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

Abstract

AbstractBackgroundIn 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.PurposeTo examine short‐term consequences of single first‐time LPD in teenagers by T2 mapping of the patellar‐cartilage state.Study TypeProspective.Population95 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).Field Strength/Sequence3.0 T; axial T2 mapping acquired using a 2D turbo spin‐echo sequence.AssessmentMRI 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.Statistical TestsANOVA analysis with Tukey's multiple comparison test, one‐vs.‐rest logistic regression analysis. The threshold of significance was set at P < 0.05.ResultsIn 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).Data ConclusionThe study revealed substantial difference in T2 changes after LPD between medial and lateral areas of patellar cartilage.Evidence Level2Technical Efficacy Stage2