Cartilage Restoration of the Patellofemoral Joint

What is Cartilage Restoration of the Patellofemoral Joint?

The articular or hyaline cartilage is the tissue lining the surface of the two bones in a joint. Cartilage helps the bones move smoothly against each other and can withstand the weight of your body during activities such as running and jumping. Articular cartilage does not have a direct blood supply to it, so has less capacity to repair itself. Once the cartilage is damaged, it will not heal easily and can lead to degeneration of the articular surface, leading to the development of osteoarthritis.

Cartilage restoration of the patellofemoral joint is a surgical technique to repair damaged or worn-out articular cartilage in the patellofemoral joint by stimulating new growth of cartilage or by transplanting cartilage into areas with defects in order to relieve pain and restore normal function to the knee.

Anatomy of the Patellofemoral Joint

The patella (kneecap) is a protective bone attached to the quadriceps muscles of the thigh by quadriceps tendon. It articulates with the femur (thigh bone) to form the patellofemoral joint. The underside of the patella rests in a groove within your femur called the patellofemoral groove. The patella is protected by a ligament called the medial patellofemoral ligament (MPFL), which prevents the kneecap from moving laterally out of the trochlear groove.

Indications for Cartilage Restoration of the Patellofemoral Joint

Damage to the articular surfaces of the patellofemoral joint is the main indication for cartilage restoration of the patellofemoral joint. The damage can occur as a result of patellar instability, overuse, trauma such as accidents, mechanical injury such as a fall, sports injuries, or from degenerative joint disease (osteoarthritis) occurring in older adults. Symptoms may include pain, swelling, stiffness, visible deformity, a decrease in the range of motion, and loss of knee function.

Cartilage restoration procedures are usually performed to treat small areas of cartilage damage typically caused by sports or traumatic injuries. It is not indicated if you have advanced arthritis of the knee.

Preparation for Cartilage Restoration of the Patellofemoral Joint

In general, preoperative preparation for cartilage restoration of the patellofemoral joint will involve the following steps:

• A thorough examination by your doctor is performed to check for any medical issues that need to be addressed prior to surgery.
• Depending on your medical history, social history, and age, you may need to undergo tests such as bloodwork and imaging to screen for any abnormalities that could threaten the safety of the procedure.
• You will be asked if you have allergies to medications, anesthesia, or latex.
• You should inform your doctor of any medications, vitamins, or supplements that you are taking.
• You should refrain from medications or supplements such as blood thinners, aspirin, or anti-inflammatory medicines for 1 to 2 weeks prior to surgery.
• You should refrain from alcohol or tobacco at least a week before surgery.
• You should not consume solids or liquids at least 8 hours prior to surgery.
• Arrange for someone to drive you home after surgery.
• A written consent will be obtained from you after the surgical procedure has been explained in detail.

Procedures for Cartilage Restoration of the Patellofemoral Joint

Most cartilage restoration procedures can be performed arthroscopically, a minimally invasive surgery that involves making small keyhole incisions around the knee joint using an arthroscope, a small flexible tube with a light and video camera at the end that enables your surgeon to view inside of the joint and perform surgery. In certain cases, open surgery may be required to access the affected area requiring longer incisions. Your surgeon will discuss the best surgical option for you based on your condition.

Usually, recovery from an arthroscopic procedure is much faster with less pain than a traditional, open surgery.

Some of the common procedures employed for patellofemoral joint cartilage restoration include:

• Microfracture: In this method, numerous holes are created in the damaged joint surface using a sharp tool. This procedure stimulates a healing response by creating a new blood supply which results in the growth of new cartilage.
• Drilling: In this method, a drilling instrument is used to create holes in the damaged joint surface. Drilling holes creates a blood supply and stimulates the growth of new cartilage. Although the method is similar to microfracture, it is less precise, and the heat produced during drilling may damage other tissues.
• Abrasion Arthroplasty/Chondroplasty: This is a minimally invasive multiple tissue debridement (removal) procedure performed to stimulate the growth of new healthy cartilage. Drilling the subchondral bone (bone underlying the cartilage) initiates the bleeding and healing response. A blood clot is formed over the debrided region which converts into fibrous tissue, replacing the worn-out articular cartilage.
• Osteochondral Autograft Transplantation: Healthy cartilage tissue (graft) is taken from the bone that bears less weight and is transferred to the damaged joint place. This method is used for smaller cartilage defects.
• Osteochondral Allograft Transplantation: A cartilage tissue (graft) is taken from a donor and transplanted to the site of the injury. Allograft technique is recommended if a larger part of the cartilage is damaged.
• Autologous Chondrocyte Implantation: In this method, a piece of healthy cartilage from another site is removed using an arthroscopic technique and is cultured in the laboratory. Cultured cells form a larger patch which is then implanted in the damaged part by open surgery.

Postoperative Care Instructions and Recovery

In general, postoperative care and recovery after cartilage restoration of the patellofemoral joint will involve the following:

• You will be transferred to the recovery area where your nurse will closely observe you for any allergic or anesthetic reactions and monitor your vital signs as you recover.
• You may notice pain, swelling, and discomfort in the knee area. Pain and anti-inflammatory medications are provided as needed.
• You will be placed on crutches with instructions on restricted weight-bearing for a specified period of time. You are encouraged to walk with assistance as frequently as possible to prevent blood clots.
• You are advised to keep your leg elevated while resting to prevent swelling and pain.
• Keep the surgical site clean and dry. Instructions on surgical site care and bathing will be provided.
• Refrain from smoking as it can hinder the healing process.
• Eating a healthy diet rich in vitamin D is strongly advised to promote healing and a faster recovery.
• Refrain from strenuous activities for the first few months and lifting heavy weights for at least 6 months. Gradual increase in activities over a period of time is recommended.
• Physical therapy and range of motion exercises will be designed to restore mobility and strengthen joints and muscles.
• You will be able to return to your normal activities in a month or two; however, return to sports may take 6 months or longer.
• Periodic follow-up appointments will be scheduled to monitor your progress.

Risks and Complications

Cartilage restoration of the patellofemoral joint is a relatively safe procedure; however, as with any surgery, some risks and complications may occur, such as the following:

• Post-operative pain
• Bleeding 
• Blood clots (deep vein thrombosis)
• Infection
• Stiffness of the joint
• Numbness around the incisions
• Injury to vessels, nerves, or healthy cartilage
• Allergic/anesthetic reactions
• Failure of the graft
• Loosening of the graft