Summer 2005

Minimally Invasive Knee Surgery Comes of Age

UCSF orthopaedic surgeons Michael Ries, M.D., and Kevin Bozic, M.D., perform minimally invasive knee replacement surgeries, but feel that the term can be somewhat misleading to patients. "It's really a spectrum of procedures that are intended to limit the extent of trauma to the knee during the operation," Ries says. "It should be called 'less invasive' surgery."

Minimally invasive knee replacement surgery is a more recent development than minimally invasive hip replacement surgery, getting going only in the last couple of years, but ultimately it may prove a bigger boon to patients. That's because replaced knees take much longer than replaced hips to fully heal -- about six months, in most cases -- so a shorter, less painful recovery could be beneficial.

In addition to improving recovery time and discomfort, the surgery could lead to improved range of motion in the healed knee, Ries says.

Like minimally invasive hip replacement surgery, the less invasive version of knee replacement surgery reduces the traditional eight- to 10-inch incision to one about four to five inches long. Muscle tissues also are less traumatized in the newer surgery. Unlike in hip surgery, only the bone surface is removed -- about a quarter-inch is taken off the end of each half of the joint. Then the artificial knee is cemented to the bone and the patella (kneecap) is resurfaced as well.

Bozic and Ries emphasize that making a smaller incision is only one of many factors that may account for the encouraging early results reported with minimally invasive knee replacement surgeries. The use of pre-emptive analgesia (giving pain medicine before the surgery) improved anesthesia and pain management techniques, more aggressive physical therapy protocols and better patient education all contribute to improved patient outcomes. "Minimally invasive joint replacement surgery is a multimodal approach to reducing pain and shortening recovery times associated with total joint replacement procedures," Bozic says.

The less invasive knee replacement surgery is not for everyone. The knee can't be severely deformed by arthritis, has to be well aligned and can't be too large or muscular, Ries says. Bozic also emphasizes that knee replacement is a highly effective procedure with excellent long-term results, and it is important that long-term patient outcomes not be compromised in order to shorten the duration of recovery and lessen the pain associated with knee replacement surgery.

Dr. Kevin Bozic can be contacted at (415) 353-2663 and Dr. Michael Ries can be contacted at (415) 353-2508. To contact the Arthritis and Joint Replacement Center, call (415) 353-2808.

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