T2 mapping of acetabular cartilage in patients with primary osteoarthritis and DDH-induced secondary osteoarthritis analyzed with 7 Tesla micro-MRI

The aim of our study was to compare acetabular cartilage affected by primary and DDH-induced secondary osteoarthritis (OA) using T2 mapping, which gives us information about cartilage water and collagen content, and the orientation of collagen fibrils. Samples of the osteochondral unit were obtained intraoperatively during total hip arthroplasty from the acetabulum of 15 patients with primary OA (pOA-Ac) and 15 patients with DDH-induced secondary OA (sOA-Ac). The samples were then scanned on a 7 Tesla micro-magnetic resonance imaging (micro-MRI) machine and the T2 values of all samples were calculated. The results were compared using a t-test. The average T2 values for the sOAAc and pOA-Ac groups were 57.28±31.87 ms and 37.54±11.17 ms, respectively. The calculated p-value was 0.019, making results statistically significant at p<0.05. This is one of the first studies performed ex vivo on the acetabular cartilage of human dysplastic hips, using a 7 Tesla MRI machine. Our results show that acetabular cartilage in DDH-induced secondary OA is more damaged than in primary OA, and offer 7 Tesla T2 reference values of acetabular cartilage for both the primary and DDH-induced secondary OA.