What breed is your dog?
How recent was the surgery?
Try staying on softer surfaces.
Aquatic therapy can be very beneficial. If a small breed, you can use a bath tub.
Consult your Vet.
It's a Pomeranian. He had his surgery like mid-September.
I would think your Vet would have recommended post- op care.
Aside from that, I would try the aquatic therapy. Since it is a Pom, assuming you have a bath tub, perfect. You can get the water deep enough so he has to paddle. You can support him with your hand underneath or use something for a sling. This will help strengthen the muscles without overtaxing the surgery sight. At least once a day fir 10-15 mins or work up to that.
If he will tolerate a blow drier (I know they have a dense coat) blow dry him afterward. If not, you might consider a lion cut until he has recovered more and while doing the water therapy.