Evaluation of Pre‐Operative Cartilage and Meniscus Ultrashort Echo Time T2 * as Biomarkers of Long‐Term Clinical Outcomes Following Anterior Cruciate Ligament Reconstruction

ABSTRACT Background Ultrashort echo time T2* (UTE‐T2*) mapping is sensitive to the composition of deep cartilage and menisci. UTE‐T2* elevations are common after anterior cruciate ligament (ACL) injuries, but their long‐term prognostic importance is unknown. Hypothesis Higher pre‐operative UTE‐T2* values will associate with greater symptoms and radiographic knee osteoarthritis (KOA) at long‐term follow‐up. Study Type Retrospective longitudinal cohort study using prospectively acquired baseline MRI and follow‐up clinical outcomes. Population Twenty‐two participants (13 female, mean [SD] age: 29 [9] years) with ACL reconstruction (ACLR). Field Strength/Sequence 3T, 3D acquisition‐weighted stack of spirals. Assessment Pre‐operative UTE‐T2* maps from participants who underwent ACLR (2009–2012) were compared to 11‐year follow‐up Knee Injury and Osteoarthritis Outcome Scores (KOOS), the Marx Activity Rating Scale scores, and radiographs. Statistical Tests Linear regression models assessed relationships between pre‐operative cartilage and meniscus UTE‐T2* and follow‐up KOOS Symptoms or Marx scores. Mann–Whitney U ‐tests assessed differences in pre‐operative UTE‐T2* by radiographic KOA status (Kellgren–Lawrence grade ≥ 2). Significance: two‐sided α < 0.05. Results KOOS and Marx scores were available for 22 participants at a median of 11.3 years (range: 10.3–12.4) after ACLR; radiographs were available for 11 participants. After adjustment for meniscus tear status, higher pre‐operative UTE‐T2* values in the deep medial femoral cartilage and medial meniscus were associated with worse KOOS Symptoms at 11 years (adjusted R 2 = 0.146–0.332). Higher femoral cartilage UTE‐T2* trended with lower Marx scores (adjusted R 2 = 0.208, p = 0.056), while higher posterior meniscus UTE‐T2* was associated with higher Marx scores (adjusted R 2 = 0.308). In the small radiographic subset, median pre‐operative posterior meniscus UTE‐T2* was 69% higher in patients with radiographic KOA. Data Conclusion Pre‐operative UTE‐T2* in medial compartment cartilage and menisci were associated with knee symptoms and activity levels 11 years after ACLR. These findings support the potential utility of elevated cartilage and meniscus UTE‐T2* as markers of pre‐osteoarthritis reflecting symptomatic and structural KOA risk after ACLR. Level of Evidence Level 3. Technical Efficacy Stage 3 Diagnostic Thinking.