Cartilage Repair

What Is Knee Cartilage and Why Does It Become Damaged?

The knee contains smooth articular cartilage that lines the ends of the femur, tibia, and the back of the patella. This cartilage allows low-friction movement and helps absorb load during walking, bending, and twisting.

Cartilage damage can happen in several ways:

• A traumatic injury, such as twisting or impact
• A lesion associated with ligament injuries
• Overload from alignment issues
• Repetitive stress from sport or heavy activity
• Early degenerative changes
• Previous surgery or joint disease

Unlike muscle or skin, cartilage has a limited blood supply, which means spontaneous healing is often incomplete. This is why symptoms may continue despite activity modification.

Symptoms of Cartilage Damage

Cartilage injuries can present differently from ligament or tendon issues. Symptoms may include:

• Localised joint pain during weight-bearing
• Swelling that worsens with activity
• A sensation of catching or grinding
• Reduced knee flexibility
• Stiffness after sitting or resting
• Discomfort when using stairs or hills
• A feeling of reduced shock absorption

Symptoms may fluctuate depending on load, and many people describe a pattern of good days and bad days.

How Cartilage Damage Is Diagnosed

Diagnosis involves understanding both the location and depth of the lesion.

Your clinician may use:

• Clinical examination to identify tender areas, swelling patterns, and motion limits
• X-rays to review joint alignment, bone surfaces, and early degenerative changes
• MRI to assess the cartilage surface, underlying bone, and any associated meniscal or ligament findings

Occasionally, cartilage damage is confirmed during knee arthroscopy when the surgeon directly visualises the joint surfaces.

When to See a Knee Specialist

You may benefit from seeing a knee specialist or orthopaedic knee surgeon in Sydney if you experience:

• Persistent swelling or discomfort during activity
• Mechanical symptoms such as clicking or catching
• Difficulty returning to sport or daily tasks
• Symptoms that have not improved with rest or physiotherapy
• Uncertainty about whether a cartilage procedure is appropriate

A detailed review helps determine whether non-surgical care or a cartilage repair technique may be suitable based on the size, location, and pattern of the lesion.

Non-Surgical Management

Many people begin with non-surgical treatment, which may reduce symptoms and improve knee function.

Management options can include:

• Physiotherapy to improve muscle support around the joint
• Strengthening of quadriceps, hamstrings, and hip stabilisers
• Activity modification to reduce overload
• Weight management if relevant
• Footwear or orthotic advice
• Anti-inflammatory measures if appropriate
• Knee hydrotherapy to maintain movement with less load

These approaches may help reduce stress on the damaged area and support better movement patterns.

When Cartilage Repair May Be Considered

Cartilage repair is typically considered when:

• A focal cartilage defect causes ongoing symptoms
• Non-surgical treatment has not improved function
• The lesion affects daily activity or sport
• The surrounding cartilage remains relatively healthy
• Imaging shows an isolated defect rather than widespread arthritis

Cartilage repair aims to improve joint surface quality, reduce mechanical symptoms, and support long-term knee health. Suitability depends on factors such as lesion size, depth, alignment, age, and activity level.

Dr Jonathan Negus may discuss whether a particular technique is appropriate based on your individual circumstances.

Cartilage Repair Techniques

Several surgical techniques may be used depending on the nature of the cartilage defect. Each has specific indications, benefits, and considerations.

1. Chondroplasty (Cartilage Smoothing)

This arthroscopic procedure gently smooths frayed cartilage edges to reduce catching or irritation. It is commonly used for smaller surface irregularities.

2. Microfracture

Small holes are made in the underlying bone to stimulate marrow cells that form a type of repair tissue. It may be suitable for certain small, well-contained defects.

3. Osteochondral Grafting (OATS or Mosaicplasty)

Healthy cartilage and bone are transferred from a non-weight-bearing area of the knee into the defect. This may be considered for medium-sized lesions in younger or active individuals.

4. Cartilage Cell Techniques (Including Matrix-Induced Repairs)

These procedures may involve using a biomaterial or cell-based approach to help restore the joint surface. Suitability varies depending on lesion characteristics and overall knee health.

5. Realignment Procedures (When Needed)

In some cases, correcting knee alignment may help reduce load on the damaged area and protect the repair. This is only considered when alignment contributes significantly to the problem.

A knee surgeon in Sydney will outline which option, if any, may be suitable and discuss the risks, benefits, and alternatives.

Recovery After Cartilage Repair

Recovery varies widely depending on the procedure performed and the size and location of the lesion.

A rehabilitation program may include:

• Managing swelling and protecting the repair site
• Gradually restoring movement
• Strengthening surrounding muscles
• Weight-bearing progression under specific guidance
• Gait retraining
• Low-impact conditioning, such as cycling or hydrotherapy
• A staged return to higher-demand activities

Some procedures require a period of limited weight-bearing to support early healing. Your physiotherapist and surgeon will outline milestones based on your specific surgery.

Long-Term Considerations

Cartilage repair does not recreate original cartilage, but it may improve symptoms and support knee function when carefully selected and combined with rehabilitation.

Ongoing strength training and load awareness may help protect the repair site over time.

Next Steps

If you have persistent knee symptoms or have been diagnosed with cartilage damage, an assessment can help determine whether a cartilage repair approach is suitable.

You can arrange a consultation with Dr Jonathan Negus, a knee specialist and orthopaedic knee surgeon in Sydney, to discuss your condition and treatment options.

This information is intended as a general guide and may not apply to every situation. Assessment and treatment recommendations vary depending on individual circumstances. Please speak with a qualified health professional for advice specific to your condition.