What are the Compartments of the Knee?
The knee can be divided into three compartments:
- Patellofemoral: compartment on the front of the knee, which contains the kneecap
- Medial compartment: compartment on the inside of the knee
- Lateral compartment: area on the outside of the knee joint
The articular surfaces of the body’s joints are lined by hyaline cartilage, a smooth tissue that serves as a shock absorber and allows easy movement of the bones within the joint. Normal wear-and-tear or injury can damage and cause defects in the cartilage, resulting in irregular articular surfaces that interfere with movement, causing pain, swelling and disability. In some cases, only one or two of the compartments of the knee get damaged by arthritis.
What is Bicompartmental Knee Resurfacing?
Bicompartmental knee resurfacing is a less invasive surgical alternative to total knee replacement surgery, where instead of all the compartments being replaced only 2 of the 3 compartments of the knee damaged by arthritis are replaced with a prosthesis. Bicompartmental knee resurfacing preserves the knee parts not damaged by arthritis as well as the stabilizes the anterior and posterior cruciate ligaments (ACL and PCL).
Indications for Bicompartmental Knee Resurfacing
Bicompartmental knee resurfacing surgery may be recommended by your surgeon if you have early-to-moderate osteoarthritis in 2 of the 3 knee compartments and you have not obtained adequate relief with conservative treatment options. This is especially useful if you are young and active.
Bicompartmental Knee Resurfacing Procedure
Bicompartmental knee resurfacing surgery is performed in an operating room under sterile conditions under general or spinal anesthesia with sedation. It may be performed on an outpatient basis as day surgery or inpatient basis with a 1-3-day hospital stay.
Your surgeon makes a small incision over the affected area of the knee to expose the knee joint. The length is about half of what is required with total knee replacement surgery.
The implants used in the partial knee resurfacing surgery are customized to your anatomy based upon CT scans of your knee. A surgical robotic arm assists your surgeon with preoperative planning and intraoperative component placement, positioning and alignment.
With the assistance of the robotic arm, your surgeon removes the arthritic damage to the bony surfaces of the femur and tibia in the medial or lateral compartments, depending on which one is affected by arthritis. The artificial components are inserted into the newly prepared area and bone cement is used to fix it in place. The patellofemoral compartment is then prepared by removing the damaged region of the patella and trochlea, the groove at the end of the femur.
The new components are fixed in place with the use of bone cement. With the new components in place, the knee is taken through a range of movements. The muscles are then approximated, the incision closed and covered with a sterile dressing.
Postoperative Recovery after Bicompartmental Knee Resurfacing
The common postoperative guidelines are listed below.
- You will be taken to the recovery room and monitored for any complications.
- You will be given pain medication or a PCA (patient-controlled analgesia) machine to keep you comfortable.
- Swelling is normal after knee surgery. Ice, compression, and elevation of the knee above your heart level are advised to minimize swelling and pain.
- You will be given specific instructions regarding the activities you can follow. Usually, there are a few activity restrictions.
- You will be referred to a rehabilitation program for exercise and strengthening.
- Eating a healthy diet and not smoking will promote healing.
Risks and Complications of Bicompartmental Knee Resurfacing
As with any major surgery, there are potential risks involved. Specific complications related to bicompartmental knee resurfacing surgery include:
- Infection: Infection can occur with any operation. In the knee, this can be superficial or deep. Infection rates are approximately 1%. If it occurs, it can be treated with antibiotics but may require further surgery.
- Deep vein thrombosis: DVT is blood clots that can form in the calf muscles and travel to the lung (pulmonary embolism). These can be serious and even life-threatening. If you get calf pain or shortness of breath at any stage, you should notify your surgeon.
- Ligament injuries: There are several ligaments surrounding the knee. These ligaments can be torn during surgery, or break or stretch out any time afterward. Surgery may be required to correct this problem.
- Injury to blood vessels or nerves: This is rare, and can lead to weakness and loss of sensation in a part of the leg. Damage to blood vessels may require further surgery if bleeding is ongoing.
- Arthrofibrosis: This is the development of thick, fibrous material around the joint that often occurs after joint injury or surgery, and can lead to joint stiffness and decreased movement.
- Wearing out: The components eventually wear out over time, usually 10 to 15 years, and may need to be changed.
- Dislocation: This is an extremely rare condition where the ends of the knee joint lose contact with each other or the plastic insert can lose contact with the tibia (shinbone) or the femur (thighbone).
- Fractures: Breaks in the bone can occur during surgery or afterward if you fall. To fix these, you may require surgery.
Advantages of Bicompartmental Knee Resurfacing
This is a less invasive bone and ligament preserving surgery. The implant placed more closely mimics actual knee mechanics than does a total knee surgery. Another advantage of bicompartmental knee resurfacing surgery is that it will not alter your ability to eventually move to a total knee replacement in the future should that become necessary.