Partial Knee Replacement: Understanding the Procedure

The knee has three compartments: the medial (inner), lateral (outer), and patellofemoral (front). When knee arthritis or damage is limited to just one of these compartments, a partial knee replacement may be the best solution. Understanding the procedure, including the preparation process, surgical steps, recovery process, and possible risks, is crucial for making an informed decision about partial knee replacement.

What Is a Partial Knee Replacement?

A partial knee replacement, or unicompartmental knee replacement (UKR), is a surgical procedure in which an artificial implant replaces one part of a damaged knee joint. Unlike a total knee replacement, which replaces the entire joint, a partial knee replacement can only replace one of the knee's three compartments. It preserves the healthy bone, ligament, and cartilage in the knee.

What Conditions Are Treated with Partial Knee Replacement?

A partial knee replacement is used to treat knee arthritis. Common conditions leading to this type of arthritis are:

• Osteoarthritis: Osteoarthritis is a degenerative joint disease and the most common form of arthritis.
• Post-Traumatic Arthritis: This type of arthritis occurs after a significant injury that causes damage to the cartilage.
• Abnormal Alignment of the Knee: A misaligned knee puts more stress on one side of the knee joint than the other, leading to pain and eventually arthritis.
• Meniscal Injury and Previous Meniscal Surgery: A meniscal tear and removal (meniscal surgery) can lead to increased stress on the knee, accelerating the development of osteoarthritis.

How to Prepare for a Partial Knee Replacement

Proper preparation for a partial knee replacement is crucial to ensure a smooth surgery and recovery. Common preparation guidelines include:

• Adjustment of Medications: It is essential to provide your doctor with a comprehensive list of all medications you are currently taking, including over-the-counter drugs and herbal supplements. This allows them to make any necessary adjustments to your medication regimen. Certain medications, such as blood thinners like aspirin or ibuprofen, may need to be discontinued several days before surgery to minimise the risk of excessive bleeding.
• Weight Optimisation: If you are overweight, gradual weight loss can significantly reduce stress on your knee and enhance surgical results.
• Pre-Operative Strengthening: Engage in low-impact exercises to strengthen the muscles surrounding your knee, promoting post-surgical stability and recovery.
• Home Recovery Setup: Create a comfortable and accessible recovery space at home, ensuring essential items are within easy reach.
• Lifestyle Modifications: Refrain from alcohol consumption and smoking, as these habits can increase the risk of complications both during and after surgery.
• Post-Operative Support: Arrange for transportation home after surgery and secure assistance for daily tasks during the initial recovery period.
• Pre-Surgical Fasting: Adhere to the prescribed fasting guidelines, typically abstaining from food and drink for 6 to 12 hours before the procedure.

What Happens During the Surgery?

Partial knee replacement surgery usually takes 1 to 2 hours to complete. It involves the following steps:

1. The patient will be given either general anaesthesia (puts the patient to sleep) or spinal/epidural anaesthesia (numbs the patient from the waist down).
2. The knee surgeon will make about 3 to 5 inches (7.5 to 13 centimetres) incision at the front of the knee.
3. The surgeon will carefully examine the entire knee joint to confirm that only one compartment is damaged.
4. The damaged cartilage and bone will be removed using a special saw.
5. Metal coverings will be attached to the bone using cement to recreate the surface of the joint.
6. A polyethylene spacer will be applied between the metal coverings to create a smooth gliding surface.
7. Once everything is in place, the incision will be closed with stitches or staples.

What Happens After a Partial Knee Replacement?

After the surgery, the patient will be taken to the recovery room, where they will be closely monitored by nurses. They may be able to go home the same day or need to stay in the hospital for a day.

Once discharged, patients will be given post-surgical care instructions to ensure safe and immediate recovery. A partial knee replacement generally has a shorter recovery time than a total knee replacement. Most patients can return to their normal activities several weeks after surgery.

Are There Any Potential Risks or Complications?

While partial knee replacement is a safe and effective procedure, like any surgery, it carries potential risks and complications, including:

• blood clots
• infections
• continued pain
• stiffness
• the need for another surgery
• arthritis progression

FAQs About Partial Knee Replacement

How common is partial knee replacement surgery?

Partial knee replacement surgery is less common than total knee replacement surgery. However, it is still widely performed, especially for patients with knee arthritis in one compartment of the knee.

What is the success rate of partial knee replacement?

Most studies show that the success rate of partial knee replacement surgery is generally high with 90 - 95% of partial knee replacements still functioning properly after 10 years. However, it is still important to note that some partial knee replacements may still require revision surgery.

Which is better, partial or total knee replacement?

Both partial and total knee replacements offer effective solutions for pain relief and mobility improvement in patients with knee arthritis or damage. The key distinction lies in the extent of the procedure: a partial knee replacement targets a single affected compartment of the knee, while a total knee replacement addresses multiple compartments, making it suitable for more widespread damage. The appropriate choice depends on the specific nature and severity of the patient's knee condition.

Takeaway

Partial knee replacement surgery offers a minimally invasive solution for patients with arthritis or damage in one compartment of the knee. While it may not be suitable for everyone, those who qualify for the procedure experience significant pain relief and a faster return to normal activities than total knee replacement.