http://www.nytimes.com/2006/04/16/sports/16boomers.html?incamp=article_popular_3
Here was the article I was talking about!
That being said, it doesn't necessarily mean that ortho will be a gold mine. It merely means new ortho docs will have plenty of opportunities to find work!
e.g. (from the article above) Dr. Thomas Schmalzried, a Los Angeles-area orthopedic surgeon who specializes in hip and knee replacement, said: "The majority of patients getting total knee and hip replacements are Medicare patients. And no one is getting rich from Medicare payments."
I guess I understand why some of the older docs around here always suggest choosing a specialty based on what you actually like. Payment, work opportunities, etc... etc... are always cyclical and unpredictable. Sometimes they increase, sometimes they decrease, and if you choose a field based on what the current work conditions are like now, you may find yourself very disappointed later on!