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Expert Consensus: Choice for UKA Patients

Nov. 01, 2023

Knee osteoarthritis (OA) is a common joint condition that can cause severe pain and decrease the patient's quality of life. At least 25% of knee OA patients suffer from medial compartment disease, which can be addressed with Unicompartmental Knee Arthroplasty (UKA).


Compared to Total Knee Arthroplasty (TKA), Unicompartmental Knee Arthroplasty (UKA) offers minimally invasive and bone-preserving benefits, enabling faster recovery, improved proprioception, and enhanced functionality, which is crucial for younger and active patients.

The primary indications for active UKA include severe osteoarthritis with significant pain necessitating knee joint replacement, complete loss of medial compartment cartilage, and medial bone-on-bone contact. Osteonecrosis is also recommended, as it has shown favorable outcomes in such cases.

Perioperative Management Expert Consensus for Unicompartmental Knee Arthroplasty [1]

The optimal indications for medial UKA surgery are as follows:

1. Symptoms originating from the medial compartment of the knee with significant pain, and conservative treatments have been ineffective.

2. Knee joint range of motion ≥ 90 degrees.

3. Knee joint stability with intact medial and lateral collateral ligaments and anterior and posterior cruciate ligaments.

4. Varus deformity ≤ 15 degrees, correctable passively.

5. Fixed flexion contracture ≤ 15 degrees.

6. Radiographic examination confirms medial compartment pathology: Weight-bearing anteroposterior X-rays show "bone-on-bone" in the medial compartment; lateral X-rays show intact articular surfaces of the posterior part of the tibial medial plateau and the medial condyle of the femur; varus stress X-rays show a normal lateral compartment gap (≥ 5 mm).

The main contraindications for medial UKA surgery are as follows:

1. Acute knee joint infection or recurrent infections.

2. Inflammatory joint diseases.

3. Full-thickness cartilage loss in the lateral compartment weight-bearing area.

4. Severe lateral patellofemoral joint degeneration with groove-like changes or subluxation.

5. Neurological or muscular system disorders, such as quadriceps muscle weakness.

6. Patients in poor general condition, including those with heart or lung function failure who are not surgical candidates.

Preoperative Imaging Examination

Routine preoperative X-ray imaging is performed with weight-bearing status in the lateral view, patellar axis view, and full-length X-ray of the affected knee joint. When necessary, X-rays are taken in varus and valgus stress positions, at 90-degree flexion, in the Rosenberg position, and MRI examinations are conducted.

Weight-bearing status in the upright position

Lateral view X-ray

Patellar axial view

Full-length X-ray of the lower limb

Medial stress view & Lateral stress view


[1] Zhang Qidong, Cao Guanglei, He Chuan, et al. Expert Consensus on Perioperative Management of Unicompartmental Knee Arthroplasty[J]. Chinese Journal of Bone and Joint Surgery, 2020, v.13(04):8-14.

Its advantages of partial replacement characterize the JUST Medical AUSK mobile-bearing Unicompartmental Knee Prosthesis System without needing anterior and posterior cruciate ligament removal or soft tissue balancing. It can be completed through minimally invasive surgery, providing a product choice that aligns with cultural traditions and delivers significant results for the Chinese population.