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

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 R2 = 0.146-0.332). Higher femoral cartilage UTE-T2* trended with lower Marx scores (adjusted R2 = 0.208, p = 0.056), while higher posterior meniscus UTE-T2* was associated with higher Marx scores (adjusted R2 = 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.