Understanding Microfracture (Knee)
If you’ve been experiencing persistent knee pain, swelling, or catching sensations due to a small, isolated area of damaged cartilage, your doctor might discuss a procedure called Microfracture. This surgery aims to stimulate the growth of new cartilage in your knee to reduce pain and improve joint function, without replacing the joint.
What’s Going On with Your Knee Cartilage?
Your knee joint is covered by a very smooth, slippery tissue called articular cartilage (also known as hyaline cartilage). This cartilage acts as a natural shock absorber and allows your thigh bone (femur) and shin bone (tibia) to glide effortlessly against each other during movement.
Unfortunately, articular cartilage has a very limited ability to heal itself when damaged. When a specific area of this cartilage is injured, perhaps from a direct blow, a twisting injury, or repeated stress, it can create a defect – like a pothole in a smooth road. This damage can lead to:
- Pain, especially with weight-bearing or activity.
- Swelling within the joint.
- Clicking, popping, or catching sensations.
- A feeling of instability or your knee “giving way.”
Microfracture is typically considered for isolated, contained cartilage defects (like a single pothole) rather than widespread cartilage loss (which is characteristic of arthritis). It’s most effective in younger, active patients with smaller defects.
How Does Microfracture Help?
Microfracture is a surgical procedure designed to encourage your body to grow new cartilage to fill in a damaged area within your knee joint. The goal is to create a smoother surface, reduce pain, and improve the overall function of your knee.
This procedure is performed arthroscopically, meaning the surgeon uses small incisions (cuts) and a tiny camera (arthroscope) to work inside your knee joint. This minimally invasive approach typically results in:
- Smaller scars
- Less pain after surgery
- Potentially faster initial recovery compared to larger open surgeries.
During the surgery, the surgeon will:
- Access the Joint: Small incisions (about the size of a buttonhole) are made around your knee.
- Visualize the Defect: The arthroscope is inserted, providing a clear view of the inside of your joint on a monitor. The surgeon can precisely identify the damaged area of cartilage.
- Prepare the Area: Any unstable or frayed cartilage around the defect is carefully trimmed away, creating a stable rim.
- Create Microfractures: Using a specialized tool (a sharp pick or awl), the surgeon creates multiple small holes (microfractures) in the bone just beneath the damaged cartilage. These tiny holes allow blood and bone marrow cells, which contain healing factors and “stem cells,” to seep out from the bone.
- Form a Clot: These cells and blood then form a “super clot” within the cartilage defect. Over time, this clot matures and forms new cartilage. While this new cartilage (called fibrocartilage) is not identical to the original articular cartilage, it can effectively fill the defect, provide a smoother surface, and reduce symptoms.
Life After Microfracture:
After your microfracture surgery, physical therapy is absolutely crucial for a successful outcome. The rehabilitation process is often very specific, cautious, and prolonged, as it takes time for the new cartilage to form and mature. Your physical therapist will guide you through a structured and progressive program, which typically includes:
- Strict Weight-Bearing Restrictions: You will likely need to use crutches and have very limited or no weight-bearing on the operated leg for several weeks to months (often 6-8 weeks) to protect the healing clot and newly forming cartilage.
- Controlled Movement: Your knee may be placed in a brace, and your therapist will guide you through gentle, controlled exercises to restore motion without putting compressive stress on the repair. Continuous Passive Motion (CPM) machines are sometimes used to gently move the knee.
- Progressive Strengthening: Your therapist will gradually introduce strengthening exercises for the muscles around your knee (quadriceps, hamstrings, glutes) and core, which are vital for supporting the joint.
- Gait Training: As weight-bearing is slowly increased, you will be retrained to walk properly.
- Gradual Return to Activity: This is a very slow and cautious process. High-impact activities or sports are typically restricted for 6-12 months or even longer, allowing the new cartilage to fully mature and become more resilient.
Recovery from microfracture is a significant commitment that requires immense patience, dedication, and strict adherence to your physical therapy program. Following your therapist’s instructions closely is paramount for achieving the best possible outcome and safely returning to your desired activities with reduced pain and improved knee function.