Cartilage repair surgery is an advanced orthopaedic procedure designed to restore damaged cartilage in joints, particularly the knee. Healthy cartilage allows bones to glide smoothly, absorbs shock during movement, and supports normal joint function. When cartilage becomes damaged due to injury, sports activities, or gradual wear, it has a limited ability to heal on its own because it has very little blood supply.

If left untreated, cartilage damage may lead to persistent pain, swelling, stiffness, reduced mobility, and, in some cases, early osteoarthritis. Modern cartilage restoration surgery offers several techniques that aim to repair or replace damaged cartilage while preserving the natural joint for as long as possible.

This guide explains how cartilage repair surgery works, who may benefit from it, the different surgical techniques available, what to expect during the procedure, and how recovery typically progresses.

What Is Cartilage Repair Surgery?

Cartilage repair surgery refers to a group of orthopaedic procedures used to treat damaged articular cartilage, the smooth tissue that covers the ends of bones within a joint. Because articular cartilage has a very limited blood supply, its ability to heal naturally after injury is limited.

The primary goals of cartilage repair surgery are to:

• Relieve joint pain
• Improve joint function and mobility
• Restore a smoother joint surface where possible
• Help patients return to daily activities or sports, when appropriate
• Preserve the natural joint and, in suitable patients, potentially delay the need for joint replacement surgery

Most cartilage repair procedures are performed on the knee, as it is the joint most commonly affected by focal cartilage injuries. However, similar articular cartilage repair techniques may also be used in selected cases involving the ankle, hip, shoulder, or elbow.

Understanding Knee Cartilage Damage

The knee is a commonly affected joint because it supports body weight during everyday activities such as walking, climbing stairs, running, and jumping. These repetitive forces make the knee more susceptible to cartilage injuries and degenerative changes over time.

Articular cartilage is a smooth, durable tissue that covers the ends of the bones within the knee joint. It allows the joint surfaces to move against each other with minimal friction while helping to distribute load and absorb shock during movement.

Cartilage damage can develop suddenly after an injury or gradually over time. Common causes include:

• Sports-related injuries
• Twisting or pivoting movements
• Falls or direct trauma to the knee
• Previous ligament injuries, such as an ACL tear
• Meniscus injuries
• Repetitive high-impact activities
• Joint instability or abnormal joint alignment
• Age-related wear and degeneration

Studies have shown that focal cartilage defects are frequently identified during knee arthroscopy, particularly in active adults and athletes. However, not every cartilage defect causes symptoms. Some are discovered incidentally, while larger or deeper lesions are more likely to cause persistent pain, swelling, stiffness, or reduced knee function. The need for treatment depends on factors such as the size and location of the defect, symptom severity, activity level, and the overall condition of the joint.

Who May Need Cartilage Repair Surgery?

Not every cartilage injury requires surgery. Many people experience improvement with conservative cartilage damage treatment, which may include physiotherapy, activity modification, weight management, pain-relieving or anti-inflammatory medications where appropriate, and, in selected cases, injectable treatments. The most suitable approach depends on the cause, location, and severity of the cartilage injury.

An orthopaedic surgeon may consider knee cartilage repair surgery when a patient has:

• Persistent knee pain that continues despite an appropriate course of non-surgical treatment
• A localised (focal) cartilage defect confirmed through clinical assessment and imaging, such as MRI
• Swelling that recurs with activity
• Mechanical symptoms, including catching or locking of the knee
• Reduced ability to participate in work, exercise, or sports because of knee symptoms
• Stable knee ligaments and satisfactory joint alignment, or conditions that can be corrected if necessary
• Healthy surrounding cartilage and sufficient bone quality to support a cartilage restoration procedure

In general, cartilage repair surgery is most commonly considered for people with isolated cartilage injuries rather than widespread joint degeneration. Younger and physically active individuals often achieve favourable outcomes, but age alone does not determine eligibility. Factors such as the size and location of the cartilage defect, overall knee health, activity level, medical history, and personal treatment goals all play an important role in deciding whether cartilage restoration surgery is an appropriate option.

Common Symptoms of Cartilage Damage

The symptoms of cartilage damage can vary depending on the size, depth, and location of the injury. Some people experience only mild discomfort, while others develop symptoms that interfere with everyday activities or sports. It’s also important to note that these symptoms are not unique to cartilage injuries and may occur with other knee conditions. A proper medical evaluation is needed to determine the underlying cause.

