluid (CF) were voided on the dilute diets and small volumes on the concentrated diets. Accordingly, plasma AVT concentrations increased with increasing sugar concentration; however, AVT outputs in CF did not change in a similar manner, rather they decreased as dietary concentration increased. It was not possible to measure plasma ALDO concentrations in the small sunbirds because of insufficient blood samples available; however, ALDO outputs in CF did vary with the sucrose diets and renal function, being highest on the most concentrated diet. In addition ALDO output in CF fell markedly when sodium was added to the 0.5 mol/l sucrose diet. We conclude that in sunbirds fed increasingly concentrated sucrose solutions, changes in CF outputs of ALDO, but not AVT, appear to reflect the water flux and hydration state of these birds.

Aldosterone↗

PubMed2004

Wear of the cup in the Charnley LFA in the young patient.

Since wear and loosening of the ultra-high-molecular-weight polyethylene cup are factors which limit the life of an arthroplasty we have attempted to identify factors associated with either low wear (0.02 mm/year or less) or high wear (0.2 mm/year or more). In a series of 1434 Charnley low-friction arthroplasties (1092 patients) 190 (13.2%) showed low wear while 149 (10.4%) showed high wear. We used chi-squared test to assess the significance of various factors. The significant factors of the low-wear group were female gender (p = 0.042), rheumatoid arthritis (p = 0.014), Charnley grade C (p = 0.03) and varus position of the stem (p = 0.003). The use of acetabular cement pressurisation (p = 0.07) and medialisation of the cup (p = 0.07) approached significance. In the high-wear group there was a predominance of men (p = 0.042) with osteoarthritis (p = 0.006) as the underlying hip pathology, and the stem in a valgus position (p = 0.023). Support of the cup by the rim of the acetabulum approached significance (p = 0.07). There was no statistical significance between the two groups for revision for aseptic loosening of the stem or fracture of the stem (p = 0.49). There was a highly significant difference (p < 0.0001) between the two groups for revision for wear and aseptic loosening of the cup, 5.3% compared with 39%. Changes in the cup geometry are probably sufficient to explain the increasing incidence of loosening and revisions with the increasing depth of penetration of the cup. There is much to be gained from the use of a low-wearing ceramic-ultra-high-molecular-weight combination. Tissue reaction to the polyethylene particles cannot be the cause of aseptic loosening of the stem.

Adolescent↗

PubMed2003

Osmoregulation in an avian nectarivore, the whitebellied sunbird Nectarinia talatala: response to extremes of diet concentration.

Water intake of nectarivores is intrinsically linked to nectar concentration. Osmoregulation in whitebellied sunbirds Nectarinia talatala (body mass 9.3+/-0.1 g, mean +/- S.D., N=7), was examined by feeding them sucrose solutions, equivalent to extreme diet concentrations (0.07-2.5 mol l(-1) sucrose; 2-65% w/w), with and without supplementary drinking water. Total water gain was 33-515% of body mass daily. Cloacal fluid (CF) volume increased with diet dilution from 0.4% to 309% of body mass while increases in evaporative water loss (obtained by difference) were also recorded. Osmolality of CF demonstrated the largest scope yet recorded for a bird and was significantly correlated with water flux: mean values were 6-460 mosm kg(-1) H(2)O (minimum 3, maximum 1900 mosm kg(-1)). When supplementary water was provided, its consumption by birds fed concentrated diets (2.5 mol l(-1) sucrose) led to a dramatic reduction in CF osmolality, from 461+/-253 to 80+/-119 mosm kg(-1) fluid. Sunbirds maintained energy balance on sucrose diets varying tenfold in concentration, from 0.25 to 2.5 mol l(-1); however, on extremely dilute diets (0.07 and 0.1 mol l(-1) sucrose, lower than natural nectar concentrations) their inability to maintain energy balance was probably due to excess preformed water. Total osmotic excretion and concentrations of Na(+) and K(+) increased with high water fluxes, and are a possible physiological constraint for nectarivorous birds on artificial dilute diets devoid of electrolytes. Even low electrolyte levels in nectars may be adequate to replace these losses, but other physiological limitations to the intake of dilute nectars are increased energetic costs of solute recovery, increased heat loss and interference with digestive processes. Sunbirds therefore deal with sugar solutions spanning the range of nectar concentrations by shutting down water excretion on concentrated diets, or, on dilute diets, by producing extremely dilute CF with some of the lowest solute concentrations recorded.

