How Many Types of Knee Prosthesis Are There and How to Choose the Right One for Osteoarthritis?

Knee arthroplasty surgery is another treatment option aimed at relieving knee pain and helping patients return to daily activities as close to normal as possible. Doctors typically recommend knee replacement after conservative treatments, such as weight loss, exercise to build thigh muscles, and pain relief medication, fail to improve the patient’s condition. However, the success of conservative treatments depends on the patient’s lifestyle as well.

In this article, we will explore the different types of knee prostheses, what TKA (Total Knee Arthroplasty) and UKA (Unicompartmental Knee Arthroplasty) are, and how to choose the appropriate one for you.

Symptoms of Osteoarthritis

ข้อเข่าเสื่อมเกิดจากการที่กระดูกผิดรูป กระดูกอ่อนสึกหรอOsteoarthritis occurs when the joint structure is altered, cartilage wears down, and the joint’s function is compromised. This prevents the knee from efficiently distributing weight, causing certain parts of the knee to bear more stress than normal, leading to osteoarthritis. Patients often feel pain in the knee joint and hear cracking sounds when standing or sitting. It commonly affects individuals over 40 years old and can be treated through weight loss, thigh muscle strengthening exercises, and pain relief medication. If these treatments do not alleviate the pain, surgery may be recommended, such as knee replacement.

What Is Knee Prosthesis Made Of?

Knee prosthesis is typically made of an alloy metal and a polyethylene insert that separates the metal components. However, there are different designs for knee prostheses:

• TKA (Total Knee Arthroplasty): Uses a fixed, non-moving insert.
• UKA (Unicompartmental Knee Arthroplasty): May include both moving and fixed inserts.

How Many Types of Knee Prosthesis Are There?

There are two main types of knee prosthesis for treating osteoarthritis, and the choice between TKA and UKA depends on the patient’s specific condition and the surgeon’s assessment:

Total Knee Arthroplasty (TKA)

TKA involves removing the entire worn knee joint—both the inner and outer parts of the joint as well as the kneecap—and replacing it with a prosthetic.

Benefits of TKA

TKA is the standard knee replacement procedure and is generally chosen because it minimizes the chances of surgical errors. It’s ideal for patients who need comprehensive knee joint replacement.

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Who is it suitable for?

• Patients with advanced osteoarthritis who are unable to perform daily activities
• Patients who have not responded to conservative treatments
• Patients with complete cartilage wear or bone-on-bone contact in the knee

Recovery After TKA

Post-surgery recovery for TKA can take up to two years for inflammation to subside. Patients may experience pain, stiffness, and muscle discomfort for the first 3 to 6 months as the body adjusts to the prosthesis, which involves more metal and a less natural movement. However, the condition improves gradually over time.

Lifespan of TKA Prosthesis

The prosthetic insert for TKA is fixed and may wear out with use. It typically needs to be replaced after 15 to 20 years.

Unicompartmental Knee Arthroplasty (UKA)

UKA is recommended when only part of the knee is damaged. The surgery involves replacing only the affected compartment (either the inner, outer, or kneecap part of the knee) with a prosthetic.

Benefits of UKA

• The healthy parts of the knee are preserved, offering more natural movement post-surgery.
• The incision is smaller than in TKA.
• The knee’s range of motion is more natural after surgery.
• Fewer complications, such as reduced risk of infection, bone fractures, and blood clots.
• Less need for pain medication after surgery, reducing side effects.

Who is it suitable for?

UKA is ideal for patients who have damage to only part of the knee, regardless of their age. It is suitable for those with localized osteoarthritis.

Recovery After UKA

Due to the smaller amount of metal used and the more natural movement design, recovery from UKA is generally faster. Patients can regain mobility and strength in around 6 weeks.

Lifespan of UKA Prosthesis

UKA typically uses a moving insert, which reduces wear and tear. Its lifespan is about 50 years.

Key Considerations Before Undergoing Knee Replacement Surgery

Patients with pre-existing conditions like hypertension or diabetes may also suffer from osteoarthritis, but it doesn’t typically interfere with surgery. However, patients with heart disease or blood vessel issues should consult a cardiologist to assess risk factors before surgery. Generally, if the risk factors are low or moderate, surgery can proceed, especially for UKA, which has fewer complications and a safer recovery.

Can Both Knees Be Replaced Simultaneously?

For patients undergoing UKA, 70% of them experience improvement in the untreated knee as well, thanks to faster recovery and reduced pressure on the non-operated knee. However, for those undergoing TKA, the unoperated leg may bear more weight and be at risk of osteoarthritis, potentially leading to the need for another surgery.

Simultaneous surgery for both knees is possible, but it depends on the surgeon’s recommendation. If UKA is performed on both knees, a one-day hospital stay for observation is typically enough, after which the patient can return home.

Potential Complications After Knee Replacement Surgery

Typical post-surgery symptoms include pain, stiffness, or numbness around the knee, which should gradually improve with proper care. However, there are some risks associated with any surgery, such as:

• Prosthesis dislocation (0.003% chance)
• Infection (0.01% chance)
• Bone fractures (0.001% chance)
• Serious complications, such as heart or brain vessel blockage, are extremely rare.

Appointments for medical consultation and diagnosis can be made at
Tel. 02-080-8999
Line @kdmshospital

Can Osteoarthritis Be Treated Without Surgery?

Yes, osteoarthritis can often be managed without surgery initially. Conservative treatments such as weight loss, exercise to strengthen thigh muscles, and pain relief medications are typically tried first. If these treatments do not resolve the pain, surgery may be recommended, including knee replacement.

Conclusion

Patients suffering from osteoarthritis who experience knee pain and do not improve with conservative treatments may be recommended for knee replacement surgery. There are two main types of knee replacement: TKA (total knee arthroplasty) and UKA (unicompartmental knee arthroplasty), each with its unique benefits. The decision on which type of surgery to undergo is based on the surgeon’s assessment for the best possible outcome.

Since UKA is a more specialized procedure, the surgeon must be well-trained and certified to perform it. ‘kdms’ Hospital offers specialized orthopedic surgeons with expertise in UKA, providing effective surgeries and comprehensive post-operative care to ensure the best recovery, helping patients return to their daily activities as much as possible.

Article By : Prof. Boonchana Pongcharoen , M.D. Hip and Knee Replacement Surgeon