Bicompartmental Knee Resurfacing

The knee can be divided into three compartments: Patellofemoral, the compartment on the front of the knee which contains the knee cap, medial compartment, the compartment on the inside of the knee, and lateral compartment which is the area on the outside of the knee joint.

Bicompartmental Knee Resurfacing is a less invasive surgical alternative to Total Knee Replacement surgery for patients who have only 2 of the 3 compartments of the knee damaged by arthritis.  To learn more about Bicompartmental Knee Resurfacing, it is important to understand the normal anatomy of the knee.

Arthritis is a general term covering numerous conditions where the joint surface or cartilage wears out. The joint surface is covered by a smooth articular surface that allows pain free movement in the joint. This surface can wear out for several reasons; often the definite cause is not known. 

When the articular cartilage wears out the bone ends rub on one another and cause pain. This condition is referred to as Osteoarthritis or “wear and tear” arthritis as it occurs with aging and use. It is the most common type of arthritis.

Causes of Arthritis

There are numerous conditions that can cause arthritis but often the exact cause is never known. In general, but not always, it affects people as they get older (Osteoarthritis).

Other causes include:

• Trauma (fracture)
• Increased stress such as overuse and overweight
• Infection of the bone
• Connective tissue disorders
• Inactive lifestyle and Obesity (overweight); Your weight is the single most important link between diet and arthritis as being overweight puts an additional burden on your hips, knees, ankles and feet.
• Inflammation (Rheumatoid arthritis)

Symptoms

Knee Arthritis causes pain and decreased mobility of the knee joint. In the arthritic knee, there is an absent joint space that shows on X-ray.  In the normal knee, there is a normal joint space.

Arthritic knee

The cartilage lining is thinner than normal or completely absent. The degree of cartilage damage and inflammation varies with the type and stage of arthritis. The capsule of the arthritic knee is swollen. The joint space is narrowed and irregular in outline; this can be seen in an X-ray image.  Bone spurs or excessive bone can also build up around the edges of the joint. The combinations of these factors make the arthritic knee stiff and limit activities due to pain or fatigue.

Diagnosis

Evaluating the source of knee pain is critical in determining your treatment options for relief of the pain. Knee pain should be evaluated by an Orthopaedic specialist for proper diagnosis and treatment. Your physician will perform the following:

• Medical History
• Physical Examination

Depending on what the history and exam reveal, your doctor may order medical tests to determine the cause of your knee pain and to rule out other conditions. 

Diagnostic Studies may include: 

• X-rays: X-rays are a form of electromagnetic radiation that is used to take pictures of bones.  An X-ray can reveal if osteoarthritis from degenerative changes is causing your knee pain. The diagnosis of osteoarthritis is made on history, physical examination & X-rays.

There is no blood test to diagnose Osteoarthritis (wear & tear arthritis).

Conservative Treatment Options

Conservative treatment options refer to management of the problem without surgery. Some conservative treatment measures for knee osteoarthritis include:

• Activity Modification and Limitations
• Weight Reduction
• Anti-inflammatory Medications
• Physical Therapy
• Orthotics such as canes, braces, or insoles
• Injection of steroid and analgesic into the knee joint

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.

Traditionally, a patient with two compartments of knee arthritis would undergo a Total Knee Replacement surgery.  Bicompartmental Knee Resurfacing is a newer less invasive surgical option that preserves the knee parts not damaged by arthritis as well as the stabilizing anterior and posterior cruciate ligaments, ACL and PCL.  This less invasive bone and ligament preserving surgery is especially useful for younger, more active patients as the implant placed more closely mimics actual knee mechanics than does a total knee surgery.

The implants used in the partial knee resurfacing surgery are customized to the patient’s anatomy based upon CT scans of the patient’s knee.  A surgical Robotic Arm assists the surgeon with preoperative planning and intraoperative component placement, positioning, and alignment.  Another advantage of Bicompartmental Knee Resurfacing surgery is that it will not alter the ability of the patient to eventually move to a Total Knee Replacement in the future should that become necessary. 

Bicompartmental Knee Resurfacing surgery is performed in an operating room under sterile conditions with the patient under general anesthesia 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. 

The 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.

With the assistance of the robotic arm, the 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 new prepared area and bone cement is used to fix it in place.  The patellofemoral compartment is then prepared by removing the damaged part 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 and the incision closed and covered with a sterile dressing.

Post-operative Recovery

Common Post-Operative guidelines include:

• 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 will be used to minimize swelling and pain.
• You will be given specific instructions regarding activity. Usually there are 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

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 are blood clots that can form in the calf muscles and travel to the lung (Pulmonary embolism). These can occasionally 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 afterwards. Surgery may be required to correct this problem.
• Injury to blood vessels or nerves:   Also rare but can lead to weakness and loss of sensation in 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.
• Wear: The components eventually wear out over time, usually 10 to 15 years, and may need to be changed.
• Dislocation:  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 (thigh bone).
• Fractures or breaks:  Can occur during surgery or afterwards if you fall. To fix these, you may require surgery.