What makes me a candidate for this surgery?
You are a candidate if you have patellar instability (kneecap dislocation), front knee pain, and focal cartilage injury. This is evaluated through your past history and the use of MRI and XRAY.
What is the medial patellofemoral ligament (MPFL) and how is it damaged?
The MPFL is a ligament that stabilizes the patella (kneecap) and keeps it from displacing laterally. It is disrupted when someone dislocates his/her patella. When the kneecap dislocates towards the outside, this stretches the ligament on the inside of the knee, which is trying to keep the kneecap in place. This can result in either a tear of the MPFL or a detachment of the ligament from the bone.
What is cartilage, why is it important, and how is it injured?
Cartilage is the shiny, smooth coating at the end of bones. It protects the bone and allows the bones to move smoothly and efficiently. Damaged cartilage is known as arthritis. When cartilage thins, or has a piece missing, it puts more stress on the bone and causes pain. The mechanism of injury for a cartilage defect is usually related to trauma, such as a dislocation that causes the cartilage to scrape along bone, or chronic friction from a maligned knee. The body cannot regenerate this type of cartilage.
What does the surgery entail?
A tibial tubercle transfer (also known as a Fulkerson Osteotomy) is a surgical procedure that is used to correct for patellar instability or patellar malalignment. The procedure consists of an incision, which is made a few centimeters below the kneecap (patella) along the top portion of the shin bone (tibia). The patella is embedded in a tendon that inserts on a bony prominence at the shin bone, known as the tibial tuberosity. The patella is repositioned by surgically cutting and moving the attachment on the shin bone. The new position is held through the use of 2 metal screws.
Then, the injured MPFL ligament will be replaced with a graft, usually a hamstring tendon from the same leg or a cadaver allograft. The graft is attached to the patella via small absorbable screws that hold the graft in place.
Using arthroscopy, the cartilage defect is debrided and restored using one of the methods described below.
The incision is then closed with absorbable sutures and Dermabond, a surgical glue and tape.
How will my cartilage be repaired?
This depends on many factors including your age as well as the size and location of the cartilage defect. The surgeon will chose from one of the following procedures:
- Procedure: Using arthroscopy, the surgeon will first remove any defective and damaged cartilage tissue from the knee joint. She will then create small holes at the site of your lesion to allow bleeding which will stimulate healing. The new tissue that grows is a hybrid of fibrocartilage and another type of cartilage that is similar to that originally in the joint. Although it is not exactly the same, this new type of cartilage is shown to be durable and to function similarly to the original articular cartilage. This procedure can be used on very small lesions successfully.
- Procedure: The surgeon will first remove any defective and damaged cartilage tissue from the knee joint. She will then patch the cartilage defect with the DeNovo cartilage cells. This consists of juvenile cartilage which is able to rejuvenate and grow.
- You may require follow-up MRIs at 3 mo, 6 mo, 12 mo, and 24 mo after surgery to follow the growth and maturation of the new cartilage.
– OCA (Osteochondral Allograft)
- Procedure: The surgeon will first remove any defective and damaged cartilage tissue from the knee joint. She will then patch the cartilage defect with a plug of allograft donor cartilage and bone. This does not rejuvenate, but is press fit into the bone. The body then grows into the new plug and it becomes your own.
– MACI (autologous cultured chondrocytes on porcine collagen membrane)
- Procedure: This is a staged surgery. Stage 1- Using arthroscopy, the surgeon will first remove any defective and damaged cartilage tissue from the knee joint. Healthy cartilage is biopsied and sent to a lab where the cartilage cells will proliferate. Stage 2- About 4-6 weeks later, the defect will be patched with your new cartilage cells.
How long will I stay in the hospital?
With this surgery, you will stay overnight. This will allow for better management of your pain. Once you are able to demonstrate successful management of pain, you will be discharged home.
What are the possible risks and complications of surgery?
As with any surgery there is a risk of DVT, nerve damage, and postoperative infection. Specific risks and complications include but aren’t limited to failure to heal, fracture, and hardware complications.
When can I drive?
You may not drive while taking pain medication. In addition, if it is your right knee that had surgery, you will not be able to drive for approximately 6 weeks after surgery or until the brace is removed.
When can I resume jogging?
You will not resume jogging until cleared by your physician. This typically is around 8-10 months after surgery. You will be allowed to begin biking without resistance once you have adequate range of motion and will begin this with your physical therapist. Once adequate quad strength is demonstrated you will transition to the Elliptical, then running is the next step after that.
When can I return to my sport?
There are many factors in returning to sport after surgery. Most patients are able to return around 7-10 months after surgery. Please see Physical Therapy and Surgical FAQ for more information on this condition.