The Predictive Value of Early Postoperative MRI-Based Bone Marrow Parameters for Mid-Term Outcome after MACI with Autologous Bone Grafting at the Knee
Matthias Jung, Stefan Ruschke, Dimitrios C. Karampinos, Christian Holwein, Thomas Baum, Alexandra S. Gersing, Fabian Bamberg, Pia M. Jungmann
Abstract
Objective The aim of this study was to longitudinally determine the prognostic value of early postoperative quantitative 3T-MRI (magnetic resonance imaging) parameters of subchondral bone marrow for 2-year clinical and MRI outcome after matrix-associated autologous chondrocyte implantation (MACI) with autologous bone grafting (ABG) at the knee. Design Consecutive subjects who received MACI with ABG for treatment of focal osteochondral defects received MRI follow-up 3, 6, 12, and 24 months postoperatively. Quantitative MRI included bone marrow edema-like lesion (BMEL) volume measurements and single-voxel magnetic resonance spectroscopy (MRS; n = 9) of the subchondral bone marrow. At 2-year follow-up, morphological MRI outcome included MOCART (magnetic resonance observation of cartilage repair tissue) 2.0 scores. Clinical outcomes were assessed using Lysholm scores. Results Among a total of 18 subjects (mean age: 28.7 ± 8.4 years, n = 14 males) with defects at the medial or lateral ( n = 15 and n = 3, respectively) condyle, mean BMEL volume decreased from 4.9 cm 3 at 3 months to 2.0 cm 3 at 2-year follow-up ( P = 0.040). MRS-based bone marrow water T2 showed a decrease from 20.7 ms at 1-year follow-up to 16.8 ms at 2-year follow-up ( P = 0.040). Higher BMEL volume at 6 months correlated with lower 2-year Lysholm (R = −0.616, P = 0.015) and MOCART 2.0 scores (R = −0.567, P = 0.027). Larger early postoperative BMEL volumes at 3 months (R = −0.850, P = 0.007) and 6 months (R = −0.811, P = 0.008) correlated with lower MRS-based unsaturated lipid fractions at 2-year follow-up. Furthermore, patients with early postoperative bony defects showed worse MOCART 2.0 ( P = 0.044) and Lysholm scores ( P = 0.017) after 24 months. Conclusion Low subchondral BMEL volume and optimal restoration of the subchondral bone at early postoperative time points predict better 2-year clinical and MRI outcomes after MACI with ABG.