Total Knee Replacement: A Patient's Guide.

Edited By: Seth S. Leopold, M.D.
Last updated Tuesday, April 15, 2008

Figure 5 - Knee arthritis can affect any of the three compartments of the knee. Medial-sided knee pain, located on the part of the knee that faces the opposite knee, is the most common location for arthritic pain.

Figure 6 - Lateral knee pain, affecting the "outside" of the knee, is sometimes the result of arthritis of the knee.

Figure 7 - Pain behind the kneecap from arthritis may occur along with arthritis elsewhere in the knee, or in isolation. Isolated patellofemoral arthritis is the least common pattern of knee arthritis.

Figure 8 - This patient had diffuse arthritis throughout his knee from an old fracture of the tibia (shinbone), which at that time was treated with the two screws that are visible. This patient was later treated with a total knee replacement, similar to the one shown in Figure 9.

Figure 9 - This patient had rheumatoid arthritis and symptoms throughout her knee, resulting in the traditional total knee replacement pictured here.

Figure 10 - This patient's arthritis was confined to the medial ("inside") compartment of her knee on x-rays, and her pain was localized to that part of the knee as well. She was a good candidate for minimally-invasive partial knee replacement.

Figure 11 - Minimally-invasive partial knee replacement may be performed for either medial ("inside" of the knee) or lateral ("outside" of the knee) arthritis patterns, provided the symptoms are limited to that one part of the knee. X-rays of two knee replacements are shown here. On the left is a lateral replacement, and on the right is a medial replacement.

Review of the condition

Characteristics of severe arthritis of the knee

Pain

Pain is the most noticeable symptom of knee arthritis. In most patients, the pain gradually gets worse over time, but sometimes has more sudden “flares” where the symptoms get acutely severe. The pain is almost always worsened by weight-bearing and activity. In some patients, the pain becomes severe enough to limit even routine daily activities.

Stiffness

Morning stiffness is present in certain types of arthritis; patients with this symptom may notice some improvement in knee flexibility over the course of the day. Rheumatoid arthritis patients may experience more frequent morning stiffness than patients with osteoarthritis.

Swelling and warmth

Patients with arthritis sometimes will notice these symptoms. If the swelling and warmth are excessive, and are associated with severe pain, inability to bend the knee, and difficulty with weight-bearing, those signs might represent an infection. Such severe symptoms require immediate medical attention. Joint infection of the knee is discussed below.

Location

The knee joint has three “compartments” that can be involved with arthritis (see figure 5). Most patients have both symptoms and findings on X-rays that suggest involvement of two or more of these compartments--for example, pain on the lateral side (see figure 6) and beneath the kneecap (see figure 7). Patients who have arthritis in two or all three compartments, and who decide to get surgery, most often will undergo total knee replacement (see figures 8 and 9).

However, some patients have arthritis limited to one compartment of the knee--most commonly the medial side (see figure 10). When patients with one-compartment arthritis (also called “unicompartmental” arthritis) decide to get surgery, they may be candidates for minimally-invasive partial knee replacement (mini knee) (see figure 11).

Types

Inflammatory arthritis

This broad category includes a wide variety of diagnoses, including rheumatoid arthritis, lupus, gout, and many others. It is important that patients with these conditions be followed by a qualified rheumatologist, as there are a number of exciting new treatments that may decrease the symptoms and perhaps even slow the progression of the joint damage.

Patients with inflammatory arthritis of the knee usually have joint damage in all three compartments, and therefore are not good candidates for partial knee replacement. However, inflammatory arthritis patients who decide to have total knee replacement have an extremely high likelihood of success; these patients often experience total or near-total pain relief following a well-performed joint replacement.

Osteoarthritis

Osteoarthritis is also called OA or “degenerative joint disease.” OA patients represent the large majority of arthritis sufferers. OA may affect multiple joints, or it may be localized to the involved knee. Activity limitations due to pain are the hallmarks of this disease.

OA patients who have symptoms limited to one compartment of the knee sometimes are good candidates for minimally-invasive partial knee replacement (mini knee).

Similar conditions

Meniscus tear

Sometimes patients with knee pain don't have arthritis at all. Each knee has two rings of cartilage called "menisci" (this is the plural form of "meniscus"). The menisci work similarly to shock absorbers in a car.

Menisci may be torn acutely, in a fall or as the result of other trauma, or they may develop degenerative tears from wear-and-tear over many years. Patients with meniscus tears experience pain along the inside or outside of the knee; sometimes the pain is worse with deep squatting or twisting. Popping and locking of the knee are also occasional symptoms of meniscus tears.

