The influence of femoral component design on postoperative periprosthetic femoral fracture after uncemented direct anterior total hip arthroplasty in the elderly.

INTRODUCTION: Aging populations and expanding indications will greatly increase the volume of total hip arthroplasty (THA) in all age groups, including patients over 70 years old. Minimally invasive, uncemented direct anterior THA offers potential advantages for treating elderly patients. However, literature indicates higher risks of postoperative periprosthetic femur fractures (PPFFs) with both direct anterior THA and uncemented femoral stems. This retrospective study investigates the influence of femoral stem design on PPFF incidence in uncemented direct anterior THA among patients older than 70 years. METHODS: 557 primary THAs in patients aged 70 or over were reviewed for PPFFs from a consecutive series of 2011 patients undergoing direct anterior THA from a fellowship-trained adult reconstruction surgeon from 2015 to 2020. Exclusion criteria included age (<70) and posterior approach. For the first cohort of 361 patients (79 of which passed exclusion criteria) the surgeon used a single-tapered, proximally porous coated, collarless titanium stem. For the next 1650, (478 of which passed exclusion), the surgeon used a dual-tapered, collared, hydroxyapatite-coated titanium stem. Included patients were carefully monitored until March 2021 for PPFFs. A Fisher's exact test was used to compare the incidence PPFFs between the 2 implant designs. RESULTS: 2 of 79 (2.5%) patients had atraumatic PPFFs at an average of 19.5 days post-operatively in the first cohort. Both experienced a Vancouver type B2 periprosthetic fracture and required femoral revision. No patients (0/478, 0%) in the second group sustained a PPFF. (P = 0.0199). CONCLUSION: In this comparison, the dual-taper, hydroxyapatite-coated implant had a significantly lower PPFF rate among elderly patients than a single-taper, proximally porous stem without a collar.

Impact of landscape management on the genetic structure of red squirrel populations.

Landscape management practices that alter the degree of habitat fragmentation can significantly affect the genetic structure of animal populations. British red squirrels use "stepping stone" patches of habitat to move considerable distances through a fragmented habitat. Over the past few decades, the planting of a large conifer forest has connected groups of forest fragments in the north of England with those in southern Scotland. This "defragmentation" of the landscape has resulted in substantial genetic mixing of Scottish and Cumbrian genes in squirrel populations up to 100 kilometers from the site of the new forest. These results have implications for the conservation management of animal and plant species in fragmented landscapes such as those found in Britain.

Linking satellite and field survey data, through the use of gis, as implemented in Great Britain in the Countryside Survey 1990 project.

The Institute of Terrestrial Ecology (ITE) has been studying land use and the effects of land use on ecology for two decades. A series of national field surveys have been undertaken by the Land Use Section of ITE since 1978, the most recent being Countryside Survey 1990 (CS1990). The three-year project brought together field survey and remote sensing data which were analyzed using Geographical Information Systems (GIS). National and regional land-cover patterns were described and changes estimated.The data collected by the field survey part of CS1990 recorded stratified samples based on a land classification. Thematic maps for surveyed 1-km squares covered physiography, agriculture and semi-natural vegetation, forestry, structures and boundaries. The same sites were surveyed in 1984 and 1990 with 14 000 digital maps produced describing both years. GIS was used to generate stock figures for each year, and overlay allowed change between survey dates to be estimated.GIS was used to compare data collected from both field survey and satellite imagery so that both sets of information could be qualified when expressed as national figures.This paper describes the historical development of the ITE Land Classification, examines the way in which data were collected for surveys, with particular reference to Countryside Survey 1990, and shows how satellite and field survey data can be linked through GIS.

Inhibition of cholesterol-induced increases in arterial wall permeability by propranolol.

Increased arterial permeability to [125I]albumin is one of the earliest abnormalities found in the cholesterol-fed rabbit model for atherosclerosis and precedes morphologic changes in the arterial wall. Since propranolol is reported to retard atherogenesis in this model, the current study was undertaken to study the effect of propranolol on arterial permeability to albumin in cholesterol-fed rabbits. Carotid permeability to [125I]albumin was measured after 1 week of (a) a control diet containing only trace cholesterol (N = 9), (b) a 1.5% cholesterol diet (N = 11), or (c) a 1.5% cholesterol diet plus intraperitoneal propranolol 5 mg/kg/day (N = 19). The carotid artery was cannulated proximally and distally and peristaltically perfused with oxygenated Modified Eagle's Medium to which [125I]albumin had been added. The permeability of the carotid artery to albumin was estimated by measuring 125I activity in peripheral venous samples obtained after 0, 15, 30, 60, 120, 180, and 240 min of carotid perfusion. 125I-radioactivity of the perfused carotid artery was also counted at the end of the experiment to measure 125I retained in the arterial wall. The transfer of [125I]albumin across the arterial wall to the venous circulation was greater in the untreated cholesterol-fed group than in controls (P less than 0.05), but cholesterol-fed animals treated with propranolol did not differ significantly from controls. 125I-albumin in the arterial wall after 240 min of perfusion was decreased in both untreated cholesterol-fed animals (1444 dpm/cm +/- 350) and in propranolol-treated animals (1629 +/- 309) when these were compared to controls (3909 +/- 693, P less than .05).(ABSTRACT TRUNCATED AT 250 WORDS)

Correction of enhanced endothelial permeability by cessation of cholesterol feeding.

Changes in endothelial permeability and the transport of macromolecules may be important in the initiation and/or progression of atherosclerosis. We have previously shown, with a carotid artery preparation isolated in situ with intact adventitia, that long-term cholesterol feeding in rabbits will result in a seven- to tenfold increase in 125I albumin transport across the artery into the systemic circulation. The current studies were undertaken to determine whether this abnormality of enhanced permeability could be reversed by cessation of cholesterol feeding and correction of the hyperlipidemia. Two groups of rabbits were fed either a standard Rabbit Chow or a diet containing 1.5% cholesterol and 5.2% corn oil for 12 to 15 weeks. Another group of rabbits was given cholesterol for 12 to 15 weeks with change to standard rabbit chow for an additional 22 to 24 weeks after which albumin transport studies were then performed. Mean plasma cholesterol level after 12 to 15 weeks of cholesterol feeding was 2052 +/- 395 mg/dl. After the animals were withdrawn from the cholesterol diet for 22 to 24 weeks, the mean plasma cholesterol level decreased to 80 +/- 21 mg/dl. The mean plasma cholesterol value in chow-fed animals was 39 +/- 6 mg/dl. Perfusion studies were done with 125I-labeled albumin and plasma radioactivity served as a measure of transport across the carotid artery. The average level of albumin transport across the artery into venous blood in the cholesterol-fed animals (13,911 dpm/ml of plasma) was significantly greater than that of control animals (2049 dpm/ml of plasma).(ABSTRACT TRUNCATED AT 250 WORDS)