Common symptoms may include:

• Knee pain during or after physical activity
• Swelling, particularly following exercise or prolonged activity
• Joint stiffness, especially after periods of rest
• Reduced range of motion
• Clicking, catching, or grinding sensations during movement
• A feeling that the knee locks or gets stuck
• Pain when climbing stairs, squatting, or kneeling
• Difficulty with running, jumping, or other high-impact activities
• Reduced ability to participate in sports or physically demanding activities

If these symptoms persist, worsen over time, or develop after a knee injury, consult an orthopaedic specialist for a comprehensive assessment. Early diagnosis can help identify the cause and guide appropriate treatment.

How Is Cartilage Damage Diagnosed?

Accurately diagnosing cartilage damage is essential for selecting the most appropriate treatment, whether that involves non-surgical care or cartilage repair surgery. An orthopaedic specialist will typically combine your medical history, physical examination, and imaging findings to assess the extent of the injury.

1. Medical History

Your doctor will begin by discussing your symptoms and overall health. Understanding how the problem developed can provide important clues about the underlying cause.

Common questions include:

• When did your knee pain begin?
• Did your symptoms start after an injury or develop gradually?
• Which activities make the pain worse?
• Do you experience swelling, locking, or catching of the knee?
• Have you tried treatments such as physiotherapy, medications, or injections?

2. Physical Examination

A clinical examination helps assess how well the knee is functioning and whether other structures may also be affected.

Your orthopaedic surgeon may evaluate:

• Joint tenderness
• Swelling or fluid within the knee (effusion)
• Range of motion
• Knee stability
• Walking pattern (gait)
• Pain during specific movements or weight-bearing activities

3. MRI Scan

Magnetic Resonance Imaging (MRI) is the preferred imaging test for evaluating suspected cartilage injuries. It provides detailed images of cartilage, ligaments, menisci, tendons, and other soft tissues within the knee. MRI can help determine the size, depth, and location of a cartilage defect and identify associated injuries that may influence treatment planning.

4. X-rays

Although cartilage itself is not visible on standard X-rays, they remain an important part of the assessment. X-rays help evaluate:

• Joint alignment
• Bone abnormalities
• Joint space narrowing, which may suggest osteoarthritis
• Previous fractures or other bony injuries

These findings help determine whether cartilage restoration procedures are appropriate or whether other treatment options should be considered.

5. Arthroscopy

In some cases, knee arthroscopy may be recommended when imaging does not fully explain a patient’s symptoms or when surgical treatment is already planned. During this minimally invasive procedure, a small camera (arthroscope) is inserted through tiny incisions, allowing the surgeon to directly inspect the cartilage and other structures inside the knee. Arthroscopy can both confirm the diagnosis and, when appropriate, enable treatment during the same procedure.

Types of Cartilage Repair Surgery

There is no single cartilage repair procedure that is suitable for every patient. The most appropriate treatment depends on several factors, including the size, depth, and location of the cartilage defect, the patient’s age, activity level, symptoms, overall knee health, and the presence of other conditions such as ligament injuries or osteoarthritis. An orthopaedic surgeon will recommend the most appropriate option after a thorough clinical evaluation and imaging studies.

1. Microfracture Surgery

Microfracture is a minimally invasive arthroscopic technique that stimulates the body’s natural healing response. During the procedure, the surgeon creates small holes in the bone beneath the damaged cartilage. This allows bone marrow cells and growth factors to enter the defect, forming a blood clot that develops into repair tissue over time.

Microfracture is generally considered for:

• Small, well-defined cartilage defects
• Younger or physically active patients
• Individuals without advanced osteoarthritis

Advantages

• Performed arthroscopically through small incisions
• Single-stage procedure
• No donor tissue or laboratory cell expansion required

Limitations

The repair tissue that forms is primarily fibrocartilage, which differs from the knee’s original hyaline cartilage. Fibrocartilage may not be as durable under repetitive high-impact loading, particularly in larger defects or highly active individuals.

