Thanks for the query. Given your prior knee injury
, with recurrence and the recommendation of getting an MRI, with now sudden buckling of the same leg with pain, makes us think about a more severe structural injury in that knee, specifically rupture of one of the meniscus
or the collateral ligaments of the knee. You should be seen promptly and perhaps again, it will be suggested that an MRI be obtained. An orthopedist or a Sports Medicine
specialist would be the go-to doctors to examine you.
Hope that helps, wish you the best,
Dr Brenes-Salazar MD
Mayo Clinic MN