Osteochondritis Dissecans (OCD) of the Knee

What is OCD of the knee?

Osteochondritis dissecans — OCD — is a condition where a small area of bone just beneath the cartilage surface loses its blood supply. The bone weakens, and the overlying cartilage and bone can soften, fragment or, in more advanced cases, separate from the underlying bone.

It's most often seen in active children and adolescents, more commonly in boys, and usually affects the inner part of the knee joint. The exact cause isn't always clear, but repetitive stress, growth-related changes and individual variation in blood supply are all thought to contribute.

The behaviour of OCD lesions varies considerably. Some heal completely, particularly in younger children with stable lesions. Others progress and may need surgical intervention.

What does it feel like?

Symptoms vary depending on the stage and stability of the lesion. Common features include:

• Aching pain in the knee, often vague and intermittent

• Pain that's worse with activity

• Swelling, particularly after sport

• Catching, locking or giving way in more advanced cases

• A sense that the knee isn't quite right but you can't pinpoint why

Earlier-stage OCD can be quite subtle. More advanced cases, particularly those with a loose fragment, produce more dramatic symptoms.

How is it diagnosed?

X-rays often show OCD lesions and are usually the first imaging arranged. MRI is essential for staging — assessing the size, depth and stability of the lesion.

The age of the child, the appearance of the lesion and how it's behaving over time all guide the management. Repeat imaging is sometimes part of the picture, particularly when watching for healing or progression.

Examination contributes by identifying tenderness, mechanical symptoms and the broader knee picture.

What are the treatment options?

Stable lesions in younger children often heal with activity modification, time and structured monitoring. Unstable lesions, larger lesions, or those in older children with closing growth plates often need surgical intervention — drilling, fixation of the fragment, or in some cases more involved cartilage procedures.

The right approach depends on the specifics — age, size and stability of the lesion, and the broader context. Nev will work through this with you and your child at your consultation, so any plan reflects what's right for the individual situation.

When should you get it checked?

Seek a specialist assessment if:

• Your child has persistent knee pain that isn't settling

• There's intermittent swelling, catching or locking

• An MRI or X-ray has shown a possible OCD lesion

• Pain is interfering with sport or activity

• You want a clear picture and a structured plan going forward

OCD is one of those conditions where outcomes are strongly influenced by the right early management. A clear assessment from someone experienced with the condition makes a real difference.