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Health condition · Clinically reviewed

Cartilage injury, focal defects, OCD and modern joint-preserving repair.

A twisted knee, a shoulder dislocation, a young athlete's aching elbow. Cartilage injuries range from small focal defects to full osteochondral fractures - and modern UK repair now saves joints that once headed straight to replacement.

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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 UK-registered orthopaedic surgeon before publication.

  • 02

    Sourced from guidance

    Checked against NICE, BOA and BASK/BASS peer-reviewed guidance you can see at the end.

  • 03

    Current for 2026

    Reflects modern UK cartilage-repair practice, including MACI, OATS, allograft and biologic scaffolds.

Key facts

Cartilage injury at a glance.

The essentials, in plain English - what it is, the types, how it is graded, and how modern UK cartilage repair is delivered.

  • What it is

    Damage to articular (joint-surface) cartilage or the underlying bone and cartilage together - focal, osteochondral or diffuse.

  • Types

    Focal chondral lesions, osteochondral defects (including OCD), diffuse osteoarthritis and specific patterns like patellofemoral chondromalacia.

  • Where it happens

    Knee, ankle (talar dome), shoulder, hip and elbow - each joint has its own patterns and treatments.

  • How it is graded

    Outerbridge I-IV or ICRS 0-4 - from softening (I) to full-thickness bone-exposed (IV).

  • Investigation

    MRI is the gold standard for cartilage - weight-bearing X-rays exclude advanced OA and CT and arthroscopy add detail.

  • Treatment goal

    Preserve the joint - repair or regenerate focal defects in the younger active patient and delay replacement.

Why this guide matters

The joint-preserving decade.

Cartilage medicine has changed. Not every painful joint needs replacement - and choosing the right operation early is what protects the next twenty years.

  • Cartilage does not repair itself

    It has no blood supply. A focal defect that hurts today will not heal tomorrow - intervention matters when symptoms are real.

  • Focal is not the same as osteoarthritis

    A traumatic hole in cartilage in a young active knee is not diffuse OA - and it deserves a joint-preserving conversation, not a replacement one.

  • Alignment is half the answer

    Repairing cartilage in a malaligned joint fails. A tibial or femoral osteotomy alongside repair often makes the difference.

How the diagnosis is made

From first twist to a clear repair plan.

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

  1. 01

    Assessing

    History and mechanism

    Twist, direct blow, dislocation or gradual onset - plus prior injury, meniscal surgery, alignment and activity level.

  2. 02

    Assessing

    Joint-specific examination

    Effusion, joint-line tenderness, mechanical signs (locking, catching, giving way), ligamentous stability and neurovascular check.

  3. 03

    Assessing

    Alignment assessment

    Long-leg standing X-rays for varus or valgus - malalignment overloads one compartment and drives further cartilage loss.

  4. 04

    Confirming

    Weight-bearing X-ray

    Screens for advanced osteoarthritis, loose osteochondral fragments, subchondral change and joint-space narrowing.

  5. 05

    Confirming

    MRI - the gold standard

    Maps cartilage integrity, subchondral bone oedema, cyst formation and concurrent meniscal or ligamentous injury.

  6. 06

    Confirming

    CT for selected bone detail

    Used when the bony component matters most - loose fragment sizing, tunnel planning or complex osteochondral defects.

  7. 07

    Mapping

    Arthroscopy with cartilage mapping

    Direct probing and photography of the defect - often the moment a definitive repair plan is confirmed.

Typical timeline: from first consultation to a definitive repair plan in weeks, not months.

Symptoms

What cartilage injury actually feels like.

The classic pattern is mechanical - focal pain, catching, swelling and giving way - and it usually traces back to a specific event, even if that event felt minor.

  • Focal pain over the joint line

    A specific spot that hurts with load - often reproducible on palpation and single-leg squat.

  • Locking and catching

    A loose osteochondral fragment or flap can catch inside the joint and give a jolting mechanical block.

  • Recurrent effusion

    A swollen joint after activity - a reliable sign of cartilage or synovial irritation.

  • Giving way

    A sense the joint gives out - especially with concurrent meniscal or ligament injury.

  • Post-traumatic onset

    A twist, direct blow, dislocation or fracture - and pain that never fully settled.

  • Insidious activity-related pain

    Slowly worsening pain on stairs, hills or sport - a common pattern in degenerative chondral loss.

  • Adolescent OCD pattern

    Vague joint ache in a young athlete - knee, elbow or talar dome are the classic sites for osteochondritis dissecans.

  • Red flag - locked joint

    A joint that will not fully straighten needs urgent orthopaedic review to protect the cartilage further.

Treatment

How cartilage injury is treated in the UK.

Conservative care first, then a ladder of joint-preserving surgery - microfracture, OATS, MACI, allograft, subchondroplasty and realignment osteotomy. Replacement is the last step, not the first.

  • Conservative first-line

    NSAIDs, activity modification, weight loss, physiotherapy, hydrotherapy, bracing or orthotics - the foundation for most cartilage problems.

  • Intra-articular injection

    Steroid, hyaluronic acid or PRP into the joint - useful for symptom control and for degenerative or small asymptomatic lesions.

  • Microfracture and drilling

    Bone-marrow stimulation for small defects under 2 cm² - grows fibrocartilage. An older technique with decreasing use in specialist centres.

  • MACI (matrix-induced ACI)

    Two-stage autologous chondrocyte implantation on a membrane - best for 2-8 cm² defects, delivered in specialist UK cartilage centres.

  • OATS and mosaicplasty

    Osteochondral autograft plugs from non-weight-bearing cartilage transferred into the defect - single-stage, ideal for small-to-medium lesions.

  • Osteochondral allograft

    A size-matched donor bone-and-cartilage graft for larger defects - preserves the joint when autograft is not enough.

