Total knee replacement

The knee joins the femur, tibia and patella, with surfaces covered by cartilage. When the cartilage wears away, pain, stiffness and deformity appear.

The prosthesis resurfaces the damaged surfaces with metal components and a low-friction polyethylene insert between them, recreating the joint's glide.

An essential part of the surgery is correcting the deformity and balancing the ligaments so the knee ends up aligned and stable; much of the result and of how the knee feels when walking depends on that balance.

That is why knee replacement depends so much on technique: two knees with the same wear can need different adjustments to end up well balanced.

As with the hip, non-surgical treatment is exhausted first. Before surgery the general condition —diabetes, anemia, weight— is optimized and any focus of infection (dental, urinary or skin) is treated, because reducing it lowers the risk of prosthetic infection.

When the wear is limited to a single compartment and the ligaments are intact, a partial (unicompartmental) replacement, which preserves the rest of the joint, may be considered in selected patients.

The surgery is planned on the radiographs to choose the size of the components and restore the alignment of the leg.

It is usually performed under spinal anesthesia, often supplemented with sedation and with local analgesia techniques that help move the knee sooner. The usual hospital stay is one or two days, with thrombosis prevention and early walking from the postoperative period.

Rehabilitation starts early and is more demanding than with the hip: regaining range of motion and quadriceps strength is key, so consistent physiotherapy during the first weeks makes the difference.

Weight-bearing and walking are progressed with support; many patients set aside their canes and resume light activities and driving over the course of a few weeks. It is normal for the knee to improve gradually over several months, and a sensation of warmth or mild swelling may persist for a time.

In most well-selected patients, knee replacement relieves pain and improves function considerably. A prosthetic knee feels different from a natural knee, and regaining full flexion requires consistency in rehabilitation.

Modern prostheses have good long-term survivorship, though they are not forever. Walking, swimming and cycling are recommended activities; high-impact sports accelerate wear. Periodic check-ups allow the state of the prosthesis to be followed.

The decision to operate is made together: we discuss your symptoms, their impact on daily life, the expected benefits, the risks and the alternatives. Surgery does not guarantee an outcome; it aims to improve pain and function in selected patients.