Animal Nutritional Physiological Phenomena↗

PubMed2003

High dose rate (192)Ir afterloading brachytherapy for cancer of the vagina.

We report results of brachytherapy for carcinoma of the vagina, utilizing a Nucletron high dose rate system for Delclos Vaginal Applicators (cylinder) and Syed Template Applicators (interstitial). The linear quadratic (LQ) model was used to determine the optimum time-dose-fractionation schedules. Interstitial doses were determined at the isodose line that included gross tumour. Cylinder doses were determined either at the vaginal surface (5 cases), at 0.5 cm depth (5 cases), or at 1.0 cm depth (1 case). For the first treatment (n=19), interstitial templates were utilized in 8 patients and vaginal cylinders in 11. 11 patients received second treatments: 6 templates and 5 cylinders. The median dose of external beam radiation (n=15) was 40.0 Gy followed, after a median 23 day interval, by high dose rate brachytherapy (HDRB) of 4 fractions in 30-42 h; then a median interval gap of 25 days, followed by repeat HDRB. The median total fractionated HDRB dose per patient was 23.0 Gy (range: 6.9 Gy to 40.4 Gy; calculated low dose rate equivalent of 29.8 Gy). Tumour histologies included 14 squamous cell carcinomas, 2 adenocarcinomas, 2 melanomas, and 1 small cell tumour. Three patients experienced early brachytherapy-related complications (diarrhoea, dysuria and labial dermatitis). Three patients (15.8%) developed serious/late complications including ureteral stenosis, painful vaginal necrosis and small bowel obstruction. The first of these patients received 2 templates, the second a cylinder followed by a template and a cylinder, and the third a single cylinder. The 2 year progression-free survival was 39.3% (median 15.7 months), while the 2 year overall survival was 66.1% (median 29.9 months). (192)Ir afterloading HDRB is a feasible approach to women with vaginal cancer with acceptable toxicity and tumour response. Potential advantages include patient preference, outpatient cost-effectiveness in the case of cylinder technique, and no radiation exposure to hospital personnel. Long-term follow-up is needed to further assess late complications, and larger studies are needed to confirm our results.

Adult↗

PubMed2003

Wear of enhanced ultra-high molecular-weight polyethylene (Hylamer) in combination with a 22.225 mm diameter zirconia femoral head.

We have prospectively studied the wear of enhanced ultra-high molecular-weight polyethylene (Hylamer) in combination with a zirconia femoral head of 22.225 mm diameter on a cemented, triple-tapered, collarless, polished stem, the C Stem. The 71 patients who underwent total hip arthroplasty had a mean follow-up of six years (3 to 8). No patient died or was lost to follow-up. The clinical results were excellent with 96% of patients satisfied. There were no revisions. Two cups were considered to be loose radiologically. One was avulsed from the cement in a skiing accident, with a periprosthetic fracture of the femur, but has remained stable for more than seven years. One femur shows radiological appearances which are compatible with a healing infection. One femoral component is at risk of loosening. The mean rate of penetration of the cup was 0.22 mm/year (0.06 to 0.55). Our results appear to be within the guidelines set by the National Institute of Clinical Excellence. We have discontinued the use of Hylamer despite excellent clinical results and no revisions to date because the high initial rates of penetration did not settle to the expected low levels within the anticipated time.

Adolescent↗

PubMed2002

Charnley low-frictional torque arthroplasty in patients under the age of 51 years. Follow-up to 33 years.

