Suggest Treatment For Knee Pain While Going Downhill

Last August I damaged my knee. I completely ruptured my ACL and tore the meniscus as well as hyperextending the MCL and PCL. It took two months before I was able to have surgery and in that time I lost ROM due to inactivity. The ACL was replaced and meniscus was repaired. 12 weeks later I went back into surgery for manual manipulation as I was not gaining ROM with PT alone. It was discovered that the ACL was discovered that the new ACL was 5% torn and the meniscus was torn again. Both were repaired again. Now 6 months later I still do not have full ROM and am wondering what options I should be considering to gain full ROM again. I am a 42 year old male and very active with walking and mountain hiking over rough uneven ground. I am able to go uphill for quite a while but going down hill is very painful.