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. 2025 Apr 28:19476035251335008.
doi: 10.1177/19476035251335008. Online ahead of print.

Long-Term Impact of Intralesional Bony Overgrowth on Opposing Cartilage Integrity: Five-Year Results Following Cartilage Repair

Felix Ragnar Merlin Koenig  1   2 , Marcus Raudner  1 , Gregor Wollner  3 , Vladimir Juras  1 , Pavol Szomolanyi  1   4 , Veronica Vetchy  2 , Johannes Leitner  2 , Victor Schmidbauer  2 , Siegfried Trattnig  1   2   5   6
Affiliations

Long-Term Impact of Intralesional Bony Overgrowth on Opposing Cartilage Integrity: Five-Year Results Following Cartilage Repair

Felix Ragnar Merlin Koenig et al. Cartilage. .

Abstract

ObjectivesThis study aimed to assess the impact of intralesional bony overgrowth (ILBO) after cartilage repair on the integrity of opposing articulating cartilage (OpAC) using T2 mapping and to correlate these findings with clinical outcomes.MethodsIn this multicenter study, magnetic resonance imaging (MRI) examinations were performed in the follow-up after cartilage repair (Microfracturing (MFX) and Matrix-Induced Autologous Chondrocyte Implantation (MACI)) in 45 patients up to 5 years after surgery. T2 values of the OpAC after 3, 12, and 60 months in patients with and without ILBO after 60 months were conducted along with clinical assessments (International Knee Documentation Committee (IKDC) and Knee injury and Osteoarthritis Outcome Score (KOOS)).ResultsAt 60 months post-surgery, 44.4% of patients presented with ILBO, which was associated with significantly higher T2 values in OpAC (P = 0.004). A tendency toward increased T2 values was observed after 12 months, although this did not reach statistical significance (P = 0.06). However, no significant differences were found in clinical outcomes between patients with or without ILBO, nor between those with or without T2 values comparable to reference cartilage.ConclusionILBO significantly affects the biophysical MRI properties of OpAC as indicated by higher T2 values after 60 months. These alterations, though not reflected in any clinical score, can suggest potential long-term implications for cartilage degeneration and may inform future monitoring strategies for cartilage repair. Further research is required to evaluate the long-term effects of these altered mechanical impacts on articulating cartilage and their clinical implications.

Keywords: articular cartilage; bone formation; follow-up studies; knee joint; magnetic resonance imaging; subchondral arthroplasty.

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Conflict of interest statement

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figure 1.
Figure 1.
Flowchart of this retrospective study.
Figure 2.
Figure 2.
Appearance of ILBO 3 to 60 months after surgery: 55.6% of all patients presented with bony overgrowth after 60 months.
Figure 3.
Figure 3.
T2 ratio of the opposing articulating cartilage in patient with ILBO (n = 25) and without ILBO (n = 20) after 60 months: No differences after 3 months, a tendency but no significant difference after 12 months and significant difference between the ILBO and No ILBO group after 60 months.
Figure 4.
Figure 4.
T2 ratio after 60 months in patient with no ILBO (n = 20), with minor ILBO (n= 14) and major ILBO (n = 11): Significant difference in both minor bony overgrowth (<50%) and major bony overgrowth (>50%) compared to the no ILBO group.
Figure 5.
Figure 5.
Differences in ILBO in the treatment groups: No ILBO: MFX vs. MACI, median 0.90 (IQR 0.4) vs. 1.07 (IQR: 0.3); ILBO: MFX vs. MACI, median 1.25 (IQR: 0.5) vs. 1.16 (IQR: 0.4).
Figure 6.
Figure 6.
ILBO after 60 months following MACI: After 3 months, no bony overgrowth was detectable. There were differences in the T2 values of the articulating cartilage (red) and the reference cartilage of the tibia (green).
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