Cartilage, tendon, ligament and muscle: what's the difference?

A painful knee does not necessarily mean damaged cartilage. Pain near the shoulder does not always come from the joint itself. And when people talk about “strengthening their joints”, they often group together structures with very different compositions and functions.

Cartilage, tendons, ligaments, muscles and bones work together, but each plays a distinct role in movement.

Understanding these differences can help us interpret what we feel and avoid a common shortcut: assuming that every pain around a joint must be osteoarthritis.

Cartilage: a surface designed to make movement easier

Articular cartilage covers the ends of bones in many joints.

Its smooth surface allows the bones to glide over one another with very little friction. Its water-rich extracellular matrix also enables it to withstand and distribute some of the mechanical forces applied to the joint.

In the knee, for example, cartilage covers certain surfaces of the femur, tibia and kneecap.

Unlike muscle, it cannot contract.

Unlike a ligament, it does not connect one bone to another.

And unlike a tendon, it does not directly transmit muscle force.

Its main function is to support smooth contact and movement between joint surfaces.

Can cartilage itself hurt?

There is an important detail here: articular cartilage has virtually no nerve supply.

Pain associated with an osteoarthritic joint therefore does not simply come from the cartilage “hurting”.

The underlying bone, synovial membrane, joint capsule and certain surrounding structures do have nerves and can contribute to symptoms.

This is also why an X-ray showing substantial cartilage thinning cannot, on its own, predict how painful a joint will be.

We explore this process in more detail in our article on what actually happens inside a joint affected by osteoarthritis.

The tendon: connecting muscle to bone

A tendon is a different type of tissue.

It extends from a muscle and transmits its force to a bone.

When the muscle contracts, that pull travels through the tendon to produce movement.

The Achilles tendon provides a clear example: it carries force from the calf muscles to the heel when we walk, run or rise onto our toes.

In the shoulder, several rotator cuff tendons help move and stabilise the arm.

Tendons are therefore closely linked to muscle function.

What is tendinopathy?

When a tendon becomes painful or tolerates certain loads less well, the condition is commonly called tendinopathy.

It may follow an overly rapid increase in activity, repetitive movements or particular workplace or sporting demands, but sometimes there is no obvious triggering event.

Pain is often brought on by movements that put the tendon under tension or require the associated muscle to exert force.

This is quite different from osteoarthritis, even though both can cause discomfort in much the same area.

For example, pain around the knee does not automatically mean the knee cartilage is responsible: several tendons may also be involved.

The ligament: the joint's stabilising support

Ligaments connect one bone to another.

Among their functions, they guide and stabilise joints by limiting excessive movement.

In the knee, the cruciate ligaments help control movement of the tibia relative to the femur.

At the ankle, several ligaments help keep the joint stable when the foot changes direction or encounters uneven ground.

When a joint is twisted suddenly, these structures may be stretched or injured.

That is what happens in many sprains.

Is a sprain a ligament injury?

Very often, yes.

A sprain involves ligament damage, which can range from a mild stretch to a more serious tear.

A swollen ankle following a sudden twist is therefore not the same as cartilage wear.

The underlying mechanism, the tissue affected and the appropriate care are different.

The distinction may seem obvious after an accident, but it is less clear when pain develops gradually without a specific injury.

That is where a basic understanding of anatomy becomes particularly useful.

And what about muscles?

Muscles provide the power for movement.

Their fibres can contract and generate force.

But they do much more than simply move our limbs.

Muscles also help control joints, absorb certain forces, maintain posture and stabilise the body as we move.

Around the knee, the quadriceps and the muscles at the back of the thigh help control the joint.

Around the hip, the gluteal muscles contribute to pelvic stability.

In other words, looking after your joints also means keeping the surrounding muscles active enough to support them.

Can a joint be healthy while the surrounding muscles are weak?

Absolutely.

Someone may struggle with stairs, standing up from a chair or maintaining a position simply because their muscle strength has declined.

This is especially common after a period of immobility or a gradual reduction in physical activity.

It can feel like a purely joint-related problem when part of the difficulty actually comes from reduced strength.

That is why muscle-strengthening exercises are an important part of many programmes designed to preserve mobility.

Our article on maintaining joint health as we age explains the connection between muscles, independence and movement in more detail.

What role do bones play in a joint?

Bones form the framework around which all these structures are arranged.

Their ends form part of the joints themselves and bear some of the mechanical loads.

But bone is also living tissue.

It is continually renewed and adapts, to some extent, to the loads placed upon it.

Calcium and vitamin D contribute to the maintenance of normal bones.

In osteoarthritis, the bone immediately beneath the cartilage can also change. This is known as subchondral bone.

A joint should therefore not be imagined as two isolated pieces of cartilage: bones, cartilage, the synovial membrane, ligaments, tendons and muscles interact constantly.

What is the difference between a tendon and a ligament?

This is probably the most common point of confusion.

The simplest distinction is this:

a tendon primarily connects a muscle to a bone; a ligament connects one bone to another.

The first transmits muscular force.

The second mainly helps stabilise and guide a joint.

