Predictive Value of Early Postoperative Subchondral Bone Marrow Parameters for Midterm Outcome after MACI with Autologous Bone Grafting at the Knee: A Quantitative Longitudinal 3T MRI Study

Presentation Format: Oral presentation.

Purpose or Learning Objective: To assess longitudinally whether early postoperative quantitative 3-T magnetic resonance imaging (MRI) parameters of subchondral bone marrow are able to predict the 2-year clinical and MRI outcome after matrix-associated autologous chondrocyte implantation (MACI) with autologous bone grafting (ABG) at the knee.

Methods or Background: A total of 18 patients who received MACI with ABG for treatment of focal osteochondral defects at the medial (n = 15) or lateral (n = 3) femoral condyle at the knee received MRI follow-up (FU) 3, 6, 12, and 24 months postoperatively. Quantitative MRI included bone marrow edema (BME) volume measurements and single-voxel magnetic resonance spectroscopy (MRS; n = 9) of the subchondral bone marrow. At 2-year FU, morphological MRI outcome included Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) 2.0 scores. Clinical outcomes were assessed using Lysholm scores.

Results or Findings: Mean BME volume showed a decrease from 4.9 cm³ at 3 months to 2.0 cm³ at 2-year FU (p = 0.033). MRS T2 showed a significant decrease from 20.7 ms at 1-year FU to 16.8 ms at 2-year FU (p = 0.040). The difference was not significant for the MRS proton-density water fraction (PDWF; p = 0.247) and the unsaturated lipid fractions (p = 0.347). Higher BME volume at 6 months significantly correlated with worse 2-year clinical outcomes (Lysholm scores; R = − 0.616; p = 0.015) and 2-year MOCART 2.0 scores (R = − 0.567; p = 0.027). Correlations for PDWF, MRS T2, and unsaturated lipid fractions were not significant (p > 0.05).

Conclusion: Quantitative subchondral bone parameters improved over time. Low subchondral BME volume at early postoperative time points predicts better 2-year clinical and MRI outcomes after MACI with ABG.

No conflict of interest has been declared by the author(s).

Publication History

Article published online:
03 June 2021