too had a very similar problem but was pre-TKR due to a asymmetrical compensation injury because of my right knee's arthritic degradation. A
I too had horrible sciatica like
@Axx72 but it was before my PKR due to asymmetric degradation of the knee putting pressure on my back.
I also have lumbar arthritis on MRI and nerve compression.
I would ask for an MRI of your back to see how much this is contributing.
Thankfully mine improved after surgery but it was miserable and in my case worse than the knee pain.
Other things that helped me were:
Gabapentin from my GP for nerve pain
A thick memory foam sciatica cushion shaped like a horseshoe that took pressure off my sciatic nerve.
Spiky pilates balls to roll on and massage the affected area
Pilates stretches and back strength exercises- although these were difficult when the pain was bad.
My surgeon said that in my case a steroid injection into the back would help if it didn't correct with my knee surgery.
I am sorry you are in pain. I would push for further investigation on the back and hip if it doesn't settle.