Unicompartmental (Partial) Knee Replacement

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Unicompartmental (Partial) Knee Replacement

Knee prosthesis implantation

Implantation of a knee endoprosthesis (knee alloarthroplasty) is a procedure to replace the joint body in significantly damaged joint structures due to an advanced knee joint disease (osteoarthritis, rheumatoid arthritis, traumatic arthritis). The procedure includes removing the damaged bone and cartilage of the lower leg, tibia and kneecap (patella) and replacing them with an artificial joint (prosthesis).

In order to establish an indication for the implantation of a knee endoprosthesis, an orthopedic specialist will determine the range of motion and stability of your knee through a clinical examination. With additional radiological diagnostics (X-rays and MR imaging), the extent of knee damage will be determined, and a decision will be made about the right therapy for each patient.

Depending on the degree and localization of the damage, but also on the information obtained from the medical history and clinical examination, the orthopedic specialist will choose between the implantation of a total knee endoprosthesis (replacement of all joint surfaces of the knee) and a partial knee prosthesis, a procedure that replaces only part of the knee (internal, outer or the kneecap).

Unicompartmental (partial) knee replacement

Partial knee prostheses are internal joint implants intended to replace only the damaged part of the joint.

They are indicated in approximately 50% of patients with osteoarthritis of the knee, thus avoiding a more extensive procedure. The advantages of such an approach are significantly faster recovery, fewer complications and the preservation of all ligaments, i.e. the anatomy of the knee.

In the case of progression of degenerative changes, the remaining parts of the joint can be replaced with partial endoprosthesis, or a conversion to total joint replacement is performed.

Model of an unicompartmental (partial) knee endoprosthesis.jpg
Image: Model of an unicompartmental (partial) knee endoprosthesis
Illustration of an outer (lateral) unicompartmental knee endoprosthesis.jpg
Image: Illustration of an outer (lateral) unicompartmental knee endoprosthesis

Who are candidates for unicompartmental knee replacement?

  • Patients with osteoarthritis of the knee
  • Patients with persistent pain despite non-operative conservative treatment methods
  • The conditions for implanting the unicompartmental knee endoprosthesis:
    • good stability of the knee (preserved function of the anterior cruciate ligament)
    • good mobility of the knee (preserved range of motion in the damaged knee)
    • correctable knee deformity (valgus (X) or varus (O))

Do you think you’re a candidate for unicompartmental (partial) knee replacement? Make an appointment.


Anatomy of the knee.jpg
  • Femur – thigh bone
  • Patella – kneecap
  • Tibia – shin bone
  • Fibula – smaller bone of the lower leg
  • Cartilage – tissue that covers the bone on joint surfaces and reduces friction during joint movement
  • Ligaments – tough, elastic connective tissue that surrounds a joint to provide stability
  • Menisci – curved cartilaginous parts in the joint that serve as shock absorbers that absorb the load, increase the contact of joint surfaces, etc.

Risks and complications

Like any surgical procedure, unicompartmental (partial) knee replacement has its own complications. Although, due to the smaller scope of the operation, compared to the installation of a total knee endoprosthesis, the complications are also less, they can be the following:

  • infection
  • thrombosis
  • injuries to vessels and nerves
  • stiffness and swelling of the knee
  • loosening and dislocation of the prosthesis
  • persistent pain

Advantages compared to total knee replacement (H2 NASLOV)

  • Greater range of motion and function of the knee after surgery
  • Minor surgery with minor tissue trauma
  • Less blood loss during surgery
  • Less chance of infection post-operatively
  • Faster recovery
  • Replacing the damaged part of the knee protects the healthy part from deterioration
  • In case of injury, disease progression or deterioration of healthy tissue, any patient with a partial knee replacement can be a candidate for a total knee replacement in the future

In a conversation with our experts, you will find out all the information about the procedure and its advantages, as well as the risks, so don’t hesitate to make an appointment.

What can you expect?

Before surgery

What can you do before seeing an orthopedist?

  • Take radiological images (X-ray of the painful knee, standing, in two directions)
  • Prepare answers to orthopedic specialist questions that include:
    • What are the symptoms, how long do they last, when did they start?
    • On a scale from 0 to 10, how much does it hurt you at rest, and how much during exercise?
    • Are there activities that increase the pain? Do you have pain at night?
    • Have you had any knee injuries so far?
    • Do you take any medications or nutritional supplements?
    • Do you have any other medical problems?
  • Prepare questions for the orthopedic surgeon
X-ray images of the right knee.jpg
Image: X-ray images of the right knee (from left to right): healthy knee; anteromedial osteoarthritis; condition after unicompartmental (partial) endoprosthesis of the medial part of the knee (Oxford)

Orthopedic specialist Examination

In order to establish an indication for the unicompartmental (partial) knee replacement, an orthopedic specialist will determine the range of motion and stability of your knee through a clinical examination. For the indication, radiological images (X-rays) of the knee joint are also necessary, which should preferably be done before coming for the examination. The orthopedic specialist will decide on any additional tests required for preoperative planning following a clinical examination.

Preanesthetic assessment

After setting the indication and agreeing on the date of the operation, it is necessary to have an examination by an anesthesiologist who will decide on the type of anesthesia.

Arrival at the hospital

Upon arrival at the hospital, the patient is placed in a room and receives the informed consent forms with all relevant information related to the surgical procedure. They sign it and the patient is prepared for the operation. Every patient is given an antibiotic before, during and after surgery to prevent postoperative infections.

During the operation

After a 10-15 cm incision of the knee, the orthopedic specialist will remove the damaged parts of the joint, bone growths (osteophytes) and shape the bone part and prepare it for the implantation of a prosthesis. After the implantation of a partial knee endoprosthesis, the cut tissues are sewn up in layers and the skin is closed with stitches or a stapler. The operation itself lasts about 1 hour. After the operation, the sutured wound is covered with plaster and bandages, and the patient is transferred to the ward.

During the operation, the patient is under general or spinal anesthesia, which is decided by the anesthesiologist. In general anesthesia, the patient is unconscious and wakes up after the operation. On the other hand, in spinal anesthesia, the patient is awake but does not feel pain from the waist down. The patient is monitored during the operation to reduce the risk of any complications.

Photo in the operating room during the unicompartmental (partial) knee replacement.jpg
Image: Photo in the operating room during the unicompartmental (partial) knee replacement

After surgery

After the operation, the patient is transferred to the ward, where they stay in the hospital for 1 or 2 days. Pain medication after surgery will be taken care of by our anesthesiologists. During your stay in the Hospital, our doctors and nurses will take care of dressing the surgical wound.

Rehabilitation begins immediately after surgery. With the help of our physiotherapists, you will learn to live and most importantly walk with your new joint. Weight bearing is allowed even without crutches during the hospital stay. Patients are discharged from the hospital one or two days after surgery and continue with physical therapy. A full return to all activities is expected within 6 to 8 weeks, and sports are even allowed.

After leaving the hospital, it is advisable to continue rehabilitation in our Center for Physical Medicine & Rehabilitation or in another rehabilitation clinic. In order to ensure the fastest and highest quality recovery, it is important to follow the instructions on dressing the wound, diet, physical activity, etc.

Follow up examinations, their frequency and additional postoperative radiological scans will be indicated by the operator.

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