Cartilage restoration may help selected focal defects, but is generally not suited to widespread arthritis. Planning considers the defect, knee alignment and other joint structures.
Who may be considered?
Evaluation includes symptoms, activity demands, prior surgery, examination, X-rays and MRI. Defect size, location, depth, underlying bone, meniscus health, ligament stability, patellofemoral tracking and overall alignment all influence suitability. Advanced diffuse osteoarthritis generally calls for a different discussion than a focal defect.
MACI: Matrix-induced autologous chondrocyte implantation
MACI uses a patient's own cartilage cells to treat qualifying symptomatic full-thickness knee cartilage defects. The process typically requires two stages: an arthroscopic cartilage-cell biopsy followed by cell expansion and later implantation of the cell-bearing membrane into the prepared defect. MACI is FDA-approved for symptomatic full-thickness cartilage defects of the knee in adults; it is not a general treatment for all arthritis, and effectiveness has not been established for patients older than 55 years or in joints other than the knee.
Osteochondral allograft transplantation (OCA)
Osteochondral allograft transplantation uses size-matched donated cartilage with supporting bone to replace an appropriately selected damaged area. It can be particularly useful when the injury includes abnormal subchondral bone, a deeper osteochondral defect or selected lesions for which cell-based resurfacing is less suitable. Graft availability, matching, implantation geometry and integration are important considerations.
Alignment correction: HTO and DFO
A cartilage restoration procedure may not hold up if abnormal limb alignment repeatedly overloads the treated area. For selected varus or valgus knees, an HTO (high tibial osteotomy) or DFO (distal femoral osteotomy) can shift load away from the damaged compartment. Osteotomy may be performed alongside or staged with cartilage restoration, depending on deformity location, stability and the treatment plan. Alignment correction is not required for every cartilage defect.
Treating the entire knee
An unstable ligament, deficient meniscus or patellar tracking disorder may need treatment at the same time to protect a cartilage graft. This is why cartilage restoration is planned as a comprehensive joint-preservation strategy rather than simply filling a defect. Learn about MPFL reconstruction and tibial tubercle osteotomy and meniscus preservation.
Recovery after cartilage restoration
Most cartilage procedures follow this protective early recovery framework. The location and size of the cartilage injury, MACI or osteochondral allograft treatment, and any alignment or ligament procedures determine your exact restrictions.
- First 6 weeks: use crutches and put only the amount of weight on the leg allowed by your protocol. Focus on prescribed knee motion and activating the quadriceps—the muscles at the front of the thigh—while the repair or bone work heals.
- Brace for 6–8 weeks: a hinged knee brace protects the knee during early recovery. Follow your protocol for settings and when to wear it.
- After 6 weeks: work toward a normal walking pattern, full knee motion and control of the thigh muscles, as cleared. Gradually increase activity and muscular endurance.
- Around 3 months: strengthening. Begin strength training when cleared, usually around 3 months depending on healing and any additional procedures. Continue to follow the milestones in your protocol before advancing activity or returning to sports.
Return to impact activity is individualized and may be delayed beyond the early milestones above. Risks include persistent symptoms, graft failure, stiffness, infection and the potential for further surgery; no technique recreates an entirely normal joint in every patient.
For regulatory information, see the FDA's MACI overview ↗.