What Is Microfracture Surgery for Knee Cartilage?

Microfracture surgery is a minimally invasive knee surgery used to treat small areas of damaged articular cartilage. During this arthroscopic procedure, the surgeon creates small holes beneath the cartilage defect, allowing blood and stem cells to flow in and form a healing clot that develops into new cartilage.

At Total Orthopedics and Sports Medicine, Dr. Charles Ruotolo, a member of the American Medical Association, performs advanced knee microfracture surgery to remove unstable cartilage. He creates evenly spaced holes in the subchondral bone beneath the defect to release stem cells, triggering a controlled healing response. Over time, the clot develops into fibrocartilage repair tissue that covers the exposed area. Contact us at 855-321-6784 to get a successful cartilage repair in Syosset.

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How Does Microfracture Surgery Repair Knee Cartilage?

Microfracture surgery repairs knee cartilage by creating tiny holes in the bone beneath a damaged area. These openings release blood, bone marrow cells, and growth factors, forming a clot that fills the defect and gradually develops into fibrocartilage, which covers the exposed bone and improves joint function.

Here’s how doctors perform this surgical technique to restore knee joint function:

1. Cartilage Defect Preparation

Microfracture surgery is usually performed as a minimally invasive knee arthroscopy. The surgeon makes several small keyhole incisions around the knee and inserts an arthroscope, a thin instrument equipped with a camera and light. The camera provides a clear view of the chondral defect and surrounding joint structures, while specialized surgical instruments are introduced through the other incisions. This approach allows the surgeon to treat the articular surface accurately while limiting disruption to the surrounding tissues.

However, before creating the microfracture holes, the surgeon carefully removes loose, frayed, unstable, or severely damaged knee cartilage. This process, known as debridement, creates normal cartilage borders around the defect and exposes a clean subchondral bone bed. Proper site preparation is also essential because unstable cartilage can interfere with clot attachment and reduce the quality of the tissue regeneration.

2. Creation of Microfracture Channels

Once the cartilage defect has been prepared, the surgeon uses a small pointed instrument, commonly called a microfracture awl or pick, to create multiple tiny holes in the exposed subchondral bone. These holes are placed at controlled intervals across the damaged cartilage. It also preserves the surrounding healthy cartilage and avoids unnecessary injury to the underlying bone structure.

Moreover, these openings penetrate the dense outer layer of bone and reach the deeper, more vascular bone marrow. This allows blood, growth factors, platelets, and bone marrow-derived mesenchymal cells to enter the cartilage defect. These biological materials initiate the body’s natural healing response and provide the cells and signaling molecules needed to promote cartilage growth.

3. Bone Marrow Release and Clot Formation

After the microfracture channels are created, blood and bone marrow elements enter through the openings and fill the cartilage defect. The released growth elements then form a marrow-rich blood clot over the exposed bone. This clot serves as a temporary biological scaffold, holding reparative cells and growth factors within the damaged area. It also protects the exposed subchondral bone during the early stages of healing.

In selected cases, synthetic scaffolds may augment microfracture procedures to achieve better results by stabilizing the clot and promoting improved cartilage repair. Because the newly formed clot remains delicate, patients must follow carefully controlled rehabilitation and weight-bearing restrictions to protect it during early healing.

4. Fibrocartilage Maturation and Remodeling

After several weeks of surgery, the bone marrow-derived cells contained within the clot multiply, mature, and begin producing a cartilage-like extracellular matrix. The repair tissue gradually fills the defect and remodels in response to controlled joint movement and progressive loading. During this time, rehabilitation plays an important role because appropriate motion supports nutrient circulation.

The tissue formed after microfracture surgery is primarily fibrocartilage rather than the knee’s original hyaline cartilage. Fibrocartilage contains a higher proportion of type I collagen. It is generally softer, less organized, and less resistant to repeated mechanical stress than native hyaline cartilage, which is rich in type II collagen. However, it can cover exposed bone, improve joint surface continuity, reduce pain, and support better knee function in properly selected patients.

Which Articular Cartilage Injuries Does This Surgery Treat?

