Reviewed by Dr Vishal Pai
Cartilage repair surgery treats a damaged area of the smooth lining on the ends of the bones in your knee (articular cartilage). It is one option among several, and many people improve without surgery. This page explains when cartilage repair is considered, the main procedures, recovery, results and risks.
At a Glance
- Small areas of cartilage damage often settle with physiotherapy, strength training and changes to activity. Surgery is considered when symptoms persist.
- The right procedure depends on the size and site of the damage, your age and activity, the alignment of your leg and the health of the meniscus.
- Options range from trimming loose cartilage to scaffold repairs, cell-based repairs and grafts of bone and cartilage.
- Recovery is slow. Most procedures need a period of limited weight bearing and several months of rehabilitation.
- No repair makes the joint surface normal again. The aim is a comfortable knee that works well for the things that matter to you.
What is cartilage repair surgery?
Articular cartilage is the smooth surface that covers the ends of the bones within the knee joint. It allows the knee to move freely and absorb load during daily activities.
Damage to this surface can occur following injury or gradually over time. Unlike other tissues, cartilage has a limited ability to heal, and untreated defects can lead to ongoing symptoms or progression of joint wear. [1] Cartilage repair surgery treats the damaged area, with the aim of easing your symptoms and protecting the knee.
Who might need cartilage repair surgery?
Not all cartilage injuries require surgery. Many people can be managed with non-surgical treatment, including physiotherapy and activity modification. Injections may give short-term relief. Surgery is considered when symptoms persist despite these measures.
Long-term research suggests that people who have no cartilage surgery can do as well as those who have microfracture or osteochondral grafting. Only chondrocyte implantation has been linked with better long-term results. [2]
The decision to proceed with cartilage repair depends on:
- The size and location of the damaged area
- The condition of the surrounding cartilage
- The alignment of your leg and whether the meniscus is intact
- Your symptoms and how much they limit you
- Your activity goals and expectations
Read more about articular cartilage injury.
What is involved in cartilage repair surgery?
Numerous surgical techniques are available to treat cartilage injuries. The choice of procedure depends on the characteristics of the damaged area and on your individual circumstances.
1. Debridement
Trimming any loose flaps around the damaged area so that the rim is stable.
2. Microfracture
Trimming the edges of the cartilage injury so that there is a stable rim, then making multiple evenly spaced holes in the bone beneath the cartilage. This allows bone marrow and blood to enter the defect, forming a clot that can develop into repair tissue. The type of cartilage produced is called fibrocartilage and differs from the type normally found within the knee joint (hyaline). [3] This helps to protect the exposed bone. Dr Vishal Pai does not perform microfracture on its own.
3. Autologous matrix-induced chondrogenesis (AMIC)
This is a microfracture procedure performed at the area of cartilage injury. A collagen scaffold is cut to size and placed over the damaged area. This is held with fibrin glue. The scaffold aims to support the formation of repair tissue. In a trial, the benefit after AMIC lasted longer than after microfracture alone. [4]
4. Cartilage cell procedures
There are two cartilage cell procedures available: AutoCart and MACI.
AutoCart (minced cartilage implantation) is a single-stage cartilage repair procedure. The damaged area is prepared, and small fragments of your own cartilage are combined with platelet-rich plasma derived from your blood. This mixture is reimplanted into the defect, where it aims to form a new cartilage layer. A biological covering is applied to protect and support the repair. Short- to medium-term results of minced cartilage implantation are similar to those of microfracture and chondrocyte implantation, but long-term results are not yet known. [5]
Two procedures are involved with matrix-induced autologous chondrocyte implantation (MACI). In the first procedure, a sample of normal cartilage is taken from the knee and sent to a laboratory. The laboratory cultures the cartilage cells and multiplies them. Approximately 6–8 weeks later, the cartilage cells are reimplanted in the area of cartilage injury with a collagen scaffold. The aim is the formation of hyaline-like cartilage. [6] In Australia, the MACI procedure is not rebatable under Medicare. Please contact the rooms for an estimate of the total cost, including hospital and anaesthetist fees.
5. Osteochondral autograft transfer
This involves harvesting a cylindrical block of bone with overlying cartilage from a non-weight-bearing part of the knee. The damaged area is then prepared to accept the graft, which is press-fit into place. This is all performed in a single operation. [7]
6. Osteochondral allograft
Donor tissue from a deceased person is used. A cylindrical block of bone with accompanying cartilage is taken from the donor and matched to the size of the defect. The damaged area is then prepared to accept the donor block, which is press-fit into place. Over time, your bone grows into the donor graft and incorporates it. [8]
How long does it take to recover from cartilage repair surgery?
