Older Australians and physical activity levels: Do we know how many are meeting guidelines?

Aim: Current recommendations suggest that older Australians (defined here as ≥65 years of age) should, for health benefits, accumulate 30 minutes of at least moderate intensity physical activity on most days each week. The aim of this study was to determine the proportion who meets this recommendation. Method: Systematic review of scholarly journals published between 1 January 2000 and 5 October 2010. Results: Of 357 potentially relevant papers, 22 met the study criteria. Estimates from the 15 studies with samples >500 suggest that between 25% and 55% of Australians ≥65 years were meeting guidelines, but in these studies definitions, measures and age ranges of participants varied widely. Discussion: Because of the heterogeneity of samples, measures and definitions, it is not possible to estimate with confidence the proportion of older adults in Australia who meet current physical activity recommendations.     

Amputation and ambulation in diabetic patients: function is the goal

The role of amputation in limb salvage is often poorly defined because the surgeon and the patient often attempt to save all limbs at all costs. The difficulty lies in selecting limb salvage versus early amputation. For the sedentary patient, a poorly functional salvaged limb can provide him/her with a higher quality of life than he/she would have with an amputation. For the active patient, early major amputation may offer the best functional outcome. Our experience with diabetic limb salvage over the last 20 years was retrospectively reviewed and compared with the existing literature in an attempt to better understand the role of amputation versus limb salvage in patients with diabetes. In the process, surgical techniques that we believe optimize foot and leg amputations were reviewed. Utilizing a team approach, limb salvage can yield a 64% ambulation rate and an 80% 2-year survival rate. Below-knee amputation led to a similar ambulatory rate, but the 2-year survival in these patients was 52%. With more severe rear-foot ulcers and osteomyelitis, the ambulatory rate declined with each comorbidity. However, those whose foot was saved had a higher chance of walking than those who underwent amputation. Function and quality of life are the outcomes of interest and may be maximized through either limb salvage or amputation. Our job as physicians is to match the correct solution to the patients' lifestyle and their medical, physical and psychological conditions so they can achieve their desired level of activity as quickly as possible.     

Prevalence of Buggy Creek virus (Togaviridae: Alphavirus) in insect vectors increases over time in the presence of an invasive avian host

Invasive species can disrupt natural disease dynamics by altering pathogen transmission among native hosts and vectors. The relatively recent occupancy of cliff swallow (Petrochelidon pyrrhonota) nesting colonies in western Nebraska by introduced European house sparrows (Passer domesticus) has led to yearly increases in the prevalence of an endemic arbovirus, Buggy Creek virus (BCRV), in its native swallow bug (Oeciacus vicarius) vector at sites containing both the invasive sparrow host and the native swallow host. At sites without the invasive host, no long-term changes in prevalence have occurred. The percentage of BCRV isolates exhibiting cytopathicity in Vero-cell culture assays increased significantly with year at sites with sparrows but not at swallow-only sites, suggesting that the virus is becoming more virulent to vertebrates in the presence of the invasive host. Increased BCRV prevalence in bug vectors at mixed-species colonies may reflect high virus replication rates in house sparrow hosts, resulting in frequent virus transmission between sparrows and swallow bugs. This case represents a rare empirical example of a pathogen effectively switching to an invasive host, documented in the early phases of the host's arrival in a specialized ecosystem and illustrating how an invasive species can promote long-term changes in host-parasite transmission dynamics.     

Skeletal effects of zoledronic acid in an animal model of chronic kidney disease

Summary

Bisphosphonates reduce skeletal loss and fracture risk, but their use has been limited in patients with chronic kidney disease. This study shows skeletal benefits of zoledronic acid in an animal model of chronic kidney disease.

Introduction

Bisphosphonates are routinely used to reduce fractures but limited data exists concerning their efficacy in non-dialysis chronic kidney disease. The goal of this study was to test the hypothesis that zoledronic acid produces similar skeletal effects in normal animals and those with kidney disease.

Methods

At 25 weeks of age, normal rats were treated with a single dose of saline vehicle or 100 μg/kg of zoledronic acid while animals with kidney disease (approximately 30 % of normal kidney function) were treated with vehicle, low dose (20 μg/kg), or high dose (100 μg/kg) zoledronic acid, or calcium gluconate (3 % in the drinking water). Skeletal properties were assessed 5 weeks later using micro-computed tomography, dynamic histomorphometry, and mechanical testing.

Results

Animals with kidney disease had significantly higher trabecular bone remodeling compared to normal animals. Zoledronic acid significantly suppressed remodeling in both normal and diseased animals yet the remodeling response to zoledronic acid was no different in normal and animals with kidney disease. Animals with kidney disease had significantly lower cortical bone biomechanical properties; these were partially normalized by treatment.