Microfracture treats small, localized, full-thickness articular cartilage defects in the knee, especially lesions on the femoral condyles, trochlea, tibial plateau, or undersurface of the kneecap. It is commonly used for osteochondral lesions that are typically smaller than 2 cm² with an exposed chondral surface.

In fact, NCBI research reported that microfracture is successful when performed in nonobese patients under 30 years old for small (<2 to 4 cm2) femoral condylar defects. Moreover, the procedure is most suitable when the injured area has clear borders and is surrounded by stable, healthy cartilage. Doctors also recommend it for articular cartilage damage caused by a sports injury, sudden impact, repetitive joint stress, or a detached cartilage fragment. In contrast, microfracture is not recommended for widespread knee arthritis or for partial-thickness damage that does not extend to the underlying bone. Similarly, it’s not recommended for patients with large or poorly contained defects and major cartilage deterioration.

Can Damaged Knee Cartilage Heal Naturally?

No, articular cartilage cannot heal itself because it lacks a blood supply. However, you can manage pain and improve joint function using conservative, non-surgical methods. While the original cartilage rarely grows back, the body can fill damaged areas with functional, dense matrix (scar tissue).

Although this tissue is not the original smooth articular cartilage, it is still durable and provides essential cushioning to restore comfortable joint movement. Besides this, to encourage this natural healing and reduce pain, Dr. Charles Ruotolo recommends the following approaches:

• Physical Activity: Strengthening the muscles around the knee, particularly the glutes and quadriceps, helps correct imbalances and reduce physical load over the damaged cartilage.
• Low-Impact Movement: Cycling, walking, and elliptical training (done at low resistance) help circulate synovial (joint) fluid. It also delivers vital nutrients directly to the avascular cartilage.
• Weight Management: Decreasing excess weight significantly reduces the daily compression and mechanical stress placed on the knee joints.
• Regenerative Therapies: For early-stage damage, most patients can use non-surgical orthobiologics like platelet-rich plasma or hyaluronic acid injections to stimulate joint motion.

According to the PMC study, 102 participants were randomly assigned to groups that received 8 weeks of high-resistance exercise (HR group), 8 weeks of low-resistance exercise (LR group), or no exercise (control group). Both exercise groups experienced significant improvements in pain, function, walking time, and muscle strength. Another NIH research reported that diet-induced weight loss combined with exercise reduced inflammatory marker levels and improved clinical outcomes in obese adults with knee OA.

When Do Doctors Recommend Knee Microfracture Surgery?

Dr. Charles Ruotolo recommends knee cartilage restoration surgery for younger patients with small defects that cause persistent pain, swelling, or reduced function despite nonsurgical treatment. It is also most suitable for highly active patients with stable knees, healthy surrounding cartilage, and limited or no osteoarthritis.

However, before recommending this orthopedic surgery, Dr. Charles Ruotolo evaluates the following factors:

Size of the Cartilage Defect

Microfracture is generally more appropriate for small, localized defects because the marrow clot can cover a limited area. In contrast, larger defects may produce less durable repair tissue, for which surgeons consider cartilage transplantation or another advanced restoration procedure. The NCBI systematic review also found that larger lesions (>3.6 cm²) and prior knee surgery are associated with a higher chance of additional surgery.

Depth of the Cartilage Defect

Microfracture is primarily designed for full-thickness cartilage injuries that expose the underlying subchondral bone. Partial-thickness damage may not benefit because it does not provide direct access to the bone marrow. When the injury extends deeply into the bone, Dr. Charles Ruotolo may consider other advanced alternatives, such as:

1. Osteochondral allograft transplantation can restore damaged articular cartilage by replacing the defect with healthy donor cartilage and underlying bone.
2. Matrix-induced autologous chondrocyte implantation (MACI) is a modern cartilage repair technique that uses a patient’s cultured cartilage cells on a specialized scaffold.
3. In selected cases, articular cartilage paste grafting may enhance cartilage repair by placing minced cartilage and bone material within the prepared defect.

