Total vs Partial Knee Replacement: What Are the Key Differences?

Osteoarthritis is a growing concern in Singapore. This increase is linked to factors such as an ageing population, sports-related injuries, and lifestyle changes. Among these cases, knee osteoarthritis is a leading cause of chronic pain and mobility issues, often requiring surgical intervention.

Knee replacement surgery becomes essential when non-surgical treatments have failed to provide relief. The two main treatment options available are total knee replacement (TKR) and partial knee replacement (UKR). These procedures offer effective solutions to ease severe arthritis pain.

What Is Total Knee Replacement?

Total knee replacement (TKR), also called knee arthroplasty, is a surgical procedure designed to resurface a severely damaged knee joint, primarily due to arthritis or injury. It involves replacing worn-out joint surfaces with durable metal and plastic prosthetic components to restore mobility and relieve chronic pain.

TKR is most commonly performed for osteoarthritis, a degenerative condition where cartilage progressively wears down, leading to bone-on-bone friction, pain, stiffness, and restricted movement.

What Is Partial Knee Replacement?

Partial knee replacement, also known as unicompartmental knee replacement (UKR), is a surgery that targets only the damaged section of the knee joint while preserving healthy cartilage, ligaments, and bone. This minimally invasive approach provides a less intensive alternative to total knee replacement (TKR), offering a faster recovery, less pain, and improved joint function for suitable candidates.

This procedure is ideal for patients with localised knee arthritis, affecting only one of the three compartments: medial (inner), lateral (outer), or patellofemoral (kneecap area). Unlike total knee replacement, a partial replacement allows patients to retain more of their natural knee structure, leading to a more natural joint feel post-operation.

Key Differences Between Total and Partial Knee Replacement

Total Knee Replacement

Surgical Procedure

In a total knee replacement, the surgeon removes damaged cartilage and bone from the thigh bone (femur), shin bone (tibia), and kneecap (patella). Artificial implants are then placed on the femur and tibia to recreate the joint surfaces, with a plastic spacer inserted between them for smooth movement. The prosthetic components are secured using either surgical cement or a porous coating that encourages bone growth into the implant.

Recovery Time

Most patients can resume daily activities within 6 weeks, although full recovery—including restored strength and mobility—can take up to a year. Walking without assistance usually begins around 3 to 4 weeks, and physiotherapy typically continues for 3 to 4 months. High-impact activities such as running should be avoided permanently.

Longevity of Results

Total knee replacements usually last 15 to 20 years, and many continue to function well beyond that.

Success Rate

Total knee replacement is considered the gold standard for treating severe knee arthritis. It has a 90% to 95% success rate at 10 years, with many implants still functioning well past 20 years. Over 95% of patients report significant improvement in mobility and pain reduction.

Partial Knee Replacement

Surgical Procedure

In a partial knee replacement, only the damaged compartment of the knee is resurfaced, preserving healthy bone, cartilage, and ligaments. The surgeon removes the worn-out tissue and replaces it with prosthetic implants. A plastic spacer is placed between the components to enable smooth knee movement.

Recovery Time

Recovery is typically faster than with total knee replacement. Most patients return to regular activities within 3 to 6 weeks, and many can walk without assistance within a few days. Low-impact sports such as golf can often be resumed within 6 to 10 weeks. However, since only part of the knee is treated, the remaining compartments may deteriorate over time, sometimes necessitating a full knee replacement in the future.

Longevity of Results

Partial knee replacements generally last 10 to 15 years. Some patients may need a conversion to a total knee replacement if arthritis progresses.

Success Rate

While less common, advances in robotic-assisted surgery and implant technology have significantly improved success rates. About 90% to 95% of partial knee replacements are still functioning properly after 10 years.

What Are the Factors to Consider When Choosing Between TKR and UKR?

Deciding between TKR and UKR depends on multiple factors, including age, severity of the condition, lifestyle, and long-term outcomes. Each procedure has advantages and limitations, making patient selection critical for optimal results.

• Patient’s Age and Implant Longevity: UKR is ideal for younger (<50) and older (>75) patients seeking less invasive surgery, while TKR is more durable for middle-aged (50-75) individuals.
• Extent and Location of Injury: UKR suits those with injury or pain in a single knee compartment, whereas TKR is better for widespread knee injury or severe pain.
• Activity Level and Lifestyle: UKR retains more natural knee function and allows higher activity, while TKR provides comprehensive pain relief for moderate activity levels.

Frequently Asked Questions

Does a total or partial knee replacement have better outcomes?

Partial knee replacement may be the better option as it preserves more of your natural knee and allows a faster return to low-impact activities. However, if knee injury is widespread, a total knee replacement offers greater durability but may limit high-impact sports.

How do I know which knee replacement is right for me?

If you want to stay active in sports, a partial knee replacement may be preferable as it preserves more natural knee function and allows a quicker return to activities like running or tennis. However, if conditions affect multiple compartments, a total knee replacement provides better long-term stability but may limit high-impact sports.

Conclusion

Choosing between total knee replacement (TKR) and partial knee replacement (UKR) depends on individual factors such as the severity of the condition, lifestyle needs, and long-term goals. Consulting an experienced knee specialist is essential to determine the most suitable procedure based on your condition and activity level, ensuring the best possible outcome for pain relief and mobility restoration.