Both are rich in connective tissue, particularly collagen, but their structure and function are not identical.

And what about the menisci?

The menisci are yet another type of structure.

The knee has two menisci situated between the femur and tibia.

They are made of fibrocartilage, which differs from the articular cartilage covering bone surfaces.

They help distribute loads and stabilise the knee.

Pain caused by a meniscal injury therefore does not have exactly the same underlying mechanism as an articular cartilage problem.

However, the two can coexist, particularly as we get older.

What is the link between cartilage and collagen?

Cartilage contains a complex matrix made up of water, proteoglycans and collagen, predominantly type II collagen in articular cartilage.

This network contributes to the tissue's mechanical properties.

But there is another misconception to avoid: collagen is not found only in cartilage.

It is also present in tendons, ligaments, bones, skin and many other tissues.

Not all types of collagen are exactly the same either.

Collagen type, its origin and the form used in a food supplement are three distinct considerations.

A dedicated article explores these distinctions, including hydrolysed collagen, collagen peptides and undenatured type II collagen.

Why is vitamin C associated with cartilage?

Vitamin C has an established role in normal collagen metabolism.

It contributes to normal collagen formation for the normal function of cartilage.

That is one reason it is commonly included in joint-nutrition formulas.

Of course, this does not mean that taking a high dose of vitamin C rebuilds a damaged joint.

Rather, it highlights a basic principle: our tissues need a range of nutrients to carry out their normal physiological functions.

And what about glucosamine and chondroitin?

These two substances have long been associated with joint nutrition.

Glucosamine is a molecule naturally present in the body and is involved in structures associated with joint tissues.

Chondroitin, meanwhile, is a component of cartilage's extracellular matrix.

That is why they are often found together in formulations intended for joint nutrition.

Their place becomes much easier to understand once we know what cartilage actually is and how it fits into the wider musculoskeletal system.

For more information, read our article on glucosamine and chondroitin: their roles, benefits and differences for joints. Read more

Why can pain near a joint be misleading?

Because several types of tissue are packed into a relatively small area.

The shoulder, for example, contains the joint itself as well as tendons, muscles and bursae.

Around the knee are cartilage, menisci, ligaments, tendons and other tissues surrounding the joint.

Someone may simply say, “My knee hurts.”

But the body does not provide a label identifying precisely which structure is responsible.

The location of pain, circumstances in which it began, movements that trigger it and a clinical examination can help guide diagnosis.

That is why joint pain is a symptom, not a diagnosis in itself.

How can you tell which structure is causing the pain?

Certain signs may provide clues, but sensations alone rarely allow a definitive answer.

Pain triggered by muscle contraction may point more towards its tendon.

Pain that starts immediately after a twisting injury may suggest ligament involvement.

Gradually developing mechanical discomfort, stiffness and reduced mobility may prompt investigation of the joint itself.

But these patterns can overlap.

It is best to use these distinctions to understand your body, rather than trying to diagnose yourself.

If pain persists, worsens or significantly limits movement, a healthcare professional can examine the affected area.

For a broader overview of the possible causes, see our guide to joint pain, its causes and everyday approaches. Read more

Can you really “strengthen a joint”?

The phrase is common, but it is not anatomically precise.

You cannot train cartilage or a ligament to grow in the same way as you build your quadriceps.

You can, however, strengthen the muscles surrounding a joint, improve coordination and maintain mobility.

That is usually what people mean when they talk about “strengthening their joints”.

A joint supported by functional muscles can be better controlled during movement.

This is why regular physical activity and strength training are so important for preserving mobility.

A joint works as a team

Cartilage, bones, muscles, tendons and ligaments each perform a different function.

Cartilage helps joint surfaces glide smoothly.

Muscles generate force.

Tendons transmit that force to bones.

Ligaments contribute to stability.

Bones provide the mechanical framework for the whole system.

None of these structures truly works in isolation.

This is also the best way to understand why caring for your mobility is about much more than cartilage alone.

Movement, muscle strength, a suitable diet and an interest in joint nutrition are different parts of the same picture.

To discover the approaches developed by Laboratoire Vital Santé around mobility and joint nutrition, explore our Joints guide. Read more

Sources

MSD Manuals — Joints: a useful reference for articular cartilage, synovial fluid, the joint capsule, menisci and how joints function. See MSD — Joints. Read more

MSD Manuals — Tendons and bursae: explains how tendons connect muscles to bones and distinguishes them from ligaments, which connect bones. See MSD — Tendons and bursae. Read more

French National Health Insurance (Assurance Maladie) — Knee ligament injuries: explains the stabilising role of ligaments, sprains and the fibrocartilaginous structure of menisci. Updated July 2026. See Ameli — Knee sprains and ligaments. Read more

Inserm — Osteoarthritis: background on the relationship between cartilage, the synovial membrane and subchondral bone. See Inserm — Osteoarthritis. Read more

EUR-Lex — EU regulation on health claims: the authorised wording states that vitamin C contributes to normal collagen formation for the normal function of cartilage. See Regulation (EU) No 432/2012. Read more