Introduction

Matrix-induced autologous chondrocyte implantation (MACI) is a method of cartilage regeneration that combines autologous cells with a type1/111 porcine membrane.^1–6 MACI was developed from collagen-covered autologous chondrocyte implantation (CACI), but cells are seeded onto the membrane 3 days before implantation. The graft is implanted “cells down” and secured in the cartilage defect with fibrin glue.

Indications and Contraindications

Surgical indications and contraindications are similar to those described by the International Cartilage Research Society for other autologous chondrocyte implantation (ACI) techniques (see also Chapters 9C and 9D):

In a pilot study on 20 arthritic patients, we achieved poor in-fill compared with unipolar cartilage defects.

Some Key Questions Are Addressed

Cartilage Biopsy

Surgical Technique

This is an arthroscopic procedure performed under general anesthesia with a thigh tourniquet. First, a thorough examination under anesthetic is performed. The whole knee joint is inspected arthroscopically and the defect evaluated.

Meniscal tears, loose bodies, or internal derangement amenable to arthroscopic treatment is dealt with.

The biopsy for MACI is similar to other ACI techniques and may be taken from the median ridge at the level of the sulcus terminalis, the distal trochlea in the intercondylar region, or the surface of a fresh osteochondral fragment (see also Chapters 9C and 9D).

Using the small notchplasty gouge, a suitable-sized volume of cartilage is “scored” as deep as the subchondral plate. Using the gouge or ring curette, the biopsy is partially levered away from the subchondral plate of bone and finally grasped with pituitary rongeurs, immediately placed in culture medium (Fig. 9E-1), and transported to the laboratory for cell multiplication preparation.

FIGURE 9E-1 Using a gouge or a ring curette, a cartilage biopsy is partially levered away from the subchondral plate from the upper medial femoral condyle and grasped with pituitary rongeurs, immediately placed in culture medium, and transported to the laboratory for cell isolation and culture expansion.

We favor using a notchplasty gouge to partly dissect a biopsy from the median ridge as deep as the subchondral plate and as peripheral as possible from an area of normal cartilage. The biopsy should include the deep proliferative layer of cells.

Tension in the lateral retinaculum makes lateral ridge harvest more difficult and probably best done with pituitary forceps.

Briggs et al.⁷ have demonstrated that surface cartilage of osteochondral fragments produces chondrocytes of good quality.