Conclusions

Based on these results, we conclude that zoledronic acid produces similar amounts of remodeling suppression in animals with high turnover kidney disease as it does in normal animals, and has positive effects on select biomechanical properties that are similar in normal animals and those with chronic kidney disease.     

Integrin‐mediated interactions with extracellular matrix proteins for nucleus pulposus cells of the human intervertebral disc

The extracellular matrix (ECM) of the human intervertebral disc is rich in molecules that interact with cells through integrin‐mediated attachments. Porcine nucleus pulposus (NP) cells have been shown to interact with laminin (LM) isoforms LM‐111 and LM‐511 through select integrins that regulate biosynthesis and cell attachment. Since human NP cells lose many phenotypic characteristics with age, attachment and interaction with the ECM may be altered. Expression of LM‐binding integrins was quantified for human NP cells using flow cytometry. The cell‐ECM attachment mechanism was determined by quantifying cell attachment to LM‐111, LM‐511, or type II collagen after functionally blocking specific integrin subunits. Human NP cells express integrins β1, α3, and α5, with over 70% of cells positive for each subunit. Blocking subunit β1 inhibited NP cell attachment to all substrates. Blocking subunits α1, α2, α3, and α5 simultaneously, but not individually, inhibits NP cell attachment to laminins. While integrin α6β1 mediated porcine NP cell attachment to LM‐111, we found integrins α3, α5, and β1 instead contributed to human NP cell attachment. These findings identify integrin subunits that may mediate interactions with the ECM for human NP cells and could be used to promote cell attachment, survival, and biosynthesis in cell‐based therapeutics. © 2013 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 31:1661–1667, 2013     

Histological evaluation of a free medial femoral condyle flap at 21 months

Recalcitrant nonunions typically require vascularized bone for reconstruction. In this report, we present a case of an index finger middle phalanx nonunion that was successfully treated with a free medial femoral condyle corticocancellous flap. Nearly 2 years after the free tissue transfer, the patient underwent debulking of the bone flap. This gave us the unique opportunity to examine the histology of the vascularized bone. © 2013 Wiley Periodicals, Inc. Microsurgery 33:567–571, 2013.     

Operative Treatment of Early Peri-Prosthetic Femur Fractures Following Primary Total Hip Arthroplasty

The risk factors for and results of operatively treated peri-prosthetic femoral fractures sustained within 90 days following primary THA were evaluated. 5,313 consecutive THAs were reviewed and 32 (0.60%) fractures were identified which included 9 A_g, 2 B₁, 18 B₂, 1 B₃, and 2 A_g/B₂ fractures. 19 (61%) patients sustained 23 complications including 9 greater trochanter non-unions, 2 femoral shaft non-unions, 3 patients with Brooker III HO, and 2 deep infections. 7 patients (23%) required a second operative procedure and one patient required a third. Peri-prosthetic fractures were associated with advancing age, female gender, developmental hip dysplasia, and cementless metaphyseal engaging components, particularly flat wedge tapers. Overall, operative treatment of acute peri-prosthetic fractures is associated with a high rate of complications (61%) and re-operation (23%).     

Trends in hip fracture rates in Canada: An age‐period‐cohort analysis

Age‐standardized rates of hip fracture in Canada declined during the period 1985 to 2005. We investigated whether this incidence pattern is explained by period effects, cohort effects, or both. All hospitalizations during the study period with primary diagnosis of hip fracture were identified. Age‐ and sex‐specific hip fracture rates were calculated for nineteen 5‐year age groups and four 5‐year calendar periods, resulting in 20 birth cohorts. The effect of age, calendar period, and birth cohort on hip fracture rates was assessed using age‐period‐cohort models as proposed by Clayton and Schiffers. From 1985 to 2005, a total of 570,872 hospitalizations for hip fracture were identified. Age‐standardized rates for hip fracture have progressively declined for females and males. The annual linear decrease in rates per 5‐year period were 12% for females and 7% for males (both p < 0.0001). Significant birth cohort effects were also observed for both sexes (p < 0.0001). Cohorts born before 1950 had a higher risk of hip fracture, whereas those born after 1954 had a lower risk. After adjusting for age and constant annual linear change (drift term common to both period and cohort effects), we observed a significant nonlinear birth cohort effect for males (p = 0.0126) but not for females (p = 0.9960). In contrast, the nonlinear period effect, after adjustment for age and drift term, was significant for females (p = 0.0373) but not for males (p = 0.2515). For males, we observed no additional nonlinear period effect after adjusting for age and birth cohort, whereas for females, we observed no additional nonlinear birth cohort effect after adjusting for age and period. Although hip fracture rates decreased in both sexes, different factors may explain these changes. In addition to the constant annual linear decrease, nonlinear birth cohort effects were identified for males, and calendar period effects were identified for females as possible explanations.