Knee Cartilage Repair and Osteotomy: 39 Questions Patients Ask

Articular cartilage is the smooth, slippery tissue that covers the ends of the bones inside the knee and lets the joint glide. It has very little blood supply, so it has a limited ability to heal on its own once it is damaged.

A cartilage defect (also called a focal or chondral defect) is a well-defined area of damaged cartilage in an otherwise healthy knee, a bit like a pothole in a road. It is often caused by a twisting injury, a kneecap dislocation or an ACL tear. If the bone under the cartilage is also involved, it is called an osteochondral defect.

Arthritis is wider wear of the cartilage across one or more areas of the joint, often with bone spurs and narrowing of the joint space on X-ray. A focal defect is a defined spot of damage. The difference matters, because cartilage repair procedures are designed for focal defects, not widespread arthritis. Untreated cartilage damage can, over time, lead to arthritis.¹ See knee osteoarthritis.

Osteochondritis dissecans is a condition in which a small segment of bone beneath the cartilage loses its blood supply and begins to separate from the surrounding bone.² The most common location is the end of the thighbone (femur) in the knee.² The piece can stay in place, become loose, or break off. See cartilage defects and OCD.

OCD develops mainly in children and teenagers, often those who play sports.² It can also be found in young adults, in whom it tends to cause more problems.²

Pain and swelling, often brought on by sports or activity, are the most common early symptoms.² Some people feel catching, locking or a sense that something is loose in the knee, or the knee gives way.

Dr. Dold will examine your knee and review X-rays, which show alignment, arthritis and many OCD lesions. An MRI shows the size and depth of the defect, the condition of the bone underneath, whether an OCD fragment is stable and any related meniscus or ligament injury. Standing long-leg X-rays may be used to measure leg alignment.

Often, in children. Resting and avoiding vigorous sports until symptoms settle often relieves pain and swelling, sometimes with crutches or a brace for a short time.² OCD lesions in children are more likely to heal on their own, especially when the child still has a lot of growing to do; in young adults the lesion is more likely to separate and need surgery.²

Adult cartilage has very little ability to heal. Small defects that cause few symptoms can often be managed with strengthening, activity changes and weight control. Defects that keep causing pain, swelling or locking usually need a procedure.

No injection has been shown to regrow a cartilage defect. Injections such as PRP may help symptoms in some people, but they do not fill in a missing area of cartilage. Read our stem cell injection facts page before paying for any product that promises to regrow cartilage.

The main options are microfracture, osteochondral autograft transfer (OATS), osteochondral allograft transplantation, matrix-induced autologous chondrocyte implantation (MACI) and the CartiHeal Agili-C implant.¹ The right choice depends on the size, depth and location of the defect, the condition of the bone underneath, your alignment, your age and your goals. See cartilage repair and transplantation for a side-by-side comparison.

Options include drilling small channels into the lesion to bring in new blood supply, fixing a loose fragment back in place with pins or screws, and replacing the damaged area with a bone and cartilage graft when the fragment cannot be saved.²

Microfracture is an arthroscopic (keyhole) procedure in which small holes are made in the bone at the base of the defect. Bleeding from the holes forms a clot that becomes a patch of scar-like repair cartilage. It is used mainly for single, smaller lesions.¹ The repair tissue is not as durable as normal cartilage, which is why other options are often considered for larger defects or very active patients.

OATS moves one or more small plugs of healthy bone and cartilage from a less important, low-weight-bearing area of your own knee into the defect. Because the donor tissue is limited, it is used for smaller defects.¹ In a randomized trial of 40 patients with defects of 2 to 6 square centimeters, those treated with OATS (also called mosaicplasty) had better knee function scores than those treated with microfracture at short, medium and long-term follow-up of at least 15 years.³

An osteochondral allograft uses a matched piece of bone and cartilage from a donor (allograft tissue) to replace the damaged area. It is considered when a defect is too large for an autograft,¹ or when the bone under the cartilage is also damaged, as with some OCD lesions.

MACI is a two-stage procedure. First, a small sample of your own cartilage is taken during arthroscopy and sent to a laboratory, where the cells are grown on a collagen membrane. In a second surgery, the membrane with your cells is placed into the defect. It is generally used for single defects larger than about 2 cm across.¹

Agili-C is a small, resorbable (gradually absorbed) implant made from aragonite, a natural mineral, that is placed into the defect. It received FDA premarket approval on March 29, 2022, for knee cartilage or osteochondral lesions with a total treatable area of 1 to 7 square centimeters in knees without severe arthritis (Kellgren-Lawrence grade 0 to 3).⁴ See CartiHeal Agili-C.

