What Is Knee Replacement Surgery?

Knee replacement surgery, also known as knee arthroplasty, involves replacing a damaged, worn, or diseased knee with an artificial joint. This surgery is commonly recommended for individuals with severe knee pain or mobility issues, typically due to arthritis or injury. The procedure involves:

• Surgeons remove damaged bone and cartilage from your thigh bone, shinbone, and kneecap.
• A prosthesis, usually made from metal alloys, high-grade plastics, and polymers, is then fitted in place of the removed cartilage and bone.
• The goal is to replicate the knee's natural movement and function, alleviating pain and improving mobility.¹

Dive deeper into the intricacies of knee replacement surgery, including various types, the preparation process, risks, and the road to recovery. Understanding these elements can empower you to make informed decisions about your health and well-being.

Introduction

Knee replacement surgery stands as a beacon of hope for those plagued by debilitating knee conditions. It's a testament to medical science's ability to restore mobility and alleviate pain. The journey through knee arthroplasty is complex, involving careful consideration, meticulous surgical technique, and dedicated post-operative care.

Types of knee replacement surgery

Total knee replacement

Also called a total knee arthroplasty, the process includes the replacement of all damaged surfaces of the whole knee joint with a special prosthesis. This method, however, is usually recommended for individuals with serious arthritis or significant knee damage, affecting a majority of the joints. The process involves replacing the top parts (distal surfaces) of the femur and tibia with a resurfaced artificial patella with metal surfaces. 

Total knee replacement is a very effective option for patients suffering from widespread cartilage destruction, when all the attempts to relieve pain turn out to be unsuccessful. As a result, it improves functionality and reduces pain, improving the patient’s quality of day-to-day activities.

Partial knee replacement

Also called the unicompartmental knee replacement, this involves replacing only one side (compartment) of the knee. This procedure is more appropriate in patients when the damage is restricted to only one section of the knee; either the middle (medial), side (lateral) or  at the front around the kneecap (patellofemoral). 

This surgical procedure for treating anterior cruciate ligament tears allows more preservation of the natural structures of the knee, retaining bones and ligaments. Because of the preservation of one’s original knee structures, many find that recovery takes f a shorter time compared with a total knee replacement.

Revision knee replacement

This complex procedure is necessary when a previous knee replacement fails, which can happen due to various reasons like wear and tear of the prosthetic components, infection, or loosening of the implant. The surgery is more complex due to the need to remove the old implants, and possibly address bone loss or deformities. It may involve using specialised implants and bone grafts to rebuild the joint. 

Revision knee replacement aims to restore the knee's stability, function, and range of motion. The long-term success can vary, and often depends on the underlying reason for the surgery, such as the patient’s overall health and the complexity of the surgical procedure.²

Each type of knee replacement surgery is tailored to the individual patient's needs and the extent of their knee damage. Deciding which procedure to go with is made after careful evaluation of the patient's medical history, physical examination, and imaging results, and significantly depends on the expertise of the orthopaedic surgeon and specific circumstances of each case.

Preparing for knee replacement surgery

Medical evaluation

This step is critical when determining the patient's overall health and readiness for surgery. 

It typically includes: 

• A thorough physical examination
• An assessment of the patient's medical history
• Tests such as blood tests and X-rays
• Possibly an MRI or CT scan to assess the extent of knee damage 

This evaluation helps identify any underlying health conditions that could impact the surgery or recovery process. For instance, conditions like diabetes or heart disease may need to be managed before proceeding with surgery.

Medication review

A comprehensive review of the patient’s current medications is crucial. Certain medications, especially those that can affect blood clotting (like aspirin or warfarin), may need to be adjusted or temporarily stopped before surgery. This is to minimise the risk of excessive bleeding during the operation. 

Additionally, the use of supplements or over-the-counter medications should be discussed with the healthcare provider, as some of these can interact with surgical drugs or affect the recovery period.³

Physical therapy

Strengthening the muscles around the knee helps in faster recovery post-surgery. Physical therapists may also teach exercises that will be important after surgery, such as exercises to improve leg strength and flexibility. This preparatory phase can also include learning how to use walking aids, such as crutches or walkers, which are often needed during the postoperative recovery period.

