The three tour Lion suffered injury during Ireland's defeat to England on Saturday as is certain to miss the showpiece tournament in New Zealand.
Murphy has plenty of experience of dealing with World Cup heartbreak having suffered a fractured leg before the 2003 edition of the competition and has sent his best wishes to the Munster flanker.
"David looked in a lot of pain and I've been in that situation," said Murphy.
"The worst time to get an injury is just before you go out to a World Cup.
"It is a huge, huge disappointment. So much effort and work has gone into the last year.
"If you miss out then there is a dark cloud hanging over your head for quite a few weeks.
"David's a fantastic player for us. We do have options in the back row, but David will be sorely missed."
Eight years on from his own World Cup misery, Murphy finds himself in a very different situation, after Felix Jones suffered his own injury, and admits the World Cup is likely to be his international swansong.
"It was quite emotional. I'd always intended to seriously consider retiring from international rugby after the World Cup.
"I have not thought about that in depth, but if I do then Saturday will have been my last run out on home soil.
"I was told last Tuesday week that there was no place for me in the squad. I played against Connacht on the Thursday and flew back to Leicester on the Friday.
"Due to injury I was called back in and then because of an injury to Rob Kearney I was back in the Test team.
"There was a full array of emotions - from disappointment to elation and then back to disappointment with not getting the win against England.
"I was injured in January and the doctor said it would be very difficult to get on the plane to New Zealand.
"I am excited, I won't lie. I thought it was a lost cause and was chasing a lost cause for a lot of the year. I pulled out a lot of stops to get there."