The surgeon who operated on the damaged left knee of Tiger Woods is known for advancing a novel procedure that may help restore the top-ranked golfer's swing.

Woods' surgeon is Thomas Rosenberg, who practices at the Rosenberg Cooley Metcalf clinic in Park City. While the doctor isn't saying what technique he used on Woods, Rosenberg is an early developer of the "double-bundle" reconstruction of the anterior cruciate ligament, or ACL.

Most surgeons repair a damaged ACL, which Woods tore, with a single strand of tendon tissue, usually taken from the patient's knee or from a cadaver. Rosenberg pioneered replacing both of the two parts of the ACL. Some specialists believe it may preserve the finely tuned "screw" action of the knee as it hinges, said John Richmond, chairman of orthopedics at New England Baptist Hospital in Boston.

"The anterior cruciate ligament guides the knee joint," said Richmond. He says he uses both methods. "The perceived advantage of double-bundle surgery is that it restores a more normal motion."

Rosenberg, 61, declined to comment. Mark Steinberg, Woods' agent at International Management Group Inc. in Cleveland, said he didn't know how or why Woods selected Rosenberg.

Woods, 32, is expected to recover from his ACL reconstruction on June 24 and the surgery won't have any "long-term effects on his career," Rosenberg said in a statement. It was the golfer's fourth knee surgery. Rosenberg cleaned cartilage from the same joint two months before Woods won the U.S. Open Tournament last week at Torrey Pines Golf Course in La Jolla, Calif. Woods wound up playing on the hurt knee over five days because of a 19-hole playoff.

Door hinge

The knee joint is similar to a door hinge in lacking side-to-side flexibility like that of the ball-shaped shoulder joint. Woods' 125-mile-an-hour swing involves sharp, excessive knee rotation that can damage ligaments, said Arnold Scheller, an orthopedist who retired as team physician of the 2008 NBA champion Boston Celtics last year.

"When you follow through, you rotate about 70 to 80 degrees across the knee," said Scheller, who also heads a clinic at New England Baptist. "That's a lot of rotational torque, and he's got a very powerful swing." Rosenberg first described the double-bundle technique in 1994, said Richmond, who says he has heard Rosenberg lecture on the approach frequently.

Joint flexes

"That's what he commonly does," Richmond said. "I would expect he would have used it, although that's just speculation." In a healthy knee, the two parts of the ACL the anteromedial and posterolateral bundles tighten and loosen independently as the joint flexes, giving the joint what surgeons call a "screw-home" motion, said Ralph Gambardella, president of the Kerlan-Jobe Orthopaedic Clinic in Inglewood, Calif. While single-bundle reconstruction gives good results, the double-bundle technique is closer to the knee's natural anatomy, he said.

"Single-bundle reconstruction doesn't reproduce the normal biomechanics of the knee," he said in a telephone interview. "If we can add one more piece and re-create the dynamics of the knee better with two bundles, this may be the correct direction to go."

Gambardella, Richmond and other orthopedists emphasized that scientific studies haven't shown the two-strand approach is superior to the more common single-bundle surgery. Surgeons said the double-bundle technique is more difficult, requires more drilling into bone and is more expensive than single-bundle.

Holy Grail

"This is an issue where you have so-called point- counterpoint," Gambardella said. "We're still looking for the Holy Grail, and the answer may not be double-bundle reconstruction."

Rosenberg also often uses a piece of the patient's hamstring rather than knee tissue, called the patellar tendon, to reconstruct the damaged ligament, said Craig Morgan, president of the Morgan-Kalman Clinic in Wilmington, Delaware. That may help patients avoid knee pain that sometimes occurs in the area of the missing tissue.

"Tom was one of the first to get away from using the patellar tendon and use hamstring autografts," said Morgan, who just performed shoulder surgery on Boston Red Sox pitcher Curt Schilling, in a telephone interview. "He's a very creative thinker."

Rosenberg is known for other innovations, surgeons said. He's the inventor of the EndoButton, a piece of polyester tape looped through an oblong metal button that holds ACL grafts in place without screws, Richmond said. It's sold by London-based Smith & Nephew Plc, an orthopedic products maker. Rosenberg also helped develop a widely used method of imaging knees for signs of arthritis.

Avid golfer

Colleagues say Rosenberg is an intense, quiet, private man who is a good athlete and avid golfer. He is team physician to the U.S. ski, skating, and snowboarding teams, according to his Web site. He graduated from medical school at the University of Utah in 1973 and has been experimenting with knee surgery since he trained as a sports medicine fellow at the University of Wisconsin in Madison, said William Clancy, who was his supervisor there.

"He's a brilliant guy with fabulous hands," Clancy said in a telephone interview from the Andrews Sports Medicine and Orthopedics Center in Birmingham, Alabama, where he's now on staff. "He may do things differently than I do them, but he does them very well. Tiger's in good hands."