Thanks for your question. I assume that the word 'reduction' is meant to be 'retraction' from your MRI report. Complete hamstring avulsions (ie all three tendons have come off the ischial tuberosity) often result in some retraction down the leg. MRI is the best study and is very accurate for this injury, so unfortunately it's unlikely to be a false positive (remember that other muscles other than your hamstrings assist in knee flexion).
Whilst I don't operate on these injuries any more, I have done extensive research on proximal hamstring avulsions. Patients with incomplete proximal tears with no retraction often do well with conservative treatment, but complete avulsions with retraction do best with surgery to repair the tendons to their bony origin. Injuries operated on within 3 months do better than chronic injuries repaired late.
Because this operation is not commonly done by many orthopaedic surgeons, it's important to find someone who is very familiar with this injury. David Wood in Sydney and Peter Annear in Perth are two surgeons who have done more of these operations than most orthopaedic surgeons in the world.
A Novel Technique for Proximal Hamstring Tendon Repair. Blakeney WG, Zilko SR, Chiri W, Annear P. Advances in Orthopedic Surgery, Vol 2014, Article ID 891875. doi:10.1155/2014/891875