Between November 1962 and December 1990 a group of 1092 patients, 668 women and 424 men, under the age of 51 years at the time of surgery, underwent 1434 primary Charnley low-frictional torque arthroplasties and are being followed up indefinitely. Their mean age at operation was 41 years (12 to 51). At the latest review in June 2001 the mean follow-up had been for 15 years 1 month. Of the 1092 patients 54 (66 hips) could not be traced, 124 (169 hips) were known to have died and 220 (248 hips) had had a revision procedure. At a mean follow-up of 17 years and 5 months, 759 patients (951 hips) are still attending. In this group satisfaction with the outcome is 96.2%. The incidence of deep infection for the whole group was 1.67%. It was more common in patients who had had previous surgery (hemi- and total hip arthroplasties excluded), 2.2% compared with 1.5% in those who had not had previous surgery, but this difference was not statistically significant (p = 0.4). There were fewer cases of deep infection if gentamicin-containing cement was used, 0.9% compared with 1.9% in those with plain acrylic cement, but this was not also statistically significant (p = 0.4). There was a significantly higher rate of revision in patients who had had previous hip surgery, 24.8% compared with 14.1% in those who had not had previous surgery (p < 0.001). At the latest review, 1.95% are known to have had at least one dislocation and 0.4% have had a revision for dislocation. The indication for revision was aseptic loosening of the cup (11.7%), aseptic loosening of the stem (4.9%), a fractured stem (1.7%), deep infection (1.5%) and dislocation (0.4%). With revision for any indication as the endpoint the survivorship was 93.7% (92.3 to 95.0) at ten years, 84.7% (82.4 to 87.1) at 15 years, 74.3% (70.5 to 78.0) at 20 years and 55.3% (45.5 to 65.0) at 27 years, when 55 hips remained 'at risk'.

Adolescent↗

PubMed2001

The effect of activity levels of total hip arthroplasty patients on socket penetration.

Survivorship of total hip arthroplasties (THAs) has been linked to penetration of the femoral head into the polyethylene acetabular cup and to polyethylene wear. The activity level of patients with THAs is considered to be an important factor affecting wear, and the purpose of this study was to explore the relationship between activity as recorded by pedometers and cup penetration. The measurement of daily activity levels of normal subjects and THA patients of various ages are discussed in another article ([1]). Subjects were monitored continuously during 2- to 4-week periods using simple pedometer devices. Patients (n = 54; mean age, 58 years) from the Centre for Hip Surgery at Wrightington Hospital for whom the penetration data also were available were included in the study. The average activity level for the patient group was 1.426 million loading cycles on each hip joint per year. Radiographic penetration measurements were compared for 81 hips in 54 patients with a mean follow-up of 13.1 years (range, 1.3-26.4 years). The overall correlation of penetration with implantation period is known to be poor, however, and did not improve significantly when the penetration was plotted against a new parameter that took account of not only implant life, but also the level of activity and patient weight. The considerable scatter of penetration levels was noted to increase with increasing implantation period, which indicates that in the multifactorial problem of polyethylene wear, other factors, particularly femoral head surface finish or polyethylene deterioration, may predominate.

Acetabulum↗

PubMed2001

Comparative study of the activity of total hip arthroplasty patients and normal subjects.

The walking activity of normal subjects and total hip arthroplasty (THA) patients from the Wrightington Hospital for Joint Disease and The General Infirmary at Leeds was assessed by means of electronic pedometers. The principal objectives were to establish the extent to which joint arthroplasty patients recover their activity relative to normal subjects and to establish the number of loading cycles to which prostheses should be subjected in joint simulator studies of implant performance. A further objective was to establish an experimental procedure for the assessment of the role of activity in contributing to the well-known scatter in the measurements of femoral head penetration into acetabular cups in in vivo studies of implant performance. The last-mentioned issue is addressed in another article ([1]). The walking activity of 2 normal subjects of disparate ages was assessed during 1 full year. It was concluded that fair estimates of activity could be achieved by recording pedometer readings during successive 2- to 4-week periods. This approach was adopted in the full assessment of the walking activity of cohorts of normal subjects and THA patients. Linear regression expressions relating the number of steps taken daily and the annual number of loading cycles on each leg to age are presented for normal subjects and THA patients. In all cases, activity declines with age, but it is shown that total joint arthroplasty is not at all restrictive on walking activity-a remarkable testimony to the efficacy of total joint arthroplasty. Attention is drawn, however, to different levels of activity of THA patients recorded in the present United Kingdom study and a similar survey conducted in California.

Activities of Daily Living↗

PubMed2001

Triple taper polished cemented stem in total hip arthroplasty: rationale for the design, surgical technique, and 7 years of clinical experience.

