Partial knee replacement retains more of the natural knee, and is typically an effective option for younger patients whose arthritis damage is limited to a single knee compartment.


Osteoarthritis is a debilitating condition that causes joint pain, dysfunction, and limits range of motion. When affecting the knees, osteoarthritis makes everyday activities, such as walking, kneeling, or gardening, immensely painful.

Patients affected by osteoarthritis have several treatment options, including both conservative approaches and surgical solutions. Certain patients may be candidates for a new and innovative knee surgery, known as partial knee replacement, which can provide the benefits of minimally invasive surgery along with the restoration of joint function and limitation of pain. This procedure often allows patients to return to their previous lifestyles with relatively little pain.

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Anatomy of the Knee

In knee osteoarthritis, the cartilage protecting the bones of the knee slowly wears away. This can occur throughout the knee joint or just in a single area of the knee.

Your knee is divided into three major compartments:

  • Medial compartment (the inside part of the knee)
  • Lateral compartment (the outside part)
  • Patellofemoral compartment (the front of the knee between the kneecap and thighbone)

Advanced osteoarthritis that is limited to a single compartment may be treated with a unicompartmental knee replacement. During this procedure, the damaged compartment is replaced with metal and plastic. The healthy cartilage and bone, as well as all of the ligaments are preserved.

Partial Knee Replacement for Unicompartmental Knee Arthritis

Advantages of Partial Knee Replacement
Multiple studies show that a majority of patients who are appropriate candidates for the procedure have good results with unicompartmental knee replacement.

The advantages of partial knee replacement over total knee replacement include:

  • Quicker recovery
  • Less pain after surgery
  • Less blood loss

Also, because the bone, cartilage, and ligaments in the healthy parts of the knee are kept, many patients report that a unicompartmental knee replacement feels more natural than a total knee replacement. A unicompartmental knee may also bend better.

Disadvantages of Partial Knee Replacement
The disadvantages of partial knee replacement compared with total knee replacement include:

  • Slightly less predictable pain relief
  • Potential need for more surgery. For example, a total knee replacement may be necessary in the future if arthritis develops in the parts of the knee that have not been replaced.

Candidates for Surgery

If your osteoarthritis has advanced and nonsurgical treatment options are no longer relieving your symptoms, your doctor may recommend knee replacement surgery.

In order to be a candidate for unicompartmental knee replacement, your arthritis must be limited to one compartment of your knee. In addition, if you have any of the following characteristics, you may not be eligible for the procedure:

  • Inflammatory arthritis
  • Significant knee stiffness
  • Ligament damage

With proper patient selection, modern unicompartmental knee replacements have demonstrated excellent medium- and long-term results in both younger and older patients.

Imaging Tests

  • X-rays. These images help to determine the extent of damage and deformity in your knee. Your doctor will order several x-rays of your knee to see the pattern of arthritis.
  • Magnetic resonance imaging (MRI) scans. Some surgeons may also order an MRI scan to better evaluate the cartilage


Hospital discharge. Partial knee replacement patients usually experience less postoperative pain, less swelling, and have easier rehabilitation than patients undergoing total knee replacement. In most cases, patients go home 1 to 3 days after the operation. Some patients go home the day of the surgery.

Pain management. After surgery, you will feel some pain, but your surgeon and nurses will make every effort to help you feel as comfortable as possible.

Many types of medicines are available to help control pain, including opioids, non-steroidal anti-inflammatory drugs (NSAIDs), and local anesthetics. Treating pain with medication can help you feel more comfortable, which will help your body heal and recover from surgery faster.

Opioids can provide excellent pain relief, however, they are a narcotic and can be addictive. It is important to use opioids only as directed by your doctor. You should stop taking these medications as soon as your pain starts to improve.

Weightbearing. You will begin putting weight on your knee immediately after surgery. You may need a walker, cane, or crutches for the first several days or weeks until you become comfortable enough to walk without assistance.

Rehabilitation exercise. A physical therapist will give you exercises to help maintain your range of motion and restore your strength.

Doctor visits. You will continue to see your orthopaedic surgeon for follow-up visits in his or her clinic at regular intervals.

You will most likely resume all of your regular activities of daily living by 6 weeks after surgery.

Partial Knee Replacement in Minneapolis

Dr. Patrick O’Keefe, Board-certified orthopedic surgeon, specializes in partial knee replacement and services the Twin Cities area from his two offices in Coon Rapids, Blaine and Otsego MN. Dr. O’Keefe evaluates all types of orthopedic problems, and focuses on applying new and innovative technologies that allow for less painful surgery and ensure a speedier recovery. For more information about partial knee replacement surgery, please schedule an appointment at Dr. O’Keefe’s offices in Coon Rapids, Blaine, and Otsego MN, to discuss potential treatment options.