New Minimally Invasive Surgical Technique Allows Less Invasive Operation And Dramatically Improves Recovery Time


Steven B. Haas, MD

Chief of Knee Service, Hospital for Special Surgery
John N. Insall Chair, Knee Surgery
Attending Orthopedic Surgeon, Hospital for Special Surgery
Professor of Orthopaedic Surgery, Weill Cornell Medical College

Small Incision Total Knee Replacement (TKR) is a new, less invasive surgical technique that enables patients to recover faster, regain more mobility and experience less pain. Dr. Steven B. Haas, Chief of the Knee Service at Hospital for Special Surgery (HSS) pioneered this new technique.


According to Dr. Richard Laskin, Co-Chief of the Knee Service at the Institute for Hip & Knee Replacement at HSS, in a recent study of over 100 Small Incision TKR surgeries, the new procedure has shown that patients recover far faster and regain excellent range of motion in four to six weeks compared to over three months with traditional TKR surgery. Traditionally, the TKR surgery involves using large instruments that require flipping the knee cap over and cutting the quadriceps tendon. By using the new Small Incision TKR technique, surgeons do not cut the quadriceps tendon, they do not flip over the knee cap and they cut less uninvolved tissue. "By doing less cutting and less stretching of the tissue," Dr. Haas said, "we do less damage to the healthy tissue, which I believe leads to a faster recovery."

Dr. Haas developed smaller surgical instruments for use with this technique. With the streamlined instruments, only a 3½ - 5 inch incision compared to the previous 10-12 inch incision is required. Dr. Haas developed these streamlined instruments in conjunction with Smith & Nephew, a globally advanced medical device company. While Haas' instruments are roughly half the size of those used in traditional TKR surgery, they still provide the precision necessary to resurface and cut the bones for the implants to be fit.

"At HSS, our mission is to constantly improve upon standard methods of surgery," said Dr. Richard Laskin. "Our success with this new procedure promises to be of enormous benefit to patients requiring such surgery." In addition to less tissue damage, a study on pain control conducted by Dr. Laskin at HSS showed that patients used the PCA (pain control) pump demand button 20% fewer times with Small Incision TKR versus traditional methods.

Dr. Haas said, "It is very satisfying to see how the Small Incision TKR surgical technique allows patients to get back to their lives with a good range of motion as much as two months faster."

One such patient, Geri Bauer had both knees replaced - one with the traditional surgery and the other with Small Incision TKR. The difference was remarkable. Her knees were replaced four years apart. After the Small Incision TKR, she walked out of the hospital with a cane and had good range of motion within a month. With the traditional method, she still experienced some pain after three months.

Although patients undergoing Small Incision TKR recover faster, they still must commit to a rehab program. While results will vary, patients typically will have 90% range of motion (approximately 115 degrees) restored by four weeks, and further motion by the end of two months. A healthy knee will flex between 125 and 150 degrees. Prior to surgery, many patients had been limited to a 90-100 degree range of motion.

While those who undergo Small Incision TKR have had positive results, not everyone is a candidate for this procedure. Large, muscular men and obese patients, as well as patients who have numerous scars over the knee from previous surgeries are often not well suited for this type of small incision. Patients should also be vigilant in picking out the right surgeon for Small Incision TKR. It is recommended that every patient considering surgery ask their doctor:

  • What is the outcome I should expect?
  • What are the risks involved?
  • How many Small Incision TKR operations have you and your hospital done?

There are approximately 250,000 total knee replacements performed annually in the U.S., 1,800 of which are performed at HSS. This is 30 times more than at most hospitals in the United States, and establishes HSS as the hospital that performs the most knee replacements in the world.

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