2. Osteochondral Autograft Transfer (OATS or Mosaicplasty)

Osteochondral Autograft Transfer System (OATS), also known as mosaicplasty, involves transferring healthy cartilage together with a small plug of underlying bone from a non-weight-bearing area of the patient’s knee to the damaged region.

Because the transplanted tissue contains native hyaline cartilage, this procedure can restore the joint surface with cartilage that closely resembles the original tissue.

OATS is generally considered for:

• Small to medium-sized focal cartilage defects
• Active individuals
• Patients with isolated cartilage injuries and healthy surrounding joint tissue

Advantages

• Replaces damaged cartilage with the patient’s own hyaline cartilage
• Single-stage procedure
• Suitable for selected focal cartilage injuries

Limitations

The amount of donor cartilage available is limited, making this technique less suitable for larger defects. Harvesting grafts may also result in discomfort at the donor site, although this is uncommon.

3. Autologous Chondrocyte Implantation (ACI)

Autologous Chondrocyte Implantation (ACI) is a cartilage restoration technique performed in two stages.

a) Stage One

Healthy cartilage cells are collected arthroscopically from a non-weight-bearing area of the joint.

b) Laboratory Phase

The collected cells are cultured and multiplied in a specialised laboratory over several weeks.

c) Stage Two

The expanded cartilage cells are implanted into the cartilage defect, where they are intended to support the formation of new cartilage-like tissue.

ACI is generally considered for:

• Larger focal cartilage defects
• Younger, active patients
• Individuals without advanced osteoarthritis or widespread cartilage loss

Compared with microfracture, ACI has the potential to produce repair tissue with characteristics that more closely resemble hyaline cartilage. However, outcomes depend on factors such as patient selection, rehabilitation, and the size and location of the defect.

4. Matrix-Induced Autologous Chondrocyte Implantation (MACI)

Matrix-Induced Autologous Chondrocyte Implantation (MACI) is a newer development of ACI. In this technique, cultured cartilage cells are seeded onto a biodegradable collagen membrane before being implanted into the damaged area.

The scaffold helps distribute the cells evenly and supports their integration into the defect.

Potential Advantages

• More uniform cell distribution
• Simplified implantation compared with traditional ACI
• Reduced surgical complexity in selected cases

Clinical studies have reported favourable mid- and long-term outcomes in appropriately selected patients. As with other cartilage restoration procedures, successful results depend on careful patient selection and adherence to a structured rehabilitation programme.

5. Osteochondral Allograft Transplantation

Osteochondral Allograft Transplantation uses cartilage and underlying bone obtained from a carefully screened donor to repair large or complex cartilage defects.

This technique is generally considered when:

• Cartilage defects are too large for autograft procedures
• Previous cartilage restoration surgery has not been successful
• There is associated bone loss beneath the cartilage defect

Because donor tissue is used, the procedure avoids harvesting cartilage from another area of the patient’s own knee, making it a useful option for selected patients with extensive cartilage damage.

How Is Cartilage Repair Surgery Performed?

The exact cartilage repair procedure depends on the size and location of the cartilage defect, the surgical technique selected, and the patient’s individual condition. Although each procedure differs, the overall treatment process follows similar stages.

1. Before Surgery

Before surgery, your orthopaedic surgeon performs a thorough assessment to determine the most appropriate treatment approach. This typically includes:

• A detailed medical history and physical examination
• MRI imaging to evaluate the cartilage defect and surrounding structures
• X-rays, if needed, to assess joint alignment and rule out underlying arthritis
• Blood tests or other preoperative investigations when clinically indicated
• An anaesthetic assessment
• A review of current medications and medical conditions

Your surgeon will also discuss the expected benefits, potential risks, recovery timeline, and the importance of postoperative rehabilitation before obtaining informed consent.

2. During Surgery

Most knee cartilage repair surgery procedures are performed under either regional or general anaesthesia, depending on the type of procedure, patient factors, and the anaesthetist’s recommendation.

Many cartilage restoration surgery techniques are performed arthroscopically using small incisions and a miniature camera (arthroscope). However, some procedures—such as Autologous Chondrocyte Implantation (ACI) or Matrix-Induced Autologous Chondrocyte Implantation (MACI)—may require a small open incision to accurately place the cartilage graft or scaffold.

