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Health condition · Clinically reviewed

Chondral injury, focal defects, modern cartilage repair and the road back to sport.

Cartilage does not heal on its own. A stepped plan from conservative care to biological repair, alignment surgery and structured rehab restores function for most patients.

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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 BASK, BOA, NICE and peer-reviewed cartilage-repair sources listed at the end.

  • 03

    Current for 2026

    Reflects modern UK practice including MACI, minced cartilage, subchondroplasty and cartilage rehab pathways.

Key facts

Chondral injury at a glance.

The essentials in plain English. What it is, where it happens, how it is graded, and how it is treated in the UK today. For the broader hub on cartilage damage across joints, see our related cartilage injury guide.

  • What it is

    A focal defect in the articular cartilage that lines a joint. The knee accounts for roughly 90 per cent of cases seen in specialist practice.

  • Where it happens

    Most commonly the medial and lateral femoral condyles, the patellofemoral joint, the talar dome (ankle), and less often the shoulder, hip, elbow or wrist.

  • Why it matters

    Cartilage does not heal on its own. Untreated focal defects can enlarge, alter joint mechanics and lead on to early osteoarthritis.

  • Classification

    Outerbridge I to IV and ICRS 0 to 4 grade the depth and size of the lesion and guide the treatment ladder.

  • MRI is gold standard

    Modern cartilage-sensitive MRI (T2 mapping, dGEMRIC) shows lesion size, depth and subchondral bone oedema before any surgery is planned.

  • Treatable

    A stepped plan from conservative care to biological cartilage repair and, where needed, realignment surgery restores function for most patients.

Why this guide matters

A stepped ladder, not a single operation.

Cartilage repair is one of the fastest-moving areas of orthopaedic surgery. The three points below shape everything on this page.

  • Cartilage does not heal itself

    Articular cartilage has no blood supply. Left alone, focal defects can enlarge and drive early osteoarthritis. Early, correct diagnosis matters.

  • The right operation for the right lesion

    Small defects, mid-sized biological repairs and larger allografts each have a place. Age, alignment and meniscal status guide the choice.

  • Rehab is half the operation

    Protected weight bearing, structured physio and a graded return to sport at six to nine months protect the repair.

How the diagnosis is made

From first twist to a clear cartilage plan.

The steps a UK sports orthopaedic surgeon will normally follow, in order, so you know what to expect and why.

  1. 01

    Assessing

    Clinical history and mechanism

    Was there a specific twist, dislocation or direct blow, or has the joint grumbled for months? Locking, catching and giving way point to a mechanical cartilage lesion.

  2. 02

    Assessing

    Joint examination

    Effusion, joint line tenderness, range of movement and joint-specific tests (McMurray, patellar grind, ankle impingement, hip FADIR) localise the problem.

  3. 03

    Assessing

    Weight-bearing X-ray

    Standing views of the affected joint look for joint space narrowing, loose osteochondral fragments and early osteoarthritis.

  4. 04

    Confirming

    Cartilage-sensitive MRI

    The gold standard investigation. T2 mapping and dGEMRIC sequences assess cartilage composition and subchondral bone marrow oedema.

  5. 05

    Confirming

    Long-leg alignment views

    For knee lesions a full-length standing X-ray checks for varus or valgus malalignment that would overload any repair.

  6. 06

    Planning

    Diagnostic arthroscopy

    Direct visualisation with a probe remains the reference standard for grading and mapping the lesion, and is often combined with a repair procedure.

  7. 07

    Planning

    MDT cartilage discussion

    Specialist cartilage centres discuss age, activity level, defect size, alignment and meniscal status to choose the right technique.

Typical timeline: a first specialist visit to a defined plan in weeks, not months.

Symptoms

What a chondral injury actually feels like.

The classic mix of mechanical symptoms, focal pain and swelling, and the features that mean it is time to escalate.

  • Mechanical locking

    A loose cartilage or osteochondral fragment can wedge in the joint and stop movement briefly.

