Unicompartmental Knee Arthroplasty (UKA): Effective Knee Solution with Quick Recovery

A knee consists of three compartments: the medial compartment (inner knee), lateral compartment (outer knee), and the patella (kneecap). The most common area affected by knee osteoarthritis is the medial compartment, accounting for approximately 90% of patients, while the remaining 10% involves the lateral compartment.
Knee osteoarthritis develops from multiple factors, including aging, cartilage wear, and excessive knee usage, leading to bone deformity and unbalanced weight distribution.
UKA (unicompartmental knee arthroplasty), or partial knee replacement, is a surgical procedure that replaces only the damaged portion of the knee while preserving the healthy parts. This approach reduces incision size, accelerates recovery, and minimizes risks associated with major surgery.
Ideal candidates for UKA surgery are patients with compartmental knee osteoarthritis who have not responded to medication, exercises, or weight loss, and whose knee pain significantly impacts daily activities.
The UKA knee arthroplasty procedure involves removing worn bone and cartilage, installing a partial knee replacement, and inserting a polyethylene bearing to restore natural movement.
Recovery after UKA surgery is remarkably quick due to minimal metal implants used. Muscle recovery is faster, with patients beginning to walk and bend their knees better within 6 weeks. Pain is reduced over 90%, and knee function returns close to normal.
Unicompartmental knee arthroplasty requires specialized expertise from an orthopedist. Surgeons must undergo training and obtain certification to perform UKA correctly. At kdms Hospital in Bangkok, Thailand, we have specialized orthopedists in partial knee replacement (UKA knee replacement) who can perform the surgery efficiently with comprehensive post-operative care to help patients regain nearly normal knee function.

A knee consists of three compartments: the medial compartment (inner knee), lateral compartment (outer knee), and the patella (kneecap). The most common area affected by knee osteoarthritis is the medial compartment, accounting for approximately 90% of patients, while the remaining 10% involves the lateral compartment. Knee osteoarthritis typically develops with age, causing patients to experience knee pain and potentially hearing clicking sounds when standing or sitting.

Unicompartmental knee arthroplasty (UKA) offers a worn knee treatment option that replaces the damaged knee with an artificial joint while preserving the healthy parts. The incision is smaller, and post-operative recovery is faster compared to total knee arthroplasty (TKA).

This article will explain what UKA or unicompartmental knee arthroplasty is, along with essential information about UKA surgery.

Table of Contents

What Causes Knee Osteoarthritis?

Knee osteoarthritis occurs when bones become misaligned or cartilage wears down and deteriorates, causing the knee mechanism to fail. The knee cannot efficiently distribute weight-bearing forces, resulting in certain knee bone portions bearing more weight than normal and leading to knee osteoarthritis.

Unicompartmental knee arthroplasty (UKA) or partial knee replacement is a surgical procedure to remove only the damaged or worn compartment of the knee, then substituting the deteriorated bone with an artificial knee joint. This can be performed on either the medial or lateral compartment. Therefore, for patients with primary knee osteoarthritis or those with the medial compartment affected only, an orthopedist will recommend UKA surgery to preserve the healthy bone structures. This eliminates the need for complete removal, reducing side effects and treatment risks.

Can Other Knee Compartments Deteriorate After UKA Surgery?

Many wonder whether, after undergoing unicompartmental knee arthroplasty (UKA) on the medial compartment, other areas like the lateral compartment and patella might develop osteoarthritis in the future. Orthopedists confirm this possibility exists but is extremely rare. The chance of the lateral compartment deteriorating after UKA surgery is only 2.5% within 15-20 years, and the patella at merely 0.002% within 15-20 years.

How Does UKA Surgery Differ from TKA Surgery?

There are two main types of knee replacement surgery: total knee arthroplasty (TKA) and unicompartmental knee arthroplasty (UKA). Total knee arthroplasty (TKA) is a surgical procedure that removes all three knee compartments (medial, lateral, and patella) and replaces them with artificial joints to treat knee osteoarthritis. Although TKA has post-treatment limitations such as knee extension and flexion, plus more risks and side effects compared to UKA surgery, it delivers equivalent results to unicompartmental knee arthroplasty in terms of equally effective pain relief.

Who Should Consider Unicompartmental Knee Arthroplasty (UKA)?

All patients with knee osteoarthritis who, after X-ray examination, show complete cartilage loss with bone-on-bone contact, accompanied by painful symptoms affecting daily life, should consider UKA. Also, for those who underwent non-surgical treatments such as weight loss, thigh muscle strengthening exercises, and pain medication but the results were not satisfying, an orthopedist will recommend partial knee replacement (unicompartmental knee arthroplasty: UKA) to restore normal knee function.

Who Is Not Suitable for Unicompartmental Knee Arthroplasty (UKA)?

Patients whose X-rays show bones not yet in contact, those with minimal cartilage wear, and those whose knee pain may originate from other sources such as the hip area or spine, as well as from other causes like back fractures or spinal nerve compression, should first pursue alternative treatments and medication. The orthopedist will perform X-rays again to confirm if the knee is truly the pain source before considering UKA surgery.

