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Unicompartmental Knee Replacement


Unicompartmental Knee Replacement

As the number of knee replacements in the United States continues to climb each year, new treatment procedures and advanced techniques are developed to offer treatment options with promising long-term outcomes.

The improvement of prosthetic designs, materials, and surgical techniques has made the unicompartmental knee replacement (UKR) a reliable and efficient treatment procedure.

UKR has excellent results with mid- to long-term outcomes for most patients. Although UKR is generally considered to be a more complicated procedure compared to a total knee replacement (TKR), there are many benefits that that can come with this type of treatment.


Knee Anatomy and Physiology

Knee Anatomy and Physiology

The knee is the largest joint in the body and consists of two different articulations. One is located between the tibia and femur, and the other one is between the patella and femur. The knee joint supports the majority of the body’s weight, and this often results in it being affected with acute injuries or interactive micro-traumas, as well as developing osteoarthritis later in life.

There are three different compartments that make up the knee, which include the inner medial femorotibial, the outer lateral femorotibial, and the patella femoral compartment. Because of damage from either an injury or osteoarthritis, all the compartments can be affected, or sometimes, just one or two are involved.

The main reason for requiring a replacement of the knee is to relieve chronic pain that is usually caused by osteoarthritis, and when other non-surgical treatments have been unsuccessful.

Why Do Knee Surgery?

The goal of surgery is to reconstruct or resurface the joint to relieve pain, and maintain its functioning and performance. When a knee replacement is being considered there are two options available, such as a total knee replacement (TKR) and the unicompartmental knee replacement (UKR). The UKR is also known as a partial knee replacement, and may be used when only one of the knee compartments is injured.

Why Do Knee Surgery?

For a period of time a UKR procedure was not a popular choice for knee replacements, but in recent years it has become a recommended treatment by many orthopedic surgeons. This is mainly due to the realization that overcorrecting the mechanical axis needs to be avoided, and many published studies have shown high rate in the success of long-term outcomes with joint survival.

Although UKR is generally considered to be a more difficult procedure compared to a TKR, it is believed that bone and uninvolved soft tissue is better able to be preserved, and operating time can be reduced, range of motion is better following the procedure, less pain, and an increase with patient satisfaction.

UKR Advantages over TKR

By selecting the appropriate patient and using a careful surgical technique, a UKR is able to provide many advantages over a TKR. These include:

  • A smaller incision when minimally invasive surgery (MIS) is utilized.
  • A shorter hospital stay.
  • Easier post-operative rehabilitation.
  • Less blood loss
  • Less joint stiffness
  • Lower risk of infection
  • Lower risk with venous thromboembolism
  • An easier revision with surgery if needed at a later date.

Study Finds UKR as Appropriate Option for Knee Procedures

The UKR has progressed into an appropriate option with diseased knees that are unable to be managed by arthroscopic treatment, as well as those who are not a good candidate for a TKR. In a paired study between a TKR and a UKR, statistically there were no significant differences with functioning between the two. This was a follow-up study of at least 48 months following the replacement, and there were indications that the functioning of the UKR maintained a higher level.

With a partial knee replacement, the surgeon will make a small incision in order to access the damaged compartment in the knee. The supporting structures for the knee are gently moved out of the way so damaged bone tissue and cartilage can be removed from the arthritic area.

The surfaces are then prepared so the prosthetic components can be inserted, which are specifically designed for each’s patient joint. A specially formulated cement is applied to secure the components, and all surrounding tissues and structures are returned to their correct anatomical position.

Depending on the knee compartment that is damaged, there are several replacements that may be used. The most commonly used prosthetic device is the unicondylar fixed bearing knee, and there is also the mobile bearing unicondylar knee. The prosthetic devices that are used are made from both metal and plastic devices.

Rehabilitation and Recovery

Those who receive a partial knee replacement will generally spend one or two nights at the hospital, and the majority of patients are able to walk independently or with assistance, on the same day of receiving the surgery. Following a UKR, rehabilitation is extremely important to successful long-term outcomes.

To better promote rapid recovery and a better range of motion, a progressive program is developed over several different stages. This program usually covers a one to two month period. There are many factors that can determine the outcome of a UKR, but as studies have shown it is an excellent alternative to TKR, with comparable long-term outcomes.

Dr. Sumit Dewanjee with FXRX is one of the top knee surgeons in Phoenix and Scottsdale. He offers comprehensive options for knee conditions, including injections, minimally invasive arthroscopy, ligament reconstructions along with partial and total knee replacement procedures.

Call (480) 449-3979 for treatment with a top knee surgeon in Phoenix and Scottsdale.


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