Knee Cartilage Injury (Chondral & Osteochondral Defects) and Cartilage Repair in Bath & Bristol

A knee cartilage injury is damage to the smooth, low-friction surface that lines the joint (articular cartilage). Cartilage problems can range from a shallow surface scuff to a deep defect exposing bone, and they can cause pain, swelling, catching, and reduced confidence in the knee - especially with sport, stairs, squats, or prolonged walking.

Mr Simon Abram, Consultant Specialist Knee Surgeon, provides specialist assessment and cartilage injury treatment options in Bath and Bristol. The most appropriate approach depends on the type of cartilage injury, its size and location, and whether there are contributing issues such as malalignment, meniscus deficiency, or ligament instability.

What is knee cartilage?

Articular cartilage is the smooth “gristle” covering the ends of the bones where they meet to form the knee joint. It helps the knee glide smoothly and spreads load across the joint. It is different from the meniscus, which is the shock-absorbing cartilage pad between the femur and tibia.

Types of cartilage injury

Partial-thickness chondral injury

A partial-thickness chondral injury means the surface cartilage is damaged but does not go all the way down to bone. It may look like softening, fissuring, fraying, or a shallow crater. These injuries can be painful and mechanically irritating, but they have different surgical options compared with deeper defects.

Full-thickness chondral injury

A full-thickness chondral defect extends through the entire cartilage layer, often exposing the underlying bone. This type of defect is more likely to cause persistent symptoms and can be a target for cartilage restoration procedures.

Osteochondral injury

An osteochondral injury involves both the cartilage surface and the bone underneath (for example an osteochondral “plug” injury or an osteochondral lesion). These injuries may occur after trauma, twisting injuries, or kneecap instability, and they sometimes require procedures that restore both cartilage and bone.

Common causes of cartilage damage

Acute injury (twist, impact, sports injury, fall)
Recurrent kneecap instability or dislocation episodes
Meniscus injury or meniscus loss (reduces shock absorption and increases cartilage load)
Ligament instability (especially ACL-related giving way that repeatedly stresses the joint surface)
Malalignment (bow-leg or knock-knee overloads one compartment)
Wear and tear (early osteoarthritis changes and progressive cartilage thinning)

Symptoms of a cartilage injury

Cartilage injuries can present in different ways. Common symptoms include:

Activity-related knee pain (especially stairs, squats, running, jumping, or pivoting)
Recurrent swelling after activity
Catching, clicking, or a “rough” sensation
Brief locking or giving way (sometimes due to loose fragments)
Reduced confidence in the knee

When to seek urgent assessment

Seek urgent medical advice if you have:

A locked knee (cannot fully straighten)
Large swelling soon after injury
Inability to weight-bear
Suspected recurrent kneecap dislocation

Diagnosis and assessment (Bath & Bristol)

Successful cartilage treatment starts with a precise diagnosis and a plan that addresses the whole knee. Mr Simon Abram offers cartilage injury assessment in Bristol and Bath, focusing on the defect itself and the factors that may have caused or be worsening it.

Assessment usually includes:

History: injury mechanism, swelling pattern, mechanical symptoms, sport/work demands, previous surgery
Examination: tenderness, effusion (swelling), range of motion, kneecap tracking, ligament stability
Alignment evaluation: whether one side of the knee is being overloaded
X-rays: to assess joint space, bone changes, and alignment
MRI scan: often used to define cartilage defect size/location, assess bone involvement, and check meniscus/ligaments

In some cases, the full extent and stability of the cartilage injury is confirmed during arthroscopy (keyhole surgery), which can also allow treatment at the same time when appropriate.

Treatment approach: repair, regeneration, and reconstruction

Cartilage procedures are often described as a spectrum. The best option depends on the defect depth, size, location, bone involvement, and patient goals.

Cartilage repair (symptom smoothing and stabilisation)

Chondroplasty is the common 'first-line' repair procedure for suitable lesions. It is usually performed arthroscopically and involves carefully smoothing unstable or frayed cartilage, removing loose flaps, reducing mechanical irritation, and stimulating healing from the underlying bone. It can improve symptoms significantly, but it does not regrow normal hyaline cartilage.

Cartilage regeneration (restoring cartilage-like tissue)

Regenerative techniques aim to encourage the body to fill a defect. These may be considered for selected full-thickness defects. The exact options vary by knee pattern, defect size, and overall joint health. Your treatment plan is tailored to the defect and the wider knee environment (alignment, meniscus, stability).

Cartilage reconstruction (replacing the damaged surface)

Reconstructive procedures aim to replace damaged cartilage with new cartilage tissue or grafts, particularly for larger, deeper, or more complex defects.

