Knee replacement surgery

The most common reason for knee replacement is osteoarthritis, where the cartilage covering the surfaces of the knee gradually wears away.

Other conditions that may lead to knee replacement include:

Knee replacement is usually considered when pain and stiffness significantly affect walking, sleep, work, exercise or normal daily activities, and non-operative treatment is no longer providing adequate relief.

The knee can broadly be divided into three compartments:

Arthritis may affect only one part of the knee or may involve several compartments.

The location and extent of arthritis are important when deciding between a partial and total knee replacement.

A partial knee replacement, also called a unicompartmental knee replacement, replaces only the damaged compartment of the knee while preserving the healthy parts of the joint.

It is most commonly performed for arthritis isolated to the medial or lateral compartment.

Importantly, partial knee replacement is suitable only for appropriately selected patients.

If arthritis is more widespread, a total knee replacement is generally a more appropriate option.

A total knee replacement (TKR) is performed when arthritis affects multiple areas of the knee or when the pattern of disease makes a partial replacement unsuitable.

During surgery, the damaged surfaces at the end of the femur and top of the tibia are carefully prepared and resurfaced with metal components.

A highly durable polyethylene bearing is placed between these components, creating a new smooth surface for movement.

The kneecap is assessed during surgery and treated according to the individual condition of the patellofemoral joint.

Modern knee replacement aims to do more than simply remove the arthritic surfaces.

Careful planning and surgical technique aim to restore:

Different implant designs and fixation methods are available. Components may be cemented or uncemented, depending on factors such as bone quality, patient anatomy and the individual requirements of the operation.

Implant selection is therefore tailored to the individual patient.

Neither operation is automatically better.

The correct procedure depends primarily on the pattern and extent of arthritis.

When arthritis is genuinely isolated to one compartment, partial knee replacement can preserve more of the natural knee and may provide excellent function.

When arthritis involves several compartments, or when significant deformity or instability is present, total knee replacement provides a more comprehensive reconstruction.

The goal is therefore not simply to perform the smallest operation, but to perform the most appropriate replacement for that particular knee.

Patients are usually encouraged to stand and begin walking soon after surgery, often on the day of surgery or the following morning.

Physiotherapy initially focuses on:

Recovery differs between patients.

Significant improvement usually occurs during the first 6–12 weeks, although strength, movement and function can continue to improve for many months.

Partial knee replacement may allow a faster early recovery in appropriately selected patients.

In practical terms, a typical knee replacement involves:

The aim of knee replacement is to allow patients to return to a comfortable and active lifestyle.

Following appropriate rehabilitation, activities such as:

are generally encouraged.

Higher-impact activities should be discussed individually.

Modern knee replacements have excellent long-term survival.

How long an implant lasts depends on several factors, including the patient's age, activity level, weight, implant type, fixation, alignment and the underlying condition of the knee.

Modern knee replacements are designed to provide reliable function for many years, and many continue to function well beyond 15–20 years.

The primary aim of knee replacement surgery is to relieve pain, restore mobility and improve quality of life.

The operation should be tailored to the individual knee.

Where appropriate, a partial knee replacement can preserve healthy bone, ligaments and unaffected parts of the joint. Where arthritis is more extensive, a total knee replacement provides a comprehensive reconstruction of the damaged joint.

The ultimate goal is a stable, well-aligned and functional knee that allows the patient to return to an active lifestyle.