What is a Biological Knee Replacement?
Loss of meniscal tissue and breakdown of articular cartilage in the knee joint due to damage by injury, wear and tear, or arthritic conditions is probably the most common reason for an individual to undergo knee replacement.
The knee is the most common location for cartilage restoration. Biologic knee replacement in principle involves restoration of the meniscus and articular cartilage.
Artificial knee replacement is a surgical procedure where defective knee joint surfaces are completely replaced with an artificial joint made of metal or plastic to resolve a painful knee condition.
Biological knee replacement is an alternative to artificial knee replacement where the damaged knee joint is reconstructed biologically (i.e. without the need for an artificial knee replacement). This is done by replacing the missing meniscus with a meniscal transplantation from a donor cartilage and covering the areas of worn out articular cartilage with an articular cartilage graft prepared by your own tissue (autograft) or a donor tissue (allograft).
Anatomy
The knee is made up of the lower end of the thighbone (femur), the upper end of the shinbone (tibia), and the kneecap (patella). The ends of these 3 bones where they meet are covered with articular cartilage, a smooth substance that protects the bones and enables them to move smoothly. The meniscal cartilage is located between the femur and tibia and functions as "shock absorbers" that cushion the knee joint. Large ligaments hold the bones together and provide stability.
Indications for a Biological Knee Replacement
Some of the common indications for a biological knee replacement include:
- Osteoarthritis
- Rheumatoid arthritis
- Gouty arthritis
- Post-traumatic arthritis
- Severe knee injury
- Knee deformity with loss of cartilage and pain
- Disorders that trigger abnormal bone growth
Your physician may advise biological knee replacement when these indications result in:
- Severe knee pain, swelling, and stiffness that limits your daily activities (such as walking, getting up from a chair, or climbing stairs)
- Moderate-to-severe pain that interferes with your quality of life and sleep
- Chronic knee pain that is not relieved with rest, medications, injections, physical therapy, or other conservative treatments
- You are feeling depressed because of the pain and lack of mobility
- You cannot have a normal work or social life
Preoperative Preparation for a Biological Knee Replacement
In general, preoperative preparation for a biological knee replacement will involve the following:
- Your doctor will review your complete medical history and perform a physical examination to ensure you are in good health before undergoing the procedure. You may undergo blood tests or other diagnostic tests.
- Inform your doctor if you have a history of bleeding disorders or if you are on any blood thinners (anticoagulant medications), aspirin, or other medications that affect blood clotting. You may need to refrain from these medications prior to the procedure.
- Inform your doctor if you are pregnant or suspect you may be pregnant.
- Notify your doctor if you are allergic to any medications, anesthesia, or latex.
- Notify your doctor of all the medications (prescribed and over-the-counter), vitamins, or supplements you are taking. You may need to refrain from some of these prior to the procedure.
- You should not consume any solids or liquids at least 8 hours prior to surgery.
- You should refrain from smoking, as tobacco affects blood circulation and increases the risk of complications.
- Arrange for someone to drive you home, as you will not be able to drive yourself after surgery.
- A written consent will be obtained from you after the surgical process has been explained in detail.
Procedure for Biological Knee Replacement
Biological knee replacement is performed under anesthesia either through an open surgery or arthroscopically. Your surgeon will discuss the options with you to determine which approach is best for you.
In general, the procedure involves a meniscal transplantation and restoration of articular cartilage.
In meniscal transplantation, the damaged meniscal tissue in the knee is first removed. A fresh-frozen meniscal allograft, preoperatively sized to your knee, is then implanted into the knee under the guidance of an arthroscope (a thin, flexible fiber-optic lighted instrument attached with a camera). Bone tunnels or bone troughs are utilized to anchor the boney attachments, and sutures are then placed to the native meniscal rim or capsule.
A paste graft is a surgical technique for articular cartilage restoration that uses your own tissue, such as bone marrow and cartilage from your intercondylar notch to form a paste that is impacted into the defected area of your knee to regrow new articular cartilage. The mixture of articular cartilage and cancellous bone appears to provide a supportive matrix for cartilage formation, providing a smooth cartilage surface in the joint.
Postoperative Care and Instructions
The general postoperative care and instructions after a biological knee replacement include:
- You will be transferred to the recovery area to be monitored until you are awake from the anesthesia.
- Your nurse will monitor your blood oxygen level and other vital signs as you recover.
- You will experience stiffness and pain in your knee following surgery. Pain medications will be prescribed to manage this discomfort.
- You will be encouraged to get up and walk frequently to prevent blood clot formation.
- Physical therapy is advised after a couple of days of surgery to boost blood flow to the tissues around the knee.
- A special brace-like device known as continuous passive-motion machine (CPM) may be recommended to assist in the movement of your knee in a gentle bending fashion.
- A balanced diet consisting of iron supplements is recommended to help your wound heal and to restore muscle strength.
- Instructions on surgical site care, driving, and bathing will be provided.
- Refrain from smoking as it can negatively affect the healing process.
- Refrain from any strenuous activities requiring weight-bearing. You should gradually increase your activity level with light activities.
- A customized exercise regimen is advised after a few weeks following surgery to strengthen the leg muscles and improve range of motion.
- You should be able to resume most of your normal activities in a couple of months following surgery.
- A follow-up appointment will be scheduled to monitor your progress.
Benefits of Biological Knee Replacement
Some of the benefits of a biological knee replacement include:
- Improved pain
- Improved mobility
- Improved joint function
- Improved quality of life
Risks and Complications of a Biological Knee Replacement
As with any surgery, some of the potential complications involved with a biological knee replacement include:
- Bleeding
- Infection
- Pain
- Damage to blood vessels and nerves
- Blood clots or deep venous thrombosis (DVT)
- Stiffness or instability in the knee
- Anesthetic complications
