This is a prospective bi-centric study, which evaluate the evolution of RMI signal of transplant till 12 months after ligament plasty surgery.

As the primary objective, the study aims to define the post-operative timeframe needed to obtain an optimal quality of repair, especially in their restarting of sportive activities, by analysis of RMI signal and biomechanic features modifications.

As secondary objectives, the study aims to:

• study the correlation between the RMI signal of plasty and the Young's modulus;
• study the evolution of RMI of plasty at M3, M6 and M12;
• study the evolution of Young's modulus at M3, M6 and M12;
• evaluate the reproductibility between 2 lector of RMI measurements;
• evaluate the reproductibility between 2 lector of elastography measurements of LTFA;
• evaluate the optimal delay of return to sport after ligament plasty surgery of ankle;
• develope a score of type SNQ for ankle ligament plasty surgery;
• evolution of AOFAS and EVA scores.

The eligible patients will be enrolled in the department of orthopaedic surgery of Ambroise Paré hospital, each patient will undergo a 12-months follow-up in the department of orthopaedic surgery in Armand Trousseau hospital for the elastography evaluations.

Inclusion Criteria:

• Patient treated priorly by ligament plastic surgery of lateral ankle plane under arthroscopy;
• Affiliated to or covered by the French social security - welfare system in France;
• Have provided written informed consent for the study;
• Be >/= 18 years of age on day of signing informed consent.

Exclusion Criteria:

• Patients who undergo iterative surgery or have history of contralateral surgery;
• Patient under guardianship or curatorship;
• Unable to understand the proposed study or provide written informed consent for the study;
• Foreign patients under AME schema, a medical help from the state in France;
• Pregnant or breastfeeding woman;
• Patient refusal.

Patients underwent a ligament plastic surgery of lateral ankle plane under arthroscopy.