Total Knee Replacement (TKR)
During a total knee replacement, the damaged joint surfaces at the end of the femur and top of the tibia are removed and reshaped. These surfaces are replaced with metal components, with a durable plastic spacer positioned between them to allow the knee to move smoothly. The underside of the kneecap may also be resurfaced depending on the procedure. The aim is to replace the damaged weight-bearing surfaces while restoring alignment and movement of the knee.

Partial Knee Replacement (PKR)
A partial knee replacement is used when the arthritis or joint damage is limited to one compartment of the knee. Only the damaged section is resurfaced and replaced with metal and plastic components, while the healthy compartments of the knee are preserved. Because less of the joint is replaced, more of your natural bone and ligament structures can usually be retained.

The major ligaments of the knee are treated differently during a total knee replacement.

Collateral ligaments
The medial and lateral collateral ligaments are generally preserved during surgery. They are important for side-to-side stability of the knee, and surgeons take care to protect them throughout the procedure.

Anterior Cruciate Ligament (ACL)
The ACL is generally removed during a total knee replacement. In many people undergoing knee replacement, the ACL is already significantly degenerated, torn or absent as a result of longstanding osteoarthritis. Modern knee replacement implants are designed to provide stability without relying on the ACL.

Posterior Cruciate Ligament (PCL)
The PCL may either be preserved or removed, depending on the type of knee replacement, implant design and the surgeon's preferred technique. Some implants are designed to retain and work with the PCL, while others replace its stabilising function through the design of the prosthesis.

So although the joint surfaces and some ligament structures change during a knee replacement, the implant and remaining soft tissues work together to provide a stable, functional knee.

Clicking or clunking from a knee replacement can be completely normal, particularly during bending the knee past 90 degrees and straightening of the knee.

Some total knee replacements use a posterior-stabilised prosthesis, particularly when the PCL has been removed. These implants use specially designed metal and plastic components to provide stability that would otherwise be assisted by the PCL. As the knee bends, particularly into deeper ranges of flexion, these components can make contact and produce an audible or noticeable click.

Clicking can also occur as tendons and other soft tissues move across the components of the knee replacement. As a result, a painless click that occurs during movement does not necessarily indicate that anything is wrong with the replacement.

However, clicking should be assessed if it is new or worsening and accompanied by pain, excessive or increasing swelling, changes in skin colour or redness, unusual warmth, fever, or a sudden change in how the knee functions. If these occur, contact your surgeon or healthcare provider for assessment.

Yes this is normal.

Yes, stiffness after sitting for a period of time is common following a knee replacement, particularly during the earlier stages of recovery.

Following a knee replacement, the bone and surrounding soft tissues have undergone significant surgical trauma and need time to heal. This includes the joint capsule, synovium, connective tissues and the tissues involved in the surgical approach. The normal inflammatory response to this tissue injury increases fluid within and around the knee, contributing to swelling, stiffness and that familiar feeling of tightness after sitting

When the knee remains still for a period of time, this swelling and joint irritation can make the knee feel tight or stiff when you first stand up and begin moving again. It will often start to loosen as you walk and move the knee.

Joint swelling can also contribute to arthrogenic muscle inhibition, where signals from the irritated and swollen knee temporarily reduce the nervous system's ability to fully activate the quadriceps which results in tightness

This is one reason rebuilding quadriceps strength and gradually restoring normal movement are important parts of rehabilitation after knee replacement.

The initial goal of rehabilitation is to regain function in your knee. This includes managing swelling and stiffness, restoring knee movement, improving your walking gait, rebuilding muscle strength and gradually returning to normal activities of daily living.

As your knee recovers, rehabilitation should progress into a structured strength and conditioning program focused on progressively increasing strength, physical capacity and tolerance to load.

Long-term strength and conditioning is an important part of recovery following knee replacement. Building strength and physical capacity helps reduce ongoing functional limitations and prepares you for higher-level activities such as longer periods of walking, stairs, recreational exercise and other activities you want to return to.

Long term strength and conditioning reduces complications and functional limitations to ensure you are able are ready for higher level activities