How is an OATS Cartilage Transplant Performed? 

An OATS procedure is performed by removing damaged cartilage, then harvesting healthy articular cartilage with supporting healthy bone from a non-weight-bearing area of the joint. This healthy cartilage restores smooth joint surfaces and improves normal function.

At Total Orthopedics and Sports Medicine, Dr. Charles Ruotolo, a member of the Arthroscopy Association of North America, helps people in Deer Park, Long Island, treat osteochondral lesions. He performs an arthroscopic examination to identify the extent of cartilage damage within the knee or ankle joint. After that, he performs the surgical procedure in which he transfers multiple tiny plugs of healthy cartilage into the defect to restore a smooth chondral surface. Contact us at 855-321-6784 to book your appointment.

What Happens During OATS Cartilage Transplant Surgery?

During osteochondral autograft transplantation surgery, the surgeon removes damaged bone and addresses cartilage defects. Then they harvest healthy cartilage-and-bone plugs from a low-load area of the joint, and press-fits them into the damaged site. These grafts restore a smooth joint surface and support durable cartilage repair.

Here’s how surgeons perform OATS surgery for cartilage restoration:

1. Diagnostic Arthroscopy

The procedure begins under general anesthesia to ensure complete patient comfort and immobility. The surgeon makes a tiny incision and inserts an arthroscope into the joint to visually examine the damaged area of the knee. This helps confirm the exact location, depth, and size of the cartilage defect while also assessing the overall joint environment. If there are any loose cartilage fragments, surgeons perform debridement to create a clean and stable surgical space for graft placement.

2. Preparing the Recipient Site

Once the defect is fully evaluated, the surgeon prepares the damaged cartilage area to receive the graft. Using a special coring tool and precision drills, a cylindrical socket is created within the lesion. This step is performed with high accuracy to match the required diameter and depth of the osteochondral plug. Additionally, proper shaping of the recipient site is essential, as it determines graft integration with the surrounding healthy cartilage and underlying bone.

3. Harvesting the Graft

After preparing the recipient site, surgeons harvest plugs from a healthy cartilage area. One or two plugs are carefully taken from a low-load, non-weight-bearing region of the joint. These donor sites are selected specifically to minimize functional impact while providing high-quality cartilage and subchondral bone. Each plug is extracted with precision to preserve its structural integrity, ensuring it can effectively restore the damaged area.

4. Graft Implantation

The harvested graft is then transferred and placed in a mosaic pattern into the prepared hole of the damaged area. The surgeon gently positions the plug into the prepared socket, ensuring it aligns perfectly with the surrounding native cartilage. This precise positioning will help them restore normal load distribution and reduce the risk of future cartilage wear or mechanical irritation.

5. Stabilization and Closing

After confirming optimal graft placement and smooth alignment of the knee joint surface, the surgeon thoroughly cleans the area to remove any residual debris. The joint is then carefully moved through a controlled range of motion to verify graft stability. Once confirmed, the surgical incisions are closed in layers, and a sterile dressing is applied.

Which Candidates Are the Best Fit for OATS Surgery?

The best candidates for OATS surgery are younger, active patients (about 15–50 years old) with a small, well‑defined, full-thickness cartilage damage. They should have stable joints, good alignment, manageable body weight, and persistent pain or activity limitations despite appropriate nonsurgical treatment.

In fact, the NCBI study reported that OATS surgery is most suitable for full-thickness cartilage lesions measuring 1-2.5 cm in diameter. Before recommending the cartilage transfer procedure, Dr. Charles Ruotolo also evaluates the defect’s depth and location using a physical examination and imaging tests. Moreover, he assesses the condition of the ligaments, meniscus, and other joint surfaces, as untreated structural problems may reduce the chance of successful OATS surgery.

Similarly, he may recommend OATS surgery for cartilage injuries caused by sports trauma, osteochondritis dissecans, or an isolated osteochondral lesion. On the other hand, surgeons do not recommend this procedure for people with the following conditions:

• Extensive cartilage deterioration
• Inflammatory joint disease
• Severe joint-space narrowing or multiple large defects

In addition, if there is significant instability or abnormal joint alignment, it may require correction before or during cartilage surgery. Moreover, patients with advanced arthritis are not suitable candidates for OATS. If persistent knee pain is limiting your joint function, schedule a consultation with our doctor to determine your eligibility for surgery.

How OATS Autograft and Allograft Transplantation Differ?

