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Biological Cartilage Repair (ACI/MACI/MSC)

Regenerative orthopedic procedures for focal articular cartilage defects including autologous chondrocyte implantation (ACI), matrix-induced ACI (MACI), and emerging mesenchymal stem cell therapies; alternatives to microfracture and osteochondral grafts for symptomatic chondral lesions in young active patients.

Written by: Saygı Hospital Health Guide Editorial Board
Last updated:

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Ortopedi ve Travmatoloji department. Book Appointment →

What is Biological Cartilage Repair (ACI/MACI/MSC)?

Biological cartilage repair encompasses several techniques aiming to regenerate hyaline-like articular cartilage in focal defects: autologous chondrocyte implantation (ACI, first generation: chondrocyte injection under periosteal cover, 1994), matrix-induced autologous chondrocyte implantation (MACI, third generation: chondrocytes seeded on collagen membrane, FDA-approved 2016), and emerging mesenchymal stem cell (MSC) therapies (bone marrow concentrate, adipose-derived MSC, allogeneic MSC products). These contrast with marrow stimulation techniques (microfracture) and osteochondral grafts (OATS, mosaicplasty, fresh allograft).

Indications include symptomatic full-thickness articular cartilage defects (Outerbridge grade IV, ICRS grade 3-4), typically 2-10 cm² in size, in skeletally mature patients <50 years with intact subchondral bone, normal alignment, stable ligaments, and normal meniscus (or treated concomitantly). Common locations include femoral condyles, trochlea, patella, and talar dome. Failure of conservative treatment (>3 months) and symptoms (pain, swelling, mechanical) are required.

MACI procedure involves arthroscopic biopsy of healthy cartilage (200-300 mg from non-weight-bearing area), 3-6 weeks of cell culture and expansion, and second-stage open implantation of chondrocyte-seeded collagen membrane fixed with fibrin glue. Postoperative protocol includes touch-down weight-bearing for 6 weeks, gradual return to activity over 6-12 months, with full sport participation possible at 12-18 months. Outcomes show superior hyaline-like cartilage formation, durable improvements in symptoms, and lower failure/revision rates compared to microfracture for lesions >2 cm² with 10+ year follow-up data.

Symptoms

Joint pain with activity (knee, ankle, hip)
Joint swelling, especially after activity
Mechanical symptoms (catching, locking, giving way)
Limited range of motion
Persistent symptoms after failed conservative treatment
Localized tenderness over articular cartilage
Joint effusion

Risk Factors

Sports-related cartilage injury (acute trauma)
Osteochondritis dissecans (OCD)
Patellar dislocation with chondral injury
Anterior cruciate ligament injury with cartilage damage
Young age with active lifestyle
Failed prior microfracture or marrow stimulation
Focal symptomatic chondral lesion (not generalized OA)

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

  • Persistent knee pain after injury
  • Recurrent joint swelling with activity
  • Mechanical symptoms (locking, catching)
  • Failed conservative treatment >3 months
  • MRI showing focal articular cartilage defect
  • Young athlete with cartilage injury
  • Considering joint preservation alternative to arthroplasty

Treatment Methods

01
Two-stage MACI: arthroscopic biopsy + cell culture + open implantation
02
ACI with periosteal cover (first generation, less common)
03
Mesenchymal stem cell therapy (bone marrow concentrate, BMAC)
04
Concomitant procedures: meniscus repair, ligament reconstruction, alignment osteotomy
05
Postoperative protected weight-bearing for 6 weeks
06
Continuous passive motion (CPM) for 4-6 weeks
07
Gradual return to sport over 12-18 months

Which Department to Visit?

You can visit our Ortopedi ve Travmatoloji department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.