Can Pain Medication Replace UKA Surgery?

Pain medication can initially treat knee osteoarthritis symptoms alongside exercises to build knee muscles and weight reduction to healthy standards. However, if these methods don’t improve the condition, you should consult an orthopedist for accurate diagnosis.

Diagnosis Before Knee Replacement Surgery

Knee replacement surgery becomes an option after non-surgical treatments such as pain medication, weight loss, and muscle-building exercises fail to relieve pain. If patients still experience pain and cannot regain proper knee functions, and X-rays confirm knee pain originates directly from knee bones, the orthopedist will recommend knee replacement surgery. The decision between TKA or UKA depends on the patient’s condition and the orthopedist‘s professional judgment.

Preparing for Unicompartmental Knee Arthroplasty (UKA)

Before partial knee replacement surgery (unicompartmental knee arthroplasty: UKA), which is major surgery, the orthopedist will prepare the patient as follows:

General physical examination by an internist to assess risk factors and determine surgical eligibility for UKA
Laboratory tests including blood work, chest X-ray, and electrocardiogram
Patient history review regarding current personal medications

The Procedure of Unicompartmental Knee Arthroplasty (UKA)

During partial knee replacement surgery (unicompartmental knee arthroplasty: UKA), the orthopedist follows these surgical steps:

Using specialized saws to remove worn or deteriorated part of the bone
Replacing damaged cartilage with an artificial knee joint
Inserting a polyethylene bearing between the artificial joints to ensure optimal function and movement comparable to the natural ones

Self-Care After Unicompartmental Knee Arthroplasty (UKA)

During the first 2 weeks post-surgery, look after for the surgical incision carefully. If bleeding occurs, visit the hospital for dressing changes.
For the first 2 weeks, avoid getting the incision wet to reduce infection risk.
If experiencing pain around the incision, take pain medication for symptom relief.
Perform ankle pumping exercises in mornings and evenings continuously. Stop if feeling excessive tightness.
Wear compression stockings to reduce blood clot risk.
Walk and exercise moderately—not too much that cause pain or too little that slow recovery.
Exercise to strengthen thigh muscles.

How to Perform Physical Therapy After Unicompartmental Knee Arthroplasty (UKA)?

Orthopedists recommend ankle pumping exercises in mornings and evenings as follows:

Have the patient lie supine, then place a pillow under the leg to elevate it slightly
Flex the ankle up and down slowly, alternating continuously
Perform it with 10-20 repetitions per session
Stop immediately if feeling tightness in the incision or foot area

Results After Unicompartmental Knee Arthroplasty (UKA)

Partial knee replacement surgery uses minimal metal implants in the body, allowing muscles to recover quickly. Patients begin recovering well and regaining better mobility approximately 6 weeks post-surgery. Additionally, mobile-bearing polyethylene inserts help patients bend and extend their knees normally in the long term.

Will the Knee Function Fully Regain After Unicompartmental Knee Arthroplasty (UKA)?

After partial knee replacement surgery, pain is reduced over 90%. The performance of knee functions as well as flexion is comparable to that of people without knee osteoarthritis.

Benefits of Unicompartmental Knee Arthroplasty (UKA)

Unicompartmental knee arthroplasty is a minimally invasive surgery that reduces various post-operative complication risks, including infection, bone fracture, and blood clots in the legs, heart, and brain. It also preserves healthy knee bone structures in their original condition. When using mobile-bearing polyethylene inserts, the performance of knee functions becomes comparable to people without knee osteoarthritis.

The Perks of Undergoing Unicompartmental Knee Arthroplasty (UKA) at kdms Hospital

Unicompartmental knee arthroplasty or UKA surgery requires specialized expertise and proficiency from the surgeon. Surgeons must undergo training to obtain certification proving they can correctly perform UKA. At kdms Hospital in Bangkok, Thailand, we have specialized orthopedists in unicompartmental knee arthroplasty or UKA knee replacement who can perform surgery efficiently. With our comprehensive post-operative care and appropriate self-care guidance for optimal recovery, we help patients regain nearly normal knee function.

In Summary

Partial knee replacement surgery or unicompartmental knee arthroplasty (UKA knee arthroplasty) is surgery to replace only the worn or deteriorated knee compartment causing dysfunction and patient pain with an artificial knee joint. Most commonly performed on the medial compartment (inner knee), UKA surgery suits patients who haven’t improved with non-surgical treatments. An orthopedist will recommend either TKA or UKA based on symptoms and the professional judgment.

To perform UKA, surgeons must hold a certificate proving capability in this specific surgical method. Therefore, choosing a reputable hospital for partial knee replacement surgery like kdms Hospital in Bangkok, Thailand, is essential. With specialized orthopedists in partial knee replacement or UKA surgery, we offer treatment and guidance holistically from consultation to comprehensive post-treatment care.

An article by Prof. Boonchana Pongcharoen, M.D., Experienced Orthopedic Surgeon (Knee and Hip Replacement Surgery)