The osteochondral autograft transplantation system uses cartilage and underlying bone harvested from the patient. In contrast, the OATS allograft transplantation uses size-matched donor tissue. Similarly, autografts are generally preferred to treat minimal cartilage damage. However, allografts can treat larger lesions without creating a second surgical harvest site.

PMC review also reported that autograft transfer is used for smaller lesions under 2 cm², and allograft transplantation for larger lesions around 2–3 cm². Moreover, in an osteochondral autograft transfer system, the surgeon removes one or more healthy osteochondral plugs from a low-weight-bearing area of the patient’s joint and transfers them into the damaged region.

As the tissue comes from the same person, it does not require donor matching and carries no risk of disease transmission. But, in such cases, the amount of available cartilage is limited, and harvesting it may cause pain at the donor site.

On the other hand, an osteochondral allograft approach provides a larger supply of mature cartilage and subchondral bone. This makes it suitable for extensive, deep, or irregular osteochondral lesions that cannot be covered adequately with autograft plugs.

Additionally, surgeons preserve the patient’s healthy cartilage during allograft transplantation because they do not remove tissue from another area of the joint. According to an NIH study, modern knee OCA transplantation also offers long-term graft survival rates of approximately 70% to 91% beyond ten years. However, in such cases, finding suitable donor tissue can be difficult, and the procedure may be more costly.

Is OATS Surgery Arthroscopic or Open?

Orthopedic surgeons can perform OATS surgery both arthroscopically and through a small open incision. They may use arthroscopy for smaller defects that are easily accessible. In contrast, a surgeon uses an open or mini-open approach for larger lesions or when the graft cannot be positioned perpendicular to the joint surface.

However, before deciding on the procedure, the surgeon uses an arthroscope with a tiny lens to examine the cartilage defect and assess the surrounding joint structures. Depending on the findings, they complete the graft transfer either through arthroscopic portals or through a limited incision.

In addition, the surgeon treats lesions of the accessible femoral condyle arthroscopically, whereas defects involving the kneecap or the trochlear groove often require open exposure. This gives a clearer view and better control over graft placement.

How Do Doctors Ensure Accurate Graft Placement?

Dr. Charles Ruotolo achieves accurate graft placement in OATS cartilage restoration surgery through MRI, calibrated sizing instruments, perpendicular socket preparation, four-quadrant depth measurements, and graft orientation. He inserts the osteochondral plug with a press-fit technique and positions it flush with the surrounding cartilage to restore a smooth joint surface.

Here’s how these techniques help him select an accurate size of the osteochondral plug:

1. Preoperative MRI Assessment

MRI helps doctors evaluate the diameter, depth, and location of the cartilage defect, the underlying bone condition, and any associated cystic changes. These findings also assist with surgical planning. However, doctors confirm the final plug diameter and depth during surgery using calibrated OATS instruments.

2. Calibrated Defect Sizing

Once the damaged, unstable cartilage is exposed, cylindrical sizing guides are placed over the lesion. The surgeon selects the smallest guide that completely covers the defect. This helps determine the appropriate diameter of the recipient socket and osteochondral plug.

3. Perpendicular Guide-Pin Placement

The sizing guide must be perpendicular to the articular surface. For this purpose, the surgeon inserts a guide pin through the center of the lesion, providing a controlled path for the recipient reamer. Correct perpendicular alignment helps prevent an angled socket and uneven graft positioning.

4. Controlled Recipient-Socket Preparation

The surgeon may use a diameter-matched reamer over the guide pin to remove the damaged cartilage and underlying bone. They select the depth based on the lesion and subchondral bone involvement, and use irrigation during reaming to reduce heat-related damage to the surrounding bone.

5. Four-Quadrant Depth Measurements

The surgeon measures the prepared socket at the 12-, 3-, 6-, and 9-o’clock positions. Measuring several points is important because the curved joint surface can produce different depths around the socket. After that, the surgeon transfers these measurements to the donor plug so its shape accurately matches the recipient site.

6. Graft Orientation and Contour Matching

Surgeons place a reference mark at the 12 o’clock position to help maintain the plug’s planned orientation. They then trim the bone portion according to the four depth measurements while preserving the cartilage surface and matching its curvature to the surrounding joint.

How Does a Surgeon Prepare the Knee Joint Before OATS?

Before OATS surgery, Dr. Charles Ruotolo thoroughly cleans the knee with an antibacterial solution, drapes it, and applies a tourniquet to temporarily restrict blood flow, creating a clear, bloodless surgical field. After that, he confirms the damage arthroscopically, measures the exact size of the lesion, and ensures the joint is ready for the procedure.