While the exact steps vary, the procedure generally involves:

1. Creating small incisions around the knee.
2. Inserting an arthroscope to examine the joint.
3. Assessing the size, depth, and location of the cartilage damage.
4. Carefully removing damaged or unstable cartilage while preserving as much healthy cartilage as possible.
5. Performing the planned cartilage repair or restoration technique, such as microfracture, osteochondral grafting, or cartilage cell implantation.
6. Inspecting the repair before closing the incisions.

The procedure typically takes between one and three hours, although the duration varies depending on the surgical technique and whether additional procedures—such as ligament reconstruction or meniscal repair—are performed at the same time.

Benefits of Cartilage Repair Surgery

The primary goal of cartilage repair surgery is to reduce symptoms, improve joint function, and preserve the natural knee whenever possible. While outcomes vary depending on factors such as the patient’s age, activity level, the size and location of the cartilage defect, the surgical technique used, and commitment to rehabilitation, many appropriately selected patients experience meaningful improvements in pain, mobility, and knee function.

Potential benefits may include:

• Reduced knee pain during daily activities
• Improved joint function and range of motion
• Better knee stability, particularly when associated conditions such as ligament injuries are also addressed
• Improved ability to return to low-impact activities and, in some cases, sports after completing rehabilitation
• Preservation of the natural joint, which may help delay the need for knee replacement surgery in selected patients
• Improved quality of life by enhancing mobility and supporting everyday function

Clinical research suggests that Autologous Chondrocyte Implantation (ACI), Matrix-Induced Autologous Chondrocyte Implantation (MACI), and osteochondral grafting can provide favourable medium- to long-term outcomes for appropriately selected patients with focal cartilage defects. However, no cartilage restoration technique can fully recreate native hyaline cartilage in every case, and long-term results depend on factors such as the extent of cartilage damage, knee alignment, overall joint health, surgical technique, and adherence to a structured rehabilitation programme.

Cartilage Repair Recovery: What to Expect

Recovery after cartilage repair surgery varies from person to person. The timeline depends on several factors, including:

• The type of cartilage repair procedure performed
• The size and location of the cartilage defect
• Your age and overall health
• Whether other knee procedures, such as ACL reconstruction or meniscus repair, were performed at the same time
• Your commitment to the prescribed rehabilitation programme
• How well the repaired cartilage heals over time

Many patients notice gradual improvements in pain, mobility, and knee function within the first few months after surgery. However, cartilage healing is a slow biological process. Depending on the surgical technique used, it may take 6 to 12 months to return to many normal activities. For more complex cartilage restoration surgery procedures, such as Autologous Chondrocyte Implantation (ACI) or Matrix-Induced Autologous Chondrocyte Implantation (MACI), rehabilitation and recovery may continue for 12 to 18 months, particularly before returning to high-impact sports.

Your orthopaedic surgeon and physiotherapist will tailor your recovery plan based on your procedure, progress, and functional goals.

Cartilage Repair Recovery Timeline

The timeline below provides a general overview. Individual recovery plans may differ, so always follow your surgeon’s advice.

Patients undergoing cartilage transplant surgery or cartilage regeneration surgery often require a slower rehabilitation programme than those treated with microfracture alone.

Rehabilitation After Knee Cartilage Repair Surgery

Rehabilitation is a crucial part of knee cartilage surgery recovery and plays an important role in achieving the best possible outcome. While cartilage repair surgery addresses the damaged cartilage, a structured rehabilitation programme helps restore joint mobility, muscle strength, and functional movement while protecting the healing tissue.

Recovery plans are tailored to the individual and depend on factors such as the type of cartilage repair procedure performed, the size and location of the cartilage defect, and whether additional procedures (such as ACL reconstruction or meniscus repair) were carried out. Always follow the rehabilitation plan provided by your orthopaedic surgeon and physiotherapist.

1. Early Rehabilitation Phase

The initial focus is on protecting the repaired cartilage, managing pain and swelling, and gradually restoring knee movement without placing excessive stress on the healing joint.

Depending on the surgical technique used, patients may be advised to:

• Use crutches or other walking aids for a period recommended by their surgeon.
• Perform gentle range-of-motion exercises under the guidance of a physiotherapist.
• Manage swelling with ice therapy, elevation, and prescribed medications where appropriate.
• Avoid high-impact activities and excessive weight-bearing until cleared by the treating team.

