Knee Replacement

Types

Orthopedic surgeons work with patients to determine which surgery fits their needs, based on factors such as medical history, patient age, activity level, weight and degree of damage to the joint. Mayo Clinic surgeons currently perform several types of knee surgery.

Total Knee Replacement

Total knee replacement (TKR) surgery, also called knee arthroplasty, is one of the most successful elective surgeries done today. The surgery replaces severely damaged cartilage tissue with a metal or plastic prosthesis that duplicates the function of the knee joint. Since the 1970s, the technology and long-term success of knee replacement surgery has improved dramatically, providing relief to people with chronic, debilitating knee pain.

Although most of the 300,000 U.S. patients who have total knee replacements are elderly, this procedure may be considered for adults of all ages. Younger patients, however, may wear out their prosthesis prematurely due to more active lifestyles. About 90 percent of patients have freedom from pain and improved mobility for up to 15 years after the surgery.

Unicompartmental (Partial) Knee Replacement

When the cartilage in one of the knee compartments has become damaged, surgeons may be able to replace just the damaged section (compartment) of the joint. This procedure is called a partial or unicompartmental knee replacement.

Implants for unicompartmental or partial knee replacement surgery have improved greatly since the early 1970s, when the surgery was introduced. As a result, partial knee replacement surgery is gaining popularity. About 7,500 partial knee replacements are done each year in the United States.

Although the incision is smaller with a partial replacement and hospitalization is usually only one night, long-term results may not be as good as with total knee replacement. In addition, future surgical procedures may be more difficult after partial replacement surgery.

The ideal patient for partial knee replacement surgery is someone who has arthritis in only one section (compartment) of the knee and is not obese. Patients under age 60 with sedentary lifestyles may also be candidates.

Bilateral Knee Replacement

If pain is experienced in both knees equally and X-rays indicate severe arthritis in both joints, bilateral knee replacement may be a option. This procedure replaces both knees at the same time, reducing the time spent in a rehabilitation center after surgery. Although not a unique surgical procedure, the operation is not as common as single-sided TKR or partial replacement surgery. Candidates for this procedure must be in good health and free of certain medical conditions, including heart or lung disease.

Minimally Invasive Surgery

Traditionally, knee replacement surgery has required lengthy incisions and dissection through the tendons of the knee to gain access for the replacement. Minimally invasive techniques now allow surgeons to perform knee replacement surgery with smaller incisions, and more importantly, less soft-tissue dissection. Minimally invasive surgery can be much more difficult to perform, however, and it is not indicated for all patients. This procedure may not be appropriate for knees that have significant deformity (bowlegged or knock-kneed) or previous major surgery. An orthopedic surgeon will determine whether this procedure is appropriate.

Computer-Assisted Surgery

In addition to traditional surgery, orthopedic surgeons at Mayo Clinic use a computer-guided imaging system during total knee replacement surgery. This new technology, also called computer-assisted surgery (CAS), helps the surgeon align the artificial joint in the bone and may increase the long-term effectiveness of knee replacements, especially in difficult cases such as those involving knock knees or bowlegs.

During computer-assisted surgery, a model of the knee is developed using infrared cameras and electromagnetic devices. The contour of the knee is projected onto a monitor, and the image helps guide the surgeon's attachment of the artificial implant to the bone. CAS provides an internal view of the joint for more precise alignment of the implant, which may improve the long-term success of the total knee replacement.

Recovery after Knee Replacement

After surgery, patients typically remain in the hospital: two to four days for total knee replacement and computer-assisted surgery; four to six days following bilateral knee replacement; and overnight for a partial knee replacement. In the hospital, patients receive physical therapy to help them adjust to the prosthesis. Patients also learn postoperative exercises to perform when they return home. Following bilateral knee replacement surgery, patients typically spend a week at a rehabilitation center before returning home.

Walking aids such as crutches and walkers are needed for about three to six weeks following surgery. With their physician's approval, patients can return to work and resume most daily activities. Once recovery is complete, low-impact activities, such as walking, golfing, dancing, swimming and bicycling, are recommended. High-impact activities should be avoided.