When Is It Time to Have a Knee Replacement

To make an appointment with one of our orthopaedic specialists or to learn more about our services, centers and treatment options, please call 410-448-6400 or complete our online form.

Knee replacement is one of the most successful operations in medicine and has improved the lives of millions of patients. Patients often ask about the correct time to have a knee replacement. Below, we present conservative treatments for knee arthritis, risks of knee replacement, and signs that it might be time to consider knee replacement.

Conservative Treatment for Knee Arthritis

I am a firm believer that conservative treatments for knee arthritis work well and are an appropriate solution for many patients.

Physical Therapy

One of the most effective means of treatment is physical therapy. The most effective therapy is called closed-chain quadriceps strengthening. With this therapy, the foot is planted on the floor to strengthen the large thigh muscles. This often improves the way the kneecap moves through the knee joint, decreasing pain and increasing ability to function.

Weight Loss

Weight loss is also a very effective means of dealing with knee arthritis. When we speak about weight, we usually speak about the body mass index (BMI), which is a ratio of weight to height that can be calculated using online calculators such as the one you can access at this link: https://www.nhlbi.nih.gov/guidelines/obesity/BMI/bmicalc.htm. People with a body mass index above 30 should consider weight loss to see whether that improves symptoms before embarking on any kind of joint replacement.

Based on the way body mechanics work, if you lose 1 pound of overall body weight, it takes 3 pounds of stress off your knee. I had several patients who were too heavy to undergo joint replacement, and I asked them to lose weight before undergoing the surgery. When they lost the weight, they came back and decided that they no longer needed the joint replacement because their pain had improved so dramatically. Certainly, this does not apply to everyone, but it has convinced me that attempting weight loss before considering knee replacement is a sound strategy if your body mass index is higher than 30.

Steroid Injections

Steroid injections into the knee are commonly used for knee arthritis treatment. Although a very small risk of infection is associated with the injections, they are remarkably effective in relieving pain. Unlike steroid pills, they rarely have any major effects on the whole body other than a temporary rise in blood sugar in diabetic patients.

Steroid injections can be administered into the knee every 3 months in the clinic (we have to wait 3 months between shots). I have had patients who have had delayed joint replacement for years with routine steroid injections.

Anti-inflammatory Medications

Anti-inflammatory medications, such as acetaminophen (e.g., Tylenol) and ibuprofen (e.g., Advil), are also very effective at relieving pain. For acetaminophen to be effective, patients should take it three times a day. For example, patients without liver problems can take two Extra-Strength Tylenol (1000 mg acetaminophen) three times a day to maximize the results. Ibuprofen and naproxen can also be used for pain relief as long as patients do not experience stomach problems, such as ulcers or bleeding. Excessive use of ibuprofen or naproxen can cause kidney damage, so follow the instructions on the bottle.

Other Nonoperative Treatments

Other treatments, such as knee unloader braces, heel wedges placed in the shoe, and injections of hyaluronic acid (a gel that is injected into the knee) have been used in the past for conservative treatment of knee arthritis. The American Academy of Orthopaedic Surgeons has not found them to be of substantial benefit. However, if the patient wants to try heel wedges, unloader braces, or injections of the hyaluronic acid gel, I am more than happy to accommodate them.

Risks Associated with Knee Replacement Surgery

Knee replacement is overall a very safe procedure. However, there are some associated risks that patients should be aware of. The biggest risks that can occur after knee replacement are infection and stiffness.


Infection is an uncommon occurrence after knee replacement. However, when it does occur, it is very disruptive to the patient's life. Treatment of infection around a knee replacement usually requires removal of the knee replacement, installation of an antibiotic knee replacement for 3 months, and later, a third operation to put a new permanent knee replacement back in place.

We take several steps to prevent infection before, during, and after surgery, and the University of Maryland is a leader in research into the prevention and treatment of knee infection.


Stiffness is another uncommon but possible complication associated with knee replacement. Most patients who undergo knee replacement are not able to fully straighten the leg before surgery. In general, knee replacement allows them to straighten the leg all the way. After knee replacement, most patients are able to bend the leg to the same degree as they were able before surgery. However, knee replacement does not usually provide increased knee bending. Some patients form exuberant scar tissue and have less motion with the knee replacement than they did before the operation.


