T₂ Mapping of Patellar Cartilage After a Single First-Time Episode of Traumatic Lateral Patellar Dislocation

In most cases, lateral patellar dislocation (LPD) is accompanied by chondral injury and may initiate gradual degeneration of patellar cartilage, which might be detected with a T₂ mapping, a well-established method for cartilage lesions assessment.

To examine short-term consequences of single first-time LPD in teenagers by T₂ mapping of the patellar-cartilage state.

Prospective.

95 patients (mean age: 15.1 ± 2.3; male/female: 46/49) with first-time, complete, traumatic LPD and 51 healthy controls (mean age: 14.7 ± 2.2, male/female: 29/22).

3.0 T; axial T₂ mapping acquired using a 2D turbo spin-echo sequence.

MRI examination was conducted 2-4 months after first LPD. T₂ values were calculated in manually segmented cartilage area via averaging over three middle level slices in six cartilage regions: deep, intermediate, superficial layers, and medial lateral parts.

ANOVA analysis with Tukey's multiple comparison test, one-vs.-rest logistic regression analysis. The threshold of significance was set at P < 0.05.

In lateral patellar cartilage, a significant increase in T₂ values was found in deep and intermediate layers in both patient groups with mild (deep: 34.7 vs. 31.3 msec, intermediate: 38.7 vs. 34.6 msec, effect size = 0.55) and severe (34.8 vs. 31.3 msec, 39.1 vs. 34.6 msec, 0.55) LPD consequences as compared to controls. In the medial facet, only severe cartilage damage showed significant prolongation of T₂ times in the deep layer (34.3 vs. 30.7 msec, 0.55). No significant changes in T₂ values were found in the lateral superficial layer (P = 0.99), whereas mild chondromalacia resulted in a significant decrease of T₂ in the medial superficial layer (41.0 vs. 43.8 msec, 0.55).

The study revealed substantial difference in T₂ changes after LPD between medial and lateral areas of patellar cartilage.

2 TECHNICAL EFFICACY STAGE: 2.