This issue is with any old injury to the digital flexor tendon it can happen again and you must be on the preventative side of life. The tendon may be healed but it’s not as strong as it was originally so the horse is most likely to have this injury re-occur if strained. I would make it a rule to always ride him in relentless sport boots these boots are designed to prevent over flexion and re-injuring the tendon. My mare had the same injury I gave here 4 months off and lineament wrapped her for a month. She was started back slow but I will not allow her to be over worked or ridden with out the sport boots or proper polos. I started from scratch on jumping again and if she goes to a show she then gets 2 days off. IF the horse re-injures it I would give him 6 months off one month of support wraps with lineament on the bad leg to draw out inflammation cold hosing and then finally he should be retired to a life of light trail riding. Even if he comes back sound it would be best for him after injuring it twice to have a different job.