T2-relaxation time of cartilage repair tissue is associated with bone remodeling after spongiosa-augmented matrix-associated autologous chondrocyte implantation

Abstract

Objective: To investigate whether T2 relaxation time measurements of cartilage repair tissue and structural changes of the knee joint are associated with subchondral bone architecture after spongiosaaugmented matrix-associated autologous chondrocyte implantation (MACI). Design: Both knees of 25 patients (25.5 ± 7.8y; 10 women) were examined preoperatively and 2.7 years after unilateral spongiosa-augmented MACI with 3T magnetic resonance (MR) imaging. Cartilage composition was assessed using T2 relaxation time measurements, subchondral trabecular bone microstructure was quantified using a 3D phase-cycled balanced steady state free-precision sequence. Structural knee joint changes were assessed using the modified Whole-Organ Magnetic Resonance Imaging Score (WORMS). The Magnetic Resonance Observation of Cartilage Repair Tissue (MOCART) score was used for the postoperative description of the area that underwent MACI. Correlations were assessed using Spearman's rank correlation coefficients. Results: Hypertrophy of the cartilage repair tissue was found in 2 of 25 patients, both after a MACI procedure at the patella, 21 patients showed congruent filling. In subchondral bone of the cartilage repair compartment, apparent trabecular thickness was significantly higher in compartments with elevated cartilage T2 (n ¼ 17; 0.37 ± 0.05 mm) compared to those showing no difference in cartilage T2 compared to the same compartment in the contralateral knee (n ¼ 8; 0.27 ± 0.05 mm; P ¼ 0.042). Significant correlations were found between the overall progression of WORMS and the ipsilateral vs contralateral ratio of average trabecular thickness (r ¼ 0.48, P ¼ 0.031) and bone fraction (r ¼ 0.57, P ¼ 0.007). Conclusions: After spongiosa-augmented MACI, T2 values of cartilage repair tissue and structural knee joint changes correlated with the quality of the underlying trabecular bone.

Cartilage T2 Relaxation Times and Subchondral Trabecular Bone Parameters Predict Morphological Outcome After Matrix-Associated Autologous Chondrocyte Implantation With Autologous Bone Grafting

“…A cross-sectional study assessing cartilage composition within the region of cartilage repair at 1 time point (2.7 years after MACI) reported a correlation between cartilage T 2 values and the quality of the underlying trabecular bone. 12 This is in line with the findings of our study, suggesting an interrelation of trabecular bone parameters and the morphological and biochemical integrity of the cartilage repair tissue.…”

“…T 2 values of cartilage repair tissue significantly decreased within the first 24 months after surgery, indicating cartilage matrix regeneration within the cartilage repair region. 12 In a study of patients who underwent autologous chondrocyte implantation without ABG, T 2 values of the graft also normalized over 24 months, and there was no difference seen in cartilage T 2 values between patients with and without hypertrophy of the graft. 29 Yet, this study did not assess morphological changes of the entire knee joint or trabecular parameters.…”

“…For the assessment of subchondral bone architecture, 3D phase-cycled balanced steady-state free precision sequences were acquired at each postoperative time point. 12 For the analysis of structural knee joint changes, sagittal T1-weighted turbo spin echo (TSE) sequences and sagittal and coronal intermediate-weighted TSE sequences were obtained of the entire knee at every pre- and postoperative time point.…”

“…17 A previous study in a series of patients who had undergone MACI with ABG showed significant correlations between the quality of the cartilage repair tissue, as assessed using T 2 relaxation times, and the architecture of the underlying subchondral bone 2.7 years after spongiosa-augmented MACI procedures. 12 Postoperative integrity of the subchondral bone architecture may be essential for optimal osteochondral repair. Maturation of the cartilage repair tissue seems to be dependent on the quality of the underlying osseous repair tissue.…”

Quantitative 3-T Magnetic Resonance Imaging After Matrix-Associated Autologous Chondrocyte Implantation With Autologous Bone Grafting of the Knee: The Importance of Subchondral Bone Parameters

“…52 Quantitative magnetic resonance imaging (MRI) techniques are increasingly applied as noninvasive biomarkers that may provide information about the biochemical composition of cartilage. 16,22 In the case of native hyaline cartilage, collagen disruption and increased intracartilaginous water content are correlated with increased T2 relaxation times. 21,33 However, the importance of MRI regarding the quantitative assessment of cartilage repair tissue, consisting of fibrous or hyaline-like cartilage instead of native hyaline cartilage, still remains unclear.…”