Hamstring pain after ACL repair surgery three weeks ago

Dear Ask The Doctor: I had ACL surgery three and a half weeks ago, and things have been going great. I almost have full extension back and I am (was) almost walking without a limp. However, I was recently walking up some stairs and stumbled a little bit. I tripped and I lifted up my left (injured) leg up a step and straightened it out to stop myself from falling. This action of straightening my leg AND pushing upwards to support my weight caused me to feel a tear. I felt the tear about 6 inches of the way up the back of my femur. If i'm not mistaken, this is the posterior end of the operation for my hamstring graft (where they removed the tendon). I now feel a strong pain to the touch of this part of my leg (6 inches up from behind my knee cap). I still have full extension (almost) but any sort of flexing hurts very badly. I'm walking with a much larger limp and the pain is rather severe. Any ideas as to what I did? If i'm correct, this isn't the new ACL that hurts, its the hamstring (or lack thereof) that is trying to heal. How is this going to affect my recovery, do you feel it is serious?

Dear Nicholas: You only have 3 weeks since your operation, you are very young and according to your description everything looks just fine, the guidelines and timeframe established in the rehab post ACL reconstructive surgery, about 4-6 weeks using crutches, non bearing weight period. After these weeks you will start progressively to bear weight on the affected knee, and more active range of motion exercises (flexion-extension), along with quads straightening, and hamstring stretches. It is expected some inflammation and pain the first weeks when you start the exercise routine, but you will control these with anti inflammatory medication (“Aleve”, “Motrin”). If after using all the rehab methods to control pain and taking anti inflammatory medication the pain has not improved I strongly recommend a knee re evaluation for the orthopedic surgeon.