Instability is one of the main reasons to have a knee replacement. In most cases, the stability of the knee replacement is better than that of the preoperative arthritic knee. However, some patients have instability after knee replacement or develop it over time and need to have the knee replacement redone to improve its stability.

Incomplete Relief of Pain

Although knee replacement is very effective at relieving pain, between 5% and 10% of patients who undergo knee replacement still have pain afterward. This can be as minimal as occasional pain on cold days or pain with climbing stairs or level walking. It is important to understand that the vast majority of patients are very happy with the pain relief, but there is a small subset of patients who have persistent pain after knee replacement.

Nerve and Artery Damage

The knee is surrounded by major nerves and arteries, and it is possible that they could become injured during surgery. With the worst injuries, the patient can lose the leg. Fortunately, this is very rare, and specific steps to avoid it are taken during surgery.

Medical Complications

Medical complications associated with knee replacement surgery are uncommon but include blood clots in the lung or leg, heart attack, stroke, and even death. These risks are minimized by optimizing the patient's weight and medical status before the operation in conjunction with the patient’s primary care doctor.

The above-mentioned risks are all very rare, but it is important to know that they are possible.

Time for Knee Replacement?

Knowing the risks, when is it time to have the operation? Below are reasons to consider knee replacement.

Marked Disruption of Everyday Activities

One of the main reasons to consider knee replacement is pain that markedly limits everyday activities despite the use of anti-inflammatory medicines. For surgery to be considered, the pain should be disruptive to the activities of daily living, especially if it’s to the point that the person stays in the house more to avoid activity altogether.

Inability to go up and down stairs and needing to use a cane are also signs that it might be time to consider knee replacement. Failure of anti-inflammatory medications to decrease pain and presence of bone-on-bone arthritis that is causing pain on an hourly basis are indications that it is probably time to consider knee replacement for pain relief.

Many patients have trouble sleeping at night because of the pain caused by knee arthritis. Failure of anti-inflammatory medications to allow patients to sleep is another indication that it might be time to consider knee replacement.

Bone-on-Bone Arthritis

Before considering knee replacement, x-rays should be obtained and should show bone touching bone somewhere in the knee. Patients who have only thinning of the cartilage without bone touching bone should not undergo knee replacement surgery except in rare circumstances. Patients who do not have bone-on-bone arthritis but nonetheless undergo knee replacement surgery are much less likely to be satisfied with the knee replacement. Other pain management strategies should be considered to help with the symptoms of thinning cartilage.


Knee arthritis can cause progressive instability of the knee with which the knee becomes much looser and more unstable than the native knee. In some cases, the instability is mild. In other cases, it is substantial enough that when the knee is in a bent position, it becomes markedly unstable.

The instability often is manifested as a "giving way" sensation to the knee. In severe cases, the knee instability causes the patient to fall. It is my feeling that for patients with bone-on-bone arthritis who have started to experience falls because of the knee arthritis, it is probably time to have a knee replacement to improve the stability of the knee and limit the chances of falling.


Some risks are associated with knee replacements, and it is important to be aware of them. However, in general, the risks rarely occur, with the exception of incomplete relief of knee pain. Approximately 5% to 10% of patients who undergo knee replacement experience incomplete relief of knee pain. The vast majority of patients are happy they had the procedure.

Only the patient can decide when he or she is ready for knee replacement. In most cases, knee replacement is an entirely elective procedure that can be done in the patient’s time frame. There usually is no rush to having the operation. The one exception to this is the patient who is starting to fall frequently because of an unstable knee. Patients who have knee arthritis and are starting to fall because of the knee arthritis should strongly consider surgery.

In summary, knee replacement is an extremely successful operation that has helped millions of patients. Knowing the risks, benefits, and options will help you to be included as part of the care team and will help you to get the most out of your knees.

Ted Manson, MD

Average rating:
(based on 0 ratings)