A focal cartilage defect is different from widespread knee arthritis. Our orthopedic surgeons evaluate the exact location, size and depth of the damage—along with the bone, meniscus, ligaments, alignment and kneecap tracking—to determine whether treatment should involve chondroplasty, marrow stimulation, OAT/OATS, osteochondral allograft transplantation or MACI.
Articular cartilage is the smooth, low-friction surface covering the ends of the bones inside the knee. It allows the femur, tibia and kneecap to glide while distributing force across the joint. Unlike the meniscus, articular cartilage is attached directly to the underlying bone.
A cartilage injury may be described as a chondral defect when the damage primarily involves cartilage, or an osteochondral defect when both cartilage and the supporting bone are involved. Symptoms can develop after trauma, recurrent instability, osteochondritis dissecans, prior surgery or repetitive overload.
“Cartilage repair,” “cartilage restoration” and “cartilage transplant” are often used interchangeably online, but the operations are not the same.
The meniscus is a C-shaped shock-absorbing structure between the femur and tibia. Articular cartilage is the smooth surface coating the bones. A patient may have damage to either structure—or both—and each requires a different treatment strategy.
Cartilage-restoration surgery is most useful when a localized defect exists in a knee that is otherwise reasonably preservable. It is not a reliable way to reverse widespread bone-on-bone arthritis.
These operations should not be presented as interchangeable. The correct technique depends on the defect, bone involvement, surrounding joint health and what has already been attempted.
These illustrations help explain how MACI and osteochondral allograft transplantation replace a cartilage defect in fundamentally different ways.
A small cartilage biopsy is obtained arthroscopically. The chondrocytes are expanded and placed on a collagen membrane, which is later shaped to the defect and implanted during a second procedure.
Read the dedicated MACI guide →
A donor graft containing mature articular cartilage and supporting bone is shaped to replace the damaged portion of the knee. This differs from MACI because the procedure transfers an intact cartilage-and-bone unit rather than cultured cells.
Cartilage stabilization or “cleanup”
Chondroplasty removes or smooths unstable cartilage flaps that are catching or shedding debris. It may improve mechanical irritation, but it does not recreate the missing normal cartilage surface.
Creates a marrow-based healing response
Small channels are created in the bone beneath a prepared cartilage defect. Marrow elements enter the area and form repair tissue. That tissue is predominantly fibrocartilage and is not identical to native hyaline articular cartilage.
Osteochondral autograft transfer or mosaicplasty
One or more plugs of your own articular cartilage and underlying bone are moved from a lower-load portion of the knee into the defect. Because donor plugs must be harvested from the same knee, the available amount is limited.
Donor cartilage-and-bone replacement
A fresh donor graft is size matched and shaped to replace the damaged articular surface and underlying bone. This can be useful for larger defects, osteochondral damage, failed prior procedures or situations where the bone also requires replacement.
Matrix-induced autologous chondrocyte implantation
MACI uses your own cultured chondrocytes on a collagen membrane. It is a two-stage process: arthroscopic biopsy followed by later implantation after the cells have been expanded.
Preserving a repairable native fragment
After a traumatic injury or osteochondritis dissecans, a viable cartilage-and-bone fragment may occasionally be repaired back to its original location. The fragment, bone quality, timing and stability determine whether fixation is realistic.
Cartilage-restoration planning combines symptoms, examination, weight-bearing X-rays, MRI, prior operative reports and the mechanics of the entire lower extremity.
Location, surface area, depth, containment and underlying bone involvement are reviewed.
X-rays identify joint-space loss, deformity, malalignment, bone changes and diffuse arthritis.
Swelling, motion, tenderness, stability, patellar tracking, strength and limb alignment are assessed.
Previous arthroscopy, microfracture, meniscus surgery, instability and rehabilitation can affect the next step.
A technically successful transplant can still fail when abnormal forces remain. The cartilage lesion must be viewed as part of the entire knee rather than as a stand-alone MRI finding.
Depending on the problem, cartilage restoration may need to be combined with meniscus treatment, ligament reconstruction, patellar realignment or an osteotomy that redistributes load.
Bowlegged or knock-kneed alignment can overload the same area being restored.
Loss of meniscus tissue increases contact stress across the cartilage surface.
ACL or other instability can expose a graft to repetitive abnormal shear.
Maltracking or recurrent dislocation may need correction with patellofemoral cartilage treatment.
Recovery depends heavily on the location and procedure. Weight-bearing may be restricted to protect a femoral-condyle graft, while patellofemoral procedures may emphasize different motion restrictions. Combined ligament, meniscus or alignment surgery can further change the plan.
The defect location, graft type, bone involvement and any combined procedure determine the actual brace, crutch, motion, driving, work and return-to-sport plan.
If an MRI report mentions a chondral defect, osteochondral lesion, cartilage fissure, full-thickness cartilage loss, osteochondritis dissecans or subchondral bone injury, you can securely upload the images or report through our MRI review portal.
We can assess whether the study appears more consistent with a focal cartilage problem, diffuse arthritis or another knee condition—and whether an in-person cartilage-restoration evaluation may be appropriate.
This is a preliminary educational review, not a formal diagnosis or substitute for an examination. It is not intended for emergencies.
Articular cartilage has limited natural healing capacity. Some symptoms improve with rehabilitation, activity modification and treatment of inflammation, but a full-thickness structural defect does not reliably recreate normal cartilage on its own.
OAT or OATS is an autograft procedure: cartilage-and-bone plugs come from a lower-load area of your own knee. Osteochondral allograft transplantation uses fresh donor cartilage and bone and can replace a larger area without harvesting a large graft from the same knee.
MACI implants your cultured cartilage cells on a collagen membrane and requires two procedures. OATS moves an intact plug of your own mature cartilage and bone during one restorative operation. Defect size, location, bone involvement and prior treatment help determine which is more appropriate.
No. Microfracture stimulates a marrow-based healing response from the bone below the defect. It does not transplant mature articular cartilage, donor tissue or cultured chondrocytes.
Focal cartilage procedures are generally intended for localized defects in a knee that remains reasonably preservable. Widespread bone-on-bone arthritis across a compartment or the entire joint usually requires a different strategy.
Diagnostic assessment, chondroplasty, microfracture and biopsy may be arthroscopic. OATS, allograft transplantation and MACI implantation may require a limited open approach so the defect can be accurately prepared and the graft positioned.
An osteotomy changes alignment to unload an overloaded portion of the knee. Restoring cartilage without correcting substantial malalignment can leave the new surface exposed to the same excessive force that contributed to the original damage.
Return depends on the specific procedure, defect location, healing, strength and any combined operation. Cartilage restoration often requires many months of rehabilitation, and high-impact or pivoting sports generally resume later than ordinary daily activities.
Atlanta Bone & Joint Specialists evaluates focal knee-cartilage injuries for patients from Atlanta and communities throughout Fulton, DeKalb, Gwinnett, Walton, Rockdale, Newton and surrounding counties.
Bring your MRI images, radiology report, prior operative reports and information about previous treatment. We will determine whether the problem is a focal chondral or osteochondral defect, diffuse arthritis or another knee condition—and explain which preservation options are realistic.
This page is provided for general educational purposes and does not constitute medical advice, diagnosis or a physician-patient relationship. Cartilage-restoration candidacy, procedure selection, graft availability, insurance authorization, restrictions and recovery depend on an individual medical history, examination, imaging and surgical findings. Seek urgent medical care for severe or rapidly worsening symptoms.