He also bends the knee (flexes) between 70 and 110 degrees to ensure the surgical tools are perfectly perpendicular to the knee cartilage. Then he uses a specialized cannulated reamer to drill a circular socket that is 5 to 10 millimeters deep. Additionally, Dr. Charles Ruotolo uses sizers and dilators to measure the depth of the newly formed socket, ensuring the accurate placement of the healthy donor plug. Reach out today for a detailed evaluation of your cartilage injury.

When Can Patients Return to Sports After OATS?

Patients can return to sedentary work within a few weeks after OATS surgery. However, full recovery after OATS may take 6-12 months. NCBI research also shows that 93% of patients return to their pre-injury sports level after osteochondral autograft transplantation. The average return time was 6.5 months, with a reported range of four to eight months.

However, this timeline may also vary depending on graft integration, muscle strength recovery, joint stability, control of pain or swelling, and the ability to perform sport-specific movements safely under surgical supervision. During the early healing period, you must perform gentle range-of-motion (ROM) exercises and progress gradually to full weight-bearing. Some patients may need crutches to avoid weight on the knee. To avoid pain and swelling, you can also use a cryocuff cold therapy unit. Additionally, elevate your leg when seated and apply ice packs to your knee to reduce pain or swelling (20 min, 3-4 times a day).

Besides this, you can use a continuous passive motion (CPM) machine for 8-10 hours a day to keep the joint mobile without stressing the graft. As healing progresses, you can perform agility drills, pivoting, jumping, and other sports-specific exercises.

What Should Patients Avoid After OATS Surgery?

After OATS surgery, you must avoid putting weight on the affected joint, engaging in high-impact activities, and taking certain pain medications like NSAIDs for knee cartilage repair. You should also avoid bending your knee more than 90 degrees during the initial 6 weeks.

Additionally, never place a pillow directly under the knee joint when resting, as this can cause the operated knee to lock in a bent position. Instead, support your heel/ankle with a pillow to keep the leg extended. Other than this, avoid standing/walking for long stretches and sitting for long periods without elevating your legs. Similarly, you must avoid submerging the surgical leg in water to avoid infection, stiffness, numbness, and inflammation.

You should also not apply Bacitracin or other topical ointments to the incisions unless specifically instructed by your surgeon. Moreover, do not drive while taking narcotic pain medication or if you have had surgery on your right leg for up to 6 weeks.

What are the Risks of Delaying Osteochondral Lesion Surgery?

Delaying osteochondral lesion surgery can lead to worsening joint pain, loss of cartilage, and permanent mobility restrictions. If left untreated, a loose bone fragment can also break off and float inside the joint, potentially causing severe locking, grinding, and the rapid onset of premature, irreversible osteoarthritis.

Furthermore, an untreated defect alters joint biomechanics, leading to cellular degeneration, subchondral bone necrosis, and end-stage knee arthritis. Persistent micro-trauma and unaddressed damage can also cause chronic pain, muscle atrophy, and a feeling of joint “giving way,” which limits both athletic and daily activities. Besides this, if the lesion enlarges or deteriorates over time, you may require more invasive procedures, such as mosaicplasty.

What Factors Impact the Success of the OATS Procedure?

The success of the OATS procedure depends on lesion size and location, patient age and activity level, joint alignment, graft fit, surgeon experience, and adherence to rehabilitation exercises. Additionally, carefully following postoperative restrictions, maintaining healthy surrounding tissue, and ensuring that cartilage damage remains localized improve surgical outcomes. Similarly, here are some other factors that slow graft integration or increase the risk of complications:

1. Smoking
2. Obesity
3. Poor bone quality
4. Uncontrolled medical conditions
5. Previous joint surgeries
6. Meniscus damage

Get Expert Evaluation from Dr. Charles Ruotolo for OATS Cartilage Transplant in Deer Park

When an osteochondral lesion damages the cartilage in your knee, you may experience persistent pain, swelling, joint locking, or difficulty walking. Without proper treatment, the defect may increase stress on surrounding cartilage and increase the risk of progressive joint deterioration.

At Total Orthopedics and Sports Medicine, Dr. Charles Ruotolo, our fellowship-trained orthopedic and sports medicine surgeon, provides advanced OATS surgery to restore joint integrity. He uses high-resolution imaging, performs an arthroscopic assessment, and precisely sizes each osteochondral plug to match the damaged area and achieve an optimal fit. Visit us at 2103 Deer Park Avenue, Deer Park, NY 11729, or call 855-321-6784 for expert knee joint treatment.

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