Types of Knee Replacements

There are two main types of replacements - partial replacement and total replacement. A partial replacement, also known as unicondylar or unicompartmental replacement, involves resurfacing either the inner or outer half of the knee joint. This is generally recommended for patients who have arthritis in only one of the three compartments of the knee.

A total replacement involves resurfacing all three compartments of the knee joint - the inner part (medial compartment), outer part (lateral compartment), and the part behind the knee cap (patellofemoral compartment). Total replacement is recommended for patients with arthritis affecting multiple compartments of the knee. It provides pain relief and improves knee function to a greater extent than partial replacement.

Process

Knee replacement surgery is usually performed under general or regional anaesthesia. It takes about 1-2 hours to complete the procedure. The surgeon first makes an incision on the front of the knee. Damaged bone and cartilage are removed from the ends of the thigh and shin bones. Metal components are implanted to resurface the ends of the bones. Plastic spacers are inserted between the metal parts. For a total replacement, the back of the kneecap may also be resurfaced with plastic. The new artificial joint is lined up and tested for movement and stability. Soft tissues like muscles and tendons are repaired. The incision is closed with sutures or staples.

Implants Used in Knee Replacement

The main components used in modern replacements include:

- Femoral component: A metal stem that is inserted into the end of the thighbone (femur) to replace the articular surface. It has curved polished surfaces to match the new tibial and patellar components.

- Tibial component: A flat metal tray that is anchored to the top of the shinbone (tibia). It has a plastic spacer rimmed to resemble the shape of the new knee joint line.

- Patellar component: A dome-shaped plastic button that is cemented or implanted to resurface the back of the kneecap in a total replacement.

- Plastic spacers or inserts: Resilient polyethylene spacers are inserted between the femoral and tibial components to simulate natural cartilage and enable smooth movement of the new knee joint.

- Bone cement: Special bone cement is used to securely anchor the new joint components in proper alignment during surgery.

Post-Surgery Recovery and Rehabilitation

It usually takes about 4-6 weeks to recover fully from replacement surgery. The first few days after surgery involve wound and leg exercises, controlling pain and swelling, and gradually regaining mobility with a walker or crutches. Physiotherapy plays a key role in the recovery period to improve strength, flexibility, and rebuild muscle mass in the operated leg.

Patients are encouraged to gradually increase weight bearing and range of motion of the new knee under supervision. Low impact exercises like swimming and cycling are ideal for recovery. Returning to normal daily activities may take up to 3 months. Sports or physically demanding jobs usually require clearance from the surgeon based on x-rays showing implant stability. Most people report significant pain relief and improved quality of life after successful replacement surgery.

Recommendation Time

Knee replacement is usually considered for advanced knee arthritis not responding to conservative treatments like medications, injections, bracing or lifestyle changes. Some key indicators for considering knee replacement surgery include:

- Severe knee pain interfering with sleep or normal daily activities.

- Significant loss of knee function and inability to bend, climb stairs or carry out tasks independently.

- Knee instability or deformity causing difficulty in walking or standing upright.

- Failure of other treatments to control arthritis symptoms over 3-6 months.

- Radiographic findings showing advanced loss of knee joint space, bone spurs and deformity.

The success rates of modern knee replacements are over 90% and most patients experience pain relief and functional improvement for 10-15 years on average. However, artificial joints do have a limited lifespan and some patients may eventually require revision surgery. Overall, knee replacement offers a very effective solution to restore mobility for individuals with end-stage arthritis.

About Author:

Ravina Pandya, Content Writer, has a strong foothold in the market research industry. She specializes in writing well-researched articles from different industries, including food and beverages, information and technology, healthcare, chemical and materials, etc. (https://www.linkedin.com/in/ravina-pandya-1a3984191)