In the FDA pivotal trial, 251 patients were randomly assigned to Agili-C or to standard surgery (microfracture or debridement, which means cleaning up the damaged cartilage). At 24 months, knee scores improved by about 43 points with Agili-C vs about 21 points with standard surgery; 77.8% vs 33.6% were responders (at least a 30-point improvement), and treatment failure occurred in 7.2% vs 21.4%.⁴ Individual results vary.

According to the FDA labeling, Agili-C should not be used in knees with severe arthritis (Kellgren-Lawrence grade 4), bone loss deeper than 8 mm under the defect, a defect without a surrounding rim of healthy bone, active infection, osteonecrosis (bone death) or tumors.⁴ Dr. Dold will review your MRI and X-rays to see whether it fits your knee.

A cartilage repair is more likely to last in a stable, well-cushioned knee. If you also have a torn meniscus, an ACL tear or kneecap instability, these problems are often treated at the same time or before the cartilage repair.

In a knee osteotomy, the shinbone (tibia) or thighbone (femur) is cut and reshaped to shift weight away from a damaged part of the knee.⁵ The bone is held with a plate and screws while it heals. See knee osteotomy.

A high tibial osteotomy realigns the upper shinbone to take pressure off the inner side of the knee. It is used for people who are bowlegged and have damage mainly on the inner (medial) side.⁵

A distal femoral osteotomy realigns the lower thighbone to take pressure off the outer side of the knee. It is used for people who are knock-kneed and have damage mainly on the outer (lateral) side.⁵

A tibial tubercle osteotomy moves the bump of bone where the patellar tendon attaches below the kneecap. Shifting it can improve how the kneecap tracks and take pressure off cartilage damage behind the kneecap. It is used for recurrent kneecap dislocation and some kneecap cartilage problems. See patellar instability.

If your leg alignment overloads the part of the knee where the defect is, a cartilage repair alone is under extra stress. Correcting alignment with an osteotomy at the same time can protect the repair. Dr. Dold measures alignment on standing X-rays to decide whether this is needed.

The American Academy of Orthopaedic Surgeons describes ideal candidates as active people under about 60 who are not overweight, have pain on only one side of the knee and no pain behind the kneecap, can fully straighten the knee and can bend it to at least 90 degrees.⁵ Osteotomy is not suitable for people with rheumatoid arthritis.⁵

They treat different situations. An osteotomy keeps your own knee and, when successful, may delay the need for joint replacement for several years, with no activity restrictions once the bone has healed.⁵ Knee replacement is generally a better fit for older patients with widespread arthritis. Having had an osteotomy can make a later knee replacement more challenging.⁵

Possible complications include infection, blood clots, knee stiffness, injury to blood vessels or nerves, and the bone not healing, which may need another surgery.⁵ The plate and screws sometimes cause irritation and may be removed later.

It depends on the procedure. After OCD surgery, crutches are typically needed for about 6 weeks, followed by 2 to 4 months of physical therapy.² After cartilage restoration, crutches are often needed for the first few weeks.¹ After osteotomy, crutches are used for several weeks while the bone heals.⁵ Dr. Dold will give you a plan for your procedure.

Return to sport usually takes several months.¹ The timeline depends on the procedure, the size and location of the defect and how your rehabilitation goes. Procedures that grow new tissue, such as MACI and Agili-C, generally take longer than OATS before impact sports are allowed.

Most people go home 1 to 2 days after surgery, and full activities may be possible 3 to 6 months after surgery once the bone has healed.⁵

You can drive when you are off narcotic pain medicine and can control the pedals safely. If the surgery was on your right leg, this is usually later than for the left. Dr. Dold will advise you based on your procedure.

A desk job may be possible within a couple of weeks once pain is controlled. Jobs that need a lot of standing, walking, climbing or lifting take longer because of crutch use and healing time. Your timeline depends on your procedure and your job.

Yes. Rehabilitation protects the repair while it heals, restores motion, and rebuilds strength in the thigh and hip muscles. Following the plan closely is one of the most important parts of a good result.

Age alone does not decide. The most suitable candidates for cartilage restoration are usually young adults with a single injury; older patients and those with many damaged areas are less likely to benefit.¹ If you have widespread arthritis, other treatments such as osteotomy or knee replacement may be a better fit.

Yes. Extra body weight increases the load on the knee and on a cartilage repair. Ideal osteotomy candidates are not overweight,⁵ and weight loss before surgery can help protect any knee procedure. Dr. Dold will talk with you about this as part of your plan.

Many of these procedures are covered when they are medically necessary, but coverage varies by plan and some procedures need pre-authorization. Our office will check with your insurer before surgery.

Dr. Dold accepts most major insurance plans, including Medicare and Tricare. Please call 469-850-0680 to confirm your coverage. See our insurance page.

Call 469-850-0680 right away if you have fever, chills, increasing redness, drainage from the incision, calf pain or swelling, chest pain or shortness of breath, or pain that is getting worse instead of better. For chest pain or trouble breathing, call 911.