We aren't doctors here and can't effectively provide a true diagnosis we can only provide support and guesses from personal experiences... BUT as a layman's guess I would say its either your meniscus or your acl. You will need to get an MRI to check for cartilage and other soft tissue damage. You can injure you meniscus by just a twist of the knee and since you are now putting more stress on the knee to compensate for the THR it wouldn't be to much of a stretch to have soft tissue damage. If its not the meniscus [which would be my first guess with a wheel spoke tear which I have had and they hurt. Because a pan handle causes your knee to lock up] I would think you over stretched and possibly caused a mild tear, severe strain/sprain to the ACL.
But if you aren't having much in the way of swelling I would lean more towards the meniscus injury. Either way you need an MRI or CT scan to see in there because an X-ray only shows bone and doctors seem to think that they can stop at an X-ray.
Another way you can do an at home test is sit on the edge of the bed, couch, ect and swing your leg out slowly from the knee. Does that hurt at the knee? I had the doctor press my knee and twist it around to see if it hurt and if there was any catching, clicking, or slipping when I had my knee injury. That was what he had me do. I am not saying have someone twist the knee who isn't a medical professional because you are injured and I don't want to see you get hurt more. Just support your hip and try to swing at the knee all the way up and see if that causes pain at the knee joint.
I would push for you to go to the doctor and request soft tissue imaging. I don't know what kind/type of hard ware they put into you so an MRI might not work but you should be able to get some kind of soft tissue scan for a diagnosis.
Best of luck
Crushed right meniscus, psvt tachycardia, ventricular tachycardia, L4-L5 bulging disc with tearing, pinched sciatic nerve left and right. L5-S1 disc gone bone remodeling with bone spur pressing on spinal cord. [Recommended spinal fusion] Modic type 2.
BACLOFEN, DICLOFENAC, PERCOCET, GABAPENTIN
If pain is weakness leaving the body then I must be a strong woman by now.