[Matrix-associated autologous chondrocyte transplantation (MACT). Minimally invasive technique in the knee]

Repair of localized cartilage defects in the knee.

Localized partial or full-thickness cartilage defects in the knee or osteochondral lesions (osteochondritis dissecans [OD]).

Generalized cartilage defects, osteoarthritis, bacterial and rheumatoid arthritis, uncorrected axis deformities, ligament instability, patella instability, meniscectomy.

Two-step procedure. 1. Diagnostic arthroscopy and cartilage biopsy for cell cultivation. 2. Minimalized arthrotomy. Defect debridement. Autologous cancellous bone grafting in OD. Glueing of the cell-loaded scaffold into the defect.

Early functional rehabilitation with knee orthosis. Partial weight bearing (20 kg) for 6 weeks.

50 patients (24 female, 26 male, age 14-44 years, mean 30.3 years) with 58 focal cartilage defects (III-IV degrees) of the knee in the medial (n = 32) or lateral condyle (n = 5), patella (n = 14) and/or trochlea (n = 7) underwent matrix-associated autologous chondrocyte implantation (MACI). The mean follow-up was 24 months (21-29 months). The mean defect size was 4.1 cm2(1.6-6.1 cm2). The Lysholm Score improved from 57.3 to 87.4 points, the DGKKT (German Society of Autologous Cartilage and Bone Cell Transplantation) Score from 55.3 to 85.5 points. Pain on a visual analog scale (VAS) diminished from 5.5 to 2.1, while subjective function enhanced from 4.5 to 7.6. All scores were significant (p < 0.01; t-test). In eleven patients (twelve defects), a second-look arthroscopy revealed a mostly fibrocartilaginous regenerative tissue in 41.7% (5/12) and a mixed fibrous/hyaline regenerative tissue in 33.4% (4/12). 54% (27/50) of the patients estimated their result as excellent, 28% (14/50) as good, 16% as fair, and 2% (1/50) as poor.