Paramagnetic contrast medium in high‑level athletes with lower limb muscle injuries: can it make the return to sport safer reducing the recurrence rate?

Purpose: The aim is to investigate whether contrast medium can improve accuracy in the assessment of healing muscle injury in high-level professional athletes. Materials and methods: Our series is a retrospective study including the records of 22 players (mean age 28 ± 5 SD) with lower limbs muscle injuries type 3a (Mueller-Wohlfarth). All athletes received two MRIs: the day after the injury and before resuming heavy effort activities. Contrast medium uptake was measured in the second MRI by comparing the mean enhancement at the lesion site (ME) with that of the healthy contralateral muscle (HM). The result is a percentage referred to as muscular contrast index (MC index). The difference between the mean MC index value between athletes with and without re-injury was assessed with both the Mann–Whitney and the Kruskal–Wallis test. Results: Twenty-nine muscle injuries matched the inclusion criteria. The mean MC index values, adjusted for the variable of time elapsed between the last contrast examination and return to the field, were significantly different in the two study groups (p <.001). Conclusion: The contrast medium in the follow-up of muscle injuries may be useful in determining the degree of scar stability in a healing injury. Injuries with a high MC index were found to be ‘unstable’, with a higher rate of recurrence than those with a low MC index. Resumption of competitive activity after achieving not only clinical resolution but also a satisfactory MC index value may increase the safety of return to the field and reduce the recurrence rate.