What Is Articular Cartilage — and Why It Matters for Knee Health

Articular cartilage is the smooth, white tissue that covers the ends of bones inside a joint. It plays a key role in pain-free movement by reducing friction and absorbing shock, allowing the bones in the knee to glide smoothly against each other. This tissue is especially important for knee health because when it gets damaged, it can lead to pain, swelling, stiffness, and difficulty moving. Since articular cartilage has a very limited ability to heal on its own, untreated damage can worsen over time and may eventually require surgical treatment.

Below is a simple, down-to-earth guide that explains what articular cartilage is, how it works, what happens when it’s damaged, and practical steps to protect your knees.

What is Articular Cartilage?

• Location: It is a smooth, slippery tissue known as hyaline cartilage that covers the ends of the bones inside the knee joint—specifically the femur (thigh bone), tibia (shin bone), and the back of the patella (kneecap).
• Composition: Articular cartilage is made up of strong collagen fibers and a soft, gel-like substance that gives it strength and flexibility, and it is cared for and maintained by special cells known as chondrocytes.
• Nutrition: Articular cartilage does not have its own blood supply, so it gets nutrients and clears waste through the surrounding joint fluid (synovial fluid). This is why regular, gentle joint movement is important to keep the cartilage healthy and functioning properly.

How articular cartilage helps your knee work

• Frictionless movement: It creates an ultra-smooth surface so bones glide without rubbing.
• Shock absorption: The gel-like matrix spreads forces across the joint, protecting bone and soft tissue when you land or push off.
• Load transmission: It helps distribute body weight through the knee evenly, so no single spot is overloaded.

Because of these jobs, cartilage keeps movement pain-free and efficient.

Why does cartilage not repair itself well?

Cartilage has very few cells and no direct blood supply. That makes natural healing slow or ineffective. Small injuries can persist and, over the years, wear down into larger problems such as osteoarthritis. That’s why preventing damage and treating it early matters.

What happens when cartilage is damaged?

Damage can be sudden (a twisting sports injury) or gradual (wear-and-tear). Typical signs include:

• Pain with activity that improves with rest.
• Swelling after activity.
• Stiffness or a feeling that the knee “catches” or locks.
• Reduced ability to walk, climb stairs, or kneel.

Left untreated, damage can progress and cause persistent pain and loss of function.

Common causes of articular cartilage damage

• Sport injuries (twisting, direct blows).
• Repetitive stress or heavy jobs.
• Age-related wear (degeneration/osteoarthritis).
• Injuries that change joint mechanics (untreated ligament tears, meniscus injuries).

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How doctors diagnose cartilage problems (simple)

Your doctor will combine your story, a physical exam, and imaging (X-rays or MRI). X-rays show bone alignment and arthritis; MRI shows cartilage and soft tissues more clearly. Sometimes, a small camera inside the joint (arthroscopy) is used to look directly.

Treatment — non-surgical and surgical options (overview)

Treatment depends on the size, depth,h and location of the defect, your symptoms, and activity goals.

Non-surgical care (oftenthe first step):

• Rest, activity modification, and weight control.
• Physical therapy to improve muscle strength and movement patterns.
• Pain relief (acetaminophen, anti-inflammatory medication when appropriate).
• Injections (corticosteroids, hyaluronic acid, or biologic options) — these may ease symptoms for months but don’t fully rebuild cartilage.

Surgical options (for more severe or persistent problems):

• Procedures that stimulate cartilage to form a repair layer (microfracture).
• Cartilage repair or restoration techniques (autologous chondrocyte implantation, osteochondral grafts) try to replace or grow new cartilage.
• Partial or total knee replacement in advanced, widespread cartilage loss (osteoarthritis).

Your orthopedic surgeon will explain which option fits your knee, lifestyle, and expectations.

Practical steps to protect your cartilage (everyday tips)

• Keep a healthy weight — less load through the knees means less wear.
• Stay active with low-impact exercise: walking, cycling, and swimming.
• Strengthen the muscles around the knee (quads and hamstrings) to support the joint.
• Avoid high-impact sports or heavy repetitive knee loading if you already have cartilage damage.
• Address injuries early — an untreated knee injury can speed cartilage wear.

Simple analogy to remember

Imagine the knee as a door hinge with grease between moving parts. Articular cartilage is the grease and the smooth metal surface — without it, the hinge squeaks, wears out, and eventually may seize. Keeping cartilage healthy keeps the hinge working smoothly.

When to see a doctor

If you have persistent knee pain, swelling, locking, or trouble doing daily activities for more than a few weeks, see an orthopedic specialist. Early assessment often gives you more treatment choices and better long-term outcomes.

Frequently Asked Questions