Knee Cartilage Removal: When It's Necessary, Procedures, and Recovery

Why remove cartilage from knee?

Removing cartilage from the knee, typically through surgical intervention, is primarily performed to alleviate severe pain, restore joint function, and prevent further damage when the cartilage is significantly torn, degenerated, or causing mechanical issues within the joint.

Understanding Knee Cartilage

The knee joint is a complex structure reliant on various tissues for its smooth operation. Central to this function are two primary types of cartilage:

• Articular Cartilage (Hyaline Cartilage): This smooth, slippery tissue covers the ends of the femur (thigh bone) and tibia (shin bone), as well as the back of the patella (kneecap). Its main role is to reduce friction during movement and act as a shock absorber. Damage to articular cartilage can lead to bone-on-bone friction, severe pain, and the progression of osteoarthritis.
• Meniscus: These are two C-shaped wedges of fibrocartilage located between the femur and tibia (medial and lateral menisci). They act as shock absorbers, distribute weight across the joint, provide stability, and aid in joint lubrication. Tears in the meniscus are common and can cause pain, swelling, locking, or catching sensations in the knee.

Unlike many other tissues, cartilage has a very limited blood supply, meaning it has poor capacity for self-repair once damaged.

When Cartilage Removal Becomes Necessary

Surgical removal or trimming of knee cartilage is typically considered when conservative treatments (rest, physical therapy, medication, injections) have failed to provide relief, and the damaged cartilage is significantly impacting joint function and quality of life. Key scenarios include:

• Meniscal Tears:
  • Symptomatic Tears: When a torn meniscus causes persistent pain, swelling, locking, catching, or instability, especially if the tear is in a non-healing zone (avascular) or is too complex for repair.
  • "Bucket Handle" Tears: A severe type of meniscal tear where a large segment of the meniscus displaces into the joint, causing the knee to lock. This often requires immediate surgical intervention.
  • Degenerative Tears: Often seen in older individuals, these tears are due to the gradual weakening of the meniscus over time. If they become symptomatic and unresponsive to conservative care, partial removal may be considered.
• Osteoarthritis (OA):
  • In advanced stages of OA, the articular cartilage progressively wears away, leading to bone-on-bone friction. While cartilage removal isn't a primary treatment for OA (as the problem is lack of cartilage), debridement (trimming rough edges of remaining cartilage or bone spurs) may be performed to smooth the joint surfaces, remove loose fragments, and alleviate mechanical symptoms, often as a temporary measure before total joint replacement.
• Chondral Defects:
  • These are localized areas of damaged articular cartilage, often resulting from acute trauma (e.g., direct impact, sports injury) or repetitive stress. If a fragment of cartilage has detached or the defect is causing significant pain and mechanical symptoms, the unstable or damaged portions may be removed or debrided to prevent further joint irritation.
• Loose Bodies (Joint Mice):
  • Fragments of cartilage or bone can break off due to injury or degenerative conditions and float freely within the joint. These "loose bodies" can cause sudden pain, locking, catching, and inflammation by interfering with normal joint mechanics. Surgical removal is necessary to alleviate these symptoms and prevent further joint damage.

Surgical Procedures for Cartilage Removal/Management

The most common surgical approach for addressing knee cartilage issues is arthroscopy, a minimally invasive procedure.

• Arthroscopy: Small incisions are made, and a tiny camera (arthroscope) is inserted to visualize the joint, along with miniature surgical instruments.
• Partial Meniscectomy: This is the most common form of cartilage removal. The surgeon removes only the damaged or unstable portion of the meniscus, leaving as much healthy tissue as possible. This aims to relieve symptoms while preserving some of the meniscus's shock-absorbing function.
• Debridement: In cases of articular cartilage damage or osteoarthritis, debridement involves smoothing down rough edges of cartilage or removing inflamed tissue or bone spurs that are causing pain or mechanical obstruction. This is palliative rather than curative for OA.
• Removal of Loose Bodies: Floating fragments of cartilage or bone are identified and extracted from the joint.

It is important to note that while some cartilage is removed, surgeons prioritize cartilage repair or regeneration techniques (e.g., meniscal repair, microfracture, autologous chondrocyte implantation, osteochondral allograft transplantation) whenever feasible, especially in younger patients with healthy surrounding tissue. Removal is often chosen when repair is not possible, or when the damage is extensive and degenerative.

The Decision-Making Process

The decision to remove cartilage is a complex one, made collaboratively by the patient and their orthopedic surgeon. Factors considered include:

• Severity and Type of Damage: The extent and location of the tear or defect.
• Patient's Symptoms: Level of pain, functional limitations, and impact on daily activities.
• Age and Activity Level: Younger, active individuals may be more candidates for repair, while older individuals with degenerative issues might lean towards removal or joint replacement.
• Overall Joint Health: Presence of arthritis or other underlying conditions.
• Response to Conservative Treatments: Whether non-surgical approaches have failed.

Potential Outcomes and Considerations

While cartilage removal can effectively alleviate pain and improve knee function in the short term, it's crucial to understand the long-term implications, particularly with meniscectomy:

• Increased Risk of Osteoarthritis: Removing even a portion of the meniscus reduces the knee's natural shock-absorbing capacity, potentially increasing stress on the articular cartilage and accelerating the development or progression of osteoarthritis over many years.
• Pain Relief and Improved Function: For the right indications, surgery can significantly reduce pain, eliminate locking/catching, and restore a greater range of motion and stability.
• Rehabilitation: Post-surgical physical therapy is crucial for regaining strength, flexibility, and proprioception, ensuring the best possible outcome.

Rehabilitation and Recovery

Following cartilage removal, a structured rehabilitation program is essential. This typically involves:

• Pain and Swelling Management: Initial focus on reducing discomfort.
• Range of Motion Exercises: Gradually restoring knee flexibility.
• Strengthening Exercises: Targeting quadriceps, hamstrings, and glutes to support the knee.
• Proprioception Training: Exercises to improve balance and joint awareness.
• Gradual Return to Activity: A progressive plan to resume daily activities and sports, guided by a physical therapist.

In conclusion, the decision to remove cartilage from the knee is a carefully considered medical intervention aimed at resolving acute symptoms and restoring function when the cartilage is damaged beyond repair or is causing mechanical issues that significantly impair quality of life. While effective, it's a procedure with long-term considerations, emphasizing the importance of shared decision-making and comprehensive postoperative rehabilitation.