Knee Cartilage Damage: Why It May Not Hurt at First
Knee cartilage damage does not always cause immediate or severe pain. You might notice an occasional ache, stiffness after sitting or discomfort during certain activities without realising that the smooth surface inside your knee has been affected.
This can make cartilage problems surprisingly difficult to recognise. In some cases, cartilage repair may be considered when damage is limited to a particular area and the rest of the joint remains relatively healthy. However, suitability depends on several factors, so early assessment can help you understand what is happening and what your options may be.
The Two Types of Cartilage in Your Knee
The word ‘cartilage’ can be confusing because the knee contains two different types.
The menisci are two tough, rubbery pads positioned between the thigh bone and shin bone. They help distribute weight, absorb shock and support the stability of the knee. A meniscus can tear suddenly during sport or become damaged gradually over time.
Articular cartilage is different. It is the smooth, slippery tissue covering the ends of the bones where they meet inside the joint. This surface allows the bones to move against each other with very little friction.
A meniscus tear and damage to the articular cartilage are therefore separate problems. They can cause different symptoms and may require different treatments. If a scan or medical report mentions cartilage damage, it is worth asking which type of cartilage is affected.
Why Cartilage Damage May Not Hurt Straight Away
Articular cartilage has no nerve endings of its own, so damage to the tissue does not directly produce pain in the same way as an injury to your skin or muscles. It also has no direct blood supply, which greatly limits its ability to heal itself.
Pain may instead come from other structures in and around the knee, including the bone beneath the cartilage, the joint lining, ligaments or surrounding tissues. Swelling and inflammation can also contribute to discomfort.
This helps explain why the amount of pain someone experiences does not always reflect the extent of the cartilage damage. A relatively small defect can sometimes be troublesome, while more widespread changes may initially cause only mild or intermittent symptoms.
Possible signs include:
- Swelling after activity
- Stiffness, particularly after sitting or resting
- Pain when climbing stairs, squatting or kneeling
- Catching, clicking or a feeling that the knee is locking
- Reduced movement
- A feeling that the knee is unstable or unreliable
These symptoms can have several causes, so they do not automatically mean that you have damaged articular cartilage. Persistent or worsening symptoms should be assessed by an appropriate healthcare professional.
Is It a Localised Defect or General Wear?
One helpful way to understand cartilage damage is to compare it with the surface of a road.
A localised cartilage defect is a little like a pothole. There is a defined area of damage surrounded by healthier cartilage. This type of injury may occur after twisting the knee, playing sport or sustaining a direct impact.
More widespread cartilage loss is closer to a road surface that has gradually worn thin. Rather than there being one clearly defined area to treat, the changes affect a broader section of the joint. This is more commonly associated with osteoarthritis.
The distinction is important because cartilage restoration procedures are generally intended for selected, localised defects rather than widespread arthritis. Treatment decisions are not based on age alone. The location and size of the damage, condition of the surrounding cartilage and bone, alignment of the leg, stability of the knee and general health of the joint all matter.
What Can Make a Cartilage Defect Suitable for Repair?
Not every cartilage defect can or needs to be repaired surgically. When a specialist considers the available options, they may look at whether:
- The damage is limited to a clearly defined area
- The surrounding cartilage remains healthy
- The bone underneath the cartilage is in suitable condition
- The opposing surface of the joint is relatively healthy
- The knee ligaments are stable
- The leg is correctly aligned
- Other causes of pain have been identified
- The patient can commit to a lengthy rehabilitation programme
The cause, depth and size of the defect are also important. Symptoms, activity levels, previous treatments and personal goals all contribute to the decision.
An X-ray can reveal changes to the joint space and bone, but cartilage itself is usually assessed more clearly using an MRI scan. In some circumstances, arthroscopy may provide additional information.
What Does Cartilage Repair Involve?
There is no single operation used for every cartilage injury. Techniques vary depending on the size, depth and position of the defect.
Bone marrow stimulation procedures, such as microfracture or drilling, create small openings in the bone beneath the damaged area. This encourages a healing response and the formation of fibrocartilage. Fibrocartilage can fill the defect, although it is not identical to the original articular cartilage.
Other procedures transplant plugs of healthy cartilage and underlying bone from a less weight-bearing part of the joint. For some larger defects, cartilage cells may be collected, grown in a laboratory and implanted into the damaged area during a later procedure.
These treatments are designed for carefully selected patients. They are not guaranteed to restore the knee to its original condition, and recovery can take many months.
Injections Can Ease Symptoms but Do Not Replace Missing Cartilage
Injections are sometimes discussed alongside cartilage treatments, but they do not serve the same purpose.
Steroid, hyaluronic acid or platelet-rich plasma injections may be offered in certain circumstances to manage pain or inflammation. The evidence and recommendations surrounding these treatments vary depending on the injection and the condition being treated.
An improvement in pain does not necessarily mean that a cartilage defect has healed. Injections should therefore be viewed as symptom-management treatments rather than a way to replace a missing section of articular cartilage.
If you are considering an injection, ask what it is intended to achieve, how strong the supporting evidence is and whether it could affect the timing of any other treatment.
Why the Alignment of Your Leg Matters
The alignment of the leg affects how pressure is distributed through the knee. If the leg bows inwards or outwards, one side of the joint may carry more weight than the other.
Treating a cartilage defect without addressing significant overloading could place additional strain on the repaired area. In some carefully selected cases, an osteotomy may be used to alter the alignment of the leg and redistribute weight towards a healthier part of the knee.
This type of surgery is not necessary for everyone. However, it demonstrates why a proper assessment should consider the whole knee rather than focusing only on the visible cartilage defect.
When Should You Have Knee Pain Assessed?
An occasional mild ache after an unusually active day may settle with rest. However, it is sensible to seek medical advice if your knee pain persists, repeatedly swells, affects everyday activities or follows an injury.
You should seek more urgent advice if you cannot put weight on the leg, the knee is badly swollen or deformed, it locks in position, or it becomes hot and red alongside a high temperature.
Cartilage damage can be easy to overlook because the tissue itself cannot directly signal that something is wrong. That does not mean every slightly uncomfortable knee needs surgery, but recurring symptoms are worth investigating.
Finding out whether the problem involves the meniscus or articular cartilage, and whether the damage is localised or widespread, can make the situation much clearer. Those answers will help determine whether the knee simply needs monitoring and rehabilitation or whether further treatment should be considered.
This is a collaborative post.