2. Strengthening Phase

As healing progresses, physiotherapy typically introduces exercises to improve muscle strength around the knee. These commonly target the quadriceps, hamstrings, gluteal muscles, and calf muscles, which help support the joint and improve stability during daily activities.

Exercises are progressed gradually based on clinical assessment to avoid overloading the repaired cartilage.

3. Functional Training

In the later stages of rehabilitation, treatment focuses on improving balance, coordination, flexibility, and movement patterns. Depending on individual goals, patients may also begin low-impact aerobic exercise before progressing to higher-level functional activities.

Athletes or physically active individuals may complete sport-specific rehabilitation before returning to training or competition. The timing of return to sport varies and should be based on clinical assessment, functional testing, and approval from the treating surgeon or physiotherapist rather than a fixed timeline.

Success Rates of Cartilage Repair Surgery

The success of cartilage restoration surgery depends on several factors, including patient selection, surgical technique, and adherence to rehabilitation.

Research published in peer-reviewed orthopaedic journals indicates that many patients experience significant improvements in pain, knee function, and quality of life after cartilage restoration procedures. Long-term studies of techniques such as ACI and MACI have reported durable outcomes extending beyond 10 years in appropriately selected patients.

However, it is important to understand that:

• Results vary between individuals.
• Larger cartilage defects may require more complex procedures.
• Advanced osteoarthritis may reduce the likelihood of successful cartilage restoration.
• Rehabilitation is essential for achieving the best possible outcome.

An experienced orthopaedic surgeon can help determine which procedure is most suitable based on imaging findings, symptoms, activity level, and overall joint health.

Frequently Asked Questions

1. What is cartilage repair surgery?

Cartilage repair surgery is a group of procedures that restore damaged cartilage within a joint to improve function, reduce pain, and preserve the natural joint.

2. Who is a good candidate for knee cartilage repair surgery?

People with isolated cartilage defects, persistent knee pain, healthy surrounding joint structures, and limited arthritis may be suitable candidates. An orthopaedic surgeon will assess each case individually.

3. How long does cartilage repair recovery take?

Most patients require 6 to 12 months for recovery, although complete healing after some cartilage restoration procedures may take longer.

4. Is cartilage repair surgery painful?

Pain is expected after surgery but is usually managed with medication, ice therapy, and physiotherapy. Discomfort generally improves as healing progresses.

5. Can damaged cartilage heal without surgery?

Small injuries may improve with non-surgical cartilage damage treatment, including physiotherapy, activity modification, medications, and injections. Larger defects often have limited natural healing potential.

6. What is the difference between cartilage repair and cartilage replacement?

Cartilage repair stimulates or restores existing cartilage, while cartilage replacement uses grafts or transplanted tissue to replace damaged areas.

7. When can I walk after cartilage repair surgery?

Walking depends on the surgical technique used. Many patients require crutches for several weeks before gradually increasing weight-bearing under medical guidance.

8. Can I return to sports after cartilage restoration surgery?

Many patients return to recreational or competitive sports after completing rehabilitation, although the timing varies depending on the procedure and individual recovery.

9. Does cartilage repair surgery prevent arthritis?

While surgery may help preserve the joint and delay arthritis progression in suitable patients, it does not guarantee that arthritis will never develop.

10. How successful is cartilage transplant surgery?

Many patients experience improved function and reduced pain following cartilage transplant surgery, particularly when treatment is performed before advanced joint degeneration occurs.

Conclusion

Cartilage repair surgery has become an important treatment option for people with focal cartilage injuries who want to reduce pain, restore knee function, and preserve their natural joints. Advances in techniques such as microfracture, osteochondral grafting, ACI, MACI, and cartilage transplant surgery allow orthopaedic surgeons to tailor treatment according to the size and location of the cartilage defect, as well as the patient’s activity level and overall joint health.

Although recovery requires patience and a structured rehabilitation programme, many patients achieve meaningful improvements in mobility and quality of life. Early assessment is especially important, as timely treatment may help prevent further joint damage and expand the range of available treatment options.

If you have persistent knee pain, swelling, or reduced mobility that does not improve with conservative care, consult an experienced orthopaedic specialist. A thorough evaluation can help determine whether cartilage repair surgery or another treatment approach is the most appropriate option for your condition.