  • Catching and clicking

    Painful catching on certain movements often reflects a chondral flap or unstable lesion.

  • Giving way

    The joint feels unreliable, especially on stairs, twisting or uneven ground.

  • Recurrent effusion

    A swollen joint that puffs up after activity is a common early sign of cartilage injury.

  • Focal, activity-related pain

    Pain sits over one part of the joint line and worsens with impact or deep flexion.

  • Post-injury stiffness

    Weeks or months after a twist or dislocation the joint stays sore and stiff rather than settling.

  • Silent lesions

    Some chondral defects are found incidentally on MRI. Whether to treat depends on symptoms, size and site.

  • Red flag - true locked joint

    A joint stuck in flexion with a hard block needs urgent orthopaedic review to exclude a displaced fragment.

Treatment

How chondral injury is treated in the UK.

Conservative care first. Biological cartilage repair for symptomatic focal defects in younger active patients. Alignment surgery and, at end stage, joint replacement.

  • Activity modification and physio

    Load management, quadriceps and hip strengthening, gait retraining and bracing form the base of every plan.

  • NSAIDs and weight optimisation

    Short-course anti-inflammatories and, where relevant, weight loss reduce joint load and pain.

  • Intra-articular injection

    Steroid, hyaluronic acid or PRP injections can settle symptoms and buy time before surgical decisions.

  • Microfracture and drilling

    Small (under 2 cm squared) defects. Creates a fibrocartilage repair. Use is declining in favour of biological techniques.

  • Autologous chondrocyte implantation

    ACI or MACI (matrix-induced). A two-stage biological repair best suited to lesions of 2 to 8 cm squared in younger active patients.

  • Osteochondral autograft (OATS)

    Mosaicplasty. Cylindrical plugs of bone and cartilage are transplanted from a low-load area to the defect.

  • Osteochondral allograft

    For larger defects or where previous surgery has failed. Donor bone and cartilage restores the joint surface.

  • Minced cartilage and scaffolds

    Newer options including Chondro-Gide, Cartistem, Novocart 3D and Agili-C use biological scaffolds to support cartilage regrowth.

  • Subchondroplasty

    Calcium phosphate injected under the defect treats painful subchondral bone marrow oedema alongside cartilage repair.

  • Realignment osteotomy

    High tibial (HTO) or distal femoral (DFO) osteotomy unloads a repaired compartment and is often done at the same sitting.

  • Meniscal preservation or transplant

    Repairing or, rarely, transplanting the meniscus protects any cartilage repair from repeat failure.

  • Partial or total joint replacement

    For end-stage joint damage where biological repair is no longer feasible.

See our related treatment guides on cartilage restoration and repair, autologous chondrocyte implantation (MACI), osteotomy realignment surgery and, at end stage, total knee replacement.

What this guide is based on

The sources behind every claim on this page.

UK national 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.

Your orthopaedic surgeon and physiotherapist know your joint, your imaging and your goals. They can tell you which parts apply to you.

  • British Association for Surgery of the Knee (BASK). Cartilage repair consensus statements.

  • British Orthopaedic Association (BOA). Standards for cartilage restoration and knee surgery.

  • International Cartilage Regeneration and Joint Preservation Society (ICRS). Classification and treatment recommendations.

  • NICE. Interventional procedures guidance on autologous chondrocyte implantation (TA477) and matrix-induced cartilage repair.

  • European Society for Sports Traumatology, Knee Surgery and Arthroscopy (ESSKA). Cartilage and osteotomy consensus.

Red flags

When a chondral injury needs urgent attention.

Most chondral injuries can be worked up in the clinic. These are the situations where a specialist opinion is needed now.

  • True locked joint

    A knee or ankle stuck in flexion with a hard mechanical block needs urgent orthopaedic review to exclude a displaced osteochondral fragment.

  • Acute large effusion after trauma

    A tense, painful swollen joint within hours of injury can mean a haemarthrosis from a significant osteochondral fracture.