Successful long-term clinical results with the Charnley low-friction torque arthroplasty have identified proximal femoral strain shielding as a long-term problem to be addressed. The problem has arisen because of the load transfer by a distally supported stem that is no longer subject to fracture. To overcome this problem and improve proximal load transfer to the femur, a continuous triple-tapered stem--the C stem--was designed. This article describes the first 500 primary hip arthroplasties at a mean follow-up of 3 years, 5 months (range, 1-7 years). There have been no revisions for aseptic stem loosening, and no stem is considered to be at risk for loosening. In 20% of cases, there was subjective radiologic improvement of the bone-cement interface.

Adolescent↗

PubMed2001

Incidence of loose bodies in an osteoarthritic hip.

In a prospective study of 75 consecutive primary Charnley low friction arthroplasties carried out for osteoarthritis, loose bodies were found in nine hip joints; an incidence of 12%. Whether their presence is the cause or the effect of the condition remains unclear. Their discoid or spherical shape suggests that they were free and had been subjected to sliding or rolling motion. Those of irregular shape may have remained partly attached within the capsule, or become confined to a space.

Adult↗

PubMed2000

Vasculogenesis in the day 6.5 to 9.5 mouse embryo.

The process of vasculogenesis was characterized in the 6.5- to 9.5-day mouse embryo and in allantoic culture by analysis of spatial and temporal expression patterns of the endothelial or hematopoietic lineage-associated proteins, TAL1, Flk1, platelet/endothelial cell adhesion molecule (PECAM), CD34, VE-cadherin, and Tie2. The study establishes that: (1) TAL1 and Flk1 are coexpressed in isolated mesodermal cells that give rise to endothelial cells and thus can be defined as angioblasts; (2) hematopoietic cells of blood islands express TAL1, but not Flk1; (3) vasculogenesis in the embryo proper is initiated by mesoderm fated to give rise to the endocardium; (4) the maturation/morphogenesis of blood vessels can be defined in terms of a sequential pattern of expression in which TAL1 and Flk1 are expressed first followed by PECAM, CD34, VE-cadherin, and later Tie2; and (5) TAL1 expression is down-regulated in endothelial cells of mature vessels. (Blood. 2000;95:1671-1679)

Allantois↗

PubMed2000

Fatal pulmonary embolism and mortality after revision of failed total hip arthroplasties.

To assess the effect of extensive surgery and delayed mobilization on postoperative incidence of fatal pulmonary embolism, we reviewed the mortality rate in 1,294 patients undergoing 1,483 revisions of failed total hip arthroplasties, in which mobilization of the patients was delayed for up to 3 weeks. There were 6 deaths (mortality rate, 0.4%). All were submitted to autopsy; only 1 death was the result of pulmonary embolism. The results of our review do not support the view that more extensive surgery and delayed mobilization of the patient, as in revision of failed total hip arthroplasties, carries a high incidence of fatal pulmonary embolism.

Arthroplasty, Replacement, Hip↗

PubMed2000

Charnley low-friction arthroplasty with an autograft of the femoral head for developmental dysplasia of the hip. The 10- to 15-year results.

Between 1983 and 1988 we carried out 45 Charnley low-friction arthroplasties with autografts from the femoral head in 41 patients for developmental dysplasia of the hip. The preoperative radiographs were assessed for the severity of DDH according to the classifications of Crowe et al, Hartofilakidis et al and Sharp. The postoperative and follow-up radiographs were analysed for coverage of the socket by the graft, for loosening and for the outcome of the fixation of the bone graft. Two patients died (two hips) at four and seven years after THR from causes unrelated to the surgery and were excluded from the final radiological analysis. The mean age of the patients at the time of operation was 46 years 3 months. The autograft of the femoral head covered a mean 26% (16 to 35) of the acetabular component. All the grafts united. Some degree of resorption of the bone graft occurred in 27 patients, and always involved the lateral part of the graft, which was beyond the margin of the socket. After a mean follow-up of 11 years there had been no revisions and 38 patients had no pain or only slight discomfort. One socket migrated and four others were fully demarcated. Our findings indicate that the Charnley LFA with an autograft of the femoral head for DDH remains successful at a follow-up of 15 years.

Adult↗