"I think at the heart of the issue is a real lack of research," Walsh, who earned 70 caps for Australia between 2004-2012 and scored more than 30 goals, told the BBC on Sunday.
Several players will miss the Women's World Cup, which kicks off on Thursday, after tearing their anterior cruciate ligaments (ACL).
Other key players missing with ACL injuries include Janine Beckie (28, Canada), Delphine Cascarino (26) and Marie-Antoinette Katoto (24, France), Vivianne Miedema (27, Netherlands) and Catarina Macario (23) and Mallory Swanson (25, United States).
Studies suggest women are two to eight times more likely to suffer ACL injuries compared to men in the same sport and 25% less likely to return after recovery.
Theories as to why women are more likely to suffer from ACL injuries range from women playing in boots designed for men to anatomical differences in female players and changing hormones during women's menstrual cycles.
"The entire high-performance environment is designed by men for men," Walsh said. "For a long time, women have been treated like little men. I would have loved to have known if my menstrual cycle would have affected any of my knee reconstructions.
"We haven't even scratched the surface. A hundred years of under-investment in women's football has brought us to this point where we have lost a number of different players for this World Cup.
"It's a shame we won't get to see them play. It's something we need to invest in, research."
The ninth women's World Cup is being hosted by New Zealand and Australia.