Cartilage restoration options

1) Chondroplasty (arthroscopic cartilage stimulation)

Most commonly used for partial-thickness chondral injury or unstable cartilage flaps
Often combined with addressing contributing issues (for example, for cartilage damage combined with an ACL reconstruction)

2) OATS (Osteochondral Autograft Transfer System)

OATS moves one or more small plugs of healthy cartilage and bone from a non-weight-bearing area of your knee to the damaged area.

Best suited to focal full-thickness or osteochondral defects of appropriate size
Uses your own tissue (autograft)
Considerations include donor-site soreness in some patients

3) ACI (Autologous Chondrocyte Implantation) - considered the gold standard for larger focal defects

ACI is a cartilage restoration technique that uses your own cartilage cells (chondrocytes) to regenerate cartilage tissue within a prepared defect. It is considered a gold-standard option for suitable patients with larger focal cartilage defects where preserving the natural knee is the priority.

Commonly used for full-thickness chondral defects, particularly larger lesions
Requires a staged approach (cell harvest, culture in a laboratory, followed by implantation)
Works best when the “knee environment” is optimised (alignment, meniscus, stability)

4) OCA (Osteochondral Allograft)

OCA uses a transplanted donor graft that includes both cartilage and underlying bone. It can be particularly useful when there is significant bone involvement.

Often considered for osteochondral defects or larger defects where bone restoration is needed
Provides a single graft that restores both surfaces (cartilage) and structural support (bone)
Planning focuses on matching graft size/shape and ensuring the knee is well aligned and stable

Getting the best result: treating the whole knee

Cartilage restoration is most successful when the factors that caused overload are addressed. Depending on your knee, the plan may include:

Alignment correction (for example osteotomy) if one compartment is overloaded
Meniscus preservation or restoration where appropriate
Ligament stabilisation (such as ACL reconstruction) if instability is contributing to cartilage damage
Patellofemoral optimisation if the kneecap joint is involved

Mr Simon Abram will discuss which combination of procedures (if any) best protects the repair and reduces the risk of re-injury.

Recovery and rehabilitation

Rehabilitation is a key part of cartilage treatment. Recovery depends on the procedure performed and the size/location of the defect.

Typical recovery pattern (guide only)

Early phase: swelling control, restoring movement, protecting the repair
Strength and control phase: progressive strengthening of quadriceps, hamstrings, hips, and movement quality
Return-to-impact phase: gradual progression to running and sport-specific drills when safe

Procedures that involve cartilage reconstruction (such as OATS, ACI, or OCA) often require a more protective early phase and a structured return to impact. Your plan is individualised based on the repair technique, your knee mechanics, and your goals.

Risks and limitations

All surgery carries risks. Specific cartilage procedure risks vary with technique, but may include:

Infection, blood clots, stiffness, or prolonged swelling
Ongoing pain or incomplete symptom improvement
Failure of the repair or need for further surgery
Donor-site discomfort (more relevant to OATS)
Graft-related issues (more relevant to OCA)
Cartilage wear progression elsewhere in the knee over time

A personalised discussion in clinic will cover the expected benefits, alternatives, likely rehabilitation course, and the risks relevant to your knee.

Frequently asked questions

What is the difference between a cartilage injury and a meniscus tear?

Articular cartilage is the smooth lining on the bone ends. The meniscus is a separate shock-absorbing structure between the bones. Both can cause pain and swelling, and they can occur together.

Can knee cartilage heal on its own?

Cartilage has limited ability to heal because it has a poor blood supply. Some symptoms can improve with rehabilitation and load management, but deeper defects often need targeted treatment if they remain limiting.

Do I need an MRI for a cartilage injury?

MRI is necessary to map the size, depth, and location of a defect and to assess the bone, meniscus, and ligaments. It helps guide treatment options.

Is ACI always the best option?

ACI is often considered a gold-standard option for suitable larger focal full-thickness defects, but is only available and offered by surgeons working in the UK specialist cartilage treatment centres - such as Mr Simon Abram. The best choice depends on your defect characteristics and the condition of the rest of the knee. Some defects are better suited to chondroplasty, OATS, or OCA and treatment by a sub-specialist in this area is crucial.

How long does recovery take after cartilage repair surgery?

Recovery varies widely. Simple chondroplasty may recover faster, while procedures like OATS, ACI, or OCA typically require a longer, structured rehabilitation period before returning to impact activity.

Can I be assessed for cartilage injury treatment in Bath or Bristol?

Yes. Mr Simon Abram offers specialist assessment and treatment planning for knee cartilage injuries in Bath and Bristol, including advice on non-surgical options, arthroscopic procedures, and the full range of advanced, sub-specialist cartilage restoration strategies where appropriate.