Page 46 - Clinical Manual of Small Animal Endosurgery

34 Clinical Manual of Small Animal Endosurgery

Fig. 2.2 Arthroscope cannula with blunt and sharp obturator.

500 h; some light units indicate remaining bulb life. Keeping a spare bulb
is sensible, in case of bulb failure. Many light sources have automatic
intensity control through feedback from the camera output, maintaining
appropriate illumination and image quality during arthroscopy. Manual
control of light intensity is also possible, enabling fine adjustment of the
image by the arthroscopist.
Light is transmitted from the lamp unit to the arthroscope through a
fibre-optic cable (Fig. 2.3), connected to the arthroscope light post. Each
manufacturer’s light source has its own connection mechanism coupling
the source to the cable and the connections joining the fibre-optic cable
to the arthroscope are also manufacturer-specific. Connection converters
are readily available to couple most fibre-optic connector styles to each
arthroscope make and model, allowing for suitable size matching between
almost any fibre-optic cable and any arthroscope. Small arthroscopes
require use of a thin light cable to prevent loss of light. The light cable
comprises a bundle of flexible yet delicate glass fibres that break if the
cable is bent or wound too tightly, hence the cable should be wound
gently when stored or transported. Fibre breakage reduces the light
transmission through the cable, eventually rendering the cable unusable.
Although the fibre-optic cable delivers ‘cold light’ at the arthroscope tip
(compared to historical systems utilising a bulb at the tip of the scope),
the light cable can heat up during use and for this reason it should not
be placed directly on the patient to avoid risk of thermal burn.