Since some of these symptoms may be present with arthritis, and the treatment of arthritis is different from that of meniscus tears, it is important to make the correct diagnosis. A good orthopaedic surgeon can distinguish the two conditions by taking a thorough history, performing a careful physical examination, and by obtaining imaging tests. X-rays and Magnetic Resonance Imaging (MRI) scans may be helpful in distinguishing these two conditions.

Joint infections

Also called infectious arthritis or septic arthritis, a joint infection is a severe problem that requires emergent medical (and often surgical) attention. If not treated promptly, knee infections can cause rapid destruction of the joint; in the worst cases, they can become life-threatening.

Symptoms of a knee joint infection include:

• severe pain,
• joint swelling and warmth,
• fevers, and
• marked inability to walk, bend the knee, or bear weight.

Patients who suffer from arthritis are not more likely to develop such infections. They may occur in anyone. Arthritis patients who develop such infections would notice a significant worsening in their pain, as well as some of the other symptoms listed above.

A physician will make the diagnosis of a joint infection based on history and physical examination, blood tests, and by sampling joint fluid from the knee.

Again, a joint infection is a serious condition that requires immediate medical attention.

Incidence and risk factors

Diagnosis

History and physical examination

An orthopaedic surgeon will begin the evaluation with a thorough history and physical exam. Based on the results of these steps, (s)he may order plain X-rays.

X-rays

If a patient has arthritis of the knee, it will be evident on routine X-rays of the joint. X-rays taken with the patient standing up are more helpful than those taken lying down, as the way the knee joint functions under load (i.e. standing) provides important treatment clues to the physician.

Also, plain X-rays will allow an orthopaedic surgeon to determine whether the arthritis pattern would be suitable for total knee replacement or for a different operation, such as minimally-invasive partial knee replacement (mini knee).

Medications

It is important to distinguish broadly between two types of arthritis: inflammatory arthritis (including rheumatoid arthritis, lupus, and others) and non-inflammatory arthritis (such as osteoarthritis).

Although there is some level of inflammation present in all types of arthritis, conditions that fall into the category of true inflammatory arthritis are often very well managed with a variety of medications, and more treatments are coming out all the time. Individuals with rheumatoid arthritis and related conditions need to be evaluated and followed by a physician who specializes in those kinds of treatments, called a rheumatologist. Excellent non-surgical treatments (including many new and effective drugs) are available for these patients; those treatments can delay (or avoid) the need for surgery, and also help prevent the disease from affecting other joints.

So-called non-inflammatory conditions, including osteoarthritis (sometimes called degenerative joint disease), also sometimes respond to oral medications (either painkillers like Tylenol, or non-steroidal anti-inflammatory drugs like aspirin, ibuprofen, celebrex, or vioxx) but in many cases, symptoms persist despite that type of treatment.

It is important to avoid using narcotics (such as Tylenol #3, vicoden, percocet, or oxycodone) since they are have many side effects, are habit-forming, and make it harder to achieve pain-control safely and effectively after surgery, should that become necessary. Narcotics are designed for people with short-term pain (like after a car accident or surgery), or for people with chronic pain who are not surgical candidates. People who feel they need narcotics to achieve pain control should consider seeing a joint replacement surgeon (an orthopaedic surgeon with experience in knee replacements) to see whether surgery is a better option.

Exercises

There is little evidence to suggest that knee arthritis can be prevented or caused by exercises or activities, unless the knee was injured (or was otherwise abnormal) before the exercise program began. There is no evidence that, once arthritis is present in a knee joint, any exercises will alter its course.

However, exercise and general physical fitness have numerous other health benefits. Regular range of motion exercises and weight bearing activity are important in maintaining muscle strength and overall aerobic (heart and lung) capacity, and help prevent the development of osteoporosis, which can complicate later treatment. Certainly, people who are physically fit are more resilient and, in general, are more able to overcome the problems associated with arthritis. Physically fit people also tend to recover more quickly from surgery, should that eventually be necessary to treat the knee arthritis.

Possible benefits of total knee replacement surgery

Regardless of whether a traditional total knee replacement or a minimally-invasive partial knee replacement (mini knee) is performed, the goals and possible benefits are the same: relief of pain, and restoration of function.

The large majority (more than 90 percent) of total knee replacement patients experience substantial or complete relief of pain once they have recovered from the procedure. The large majority walk without a limp, and most don’t require a cane, even if they used one before the surgery. It is quite likely that you know someone with a knee replacement who walks so well that you don’t know (s)he even had surgery! Frequently, the stiffness from arthritis also is relieved by the surgery. Very often, the distance one can walk will improve as well, because of diminished pain and stiffness. The enjoyment of reasonable recreational activities, such as golf, dancing, traveling, and swimming almost always improves following total knee replacement.

Surgery for Severe arthritis of the knee at the University of Washington

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