MR imaging of osteochondral grafts and autologous chondrocyte implantation

Surgical articular cartilage repair therapies for cartilage defects such as osteochondral autograft transfer, autologous chondrocyte implantation (ACI) or matrix associated autologous chondrocyte transplantation (MACT) are becoming more common. MRI has become the method of choice for non-invasive follow-up of patients after cartilage repair surgery. It should be performed with cartilage sensitive sequences, including fat-suppressed proton density-weighted T2 fast spin-echo (PD/T2-FSE) and three-dimensional gradient-echo (3D GRE) sequences, which provide good signal-to-noise and contrast-to-noise ratios. A thorough magnetic resonance (MR)-based assessment of cartilage repair tissue includes evaluations of defect filling, the surface and structure of repair tissue, the signal intensity of repair tissue and the subchondral bone status. Furthermore, in osteochondral autografts surface congruity, osseous incorporation and the donor site should be assessed. High spatial resolution is mandatory and can be achieved either by using a surface coil with a 1.5-T scanner or with a knee coil at 3 T; it is particularly important for assessing graft morphology and integration. Moreover, MR imaging facilitates assessment of complications including periosteal hypertrophy, delamination, adhesions, surface incongruence and reactive changes such as effusions and synovitis. Ongoing developments include isotropic 3D sequences, for improved morphological analysis, and in vivo biochemical imaging such as dGEMRIC, T2 mapping and diffusion-weighted imaging, which make functional analysis of cartilage possible

Osteochondral autografting (mosaicplasty) in grade IV cartilage defects in the knee joint: 2- to 7-year results

The use of autologous osteochondral grafts (mosaicplasty) to repair articular cartilage defects is a well-established technique. Between 1998 and 2003, 19 patients with grade IV cartilage defects in the knee joint were treated by mosaicplasty. The average age of these 13 men (68%) and six women (32%) was 33.1 years (20–46). The mean follow-up was 32.4 months (84–24). The mean preoperative and postoperative Lysholm score was 45.8 (21–60) and 87.5 (74–100), respectively (p<0.001). Postoperative evaluation showed significant improvement. The results at the last follow-up were excellent in seven patients (27%), good in 11 patients (58%) and fair in one patient (15%). Preoperative complaints of pain, crepitation and locking disappeared in all patients. Magnetic resonance imaging (MRI) examination at the last follow-up visit revealed that congruency was restored in 16 (84.2%) without any signs of fissuring or delamination but in three patients (15.8%) a 1-mm difference between graft and recipient surface was detected. No complications were observed in the patients. Mosaicplasty is a really effective method of treatment for grade IV cartilage lesions in the knee joint