Rehabilitation after most cartilage procedures is prolonged and restrictive, with a period of limited weight bearing. Your programme depends on the procedure and where the damage is, and there is no single standard programme. [9] [10] Following the weight-bearing and loading programme is a large part of the result. As a rough guide:
- Day of surgeryYou will usually go home on the day of surgery.
- 2 weeksYour wound is checked at your first follow-up appointment.
- 1 to 2 weeksAfter a debridement alone, people with an office-based job can often return to work at this stage.
- 6 to 12 weeksAfter a repair on the main weight-bearing surface, most people can put their full weight on the leg at some point in this period. After a repair behind the kneecap, full weight is often allowed sooner.
- 5 to 12 monthsReturn to sport is usually possible in this period. It tends to be quickest after an osteochondral autograft and slowest after a cell-based repair.
These times are a guide from published studies. [9] [10] [11] Dr Vishal Pai will give you a programme for your own procedure.
What results can you expect?
Success depends on the technique used, the size and location of the damaged area, and the condition of the rest of the knee. Published series report improvement in pain and function in well-selected people, though results vary between techniques and no cartilage repair restores the joint surface to normal.
About 3 in 4 people return to sport after cartilage repair surgery. More people return after an osteochondral autograft, and fewer after microfracture. [11]
Microfracture often helps for the first few years, but the benefit tends to fade. For medium to large areas of damage, close to half of people show worsening arthritis on X-ray 10 or more years later. [12]
For larger areas of damage, MACI gave better pain and function than microfracture in a trial, although not every study agrees. [6] [13] Over the long term, a small number of people need further surgery or a knee replacement after MACI. [14]
Most osteochondral allografts are still working 10 years after surgery. [8] These figures are averages from published studies, not one surgeon’s results.
The realistic aim is a knee that is comfortable and works well for the activities that matter, not a knee that is biologically new.
What are the risks and complications?
Every operation carries risks, and Dr Vishal Pai goes through them with you before you decide. The risks that apply to you depend on the procedure, the size and site of the damage and your general health. The main risks of cartilage repair surgery are:
- Infection, bleeding and blood clots, the general risks of any knee operation.
- Stiffness of the knee, or numbness near the small cuts.
- The repair not taking, or wearing out over time. Further surgery is sometimes needed; for example, about 3 in 10 people have another operation after an osteochondral allograft. [8]
- Symptoms where a graft is taken from within the knee, in about 6 in 100 people after an osteochondral autograft. [15]
- Two operations and two recoveries for two-stage procedures such as MACI.
- Arthritis getting worse in the knee over time, even after a repair. [12]
Rarely, a blood clot travels to the lungs (pulmonary embolism), or a heart attack or stroke happens around the time of surgery.
Where does Dr Vishal Pai consult and operate?
Dr Vishal Pai consults at Sandringham Orthopaedic Specialists, Suite 1, 60 Bay Road, Sandringham. He performs cartilage repair surgery at Calvary Holmesglen Private Hospital, 490 South Road, Moorabbin, and The Avenue Hospital, 40 The Avenue, Windsor. Patients come from across Bayside, Glen Eira and the Mornington Peninsula, and some travel from regional Victoria.
References
Show all 15 referencesHide references
- Houck DA et al. 2018. Do focal chondral defects of the knee increase the risk for progression to osteoarthritis? A review of the literature. Orthopaedic Journal of Sports Medicine.
- Birkenes T et al. 2024. Long-term outcomes of arthroscopically verified focal cartilage lesions in the knee. The Journal of Bone and Joint Surgery (American Volume).
- Orth P et al. 2019. Microfracture for cartilage repair in the knee: a systematic review of the contemporary literature. Knee Surgery, Sports Traumatology, Arthroscopy.
- Volz M et al. 2017. A randomized controlled trial demonstrating sustained benefit of autologous matrix-induced chondrogenesis over microfracture at five years. International Orthopaedics.
- Caplan BE et al. 2026. Short- to midterm clinical outcomes after autologous minced cartilage implantation for focal chondral defects of the knee are comparable to microfracture and autologous chondrocyte implantation: a systematic review. Arthroscopy.
- Brittberg M et al. 2018. Matrix-applied characterized autologous cultured chondrocytes versus microfracture: five-year follow-up of a prospective randomized trial. The American Journal of Sports Medicine.
- Hangody L et al. 2008. Autologous osteochondral grafting: technique and long-term results. Injury.
- Familiari F et al. 2018. Clinical outcomes and failure rates of osteochondral allograft transplantation in the knee: a systematic review. The American Journal of Sports Medicine.
- Dhillon J et al. 2022. The most common rehabilitation protocol after matrix-assisted autologous chondrocyte implantation is immediate partial weight-bearing and continuous passive motion. Arthroscopy, Sports Medicine, and Rehabilitation.
