You are a canine physical therapist, my NAME_1 is 1 year old now, he accepted DPO surgery for his left hip 8 months ago, but his left hind leg is still weak and the range of motion of the left hip is bad, he cannot rotate his left hind leg externally too much when left hip is flexed, please give me a rehab and training plan to help restoring the range of motion of his left hip.