  • Osteochondritis dissecans in a child

    Bone and cartilage fragment separation in children or adolescents (knee, elbow, talus) needs early paediatric orthopaedic input.

  • Loose body symptoms

    Recurrent locking, catching or a palpable moving lump inside the joint suggests a loose fragment that needs removal or fixation.

  • Rapidly progressive pain and swelling

    Escalating rest pain, night pain or systemic symptoms need urgent review to exclude infection, avascular necrosis or tumour.

  • Failed prior cartilage surgery

    Ongoing symptoms after microfracture, ACI or osteotomy warrant referral to a specialist cartilage centre for revision options.

  • Sudden inability to weight bear

    A joint that will no longer take weight after a twisting injury needs prompt imaging and orthopaedic assessment.

  • Fixed deformity

    A new varus or valgus deformity in a symptomatic joint changes surgical planning and should be flagged early.

  • Suspected infection

    Hot, red, systemically unwell joint after any injection or surgery is a septic joint until proven otherwise.

Living with it

A treatable injury, with a clear rehab ladder.

Four things that make the biggest difference after cartilage surgery. Respect the timeline, do the rehab, fix the mechanics, and think in years not weeks.

A quiet reminder

Cartilage rewards patience.

A repair that is loaded too soon can fail. Weeks of protected rehab now protect the joint for years.

  1. 01 Load

    Respect the healing timeline

    Cartilage repairs are slow. Expect protected weight bearing for around six weeks and a graded return to sport at six to nine months.

  2. 02 Rehab

    Specialist cartilage rehab

    Structured physio, continuous passive motion where indicated and progressive loading are as important as the surgery itself.

  3. 03 Alignment

    Fix the underlying mechanics

    A repair placed into a malaligned joint will fail. Address alignment, meniscal loss and instability at the same time.

  4. 04 Longevity

    Play the long game

    The aim is to delay or prevent osteoarthritis. Weight, strength and activity choices over years matter as much as the operation itself.

Frequently asked

Everything we get asked about chondral injury.

Quick answers on grading, imaging, cartilage repair techniques and rehab.

  • What is a chondral injury?

    A chondral injury is a focal defect in the articular cartilage that lines a joint. It can be caused by a specific twist, blow or dislocation, or develop over time from malalignment, meniscal loss or previous injury. The knee is by far the most common site.

  • How is a chondral injury different from arthritis?

    Osteoarthritis is diffuse wear across the whole joint surface. A chondral injury is a focal, well-defined defect that can often be repaired biologically. Untreated chondral defects can, over time, contribute to osteoarthritis. See our related guide on cartilage injury for the broader picture.

  • What is the Outerbridge classification?

    Outerbridge grades chondral damage from I to IV. Grade I is softening of the cartilage. Grade II is fissuring under 1.5 cm. Grade III is fissuring over 1.5 cm reaching the subchondral bone. Grade IV is full-thickness cartilage loss with exposed bone. The ICRS 0 to 4 system is used similarly in specialist practice.

  • What is osteochondritis dissecans (OCD)?

    OCD is a separate but related condition where a fragment of bone and its overlying cartilage separates from the joint surface. It classically affects children and adolescents in the knee, elbow or talus and needs early specialist assessment because the fragment can loosen and become a loose body.

  • Do I always need surgery?

    No. Many chondral injuries settle with conservative care - activity modification, physiotherapy, weight optimisation and, where appropriate, intra-articular injection. Surgery is considered for symptomatic focal defects in younger, active patients, or for loose bodies, mechanical locking and failed conservative care.

  • Which cartilage repair technique is right for me?

    It depends on the size and site of the defect, your age and activity level, joint alignment and meniscal status. Small defects may suit minced cartilage or microfracture. Mid-sized defects of 2 to 8 cm squared often suit MACI. Larger defects may need osteochondral allograft, with realignment osteotomy if the joint is unbalanced. A specialist cartilage MDT will guide the choice.

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