Abstract
Introduction and Aims: Conventional histology requires the traumatic removal of tissue from its native environment. This is not only a destructive process but also leads to tissue preparation artefact. We report on a novel arthroscopic instrument, the laser scanning confocal arthroscope (LSCA), which can image tissues of the knee at depth without the need for a damaging tissue biopsy.
Method: The new confocal arthroscope contains 4.4mm diameter with a 90-degree lens. Using three knee joints from two adult Merino sheep we imaged muscle, cartilage, ligament, tendon, synovium, meniscus and loose connective tissue. The knees were separately injected with three fluorophores (Acridine Orange, Acriflavine/Calcein-AM or Fluorescein) prior to imaging. Using a medial para-patellar incision, the contents of the knee were exposed and the confocal arthroscope was held directly on the tissue of interest. A second operator captured the images on a computer.
Results: We were able to demonstrate the common histological features of normal sheep articular cartilage, meniscus, synovium, ligament, tendon and muscle. Tissues were imaged to depths of 200 microns. Articular cartilage was characterised by a layer of dense superficial cells surrounded by extracellular matrix. There was no visible orderly arrangement of cells in this layer. Meniscus was characterised by closely packed circumferential collagen fibres. Synovium demonstrated a dense collection of cells in a thin membrane, typical of this secretory tissue. Ligament and tendon were characterised by bundles of parallel collagen fibres interspersed by scattered cells. Muscle revealed a typical arrangement of muscle fibres surrounded by a loose connective tissue and separated by capillaries and nerves. Eccentric nuclei were seen, however striations were beyond the imaging resolution of the arthroscope.
Conclusion: This study demonstrates the use of a novel arthroscopic instrument for the non-destructive examination of the components of the sheep knee joint. We foresee that the laser scanning confocal arthroscope will have future application in the assessment of cartilage grafting techniques and arthritis modifying drugs.
These abstracts were prepared by Editorial Secretary, George Sikorski. Correspondence should be addressed to Australian Orthopaedic Association, Ground Floor, The William Bland Centre, 229 Macquarie Street, Sydney, NSW 2000, Australia.
At least one of the authors is receiving or has received material benefits or support from a commercial source.
