Microfracture (Cartilage Repair)

Why this approach — at MOS

Microfracture is appropriate for the right patient with the right defect. We are candid with patients when the defect characteristics, patient age, or activity demands suggest that a cartilage transplant procedure — OATS or osteochondral allograft — will produce more durable results. The published literature is fairly clear: microfracture for defects smaller than 2 cm² in young, active patients produces satisfactory results; results decline for larger defects, older patients, and those with uncorrected biomechanical issues.

When microfracture is the right choice, we ensure proper defect preparation — debridement to stable edges and removal of the calcified cartilage layer — because these technical steps directly affect outcome. We also counsel patients rigorously about post-operative compliance: the restricted weight-bearing period is not optional. Patients in Germantown, Bethesda, and Rockville who undergo microfracture are followed closely through our in-house physical therapy program with protocols designed specifically for cartilage healing.

Biological augmentation of microfracture — applying platelet-rich plasma or scaffold materials over the defect — is an active area of research. We follow this literature and discuss augmentation options with appropriate candidates.

Who is a candidate?

Indications

• Focal, full-thickness chondral defect (International Cartilage Repair Society grade 3 or 4) with stable, healthy surrounding cartilage
• Defect size ≤2–3 cm² — larger defects have less reliable fibrocartilage fill
• Younger patients (generally under 40) with good baseline cartilage quality
• Active patients with functional limitations from a confirmed focal cartilage injury
• Contained defects (normal cartilage walls on all sides) — provides better defect fill environment

Contraindications

• Advanced diffuse osteoarthritis — microfracture treats focal defects, not widespread arthritis
• Large defect (>3–4 cm²) — cartilage transplant procedure (OATS or OCA) has better outcomes for large defects
• Uncorrected malalignment — performing microfracture without addressing varus or valgus deformity causes the repair tissue to fail under abnormal load distribution
• Ligamentous instability — an unstable knee creates shear forces that prevent fibrocartilage maturation
• Inability to comply with post-operative restricted weight-bearing protocol

Conservative Treatment First

Many focal cartilage lesions are discovered incidentally on MRI or during arthroscopy for another reason, in patients with minimal symptoms. A trial of conservative management — activity modification, physical therapy to strengthen the surrounding musculature, NSAIDs, and corticosteroid or hyaluronic acid injection — is appropriate before cartilage surgery is considered. Microfracture is indicated for symptomatic, confirmed focal lesions that have not improved with a sufficient conservative trial, particularly in younger, active patients whose activity level is significantly limited.

The procedure

What Is Microfracture (Cartilage Repair)?

Microfracture is an arthroscopic procedure that treats a focal cartilage defect in the knee by making small holes in the underlying bone to release marrow stem cells that form a repair cartilage (fibrocartilage) over the defect. It is the least invasive cartilage treatment option and is best suited for defects smaller than 2–3 cm² in patients under 40.

Articular cartilage — the smooth, glistening tissue covering the ends of bones inside the knee — has almost no blood supply of its own. This makes spontaneous healing of cartilage injuries essentially impossible. When a focal area of cartilage is damaged — by acute injury, osteochondritis dissecans, or localized wear — the resulting "pothole" in the joint surface causes pain, swelling, catching, and over time, progressive arthritis if left untreated.

Microfracture was developed in the 1990s by Dr. Richard Steadman as a way to harness the body's own healing biology. By making small perforations (microfractures) through the subchondral bone plate at the base of the defect, the surgeon accesses the marrow space beneath. Marrow-derived mesenchymal stem cells and growth factors flow into the defect and form a clot that gradually matures into fibrocartilage — a repair tissue that fills the defect and provides a smoother, more protective surface than raw bone. Fibrocartilage is not identical to native hyaline cartilage in its mechanical properties, but in appropriately selected patients it reduces pain and improves function durably.

What Happens During Microfracture?

Microfracture is performed arthroscopically at an ambulatory surgery center. After anesthesia and tourniquet placement, arthroscope portals are established and the entire joint is inspected. The cartilage defect is identified and its size, depth, and surrounding cartilage quality are assessed.

The defect is prepared by removing all damaged cartilage back to a stable, vertical edge — a process called debridement to stable shoulders. The calcified cartilage layer on the exposed bone base is removed with a small curette or shaver to expose healthy subchondral bone. This step is important: leaving calcified cartilage in place reduces stem cell adhesion and impairs tissue formation.

A surgical awl is then used to make perforations approximately 3–4 mm apart across the entire base of the defect, each to a depth of about 4 mm. The number of perforations depends on defect size; the surgeon confirms marrow-derived fat droplets emerge from each hole. After the microfracture is complete, the tourniquet is released and blood and fat droplets are seen filling the defect — these are the marrow elements that will form the healing clot.

The portals are closed and the knee is dressed. Post-operative weight-bearing restrictions begin immediately and are critically important to allow the clot to mature undisturbed.

Recovery timeline

Frequently Asked Questions