All You Need To Know About Total Knee Replacement

People whose knees are severely damaged by arthritis or injury may have a hard time performing simple activities, such as walking or climbing the stairs. Pain may even be felt when sitting or lying down.

One might want to consider total knee replacement surgery if nonsurgical treatments, such as medications and using walking supports, are no longer helpful. Joint replacement surgery, like total knee replacement surgery, is a safe and effective procedure. It relieves pain, corrects leg deformity and helps the patient resume normal activities.

Improvements in surgical materials and techniques have led to increased effectiveness in knee replacement surgery since it was first performed in 1968. Furthermore, total knee replacements are one of the most successful procedures in all of medicine. In fact, it is so common and effective that more than 790,000 knee replacements are performed each year in the United States, according to the Agency for Healthcare Research and Quality. 

This article aims to provide more understanding of this valuable procedure, whether one has already decided on total knee replacement surgery or just begun exploring treatment options.

Which part of the leg does it concern?

Because the knee is the largest joint in the body, having healthy knees is necessary in performing most everyday activities.

The knee is formed by three parts — the lower end of the thighbone (femur), the upper end of the shinbone (tibia) and the kneecap (patella). The ends of these bones are covered with articular cartilage, a smooth substance that protects the bones and enables them to move easily within the joint.

Menisci are C-shaped wedges that act as “shock absorbers”, cushioning the joint. They are located between the femur and tibia. 

Large ligaments hold the femur and tibia together and provide stability. The long thigh muscles also give the knee strength.

A thin lining called the synovial membrane covers the remaining surfaces of the knee. This membrane lubricates the cartilage by releasing a fluid, reducing friction until it is nearly gone in a healthy knee.

Typically, all of these components work together in harmony. However, disease or injury can disrupt this unity, causing muscle weakness, pain and reduced function.

What causes knee pain and disability?

Arthritis is the most common cause of chronic knee pain and disability. Although there are many forms of arthritis, the majority of knee pain is caused by these three types: osteoarthritis, rheumatoid arthritis and post-traumatic arthritis.


Osteoarthritis is an age-related “wear and tear” kind of arthritis. The cartilage that cushions the bones of the knee softens and wears away. This results in the bones rubbing against one another, causing knee pain and stiffness. Bone spurs are a common symptom of osteoarthritis. Although it typically occurs in people 50 years old and above, it may also occur in younger people.

Rheumatoid arthritis

Rheumatoid arthritis is the most common form of a group of disorders known as “inflammatory arthritis”. It is a disease in which the synovial membrane surrounding the joint becomes inflamed and thickened. This chronic inflammation can damage the cartilage and eventually cause cartilage loss, pain and stiffness.

Post-traumatic arthritis

Post-traumatic arthritis can occur following a severe knee injury. Fractures of the bones that surround the knee or tears of the knee ligaments may cause damage to the articular cartilage over time. As a result, the knee function is limited and pain will be felt.

What is a total knee replacement?

A knee replacement, also known as knee arthroplasty, is actually more like a knee “resurfacing” because only the surface of the bones is replaced.

A knee replacement procedure consists of four basic steps:

  • Preparation of the bone. Firstly, the damaged cartilage surfaces at the ends of the femur and tibia are removed, along with a small amount of underlying bone.
  • Positioning of the metal implants. Secondly, the removed cartilage and bone are replaced with metal components that recreate the surface of the joint. These metal parts may be cemented or “press-fit” into the bone.
  • Resurfacing of the patella. Next, the undersurface of the patella (kneecap) is cut and resurfaced with a plastic button. Depending on the case, certain surgeons do not resurface the patella.
  • Insertion of a spacer. Lastly, a medical-grade plastic spacer is inserted between the metal components to create a smooth gliding surface.

How does one know if total knee replacement is a suitable option?

The patient may be referred to an orthopaedic surgeon for an in-depth examination to determine if total knee replacement surgery will be beneficial. Ultimately, the decision of undergoing the procedure should be agreed upon by the patient, their family, the primary care doctor and orthopaedic surgeon.


