Knee · Cartilage
MACI cartilage implantation — femoral condyle
Femoral Condyle (Thigh Bone) Cartilage Defect — Matrix-Induced Autologous Chondrocyte Implantation
The condition
Articular cartilage is the smooth tissue covering the end of the thigh bone (femoral condyle), where the knee bears your weight. A cartilage defect is a spot where it has worn or broken away, like a pothole. It heals poorly on its own and can cause pain, swelling, and catching.
The surgery
MACI repairs the defect with your own cartilage cells and takes two surgeries, both typically outpatient. Stage 1 (biopsy): through small incisions with a camera, a small sample of healthy cartilage is taken, and your cells are grown in a lab. Stage 2 (implant): usually 4–6 weeks later, the cells, on a thin membrane, are glued into the defect through a small open incision. The final plan is determined during surgery.
Recovery at a glance
- After Stage 1
- Quick recovery: walking as tolerated (crutches for a few days if needed); desk work and daily activities within ~1 week.
- Weight-bearing
- After Stage 2: crutches, with weight added weekly from ~20% of body weight to full at 8 weeks. A hinged brace is worn for walking; both are off by ~10 weeks.
- Motion
- A motion (CPM) machine is used daily for the first 6 weeks. Bending to 90° by 3–4 weeks and 120° by 6 weeks; full motion from 7 weeks.
- Daily life
- Desk work often within 2–4 weeks. Low-impact exercise (cycling, swimming) from ~3 months. No driving while taking narcotic pain medication.
- Running & sports
- The new cartilage matures over 1–2 years. Jogging begins at 6–9 months, once cleared. Impact, cutting, and contact sports no sooner than 12 months; full release typically 12–18 months.
A general guide. Your restrictions and timeline may change based on what is found and done at surgery.
Risks & benefits
Benefits: Most patients have less pain and better function, with lasting results in long-term studies. Risks are uncommon and include infection, blood clots, the implant not bonding or coming loose, overgrowth of the new cartilage (which may need trimming), a reaction to the implant materials, injury to nearby structures (such as nerves, blood vessels, or cartilage), stiffness, persistent pain, and the need for further surgery. These will be reviewed with you in detail before surgery.
Patient Surgical Information
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Before & after every surgery