So, Surgeon isn't sure what the problem is, but my own reading/investigation makes me think my original idea was correct, and a few cases documented on line with similar.
As far as walking, mobility, range of movement I've been great from around week 2 with little pain in joint area, just a few joint aches & knee pains, and been able to put my own shoes & socks on from about week 5 and at week 9 now can cut my toenails again.
The problem has been this large lump then followed by the the infected skin area with it then popping and drainage.
This was large lump that formed which I thought was a Seroma, not Hematoma, about size of half a grapefruit.
This is a diagram of a Seroma post operation
That never really went down, I mentioned about drainage of the lump but Surgeon said they don't like to go back in after stitching and risk infection and normal, and body will resolve over time, like a bruise.
Pressure and hardness in area was rock solid.
As a reminder, this then developed this angry looking area on the top of this lump
Then it popped with mild drainage of a clear/yellow/watery fluid which I'm sure is called Serous Fluid and is a natural, healthy part of healing and basically plasma, proteins, sugars.
I've been having to put on dressings about 3 times per day to capture this drainage and protect the area, and had some fluid leak out between bandage changes.
So, no real leakage over night, changed the dressing again this morning and felt up for a fast long walk with wife & dog.
Was all going great on a lovely sunny morning and then felt wet down side of my leg and Boom!!!
Flooded out with this Serous fluid and I'm sure now this is the big lump that has just pumped out the fluid with the movement of the leg. The hard area now seems softer, more mushy, less taught with most of lump gone so hopefully its sorting itself by just self draining.
Posting all this as may help others who may have similar now or in the future. Half-way through anti-biotics though I don't think needed as no sign of infection in the fluid, and another follow-up with Surgeon on Monday.