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Health condition · Clinically reviewed

Osteochondritis dissecans, a loose piece of bone and cartilage - and why staging matters.

A condition of the growing joint, most common in active children and teenagers. Getting the stability of the fragment right on MRI shapes the entire treatment plan.

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A radiographer guides a patient onto the bed of an advanced 3 Tesla MRI scanner in a London imaging suite

Why trust this guide

  • 01

    Clinically reviewed

    Written by our editorial team and reviewed by a registered UK clinician before publication.

  • 02

    Sourced from guidance

    Checked against BOA, BOAST and peer-reviewed orthopaedic sources you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK paediatric orthopaedic practice, including MRI staging and cartilage restoration options.

Key facts

Osteochondritis dissecans at a glance.

The essentials, in plain English - what it is, where it strikes, and how staging shapes treatment in the UK today.

  • What it is

    A disruption in the blood supply to a small area of subchondral bone, causing a fragment of bone and overlying cartilage to separate.

  • Who it affects

    Mostly children and adolescents active in sport, typically aged 10 to 15, though adult-onset cases occur.

  • Where it strikes

    Most commonly the knee (medial femoral condyle), also the elbow (capitellum) and the ankle (talar dome).

  • Key distinction

    OCD is the underlying disease process. An osteochondral defect is what happens once a fragment has separated or detached.

  • Key investigation

    MRI is essential - it grades lesion stability and cartilage integrity, and drives every treatment decision.

  • Good news

    Stable lesions in skeletally immature patients have strong healing potential with activity modification alone.

Why this guide matters

Staging the lesion changes everything.

Osteochondritis dissecans is common in active young people and usually treatable - but getting the stability assessment right is what determines the right path. The three points below shape everything else on this page.

  • MRI drives the decision

    Stability on MRI, not the X-ray appearance alone, determines whether conservative or surgical treatment is right.

  • Skeletal maturity matters

    Younger, skeletally immature patients with stable lesions have the best chance of healing without surgery.

  • Mechanical symptoms change the plan

    Locking, catching or instability signal a fragment that may need fixation or removal, not just rest.

How the diagnosis is made

From vague joint pain to a clear plan.

The steps a UK GP, paediatric orthopaedic surgeon or sports medicine specialist will normally follow, in order - so you know what to expect and why.

  1. 01

    Assessing

    History and activity review

    Vague, poorly localised joint pain that worsens with activity and eases with rest, often in a sporty child or teenager.

  2. 02

    Assessing

    Examination for effusion

    Looking for joint swelling, tenderness over the lesion site, and reduced range of movement.

  3. 03

    Assessing

    Mechanical symptom check

    Locking, catching or a sense of instability suggests the fragment may already be unstable or partially detached.

  4. 04

    Confirming

    Plain X-ray

    Weight-bearing and tunnel views may show the characteristic lesion, though early or small lesions are easily missed.

  5. 05

    Confirming

    MRI staging

    The key investigation - it assesses fragment stability and cartilage integrity, which is essential for planning treatment.

  6. 06

    Preparing

    Specialist referral

    Paediatric orthopaedic or sports medicine referral to confirm staging and agree a management plan.

  7. 07

    Preparing

    Baseline function assessment

    Documenting current activity level and symptoms so recovery and return to sport can be tracked over time.

Typical timeline: a first visit to a staged MRI plan within a few weeks.

Symptoms

What osteochondritis dissecans actually feels like.

Often vague at first, then more specific once the fragment becomes unstable. And the features that mean it’s time to escalate.

  • Vague, poorly localised pain

    Aching joint pain that is hard to pinpoint and typically worse with activity or sport.

  • Joint swelling

    Intermittent swelling around the affected joint, often noticed after activity.

  • Joint effusion

    A build-up of fluid within the joint capsule, sometimes visible and sometimes only felt on examination.

  • Locking

    The joint suddenly catches or jams mid-movement - a sign the fragment may be unstable.

  • Catching sensation

    A grinding or catching feeling during movement, suggesting cartilage surface irregularity.

  • Instability

    A feeling that the joint may give way, more common once a fragment has become detached.

  • Reduced range of movement

    Stiffness or difficulty fully bending or straightening the affected joint.

  • Red flag - sudden locking or giving way

    A joint that suddenly locks or gives way needs urgent orthopaedic assessment for a loose fragment.

Treatment

How osteochondritis dissecans is treated in the UK.

Activity modification and observation for stable lesions first, escalating to fixation, drilling or cartilage restoration when needed - staged by MDT.

  • Activity modification

    For stable lesions in skeletally immature patients - reducing impact sport allows the natural healing potential to work.

  • Observation with imaging review

    Serial X-ray or MRI to confirm healing progress in lesions being managed conservatively.

  • Non-weight-bearing or bracing

    A period of protected loading or immobilisation for some stable lesions to encourage healing.