When is surgery recommended?

There are multiple reasons as to why knee replacement surgery may be recommended. Below are some symptoms of patients who may benefit from total knee replacement:

  • Moderate to severe knee pain while resting, either in the day or at night
  • Severe stiffness or knee pain that limits everyday activities such as walking, climbing stairs, and getting on and off chairs.  It may be hard to walk more than a few blocks without significant pain. Thus, a cane or walker might be necessary.
  • Knee deformity — a bowing in or out of the knee
  • Chronic knee inflammation and swelling that does not improve with medications or rest
  • No significant improvement with other treatments such as physical therapy, anti-inflammatory medications, lubricating injections, cortisone injections, or other surgeries

What requirements must candidates for total knee replacement meet?

There are no absolute weight or age restrictions for total knee replacement surgery. Although the majority of people who undergo total knee replacement are between the ages of 50 to 80, orthopaedic surgeons evaluate patients individually. Total knee replacements have been performed successfully across all ages, from the young teenager with juvenile arthritis to the elderly patient with degenerative arthritis. Recommendations for surgery are dependent on a patient’s pain and disability, instead of their age.

How is an orthopaedic evaluation carried out?

An orthopaedic evaluation consists of steps:

  • Inquiry of patient’s medical history. The orthopaedic surgeon will gather information about the patient’s general health and inquire about the extent of the knee pain and ability to function.
  • Physical examination. An assessment of the knee motion, stability, strength and overall leg alignment will be carried out.
  • X-rays. The image results help to determine the severity of the damage and deformity in the knee.
  • Other tests. Once in awhile, blood tests or advanced imaging, such as a magnetic resonance imaging (MRI) scan, may be needed to evaluate the condition of the bone and soft tissues in the knee.

After reviewing the evaluation results, the orthopaedic surgeon will discuss with the patient whether total knee replacement is the best method to relieve pain and improve function in the knee. Other treatment options will also be considered and discussed. These include physical therapy, injections, medications or other types of surgery.

Additionally, the potential risks and complications of total knee replacement will also be explained. Such risks and complications include those related to the surgery itself and those that may occur over time post-surgery.

How should one decide to undergo knee replacement surgery?

Realistic expectations

Understanding what total knee replacement can and cannot do is a crucial factor in deciding whether to undergo the procedure.

Majority of patients who undergo total knee replacement experience a drastic reduction of knee pain and a significant improvement in the ability to perform normal everyday activities. However, total knee replacement will not allow one to do more than they could before they developed arthritis.

Every knee replacement implant starts to wear in its plastic spacer with normal use and activity. Excessive weight or activity may speed up this normal wear and cause the replacement to loosen and become painful. As such, patients are advised to refrain from high-impact activities such as jumping, jogging, running or other high-intensity sports for the rest of their life post-surgery.

On the other hand, activities that patients can realistically participate in post-surgery include unlimited walking, biking, driving, swimming, light hiking, golf, ballroom dancing and other low-impact activities.

If the patient’s activity is appropriately modified, the knee replacement can last for many years.


What are the possible complications of total knee replacement surgery?

Fortunately, the complication rate following a total knee replacement is generally low. Severe complications like knee joint infection occur in less than 2% of patients. Furthermore, major medical complications such as a heart attack or stroke occur even less often. However, chronic illnesses may increase the risk of complications occurring. Although uncommon, when such complications occur, full recovery can be prolonged or limited.

Patients are advised to thoroughly discuss their concerns with an orthopaedic surgeon before surgery.

Infection may occur in the wound or deep around the prosthesis. This can happen within days, weeks or even years after surgery. Generally, minor infections in the wound area are treated with antibiotics. As for major or deep infections, they may require more surgery and removal of the prosthesis. Furthermore, any infection in the body can spread to the joint replacement. 

