Overview of Osteochondral Autograft Transplantation
Different methods have been used to treat cartilage defects. For full-thickness defects, which are unlikely to heal naturally, micro-fracture surgery has been a typical approach to treat smaller issues. However, this treatment forms a type of cartilage called fibrocartilage, which might not hold up well with regular pressure and weight-bearing, potentially causing harm to the joint over time and leading to poor patient outcomes.
There are also more advanced procedures. One of those is called autologous chondrocyte implantation, where doctors take the patient’s own cartilage cells, increase them in the lab, and then implant them back into the defect and secure it. This process may be technically difficult, but it could be a suitable option for larger defects. Another approach is osteochondral autograft transplantation, where a piece of cartilage (or even several pieces) from a different healthy part of the body is taken and put into the defect.
When multiple cartilage pieces are used to fill the defect, it’s called mosaicplasty. For this procedure to work well, the cartilage’s original structure doesn’t need to be perfect since multiple pieces are used, and the spaces between can be filled with a kind of cartilage called fibrocartilage for added support. In the past, treatments for cartilage damage involved abrasion or drilling at the damage site, while for more critical conditions, larger pieces of cartilage from another person have been used. However, these kinds of treatments are only reserved for exceptionally large defects, larger than 10 square cm or roughly 1.5 square inches.
Another treatment uses osteochondral plugs, essentially chunks of bone and cartilage together, from the patient or a donor. There are a few reasons these have become popular:
- They can be performed in a single procedure.
- They offer an opportunity to truly resurface with hyaline cartilage, a specific type of cartilage.
- No outside lab assistance is needed to grow more cells.
- It can be done using reusable equipment.
Anatomy and Physiology of Osteochondral Autograft Transplantation
The human body has five types of cartilage, which essentially are firm, flexible tissues. These types include hyaline, fibroelastic, fibrocartilage, elastic, and physeal cartilage. The cartilage that you find on the surfaces of our joints, allowing them to move smoothly, is mainly hyaline cartilage. It helps to provide a slick, frictionless surface that can handle the stress of frequent joint movement. This hyaline cartilage is made up primarily of water, a protein called collagen type 2, and compounds called proteoglycans.
About 70 to 80% of the hyaline cartilage’s weight comes from water. When a joint condition called osteoarthritis occurs, there’s more water in the cartilage which reduces its strength. The cartilage that’s present in our joints can be divided into five layers: the superficial zone, intermediate zone, deep layer, tidemark, and subchondral bone. If there’s an injury to the cartilage that reaches beyond the tidemark layer, a different type of cartilage, called fibrocartilage, starts to form. This fibrocartilage develops following the release of versatile cells, known as mesenchymal cells, from the bone marrow.
Why do People Need Osteochondral Autograft Transplantation
Getting an osteochondral autograft transplantation is a surgical procedure that can be beneficial for certain patients. An osteochondral autograft transplantation is a surgical technique used to treat damaged areas in your joint. When considering this type of surgery, doctors often aim for making the most out of the operation. They usually opt to perform this surgery on people under 45 who are in good health and have specific damaged spots on their joints.
Patients with an overall severe joint disease might not be the best candidates for this procedure, whereas those with a small, painful area caused by an injury could benefit more from the surgery. As long as a healing response from the bone can be expected, individuals of many age groups can be chosen for the operation. The knee joint is usually the optimal choice for this technique due to its size and the variety of problems it can present.
When it comes to the surgical procedure, there are different approaches depending on the joint’s location. A piece of the femur, or the thigh bone, can be replaced using an open surgery or a less invasive method known as arthroscopy. However, the area behind the kneecap and the groovy part of the thigh bone near the knee, which helps hold the kneecap in place, requires an open surgery. The shinbone, or the tibia, presents a unique challenge because surgeons cannot directly access it. A method involving reverse replacement can be used instead. It is important that the transplanted joint tissues from a donor are appropriately angled to match the recipient’s damaged area. Normally, damaged joint areas between 0.4 and 1 inch in diameter are considered suitable for this procedure. While larger areas may have shown positive results in studies, these outcomes are not widely accepted as standard.
When a Person Should Avoid Osteochondral Autograft Transplantation
There are some situations in which a person can’t have an osteochondral autograft, which is a type of surgery to fix damaged cartilage and underlying bone. Here are a few reasons:
One reason is global arthrosis, which is severe damage to all portions of the joint. This is the most serious exclusion for this procedure.
“Kissing” lesions, which are areas where the cartilage is damaged in two spots that touch each other, can also prevent this surgery from being the right choice.
Also, having inflammatory diseases of the joints (inflammatory arthropathies) or an infection called septic arthritis can make the surgery too risky to perform.
If the joint line, which is the place where two bones meet in the joint, has been changed due to injury or disease, the surgery may not be a good option.
Lastly, if there are widespread degenerative changes – meaning that there is general wear and tear in the joint, having this surgery might not be the best plan of action.
However, the procedure might still work for those with isolated or “focal” lesions in two or more areas of the knee. But if there are changes such as osteophytes, or abnormal lumps of bone, or decreased space in the joint, the procedure may not work as well.
Equipment used for Osteochondral Autograft Transplantation
For this procedure, we’ll need to use an operating room. Within this room, we’ll work with a standard operating table that has a leg holder attached. This is to ensure your leg remains stable throughout the process. We’ll also use a device called an arthroscopic camera (or tower). This will allow us to clearly see and monitor the procedure area via small, minimally invasive cuts instead of larger incisions.