  • Osteotomy realignment

    High tibial or distal femoral osteotomy to offload a damaged compartment - protects the repair and delays replacement.

  • Joint replacement

    Partial or total arthroplasty for end-stage disease - considered when joint-preserving options are no longer appropriate.

Where this happens

Specialist UK cartilage centres.

Complex cartilage repair belongs in high-volume MDTs. Recognised UK centres include the RNOH, the Christie, Nuffield Health hospitals, Cambridge, Sheffield, Oxford, Manchester, Norwich and Southampton. Care is shared with orthopaedic sports surgeons, specialist physiotherapists and rehabilitation teams.

What this guide is based on

The sources behind every claim on this page.

UK national guidance and international 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 GP, sports physician or orthopaedic surgeon knows your joint, your imaging and your goals - and can tell you which parts of this guide apply to you.

  • NICE. Autologous chondrocyte implantation for treating symptomatic articular cartilage defects of the knee (TA477).

  • British Orthopaedic Association (BOA) and BASK. Standards for cartilage repair surgery.

  • International Cartilage Regeneration and Joint Preservation Society (ICRS). Cartilage injury grading and evaluation.

  • ESSKA. Consensus on treatment of focal cartilage defects in the knee.

Red flags

When cartilage injury needs urgent attention.

Most cartilage problems are managed electively. These are the situations that need a same-week orthopaedic opinion or, in some cases, emergency care.

  • Locked joint

    A joint that cannot fully extend or flex - suggests a displaced osteochondral fragment. Needs urgent orthopaedic assessment.

  • Acute haemarthrosis after trauma

    A tense, bloody effusion within hours of injury - a marker of significant intra-articular damage, including osteochondral fracture.

  • Progressive pain after minor injury

    Symptoms that steadily worsen instead of settling in 6 weeks - consider chondral or osteochondral injury.

  • Adolescent knee or elbow pain

    A young athlete with persistent joint pain deserves an MRI to rule out osteochondritis dissecans before growth plates close.

  • Post-dislocation instability

    Patellar or shoulder dislocation often shears cartilage - persistent pain or effusion warrants imaging.

  • Suspected avascular necrosis

    Deep joint pain with risk factors (steroids, alcohol, sickle cell) - MRI is the test of choice. See our guide on avascular necrosis.

  • Rapidly progressive OA

    Sudden severe pain and joint-space collapse over months - specialist review to exclude subchondral insufficiency fracture.

  • Systemic inflammatory features

    Multiple joints, morning stiffness or systemic upset - consider inflammatory arthritis before labelling as mechanical.

  • Suspected infection

    Hot, red, painful joint with fever - a surgical emergency until septic arthritis is excluded.

Living with it

A patient condition, with a patient repair.

Cartilage repair is slower than most orthopaedic surgery - and that patience is what protects the result. Four habits that make the biggest day-to-day difference.

A quiet reminder

The rehab is the operation.

A brilliant repair with the wrong rehab fails. A modest repair with the right rehab keeps working - so protect the programme.

  1. 01 Rehab

    Protect the repair

    Non- or partial-weight-bearing for around 6 weeks after cartilage surgery, then a graded return over 6-9 months.

  2. 02 Load

    Manage weight and alignment

    Every kilogram off reduces joint load - and correcting malalignment early protects both native and repaired cartilage.

  3. 03 Motion

    Movement is the medicine

    Continuous passive motion, hydrotherapy and cycling keep cartilage nourished without impact.

  4. 04 Team

    A cartilage centre matters

    Complex repairs belong in high-volume UK cartilage MDTs - it is worth travelling for the right team.

Frequently asked

Everything we get asked about cartilage injury.

Quick answers on grading, MRI, MACI, OATS, allograft and return to sport.

  • What is a cartilage injury?

    Damage to the smooth articular cartilage lining a joint, or to the cartilage and its underlying bone together (an osteochondral injury). It can be a focal defect from trauma, a piece that loses its blood supply (osteochondritis dissecans), or the diffuse wear of osteoarthritis. Common sites are the knee, ankle (talar dome), shoulder, hip and elbow.

  • How is a cartilage injury graded?

    Two systems are used. Outerbridge grades the surface from I (softening) through II (fissuring under 1.5 cm) and III (fissuring over 1.5 cm) to IV (full-thickness with exposed bone). The ICRS system runs 0-4 with more detailed sub-grades. Both help the surgeon choose the right repair.

  • Why is MRI the main scan?

    MRI shows cartilage integrity, subchondral bone oedema, cysts, loose fragments and any concurrent meniscal or ligament injury - all in one study, without radiation. Weight-bearing X-rays add information on alignment and joint-space narrowing, and CT is used selectively for bony detail.

  • When is surgery needed?

    For a symptomatic focal chondral or osteochondral defect in a younger, active patient - especially when conservative care has failed. Options range from microfracture and OATS (small defects) to MACI and osteochondral allograft (larger defects), often combined with meniscal repair or osteotomy for alignment.

  • What is MACI and how does it work?

    MACI (matrix-induced autologous chondrocyte implantation) is a two-stage cartilage-regeneration operation. A small cartilage biopsy is taken, chondrocytes are grown in the laboratory on a membrane, and the membrane is implanted into the defect at a second operation. It is best for defects of 2-8 cm² and is delivered in specialist UK cartilage centres. See our guide on autologous chondrocyte implantation.

  • Can I return to sport after cartilage surgery?

    Usually yes, but slowly. Most patients are non- or partial-weight-bearing for around 6 weeks, then follow a structured rehabilitation programme with hydrotherapy and cycling before jogging and cutting sports. A return to competitive sport typically takes 6-9 months and depends on the joint, the procedure and how well alignment and stability were addressed.

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