What Is a Total Knee Replacement? An Orthopedic Surgeon Explains.

The chief of USC Orthopaedic Surgery explains what undergoing and recovering from a total knee replacement looks like today. 

USC Orthopaedic Surgery, part of Keck Medicine of USC, has a group of surgeons with extensive experience in arthroplasty (joint surgery) and can help patients determine whether they need a total knee replacement — and, if so, how best to proceed.  

For people who need a total knee replacement, knee pain is not a recent development. It is an ongoing issue. 

“This is usually a chronic problem. It is usually not associated with an acute injury,” says Jay R. Lieberman, MD, chief of USC Orthopaedic Surgery. 

Typically, these individuals have had knee pain for months or even several years, without improvement from conservative therapy. Such therapy might start with icing, physical therapy and home exercises, and anti-inflammatory medicines. If the patient does not experience pain relief, then the treatment can progress to injections including corticosteroids, hyaluronic acid and platelet-rich plasma. 

Often, these patients suffer from degenerative arthritis, which may have resulted from wear and tear of the knee over time or secondary to trauma, or inflammatory arthritis, which might stem from an autoimmune disease such as rheumatoid arthritis. 

Do I need a total knee replacement or a partial knee replacement? 

The knee has three compartments: inner (medial), outer (lateral) and kneecap (patellofemoral). Patients who have disease in just one compartment — and who have not seen improvement from conservative therapy — tend to be better candidates for partial knee replacement. 

For patients needing total knee arthroplasty, the procedure typically involves removing the damaged surfaces of the femoral and tibial parts of the knee, then replacing them with metal and plastic prostheses to reproduce the joint. 

Will the new knee be painful? 

“Total knee arthroplasty is perceived to be painful and hard to recuperate from,” Dr. Lieberman says. However, improvements in pain management have led to decreased postoperative pain and facilitated faster recovery. 

Many patients start taking pain medications several days before the procedure. During surgery, patients receive spinal anesthesia with intravenous sedation so that they remain asleep. At the end of the surgery, some patients have pain medication injected into the joint, the effects of which last about a day. Patients may also receive peripheral nerve blocks that provide more sustained pain relief after the procedure. 

“The goal is to provide pain relief beyond the operation itself,” Dr. Lieberman says. Afterward, patients can take both acetaminophen and anti-inflammatory pain medications to help relieve the pain. 

How long does it take to recover from a total knee replacement? 

In the first two weeks after surgery, patients work on gaining full extension of the knee. However, there is less focus today than in the past on having patients undergo aggressive physical therapy during the first couple of weeks after surgery. Instead, patients are advised to proceed with their daily activities but not to overdo it to avoid swelling. 

Once the wound is healed and the swelling is under control, then patients can start doing exercises to improve flexion and strength. It is critical that patients strengthen their quadriceps and hamstrings because these muscles support knee function. 

“By six weeks to two months, most patients are moving well. By three to four months, they are quite active,” Dr. Lieberman says. Patients who keep up with their home exercises tend to see the most progress, he adds. 

When can I start driving again after a knee replacement? 

As long as they can react quickly enough, patients whose left knees have been replaced can start driving two weeks after the procedure, but there is variability between individuals. Patients with new right knees should wait at least three or four weeks, and it may be longer in some cases. 

In either case, do not drive on your own at first. “We always recommend that patients go out with someone and practice driving before they do it alone,” Dr. Lieberman says. 

When can I participate in sports again after a knee replacement? 

With any sport, Dr. Lieberman advises starting slow. Then, gradually increase the intensity to build up leg strength in both legs. This is important because patients with knee pain might not have been active for a long time. 

After any activity, always ice the knee for 10 to 20 minutes to reduce pain and swelling. 

What is the long-term outlook after a knee replacement? 

Most total knee replacements can last about 20 years. And with recent advances in the plastic used, some artificial knees could last even longer. 

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