  • Physiotherapy-guided rehabilitation

    Building strength and range of movement before a graded, physiotherapy-supervised return to sport.

  • Arthroscopic drilling

    Stimulates new blood supply and healing in stable lesions that have not responded to conservative treatment.

  • Fixation of unstable fragments

    Screws or pins secure a fragment that remains attached but unstable, preserving the patient’s own cartilage.

  • Microfracture

    For detached or unsalvageable fragments - small perforations in the bone stimulate fibrocartilage repair.

  • Osteochondral grafting

    Transfers healthy bone and cartilage to restore larger or unsalvageable defects, used for more extensive damage.

What this guide is based on

The sources behind every claim on this page.

UK national orthopaedic guidance and specialist society standards, current at the time of last review.

Key references

Guidelines and standards we relied on.

A quiet reminder

This guide is for information, not medical advice.

A paediatric orthopaedic surgeon or sports medicine specialist knows your child’s joint and imaging and can tell you which parts apply to them. If in doubt, get seen.

  • British Orthopaedic Association (BOA). Standards for paediatric musculoskeletal conditions.

  • BOAST - British Orthopaedic Association Standards for Trauma and Orthopaedics.

  • Royal College of Surgeons. Guidance on paediatric knee and joint conditions.

  • Peer-reviewed orthopaedic literature on osteochondritis dissecans staging and management.

Red flags

When it needs urgent attention.

Most osteochondritis dissecans is manageable with staged, specialist-led care. These are the situations that need faster escalation.

  • Sudden locking of the joint

    A joint that suddenly jams or cannot be straightened suggests a loose fragment and needs urgent orthopaedic review.

  • True giving way or instability

    A joint that repeatedly gives way, especially with swelling, points to an unstable or detached fragment.

  • Large joint effusion

    A tense, significant effusion after activity can signal an unstable lesion or loose body within the joint.

  • Persistent pain despite rest

    Pain that fails to settle with activity modification over several weeks warrants MRI and specialist review.

  • Skeletal maturity approaching

    Lesions in patients nearing skeletal maturity have lower spontaneous healing potential and need closer monitoring.

  • Bilateral or multiple joint involvement

    Symptoms in more than one joint should prompt a wider assessment for underlying skeletal conditions.

  • Failed conservative management

    No improvement after an adequate trial of activity modification is a clear indication for surgical opinion.

  • Visible loose body on imaging

    A clearly separated fragment on X-ray or MRI usually needs surgical fixation or removal.

Living with it

A treatable condition, with a staged plan.

Four things that make the biggest difference day to day - sensible activity levels, patience with healing, a proper rehab plan and prompt reporting of new symptoms.

A quiet reminder

Consistency beats rushing back, every time.

A steady, supervised return to sport protects the joint far better than getting back on the pitch a few weeks early.

  1. 01 Activity

    Modify, don’t stop entirely

    Low-impact activity often continues while high-impact sport is paused - your team will guide the balance.

  2. 02 Patience

    Healing takes months, not weeks

    Conservative treatment for stable lesions can take three to six months or longer to show healing on imaging.

  3. 03 Rehab

    Follow the physiotherapy plan

    A graded, supervised return to sport reduces the risk of re-injury or the lesion becoming unstable again.

  4. 04 Monitor

    Report new mechanical symptoms

    Any new locking, catching or instability should be flagged promptly rather than waiting for the next review.

Frequently asked

Everything we get asked about osteochondritis dissecans.

Quick answers on staging, surgery, and returning to sport.

  • What is osteochondritis dissecans?

    A joint condition, most common in children and teenagers active in sport, where a disruption to the blood supply causes a fragment of bone and its overlying cartilage to partially or fully separate from the surrounding bone. It most often affects the knee, but also occurs in the elbow and ankle.

  • Is osteochondritis dissecans the same as an osteochondral defect?

    No, though they are closely related. Osteochondritis dissecans is the underlying disease process. If the fragment progresses to separate or detach, the resulting gap in bone and cartilage is called an osteochondral defect.

  • What tests are used to diagnose it?

    An X-ray may show the characteristic lesion, but MRI is the key investigation. It assesses how stable the fragment is and how healthy the overlying cartilage remains, which is essential for planning treatment.

  • Will my child need surgery?

    Not necessarily. Stable lesions in skeletally immature patients often heal with activity modification and observation alone. Surgery is reserved for lesions that are unstable, detached, or fail to respond to conservative treatment.

  • What happens if the fragment becomes loose?

    An unstable or detached fragment can cause locking, catching or a feeling of instability in the joint. This usually needs surgical fixation if the fragment is salvageable, or removal with cartilage restoration if it is not.

  • When can my child return to sport?

    Return to sport is guided by physiotherapy and imaging, not by symptoms alone. A graded return, agreed with the specialist team, reduces the risk of the lesion becoming unstable again.

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