Assessment of early cartilage degeneration after slipped capital femoral epiphysis using T2 and T2* mapping

Abstract

Background: T2 and T2* mapping are novel tools to assess cartilage quality.

Purpose: To evaluate hip cartilage quality in the long-term follow-up of patients with slipped capital femoral epiphysis (SCFE) with T2 and T2* mapping.

Material and methods: Thirty-three patients (19 men, 14 women, mean age 24 ± 6.0 years, range 18-51 years) with a history of SCFE in 41 hips and 10 healthy controls (seven men, mean age 22 ± 4 years) were included. Follow-up period was 12 ± 6 (range 4-39 years) years. Coronal T2 and T2* mapping were performed on a 1.5 T scanner. T2 and T2* values of the hip articular cartilage were determined in the medial, central, and lateral portion of the hip within the weight bearing zone. Clinical symptoms including pain were assessed with the Harris hip score. Statistical analysis was performed using Mann-Whitney U test and Spearman rank sum test.

Results: In hips after SCFE T2 (central portion: 25.71 ms ± 4.84 ms vs. 29.71 ms ± 7.04 ms, p<0.05) and T2* (central portion: 20.76 ms ± 3.17 ms vs. 23.06 ms ± 2.68 ms, P<0.01) of cartilage were significantly lower, compared to controls. The differences were most apparent in the lateral portion of the hip articular cartilage. Abnormal cartilage T2 and T2* were not associated with hip pain or impaired hip function. SCFE was unilateral in 23 cases (70%). In the patients' unaffected hips without SCFE, areas of significantly reduced T2 (central portion: 26.07 ms ± 4.27 ms, P<0.05) and T2* (lateral portion: 23.23 ms ± 2.45 vs. 25.11 ms ± 3.01 ms, P<0.05) were noted.

Conclusion: T2 and T2* mapping of the hip in patients after SCFE are significantly different from healthy controls and may offer additional information about cartilage quality.