- Yeo J et al. 2025. Rehabilitation of the knee after autologous matrix-induced chondrogenesis: a systematic review of rehabilitation protocols and clinical and radiological outcomes. Orthopaedic Journal of Sports Medicine.
- Krych AJ et al. 2017. Return to sport after the surgical management of articular cartilage lesions in the knee: a meta-analysis. Knee Surgery, Sports Traumatology, Arthroscopy.
- Gopinatth V et al. 2024. Microfracture for medium size to large knee chondral defects has limited long-term efficacy: a systematic review. Journal of Experimental Orthopaedics.
- Kraeutler MJ et al. 2018. Microfracture versus autologous chondrocyte implantation for articular cartilage lesions in the knee: a systematic review of 5-year outcomes. The American Journal of Sports Medicine.
- Wang AS et al. 2024. Minimum 10-year outcomes of matrix-induced autologous chondrocyte implantation in the knee: a systematic review. The American Journal of Sports Medicine.
- Andrade R et al. 2016. Knee donor-site morbidity after mosaicplasty: a systematic review. Journal of Experimental Orthopaedics.
Frequently asked questions
Can knee cartilage heal or grow back on its own?
Cartilage has very little ability to repair itself because it doesn’t have a strong blood supply. This means that once it is damaged, it usually doesn’t fully grow back.
That said, many people still improve without surgery.
If the damage is small, or if the pain is coming from inflammation rather than the cartilage itself, symptoms can settle over time. With the right approach, including physiotherapy, activity modification and strength work, the knee can become comfortable and functional again, even if the cartilage doesn’t fully heal.
However, larger or more severe defects, especially where the bone is exposed, are much less likely to improve on their own. In these cases, symptoms often persist and surgery may be considered.
Is cartilage damage the same as arthritis?
No. They are related, but not the same.
Cartilage damage is usually focal, affecting a small area of the joint, and is often linked to an injury or specific event.
Osteoarthritis, on the other hand, is a whole-joint process involving gradual wear and tear over time, with contributions from genetics, age, and joint loading. While a focal cartilage injury can increase the risk of developing arthritis later, the two conditions are distinct in how they start and progress.
What are the symptoms of cartilage damage in the knee?
Cartilage damage can cause pain, swelling, and mechanical symptoms such as clicking, catching, or a feeling of something not moving smoothly within the joint. The knee may feel stiff, and symptoms often worsen with activity.
The impact of cartilage damage varies: some people have mild symptoms, while others experience pain and limitation comparable to osteoarthritis, particularly if the defect is larger or located in a high-load area of the joint.
What causes cartilage damage in the knee?
Cartilage damage can occur for several reasons. The most common include injury, repetitive loading, and gradual wear.
A single event, such as a twist, fall or sporting injury, can cause a focal area of cartilage to be damaged. This is often seen alongside ligament or meniscus injuries. In other cases, cartilage is affected by repeated stress on the joint, particularly during high-impact activities.
Over time, factors such as age, joint alignment, body weight, and genetics can also contribute to cartilage wear.
What is the best cartilage repair procedure?
There isn’t a single “best” procedure for cartilage repair. The right option depends on you and the specific problem. Factors such as the size and location of the damaged area, your age and activity level, knee alignment, and whether the meniscus is intact all play an important role in deciding the most suitable treatment.
Different procedures each have strengths in certain situations, so the goal is to choose the approach that best matches your knee.
What happens if cartilage repair fails?
Not every cartilage repair works, and a repair can deteriorate over time even when it settles well initially. Failure usually shows itself as a return of pain, swelling or mechanical symptoms, and is confirmed on examination and magnetic resonance imaging (MRI).
Failure of one procedure does not close off the others. Depending on what was done the first time, the size of the remaining defect and the state of the rest of the knee, the options may include a revision cartilage procedure, an osteotomy to take load off the affected area, or, in an older knee with more widespread wear, partial or total knee replacement.
Symptoms that return after cartilage repair are worth reviewing rather than leaving to settle, because the choice of salvage procedure is easier while the defect is still contained.
When should I seek help after surgery?
Contact Dr Vishal Pai’s rooms or your GP, or go to your nearest emergency department, if you notice:
- Increasing swelling, redness or warmth around the wound
- A temperature above 38°C for 12 hours or more
- Drainage from the wound after 72 hours
- Pain or swelling in your calf
Call 000 if you have chest pain or shortness of breath.
Next step
Talk through your options
If you are weighing up cartilage repair surgery, Dr Vishal Pai can examine your knee, review your scans and explain all your options, including treatment without surgery.