Knee Cartilage Removal: Procedures, Damage, and Recovery

How do they remove cartilage from the knee?

The removal of cartilage from the knee is typically a surgical procedure performed to address damaged or degenerated cartilage, most often as part of a broader strategy to alleviate pain, restore function, and prevent further joint deterioration.

Understanding Knee Cartilage and Its Damage

The knee joint contains two primary types of cartilage crucial for its function:

• Articular Cartilage (Hyaline Cartilage): This smooth, slippery tissue covers the ends of the femur (thigh bone), tibia (shin bone), and patella (kneecap). Its primary role is to reduce friction and absorb shock, allowing the bones to glide effortlessly against each other. Damage to articular cartilage can range from minor softening to full-thickness defects, often leading to pain, swelling, and reduced mobility.
• Meniscus (Fibrocartilage): The menisci are two C-shaped wedges of tough, rubbery cartilage located between the femur and tibia. They act as shock absorbers, stabilize the knee, and help distribute weight evenly across the joint surface. Meniscal tears are common injuries, especially in sports, and can also result from degenerative processes.

Causes of Cartilage Damage: Cartilage damage can stem from several sources:

• Acute Injuries: Sudden trauma, such as a twist or direct impact, can tear a meniscus or create a defect in the articular cartilage.
• Chronic Overuse or Repetitive Stress: Gradual wear and tear can lead to degenerative changes.
• Degenerative Conditions: Osteoarthritis, a progressive joint disease, involves the breakdown of articular cartilage.
• Inflammatory Conditions: Certain autoimmune diseases can also affect cartilage health.

The goal of "removing" cartilage is rarely to completely excise it, but rather to remove the damaged or unstable portions that cause symptoms, or to prepare the joint for repair or replacement procedures.

Diagnostic Procedures

Before any intervention, a thorough diagnosis is essential:

• Clinical Examination: A physical assessment by an orthopedic surgeon to evaluate range of motion, stability, and specific pain points.
• Imaging Studies:
  • X-rays: Primarily used to assess bone structure and identify signs of advanced arthritis (e.g., joint space narrowing), though cartilage itself is not visible.
  • Magnetic Resonance Imaging (MRI): The gold standard for visualizing soft tissues, including articular cartilage and menisci, providing detailed images of tears or defects.
• Diagnostic Arthroscopy: In some cases, a minimally invasive arthroscopic procedure may be performed to directly visualize the joint and assess the extent of cartilage damage.

Surgical Techniques for Cartilage Management and Repair

When non-surgical treatments fail, various surgical techniques are employed to manage or "remove" damaged knee cartilage. The choice of procedure depends on the type, size, location, and severity of the cartilage defect, as well as the patient's age, activity level, and overall health.

• Arthroscopic Debridement and Lavage (Chondroplasty):

  • Procedure: This is the most direct form of "removal." Using a small camera (arthroscope) and specialized instruments inserted through tiny incisions, the surgeon trims away frayed, unstable, or damaged cartilage (both articular and meniscal) and smooths the remaining surface. The joint is then flushed with sterile fluid to remove debris.
  • Purpose: To alleviate mechanical symptoms like catching, locking, and pain caused by loose cartilage fragments or rough surfaces. It does not regenerate new cartilage but can provide symptomatic relief.

• Meniscectomy (Partial or Total):

  • Procedure: Specifically for torn menisci. A partial meniscectomy involves arthroscopic removal of only the damaged or unstable portion of the meniscus, preserving as much healthy tissue as possible. A total meniscectomy (rarely performed today due to long-term consequences) involves removing the entire meniscus.
  • Purpose: To remove the torn fragment that causes pain, locking, or clicking, while aiming to maintain the meniscus's shock-absorbing function.

• Microfracture:

  • Procedure: For small, full-thickness articular cartilage defects. The surgeon creates tiny holes in the underlying bone (subchondral bone) using an awl. This stimulates bleeding from the bone marrow, which contains stem cells.
  • Purpose: To encourage the formation of a new "fibrocartilage" repair tissue. While not true hyaline cartilage, it can fill the defect and provide pain relief.

• Osteochondral Autograft Transfer (OATS) / Mosaicplasty:

  • Procedure: Healthy cartilage and underlying bone plugs are harvested from a less weight-bearing area of the patient's own knee (autograft) and transplanted into the damaged area. Multiple small plugs are used in mosaicplasty.
  • Purpose: To replace damaged articular cartilage with healthy hyaline cartilage. Best for isolated, full-thickness defects.

• Autologous Chondrocyte Implantation (ACI):

  • Procedure: A two-stage process. First, a small sample of healthy cartilage cells (chondrocytes) is harvested from the patient's knee. These cells are then sent to a lab to be cultured and multiplied. In a second surgery, the grown cells are implanted into the cartilage defect, often under a patch or membrane.
  • Purpose: To regenerate a more durable, hyaline-like cartilage repair tissue for larger articular cartilage defects.

• Knee Arthroplasty (Partial or Total Knee Replacement):

  • Procedure: In cases of severe, widespread cartilage damage (e.g., advanced osteoarthritis), the damaged articular cartilage and underlying bone are removed from the ends of the femur and tibia (and sometimes the back of the patella). These surfaces are then replaced with metal and plastic implants. A partial knee replacement addresses only one compartment of the knee, while a total knee replacement addresses all three.
  • Purpose: To relieve severe pain and restore function in knees with end-stage arthritis where cartilage is extensively eroded. This is the most comprehensive form of "removal" of the diseased cartilage and bone.

Post-Surgical Recovery and Rehabilitation

Regardless of the specific procedure, post-surgical recovery and rehabilitation are critical for optimal outcomes. This typically involves:

• Pain Management: Medications to control discomfort.
• Physical Therapy: A structured program to restore range of motion, strength, stability, and proprioception. This may include non-weight-bearing exercises initially, followed by progressive loading.
• Activity Modification: Gradual return to activities, with restrictions on high-impact or twisting movements depending on the procedure.
• Adherence to Protocols: Strict adherence to the surgeon's and physical therapist's guidelines is paramount to protect the healing tissues and ensure successful recovery.

When is Cartilage "Removed"? Considerations and Goals

It's important to understand that complete, healthy cartilage is rarely "removed" from the knee. Instead, surgical interventions focus on:

• Removing damaged or unstable fragments: To eliminate mechanical symptoms and sources of inflammation.
• Preparing the joint for repair: Creating a suitable environment for new cartilage growth or implantation.
• Replacing severely diseased surfaces: In cases of extensive, irreversible damage where the cartilage is no longer functional.

The overarching goals of these procedures are to reduce pain, improve knee function, and, where possible, delay or prevent the progression of osteoarthritis, allowing individuals to return to their desired level of activity and improve their quality of life.