Blood clots
One of the most common complications of knee replacement surgery is blood clots in the leg veins. Although blood clots can occur in any deep vein, they most commonly form in the veins of the pelvis, calf, or thigh. These clots can potentially become life-threatening if they break free and travel to the lungs. A prevention program will be outlined by the surgeon, which may include medication to thin the blood, periodic elevation of the legs, lower leg exercises to increase circulation and support stockings. 

Implant problems
Even though surgical techniques and implant materials and designs continue to advance, implant surfaces may still wear down and the components may loosen. Furthermore, although an average of 115 degrees of motion is usually expected after surgery, scarring of the knee can sometimes occur. As a result, motion may be more limited, particularly in patients with already limited motion before surgery.

Continued pain
A small fraction of patients has reported experiencing continued pain after knee replacement. However, this complication is rare as most patients experience great pain relief post-surgery. 

Neurovascular injury
Although this is rare, injury to the nerves or blood vessels around the knee can occur during surgery. 

How should one prepare for a total knee replacement?

Medical evaluation

Once total knee replacement surgery has been decided on, the orthopaedic surgeon may ask for a complete physical examination to be scheduled with a doctor several weeks before the procedure. This is necessary for ensuring the patient is healthy enough to undergo the surgery and complete the recovery process. Patients with chronic medical conditions such as heart disease may also be evaluated by a specialist, like a cardiologist, before the procedure.


In order to help the orthopaedic surgeon plan the surgery, several tests such as an electrocardiogram and blood and urine samples may be required.


Current medications taken by the patient will be discussed with the orthopaedic surgeon. The patient will then be advised on which ones to stop taking before the surgical procedure.

Dental evaluation

Even though the incidence of infection after knee replacement is very low, an infection can occur if bacteria enter the bloodstream. Therefore, to lower the risk of infection, major dental procedures, such as tooth extractions and periodontal work, should be completed before total knee replacement surgery. 

Urinary evaluations

Patients who have a history of recent or frequent urinary infections should undergo a urological evaluation before surgery. Older men with prostate disease, especially, should consider completing the required treatment before undergoing knee replacement surgery.

Social planning

Even though one will be able to walk with crutches, a cane or walker soon post-surgery, help will probably be needed to accomplish certain tasks. These can include bathing, cooking, shopping and doing laundry.

If the patient lives alone, a discharge planner or social worker at the hospital can help to make advance arrangements for some assistance at home. Alternatively, a short stay in an extended care facility during recovery can also be arranged. 

Home planning

There are several changes that one can make to their home in order for easier navigation during the recovery process. The modifications below may help make everyday activities easier: 

  • If the house is a multi-storey one, a temporary living space on the same floor can help because walking up and down stairs can be difficult during the initial stages of recovery
  • Removing all loose carpets and cords
  • A stable chair during the early stages of recovery with a firm seat cushion and back, a height of 18 to 20 inches, two arms, and a footstool for intermittent leg elevation
  • Secure handrails along the stairways
  • Secure handrails or safety bars in the shower or bath
  • A stable shower bench or chair for bathing
  • A toilet seat riser with arms if one has a low toilet

How is the total knee replacement surgery process like?

The patient will either go home or be admitted to the hospital on the day of surgery. This should be discussed with the surgeon before the surgery.


Upon arriving at the hospital or surgery centre, the patient will be evaluated by a member of the anaesthesia team. The most common kinds of anaesthesia are general (where one is put to sleep), spinal, epidural or regional block anaesthesia (where one is awake but the body is numb from the waist down). Taking the patient’s input into consideration, the anaesthesia team will determine the most suitable form of anaesthesia for the procedure.


Typically, the surgical procedure will take about 1 to 2 hours. First, the orthopaedic surgeon will remove the damaged cartilage and bone. Next, the new metal and plastic implants are positioned to restore the alignment and function of the knee. Depending on the individual’s needs, different kinds of knee implants are used.

After the procedure, the patient will be moved to the recovery room. They will remain there for several hours while the recovery from anaesthesia is monitored. Once the patient has woken up, they will be taken to their hospital ward or discharged home.

What should one expect during their stay at the hospital?

If admitted, the patient will probably stay in the hospital for one to three days.

Pain management

After surgery, it is normal to feel some pain. This is a natural part of the recovery process. The doctor and nurses will work to ease the pain, which can help to speed up the healing.

Normally, medications are prescribed for short-term pain relief after surgery. There are several kinds of medicines available to help manage pain. These include local anaesthetics, acetaminophen, nonsteroidal anti-inflammatory drugs (NSAIDs) and opioids. A combination of these medications may be used to improve pain relief and minimise the need for opioids.

One should be aware that even though opioids help to relieve pain post-surgery, they are a narcotic and can be addictive. In fact, opioid dependency and overdose have become a major public health issue in the U.S. Therefore, it is crucial to use opioids only as directed by one’s doctor. The usage of opioids should be stopped as soon as the pain begins to improve. If it has not begun to improve within a few days post-surgery, one should consult their doctor.

Blood clot prevention

In order to prevent blood clots and decrease leg swelling, one or more measures may be prescribed by the surgeon. These can include blood thinners, inflatable leg coverings (compression boots) and special support hose.

Additionally, foot and ankle movement is encouraged immediately after surgery to increase blood flow in the leg muscles. This will in turn help to prevent leg swelling and blood clots.

Physical therapy

Majority of patients will be able to begin exercising their knee hours after surgery. A physical therapist will teach specific exercises to strengthen the leg and restore knee movement to allow walking and other everyday activities soon after the operation.

To further restore movement in the knee and leg, the surgeon may use a knee-supporting device called a continuous passive movement (CPM) exercise machine. This device slowly moves the knee while the patient is in bed. Although there is no evidence yet to show that these machines improve outcomes, certain surgeons believe in its benefits. It is perceived to decrease leg swelling by elevating the leg and improve blood circulation by moving the muscle of the leg.

Preventing pneumonia

Shallow breathing in the early postoperative period is not uncommon in patients. This is normally because of the effects of anaesthesia, pain medications and prolonged time spent in bed. As a result of shallow breathing, a partial collapse of the lungs, known as atelectasis, can occur. This can make patients susceptible to pneumonia. To help prevent this, it is crucial to take frequent deep breaths. A simple breathing apparatus called a spirometer may be provided to encourage deep breathing.

What should one expect during their recovery at home?

The success of the surgery is dependent on how well the orthopaedic surgeon’s instructions are followed in the first few weeks after surgery at home.

Wound care

The patient will either have stitches or staples running along the wound or a suture beneath the skin on the front of the knee. While a suture beneath the skin does not require removal, stitches or staples will be removed several weeks post-surgery.

One should refrain from soaking the wound in water until it has fully sealed and dried. The wound may be bandaged to prevent irritation from support stockings or clothing.


It is common for there to be some loss of appetite for several weeks post-surgery. It is essential to maintain a balanced diet, usually with an iron supplement, to help the wound heal and restore muscle strength.


A crucial portion of home care is exercise, especially during the first few weeks post-surgery. One should be able to resume most everyday activities after 3 to 6 weeks, although some pain at night and with activity is not uncommon.

Physical therapy is helpful in restoring movement and function. An effective activity program should include the following:

  • Specific exercises several times a day to restore movement and strengthen the knee. The exercises should be able to be done without help, but one may have a physical therapist help them at home or in a therapy centre the first few weeks post-surgery.
  • Resuming normal everyday household activities such as sitting, standing, and climbing stairs
  • A graduated walking program to slowly increase mobility, initially at home and later outside

Most patients are able to go back to driving about 4 to 6 weeks post-surgery. Driving can probably be resumed when the knee is able to bend enough to enter and sit comfortably in the car. Muscle control should also provide enough reaction time for braking and accelerating.

How can one avoid problems after total knee replacement surgery?

Recognizing the signs of a blood clot

The orthopaedic surgeon’s instructions should be followed carefully to reduce the risk of blood clots developing during the initial weeks of recovery. The continuation of blood-thinning medications may be recommended. It is important to notify one’s doctor if any of the following warning signs are developed.

Warning signs of blood clots
The warning signs of possible blood clots in the leg can include the following:

  • New or increasing swelling in the calf, ankle, and foot
  • Increasing pain in the calf
  •  Pain or tenderness above or below the knee, often described as a cramp
  • Reddish or bluish skin discolouration

Warning signs of pulmonary embolism
The warning signs that a blood clot has travelled to the lungs can include the following:

  • Rapid heart rate
  • Localized chest pain with coughing
  • Sudden sharp chest pain that worsens upon coughing or taking a deep breath
  • Sudden shortness of breath
  • Unexplained cough that brings up pink (bloody), foamy mucus.


Preventing infection

A common cause of infection after total knee replacement surgery is from bacteria that enter the bloodstream during skin infections, urinary tract infections or dental procedures. These bacteria can lodge around the knee replacement, causing an infection.

After knee replacement surgery, patients with certain risk factors may require antibiotics prior to dental work, even dental cleanings, or any surgical procedure where bacteria may enter the bloodstream. The orthopaedic surgeon and patient should discuss whether taking preventive antibiotics before dental procedures is necessary for each individual situation.

Warning signs of infection
It is crucial to notify a doctor straight away if any of the following signs of a possible knee replacement infection are developed:

  • Increasing knee pain with both activity and rest
  • Increasing swelling, tenderness or redness of the knee wound
  • Drainage from the knee wound
  • Chills
  • Persistent high fever


Avoiding falls

A fall during the initial weeks after surgery can be damaging to the new knee and may result in a need for further surgery. Stairs, in particular, can be hazardous until the knee is strong and mobile. A walker, cane, crutches, handrails, or someone to assist with walking can be useful until one’s balance, flexibility and strength are improved.

The required assistive aides post-surgery and when they can be safely discontinued will be decided by one’s surgeon and physical therapist.

What are the outcomes of total knee replacement?

How different is the new knee?

Although improvement of knee motion is a goal of total knee replacement, restoration of full motion is not normal. The motion of one’s knee replacement post-surgery can be predicted by the range of motion in the knee before surgery. Majority of patients can expect to be able to almost fully straighten the replaced knee, bend it enough to climb stairs and get in and out of a car. Even though kneeling might sometimes be uncomfortable, it is not harmful. 

It is not uncommon to feel some numbness in the skin surrounding the incision. Some stiffness may also be felt, particularly with excessive bending activities.

On top of that, some clicking of the metal and plastic with knee bending or walking may also be heard or felt. This is expected and normal. In fact, these differences usually fade away with time. Most patients even normally find them to be tolerable when compared with the pain and limited function pre-surgery.

Additionally, the knee replacement may activate metal detectors required for security. If the alarm is activated, simply inform the security agent of the knee replacement.


How can the knee replacement be protected?

After the surgical procedure, it is important to do the following:

  • Regularly participate in light exercise programs to maintain proper strength and mobility of the new knee.
  • Take extra precaution to avoid falls and injuries. If a bone is broken in the leg, more surgery may be required.
  • Ensure the dentist knows of the knee replacement. One should discuss the need for antibiotics prior to dental procedures with their orthopaedic surgeon.
  • Visit the orthopaedic surgeon periodically for a routine follow-up examination and X-rays. The frequency and timing of these visits will also be discussed.


How can the life of the knee implant be extended?

As of today, over 90 per cent of modern total knee replacements are still performing well 15 years after surgery. It is essential to follow instructions given by one’s orthopaedic surgeon post-surgery, take care of one’s general health and protect the knee replacement. These are all crucial ways that can contribute to the final success of the total knee replacement surgery.