STERILIZATION OF FUJI PRESSURE-SENSITIVE FILM

Fuji Prescale film is a pressure-sensitive medium which produces a cha racteristic pink stain on the application of pressure. Up to a saturat ion level, increases in pressure will produce a denser stain, thereby providing a method of determining pressures within the interface betwe en two articulating surfaces. The relationship between the magnitude o f applied pressure and the optical density of the resulting stain is n on-linear; this relationship also varies with ambient temperature and humidity, in addition to load rate, and therefore requires a calibrati on procedure prior to use. The use of Fuji prescale film for recording interface pressures within the joint space in vitro has been widely r eported; however, the object of this study teas to assess the effects of sterilizing this medium, with a view to future in vivo applications . Samples of Fuji film mere sterilized using a standard ethylene oxide (ETO) gas process and their subsequent pressure-recording properties were compared to a control group of samples. The 'optical-density vs p ressure' relationship for the sterilized group teas significantly diff erent from that of the control group (paired Student's t-test, P < = 0 .001); however, both groups provided reliable data across the same pre ssure-range and both exhibited an excellent degree of repeatability (c oefficient of variation < 2.5%). it war concluded that Fuji film will continue to produce pressure-stains following ETO sterilization; howev er, the calibration of this film will only be valid if it is conducted using film from the sterilized group.