Early knee changes in dancers identified by ultra-high-field 7 T MRI

Abstract

We aimed to determine whether a unique, ultra-high-field 7 T magnetic resonance imaging (MRI) scanner could detect occult cartilage and meniscal injuries in asymptomatic female dancers. This study had Institutional Review Board approval. We recruited eight pre-professional female dancers and nine non-athletic, female controls. We scanned the dominant knee on a 7 T MRI scanner using a three-dimensional fast low-angle shot sequence and a proton density, fast spin-echo sequence to evaluate cartilage and menisci, respectively. Two radiologists scored cartilage (International Cartilage Repair Society classification) and meniscal (Stoller classification) lesions. We applied two-tailed z- and t-tests to determine statistical significance. There were no cartilage lesions in dancers or controls. For the medial meniscus, the dancers demonstrated higher mean MRI score (2.38 ± 0.61 vs 1.0 ± 0.97, P < 0.0001) and higher frequency of mean grade 2 lesions (88% vs 11%, P < 0.01) compared with the controls. For the lateral meniscus, there was no difference in score (0.5 ± 0.81 vs 0.5 ± 0.78, P = 0.78) in dancers compared with the control groups. Asymptomatic dancers demonstrate occult medial meniscal lesions. Because this has been described in early osteoarthritis, close surveillance of dancers' knee symptoms and function with appropriate activity modification may help maintain their long-term knee health.

Keywords: 7 Tesla; MRI; dancers; knee; meniscus.

Figure 1

Sagittal 7T MR images from a dancer (left panel) and a control (right panel) demonstrating normal articular cartilage along both the femoral and tibial articular surfaces (TR/TE = 26 ms/5.06 ms, 0.234 mm × 0.234 mm × 1 mm).

Figure 2

Sagittal 7T MR image (TR/TE = 3270 ms/26 ms, 0.357 mm × 0.357 mm × 3 mm) demonstrating Stoller grade 3 (left panel) and grade 2 (middle panel) signal within the posterior horn of the medal meniscus in asymptomatic dancers. The meniscus from a healthy control is shown for comparison (right panel).