WHAT IS NANOTECHNOLOGY ?
B ) ITS ROLE IN ORTHOPAEDICS ?
C ) RECENT ADVANCES IN DETECTION OF PERIPROSTHETIC INFECTIONS ?
A 1 A ) INTRODUCTION
Nanotechnology (nanotech) is the manipulation of matter with at least one dimension sized from 1 to 100 nm
DEFINITION
1 National Nanotechnology Initiative (NNI) defines nanotechnology as the understanding of control of matter at dimensions between 1 and 100 nanometers.
2 To put size into perspective, a sheet of paper is about 100,000 nanometers thick and one inch contains about 25.4 million nanometers.
B ) ROLE IN ORTHOPAEDICS / USES
1 For osseointegration of implants -
A ) as it increases attachment and proliferation of osteoblasts
B ) Recently, injectable nanostructured three-dimensional hydrogel scaffolds were developed that showed enhanced osteoblast adhesion and displayed suitable mechanical properties in the range of human cancellous bone
2 For targeted drug therapy -
A ) Nanotech is being used in the field of targeted drug therapy for long-term inhibition of bacterial growth.
B ) Although earlier studies successfully incorporated large molecules, such as growth factors, into nanostructured materials
C ) more recent studies have created nanofibrous scaffolds that incorporate smaller molecules, such as doxycycline and silver particles - These can be released in a controlled manner with long-term duration.
D ) Recently, implant nanocoatings were developed that contain monocyte chemotactic protein-1 and interleukin-12, which prevent infection by enhancement of the recruitment and activation of macrophages.
3 For regeneration of annulus fibrosus
4 For repairing osteochondral defects
5 For repairing damaged meniscus
C ) RECENT ADVANCES IN DETECTION OF PERIPROSTHETIC INFECTIONS
1 Use of leukocyte esterase assay or strip test -
A ) Leukocyte esterase is an enzyme secreted by activated neutrophils that have migrated to the site of infection.
B ) A colorimetric strip test for this enzyme has been in use for decades for diagnosis of urinary tract infection.
C ) The color of the reaction on the strip is either negative (no color change), trace, + or ++.
D ) The use of leukocyte strip for diagnosis of PJI was recently described by Parvizi et al - They found sensitivity of 80.6% and specificity of 100% if ++ was used as an indication of PJI. Positive and negative predictive values of the test were 100% and 93.3% respectively.
E ) A recent study by other authors also confirmed high sensitivity and specificity of leukocyte esterase
1 Using a synovial fluid white blood cell count of greater than 3000 cells per microliter as an indicator of PJI, the sensitivity and specificity of the leukocyte esterase strips were 92.9% and 88.8%, respectively.
2 When using positive cultures for diagnosis of PJI, sensitivity and specificity of leukocyte esterase strips were found to be 93.3% and 77.0%, respectively.
F ) The advantage of the inexpensive leukocyte esterase test is that it relies on one drop of synovial fluid for determination of PJI and can be performed in one minute.
G ) The main disadvantage of the test is that it cannot be performed with blood stained fluid due to its reliance on a colorimetric change ( vv imp )
2 measurement of synovial fluid inflammatory markers - IL 1 , IL 6
3 use of IBIS T 5000 universal biosensor -
A ) The Ibis T5000 universal biosensor which operates based on broad-range polymerase chain reaction (PCR) and high-performance mass spectrometry seems to be more accurate than conventional PCR.