Partial knee replacement is option for some patients

Patients find quick return to normal activity

Patients with limited arthritis in their knees typically had to live with pain and discomfort or wait until deterioration reached a point at which they could undergo a total knee replacement, but new technology gives patients a third option that allows them to return to normal activity without pain earlier in their lives.

Partial knee replacements reduce the cost of the procedure and enable a patient's quicker return to normal activities. The procedure is another orthopedic surgery that easily can be moved to the outpatient surgery program.

"Because this procedure is minimally invasive there is little blood, and it is routinely performed on younger, healthier patients, so it is ideal for the outpatient or 23-hour stay setting," says Keith Berend, MD, orthopedic surgeon at Joint Implant Surgeons in New Albany, OH. "Patients who are good candidates for this procedure are usually working, so they don't want to undergo a procedure that requires the eight- to 10-week recovery required by a total knee replacement, but they want to eliminate the joint pain caused by arthritis in their knee."

A partial knee replacement can be performed on patients who have knee arthritis limited to one side of the knee joint and have no torn meniscus, says Frosty Moore, MD, an orthopedic surgeon in Austin, TX. "I always order an MRI to rule out other damage to the knee," he says.

In addition to making sure that the patient doesn't have any other knee damage, there are other attributes of the ideal candidate for partial knee replacement, suggests Moore. "Patients must be motivated to follow through on physical therapy, they must understand pain and how to deal with it, and they must be younger and willing to get up and get moving quickly," he says.

In a partial knee replacement, an implant replaces the diseased part of the knee to correct the deformity caused by arthritis and to restore the knee to the pre-diseased state, says Berend. Partial knee replacement requires less removal of bone and cartilage and gives patient a more natural motion following surgery, he adds.

Berend uses the Biomet Partial Knee System that has been approved by the Food and Drug Administration (FDA) for this use. It differs from other partial knee implants because it contains a free-floating meniscal bearing, he says.

The FDA approval mandates specific training with the device before use on patients, he points out. This is an important issue for outpatient surgery managers who are reviewing privileges for new procedures, Berend adds. "Not only should surgeons who want to perform partial knee replacements on an outpatient basis be experienced with the procedure in the inpatient department, but if they are using the Biomet system, they must attend Biomet-specific training courses," he says. This additional training ensures not only that the surgeon understands the implant, which does differ from other implants, but that all other aspects of the procedure and the recovery process are addressed, he adds.

Training for the operating room staff involves a demonstration of the special leg holder that is used for the partial knee replacement, points out Berend. "This leg holder and the position in which the patient's leg must be placed during the procedure is different from other knee procedures," he says.

Although the implant and the surgeon's skill are important to a good outcome, Moore believes that patient education prior to the procedure is just as critical to a successful recovery. "We set expectations up front by lining up physical therapy, setting up an exercise schedule, and continuous passive motion," says Moore. Patients also are told what type of pain to expect so they can distinguish between normal pain during recovery and unusual pain that requires a call to the surgeon, he adds.

Pain control begins before the procedure as the anesthesiologist administers a femoral nerve block and then places an indwelling catheter that will remain for two days to block the pain in the knee, explains Moore. "By reducing the pain during the first days, we increase the patient's mobility and that improves recovery," he says.

Because the typical patient for this procedure is between 40 and 60 years of age and is working, reimbursement is not an issue, Moore says. Patients are usually covered by private insurance offered through their employers rather than Medicare, he explains. "The cost of the implant varies according to contracts with the vendor, but insurance companies like the lower cost of the outpatient procedure compared to the cost of an inpatient stay," he says.

Partial knee implants last up to 20 years, so there should be no reason for another surgery, says Berend. "There is always a chance that arthritis might develop on the other side of the knee but generally, it does not," he says.

Patients are grateful that the partial knee replacement option exists, says Moore. "Our pre-op planning and education teaches patients how to recover, so after the surgery they are ready to go home, which is where they want to recover," he says.


The following companies offer partial knee implants:

  • Biomet, 56 E. Bell Drive, P.O. Box 587, Warsaw, IN 46581-0587. Phone: (574) 267-6639. Fax: (574) 267-8137. Web:
  • Wright Medical Technology, 5677 Airline Road, Arlington, TN 38002. Phone: (800) 238-7117 or (901) 867-9971. Fax: (901) 867-9534. Web:
  • Stryker Orthopaedics, 325 Corporate Drive, Mahwah, NJ 07430. Telephone: (201) 831-5000. Web: