The knee is the largest joint in the body and having healthy knees is required to perform most everyday activities. In a healthy knee, the structures of the knee (bones, ligaments, cartilage, and more) work together to ensure smooth, natural function and movement.
Normally, all of these components work in harmony, but disease or injury can disrupt this harmony, resulting in pain, muscle weakness, and reduced function.
Your loved one may need knee arthroplasty (replacement) if their knee causes great pain and limits their daily life. Examples may be if your loved one's knee is hurting so bad they can't sleep. It's hard for them to bathe, clean, make it to the mailbox, or shop at the grocery. If they have a damaging and deteriorating condition in their knee that has become debilitating and less invasive methods (medications, walking aids, physical therapy, etc.) are not successful, there's a good chance they need a knee replacement.
Symptoms of a bad knee
The following symptoms may indicate that knee arthroplasty (replacement) is needed and may be resolved by having a knee replacement (the list is not exhaustive).
Pain in the side of the knee or under the kneecap
Pain that has not gotten better with other treatments (physical therapy, medications, walking aids)
Pain with activity, though also when at rest
Continuously disrupted sleep
Pain that gets worse when putting weight on the affected side, even with a cane or walker
Persistent pain, worsening pain, or new compounding pain, despite medication
Stiffness/tightness of the knee that limits the range of motion or mobility
The knee "gives" (suddenly weakens) when walking or during activity
Difficulty walking more than a few blocks without significant pain and necessary to use a cane or walker
Limits the ability to walk up or down stairs, or even rise from a seated position
Pain or loss of function limits or prohibits performing normal activities, such as bathing, preparing meals, doing household chores, and walking
Difficulty putting on shoes and socks
Indications for knee arthroplasty (replacement)
Total knee arthroplasty (TKA, or total knee replacement) is typically performed on people between 50-80 years old but can occur for younger people as well. Several less invasive interventions are tried before considering knee replacement surgery. The primary care provider may offer medications, knee injections, recommend exercises, activity modification, weight loss, or use of a walking aid.
The decision to undergo total knee replacement is a quality-of-life choice. People typically consider having surgery when they find themselves avoiding activities like walking, shopping, or reasonable recreational pastimes because of knee pain.
This surgery is usually performed on middle-aged and older adults after other treatments have failed to help. A knee replacement may be needed because of:
Osteoarthritis - commonly known as wear-and-tear arthritis, osteoarthritis damages the slick cartilage that covers the ends of bones and helps joints move smoothly, and the knee may "give" (weaken suddenly) because the joint is not stable
Inflammatory arthritis (rheumatoid arthritis, psoriatic arthritis) - caused by an overactive immune system, inflammatory arthritis erodes cartilage and occasionally underlying bone, resulting in damaged and deformed joints
Post-traumatic arthritis - follows serious knee injuries such as fractures of the bones surrounding the knee or tears in the knee ligaments and tendons that damage the cartilage over time, causing knee pain and limited function
A knee severely damaged by joint swelling or an injury
Osteonecrosis (avascular necrosis) - when there isn't enough blood supply to the knee joint and associated structures
Tumor in the knee joint
Knee deformity — a bowing in or out of the knee
Childhood (congenital) knee disorders
Because all surgeries have risks, and prostheses can fail as time goes by, the surgeon may recommend delaying a knee replacement until more severe symptoms are present.
Contraindications - Who shouldn't have knee surgery
Talk to your loved one's healthcare providers about issues that may disqualify them from having knee arthroplasty (replacement). Knee replacement surgery isn’t for everyone. Even if someone is in pain and can’t move their knee as well as expected, they aren’t automatically considered for a knee replacement. Your loved one might be ineligible if they have:
Severe medical problems such as end-stage heart, lung, liver, or kidney disease, anemia, recent heart attack, unstable angina, advanced osteoporosis, and others
An active infection
Irreversible or permanent muscle weakness, with or without nerve involvement
Paraplegia or quadriplegia
Severe morbid obesity (more than 100 pounds over ideal weight or BMI over 40)*
*This is determined solely by the orthopedic surgeon and may not be a contraindication to knee replacement surgery.
Making the decision
The decision to have total knee arthroplasty (replacement) should be a cooperative one between you, your loved one, their primary care doctor, and the orthopedic surgeon. The primary care doctor will refer your loved one to an orthopedic surgeon for a thorough evaluation to determine if they might benefit from this surgery.
The orthopedic surgeon will review the results of the evaluation and discuss whether total knee replacement is the best method to relieve pain and improve function. Other treatment options — including medications, injections, physical therapy, walking aids, weight loss, or other types of surgery — may also be considered and discussed.
The orthopedic surgeon will explain the potential risks and complications of total knee replacement, including those related to the surgery itself and those that can occur over time after surgery.
An important factor in deciding whether to have total knee arthroplasty (replacement) surgery is understanding what the procedure can and cannot do.
Most people who have total knee replacement surgery experience a dramatic reduction in knee pain and a significant improvement in the ability to perform daily activities. Often they can even go back to an active lifestyle and the recreational things they enjoy. But total knee replacement does not give someone the ability to do more than they could before developing arthritis. A knee replacement doesn't give the person a bionic knee with enhanced performance.
With normal use and activity, every knee replacement implant begins to wear in its plastic spacer. Chronic illness, excessive activity, or increased weight may accelerate wear and even cause the knee replacement to loosen and become painful. Therefore, most surgeons advise against high-impact activities such as running, jogging, jumping, or other high-impact sports (for the remainder of the person's life).
Realistic activities following total knee replacement include unlimited walking, swimming, golf, driving, light hiking, biking, ballroom-style dancing, and other low-impact sports and activities.
With appropriate activity modification, knee replacements can last for many years and restore quality of life.