We’ll be using some specialized tools made specifically for working with osteochondral autografts. In simple terms, osteochondral autografts are small pieces of bone and cartilage taken from a healthier part of your body to replace damaged or diseased tissue. There are several such systems available, and we could use any of them depending on what’s best for your situation.
Who is needed to perform Osteochondral Autograft Transplantation?
This medical procedure will need a team of trained healthcare professionals to make sure it’s done safely in the operating room. This team includes doctors known as orthopedic surgeons, who specialize in bones, joints, and muscles. Other important team members are the surgical assistants, who help the surgeon throughout the surgery, and scrub techs, who assist by providing the necessary medical tools.
The circulating nurse will be managing the operating room, making sure everyone is where they should be and has what they need. An anesthesia provider is also there. They’re the one who puts you under anesthesia – in other words, they help you sleep painlessly through the procedure.
There’s also the ancillary operating room staff, who might help out with a variety of tasks, and a medical device representative, a person who provides expertise on any complicated medical tools used in the procedure. The preoperative care team prepares you for the surgery, while the post-operative care team looks after you as you recover, making sure you’re healing well and managing your pain.
Preparing for Osteochondral Autograft Transplantation
Before a surgical procedure, doctors need to understand a patient’s condition thoroughly. To do this, they use various diagnostic images like X-rays or MRI scans. These are especially useful when dealing with conditions like full-thickness cartilage lesions that can occur alongside other knee injuries. This type of knee damage is often reported after a traumatic event or an accident, such as a heavy fall or direct impact on the knee.
Firstly, a doctor will take standard X-ray images of the knee from different angles. However, X-ray images aren’t always the best at spotting cartilage defects. For this reason, doctors usually also use an MRI scan. This type of scan is really good at finding out the size and depth of the damaged cartilage area, which is vital information for planning the best treatment.
The size of the damaged cartilage area is particularly important because smaller lesions (less than 1cm in diameter) and larger lesions (more than 2.5 cm in diameter) may require different repair techniques. This detailed knowledge helps doctors choose the best treatment strategy for each individual patient.
How is Osteochondral Autograft Transplantation performed
If you need osteochondral autograft, a procedure to transplant a healthy piece of bone and cartilage to repair damaged joint, you’ll want your doctor to follow a careful plan for the best results. The doctor will always try to work perpendicular (or at right angles) to the joint surface they are repairing. This often involves injuries at the back of the round, bumpy end of your thigh bone, and so it’s important for the doctor to be able to bend your knee completely (hyper-flex) to see what they’re doing.
The surgery begins by examining the joint surfaces, ligaments, and other parts of the knee using an arthroscopy, a type of telescope designed to look inside joints. All loose bits of cartilage, sometimes called ‘loose bodies’, are removed. It’s very important that the doctor can clearly see what they’re doing and can easily reach the area that needs to be fixed. To ensure this, a needle can be used to test the correct position from which to approach the damaged area.
Once the doctor has found the best approach, they will clean the damaged area and identify its borders. Any flapping parts of cartilage will be removed. The doctor then measures the area and decides how many plugs of new cartilage to use. The measured area is then drilled in a direction perpendicular to the smooth, protective layer covering the ends of the bones in a joint (known as the articular surface). The drill bits often have markings on the side to tell the doctor how deep they are drilling. By comparing the drill bit markings with the surrounding, healthy cartilage, the doctor knows how far to drill.
Once the site is prepared, the doctor’s attention turns to removing the new cartilage from its source, the donor site. Common places for this would be the inside and outside grooves at the bottom of your thigh bone. People who have had this surgery often also have an Anterior Cruciate Ligament (ACL) injury, and in those cases, the surgeon may want to take the new cartilage from a considerably different place. The site from which the new cartilage is taken then has a special instrument used to cut out new cartilage, which is lined up with the hole drilled earlier. The new cartilage is then lifted out and put in to a delivery device.
This device is used to put the new cartilage into the damaged area. Research has shown that it’s important not to use too much force (over 400N) on the new cartilage and the fit needs to be just right. The cartilage should be no more than 1 mm above or below the surface of the joint. If it sticks out too much, it’s at risk of failing.
Possible Complications of Osteochondral Autograft Transplantation
Osteochondral autografting, a procedure where healthy cartilage is moved from one part of the body to a damaged area, can sometimes cause complications. Here’s what you should be aware of:
- The healthy cartilage that’s moved could get injured during the process, leading to decay and the graft not working as intended.
- The grafted cartilage may not perfectly match the shape of the area it is moved to. If it doesn’t fit right, it can cause extra pressure on the edges, potential infection, and the graft might become unstable and loosen over time.
- Another concern is the area where the healthy cartilage was taken from can experience problems after the procedure, like severe bleeding and ongoing pain.
Remember, your health provider will aim to minimize these risks and is the best person to address any concerns you have about this procedure.
What Else Should I Know About Osteochondral Autograft Transplantation?
When a part of the body, like a knee or ankle, has damaged cartilage, doctors can perform a specific procedure known as osteochondral autografting to restore it. Cartilage is a type of tissue that helps joints move smoothly. If done right, this procedure can successfully repair the damage in almost three-quarters of patients, working effectively for a decade.
This procedure is sometimes chosen over another type called micro-fracture surgery because it helps to reduce the growth of fibrocartilage, a type of tissue that is less resilient and does not protect the joints as well. By reducing fibrocartilage, osteochondral autografting can help prevent the development of arthritis, a disease that causes pain and inflammation in the joints.
