Characteristics of intramuscular increased signal intensity on fluid-sensitive MRI sequences of initial injury and at return to play (RTP)
| Initial injury | RTP | |||
|---|---|---|---|---|
| Intramuscular increased signal intensity | ||||
| Present | 53/53 | 100% | 47/53 | 89% |
| Absent | 0/53 | 0% | 6/53 | 11% |
| Involved muscles | ||||
| Biceps femoris long head | 44/53 | 83% | 39/47 | 83% |
| Biceps femoris short head | 0/53 | 0% | 0/47 | 0% |
| Semitendinosus | 2/53 | 4% | 1/47 | 2% |
| Semimembranosus | 9/53 | 17% | 8/47 | 17% |
| Grades | ||||
| 1 | 27/53 | 51% | 37/47 | 79% |
| 2 | 26/53 | 49% | 10/47 | 21% |
| 3 | 0/53 | 0% | 0/47 | 0% |
| Extent of increased signal intensity | ||||
| Mean longitudinal length (SD) | 132 mm | ± 62 | 77 mm | ±53* |
| Median involved cross-sectional muscle area (minimum–maximum) | 28% | 1–100 | 8% | 0–90* |
*Statistically significant difference between initial injury and RTP: p=0.000.