Location of the Cartilage Damage

The defect’s location determines the amount of pressure and friction the repaired area will experience. Lesions on weight-bearing surfaces may be subjected to greater mechanical stress. In contrast, defects involving the kneecap or the trochlear groove may be associated with different contact forces. According to the PMC study, microfracture produced the best results for femoral condyle lesions. Researchers also found that outcomes for patellar, trochlear, and tibial defects deteriorate between 18 and 36 months after surgery. Besides this, location also affects surgical access, hole placement, and the rehabilitation plan.

Quality of the Surrounding Cartilage

Healthy, stable cartilage around the defect provides firm borders that help contain the blood and bone marrow clot created during microfracture. If the surrounding cartilage is loose, thin, unstable, or severely deteriorated, the clot may not remain securely in place. Moreover, when cartilage degeneration is widespread, microfracture may be less effective, and Dr. Charles Ruotolo may recommend an alternative procedure.

Knee Alignment

Our surgeon checks whether the leg is properly aligned, bow-legged, or knock-kneed. Poor alignment can exert excessive pressure on the damaged compartment and overload the newly formed repair tissue. In such cases, Dr. Charles Ruotolo may perform osteotomy before or alongside cartilage surgery to redistribute weight from the treated area.

Ligament Stability

Stable knee ligaments are necessary to protect the healing cartilage surface. An ACL, PCL, or other ligament injury can allow abnormal joint movement. This increases stress on the treated defect and raises the risk of surgical failure. Therefore, our surgeon may recommend ligament reconstruction before or during the cartilage repair procedure.

Condition of the Meniscus

The meniscus absorbs shock and distributes pressure across the knee joint. A torn, damaged, or previously removed meniscus increases the mechanical load placed on the cartilage defect. In these cases, our surgeon may perform meniscal repair, transplantation, or another protective procedure to improve the conditions for cartilage healing.

Patient’s Activity Level

Activity level helps our surgeon determine whether the expected repair tissue can tolerate the patient’s future physical demands. Microfracture may provide satisfactory improvement for patients who participate in controlled or low-impact activities. In contrast, competitive athletes or patients expecting frequent running, jumping, or pivoting may require a more durable procedure to repair damaged knee cartilage.

Ability to Follow Rehabilitation

Successful outcomes of knee cartilage repair depend heavily on following a structured rehabilitation program. Therefore, patients must be prepared to follow weight-bearing restrictions, perform prescribed range-of-motion exercises, and delay high-impact activity while the new tissue matures. If a patient cannot adhere to these restrictions, our surgeon may postpone surgery or recommend an alternative treatment approach.

How Do Doctors Diagnose a Cartilage Defect?

Dr. Charles Ruotolo uses medical history, performs a physical examination, advanced imaging, and sometimes diagnostic arthroscopy to diagnose cartilage defects. During the physical examination, he may ask about your knee pain levels, swelling, activity demands, and any specific injuries or trauma you’ve experienced.

Moreover, he will check the stability, range of motion, and swelling of your joints. Our surgeon may press on specific areas to locate tenderness or ask you to squat to observe joint function under stress. He also notes symptoms that often include clicking, grinding, joint locking, or a feeling that it’s “giving way”. After that, Dr. Charles Ruotolo performs X-rays to identify bone fractures or determine if advanced cartilage loss has caused space narrowing in other joints.

Similarly, he may use an MRI to produce highly detailed 3D images of soft tissues, which helps him identify the exact size, depth, and location of a cartilage lesion. It also helps him analyze associated ligament or meniscus damage. If imaging results are unclear or our doctor needs to visualize the damage in real time, he may perform an arthroscopy. This is a minimally invasive procedure where a tiny camera is inserted into the joint through a small incision. In small-defect cases, he will treat and repair the defect in the same procedure. Schedule a consultation today to accurately diagnose your cartilage injury.

How Long Does Cartilage Repair Take to Heal?

Microfracture cartilage repair surgery typically takes 6 to 12 months for complete healing and a safe return to sports or high-impact activities. The procedure is a lengthy tissue regeneration process that requires strict adherence to a progressive rehabilitation program to ensure the development of durable fibrocartilage.

