Tibial cartilage hypertrophy due to matrix-associated autologous chondrocyte transplantation of the medial femoral condyle. A case report.

Osteochondral graft hypertrophy is commonly seen after autologous chondrocyte transplantation with use of a periosteal flap1,2. Reoperation may be performed because of a high grade of hypertrophy causing persistent clinical symptoms. The use of a collagen membrane to cover the chondrocyte suspension can reduce the risk of graft hypertrophy3,4. Further technological advances have led to a third generation of autologous chondrocyte transplantation with use of biomaterials seeded with chondrocytes as so-called all-in-one scaffolds that generate new articular cartilage5. Nevertheless, graft hypertrophy continues to occur, although the prevalence has been reduced with matrix-associated autologous chondrocyte transplantation6,7. We present the case of a patient who complained of a reduced range of motion after matrix-associated autologous chondrocyte transplantation of the medial femoral condyle. The patient was found to have tibial cartilage hypertrophy opposite the site of the matrix-associated autologous chondrocyte transplantation. The patient was informed that data concerning the case would be submitted for publication, and he consented. A forty-nine-year-old man was treated with matrix-associated autologous chondrocyte transplantation for a single full-thickness cartilage defect of the medial femoral condyle. The nature of the cartilage defect was traumatic, and the time interval between the initial symptoms and diagnosis was approximately six months. Surgical treatment followed after another six months, as nonsurgical therapy did not provide substantial clinical improvement. During the two-step surgical procedure, in a first arthroscopic step (Fig. 1), the isolated nature of the cartilage defect was documented, the borders of the defect were debrided, approximately 200 mg of normal cartilage tissue was harvested for culture, and the chondrocytes were cultured for three weeks. In the second step, with use of a mini-arthrotomy, a hyaluronan-based scaffold (Hyalograft C; Fidia Advanced Biopolymers, Abano Terme, Italy), seeded with the cultured chondrocytes, …