Psychological preparation

Undergoing major surgery can be a source of anxiety and stress for many patients. Psychological preparation, including discussions with healthcare providers about expectations and concerns, can be beneficial. Some patients may also find it helpful to talk to others who have gone through the procedure or to participate in support groups.⁴

By thoroughly preparing for knee replacement surgery, patients can not only enhance their chances for a successful outcome but also potentially reduce their recovery time and improve their overall postoperative experience.

The surgical procedure

Knee replacement surgery typically takes an orthopaedic surgeon between 1 to 2 hours, as it’s a complex procedure that requires precision and skill. 

Anaesthesia administration

Before the surgery begins, an anaesthetic is given to ensure the patient experiences no pain during the procedure. The type of anaesthesia used can vary:

• General anaesthetic: This makes the patient completely unconscious during the surgery. It's administered through an IV or a mask
• Epidural anaesthetic: This involves injecting near the spinal cord to numb the lower body. The patient remains awake but will not feel any sensation from the waist down. Sometimes, sedatives may be given alongside to help the patient relax

Incision and removal

• Making the incision: The surgeon makes an incision in the front of the knee to access the joint. The length and exact placement of the incision can vary based on the specific surgical approach
• Removing damaged joint surfaces: Once the knee joint is exposed, the surgeon removes the damaged or diseased part of the knee joint. This involves carefully cutting away the damaged parts of the femur (thigh bone) and the tibia (shin bone), as well as a part of the patella (kneecap) if necessary.

Implant placement

Fitting the prosthesis

The surgeon then positions the prosthetic components to replace the bone and cartilage. The femoral component (usually made of metal) is attached to the end of the femur, and the tibial component (often metal with a plastic surface) is attached to the tibia. If necessary, a patellar component (usually plastic) is also used to resurface the underside of the kneecap

Testing for fit and function

After the components are in place, the surgeon tests the new joint, ensuring it has the correct alignment, stability, and range of motion. This step is crucial to ensure that the knee will function correctly after the surgery¹

Closure

Securing the implants and closing the incision 

Once the surgeon is satisfied with the placement and function of the implants, the knee is closed. The layers of tissue and muscle around the knee are stitched or stapled back together.

Dressing

The incision site is then cleaned and dressed to prevent infection. A sterile bandage is applied over the wound.

Post-operative measures

Immediate aftercare 

After the surgery, the patient is moved to a recovery area where they are closely monitored as the anaesthesia wears off. Vital signs such as heart rate, blood pressure, and oxygen levels are recorded.

Pain management 

Postoperative pain management begins immediately, often involving medications that reduce pain and inflammation.

Initial mobilisation

Depending on the type of anaesthetic and the patient's overall condition, initial mobilisation, like moving the leg or walking, can start within a few hours after surgery under medical supervision.

Each step in the knee replacement procedure is critical and is performed meticulously to ensure the best possible outcome for the patient. The combination of surgical expertise, prosthetic, and postoperative care play a pivotal role in the success of the surgery.³

Risks and complications

Like any major surgery, knee replacement has potential risks, including infection, blood clots, implant problems, and continued pain. Rigorous surgical standards and postoperative care are crucial in mitigating these risks.³

Recovery and rehabilitation

Recovery involves a hospital stay, followed by weeks to months of physical therapy. Rehabilitation focuses on reducing swelling, increasing knee strength, and regaining mobility, with most people returning to normal activities within 3-6 months.

Long-term care

Going for regular check-ups and avoiding high-impact activities are recommended for prolonging the life of the artificial knee. Most knee replacements last 15-20 years, significantly improving quality of life.

Summary

Knee replacement surgery is a well-tested method of giving people their lives back after they have had their knees damaged severely. This voyage will be understood through knowing its various types, preparation, process, and recovery. Over time, modern medicine has led to much more successful results and outcomes after surgery; with that, patients are now looking forward to better lives.

FAQs

How long does a knee replacement last?

Most knee replacements last 15-20 years.

What is the success rate of knee replacement surgery?

Knee replacement surgery has a high success rate, significantly improving pain and mobility in over 90% of patients.

Is the recovery painful?

Post-operative pain is expected but is manageable with medications and physical therapy.

When can I return to normal activities?

Most people return to regular activities within 3-6 months post-surgery.

Can I engage in sports post-surgery?

Low-impact activities are encouraged, but high-impact sports should be avoided to prolong the implant's lifespan.