NEW YORK (CNN/Money) - As Stryker Corp. gets set to announce fourth-quarter earnings Wednesday, analysts wondered whether the maker of artificial hips and knees can keep up its prodigious, long-term earnings growth under the direction of a new CEO.

Stryker, a medical supplies firm specializing in artificial hip and knee replacement, has posted 20% revenue growth over the last 20 years under CEO John W. Brown, according to analysts. But Brown, stepped down last month, and Stephen MacMillan, previously a vice president for Pharmacia Corp. and president of Johnson & Johnson-Merck Consumer Pharmaceuticals, has taken the CEO reins.

Stryker (Research) is currently trading at $48.65 per share, 28 times the earnings estimate of 1.72 for 2005, and analysts projected that the company will continue to post strong earnings growth, even if investors are unsure about the new leadership.

"I think the company in general is in very good shape, but there are some general investor concerns about how long Stryker can maintain its 20-plus percent growth in earnings operational rate," said Benjamin Andrew, analyst for William Blair & Company.

"[MacMillan] has big shoes to fill and he's inheriting a legacy of 20% earnings growth," said Mark Landy, analyst for Susquehanna Financial Group. Landy said the new CEO will be aided by the presence of Brown, who will remain on the board for a year.

Stryker reported 26 percent earnings growth in 2004, compared to 18 percent earnings growth in the medical supplies industry, according to Thomson Financial. Andrew said he expects Stryker to maintain earnings growth of at least 20 percent throughout 2005, but said that MacMillan's appointment to CEO is "the primary concern for investors." MacMillan, who has been groomed to be Brown's successor since joining Stryker as chief operating officer in 2003, was appointed the top job last month. Brown remains chairman.

MacMillan's appointment "makes people nervous," said Jason Wittes, analyst for Leerink Swann because his abilities in running the Stryker are largely unknown outside the company.

"Externally, [MacMillan] has not been that visible," said Wittes, who considers Stryker a "healthy company."

With a short interest of 2.11% according to Nasdaq, the market seems relatively sure that Stryker is a safe bet for now. Analysts estimated Stryker's earnings per share to be 39 to 41 cents for the fourth quarter of 2004, 40 to 41 cents for the first quarter of 2005 and $1.70 to $1.71 for the full year of 2005

Stryker, based in Kalamazoo, Mich., develops, manufactures and markets specialty surgical and medical products that are sold to hospitals internationally. Like other orthopedics companies including Zimmer Holdings Inc. (Research) and Biomet Inc. (Research), Stryker is likely to see a surge in business as the baby boomers come of age and start swapping their aging hips and knees with artificial replacements. The companies are already cashing in on overweight and out-of-shape baby boomers in need of implants.

"You're not going to see a 60-year old guy with a limp or on crutches," said Wittes. "He's going to get an artificial hip."

The key to remaining competitive for a medical supplies company is to keep up the flow of new products, which requires an ample investment in research and development, said Andrew.

"If you don't invest in R&D, you're going to get left behind, because all the other companies are doing it," said Andrew.

Landy said that Stryker has invested competitively in R&D, particularly with regards to ceramics technology for bone-and-socket replacements and proteins that induce bone tissue to grow.

"You can't just sit back on your laurels," said Landy. "You have to constantly innovate."

Biomet has also enjoyed expanding earnings, reporting 18% growth in earnings per share to $1.57 in fiscal year 2005, which ended in May, meeting analysts' estimated range of $1.56 to $1.59. Estimates for fiscal year 2006 project 16% growth in earnings per share, to $1.83, according to Thomson.

"We have had record quarters every quarter since our inception [in 1977,]" said Barbara Goslee, corporate communications manager for Biomet.

Zimmer spokesman Brad Bishop declined to comment ahead of Monday's scheduled earnings report for the fourth quarter. Analysts have estimated Zimmer's growth in earnings per share at 21% to $2.83 in 2004, according to Thomson.

A spokesman for Stryker did not return a phone message ahead of the company's earnings report.