Besides this, the recovery timeline after this surgery is divided into the following phases:

Phase 1: Protection and Non-Weight Bearing (0–6 Weeks)

During the first six weeks, your primary goal is to protect the healing cartilage and prevent excessive pressure on the treated area. You are generally instructed to use crutches and avoid placing weight on the affected leg. This restriction may last 6 to 8 weeks, depending on the defect’s location and the surgeon’s protocol.

In addition, your surgeon may recommend using a continuous passive motion machine for six to eight hours each day. This will help you gently move your knee, maintain joint mobility, and support cartilage healing. They may also restrict driving for at least six weeks, particularly if they treated your right knee or you are still taking pain medication.

Phase 2: Weight Bearing and Strengthening (6–12 Weeks)

Between six and twelve weeks, you can gradually place weight on the treated leg after receiving clearance from your surgeon. Weight bearing is usually increased at this stage to prevent excessive stress on the developing repair tissue. Additionally, you may begin low-impact activities, such as stationary cycling, pool exercises, or swimming, without worsening pain or swelling.

Phase 3: Gradual Return to Activity (3–6 Months)

For three to six months, rehabilitation focuses on rebuilding strength, endurance, coordination, and functional movement. You may start light jogging and controlled sport-specific exercises when you have gained adequate strength. However, you should gradually increase the activity intensity under your surgeon’s guidance. Although cartilage healing continues during this period, many patients experience noticeable pain relief, improved mobility, and better knee function by approximately six months.

Phase 4: Full Recovery (6–12 Months)

You should postpone high-impact sports and movements that involve running, jumping, pivoting, or cutting for 6 to 12 months to protect the newly formed repair tissue. Moreover, before returning to activities such as soccer or basketball, you should gain sufficient strength and functional control.

What Complications Can Occur After the Surgery?

Infection, blood clots, bleeding, joint stiffness, persistent pain, swelling, limited motion, and damage to nearby nerves or tissues may occur after microfracture surgery. The new fibrocartilage may also form incompletely or deteriorate over time, leading to recurrent symptoms and, in some cases, requiring additional cartilage-restoration surgery.

According to the Sage Journal review, 93% of patients who failed microfracture also showed osseous overgrowth, and patients with osseous overgrowth had a higher failure rate (25%). Moreover, creating small holes in the subchondral bone may contribute to cyst formation or bone overgrowth beneath the treated area. These changes can interfere with cartilage healing and may complicate future procedures if the microfracture fails to heal. Besides this, excessive scar tissue in the knee can restrict flexion or extension, making movement uncomfortable.

In addition, general risks associated with breathing or medication reactions can occur after the surgery. To reduce these risks, Dr. Charles Ruotolo prescribes a strict rehabilitation protocol that includes crutches to limit weight-bearing and targeted exercises to promote proper cartilage maturation. Reach out today to discuss your symptoms and treatment options.

How Successful Is Knee Cartilage Repair?

Microfracture surgery shows good or excellent results in 67% of athletes according to the PMC study. Researchers also found that 80% of patients experienced clinical improvement, with significant gains in Lysholm scores and Tegner activity scores. Overall, 66% returned to sports within an average of eight months, and 67% resumed competition at their preinjury level. However, only 42% experienced a decline in function within two to five years after surgery. Another NIH research found that return-to-sport rate after microfracture surgery ranged from 17.2% to 20%.

Consult Dr. Charles Ruotolo for Knee Cartilage Repair in Syosset

A knee cartilage defect may lead to recurrent joint locking, instability, reduced weight-bearing capacity, difficulty climbing stairs, and progressive loss of knee function. Moreover, because articular cartilage has a limited capacity to heal, untreated defects damage the underlying bone and increase the risk of osteoarthritis.

At Total Orthopedics and Sports Medicine, Dr. Charles Ruotolo precisely removes unstable cartilage and controls bone marrow stimulation to promote tissue growth. Additionally, our team offers a secure patient portal, easy online bill payment, and referral management to streamline your treatment process. Visit at 115 Eileen Way, Syosset, NY 11791, or contact us at 855-321-6784 to schedule your knee cartilage evaluation.

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