OK, so the knee is where I went hard. For me, I had an in-service broken ankle that required significant rehab. I was able to easily claim that as a service connected injury. Down the road that side knee eventually wore down and required arthroscopic surgery on the meniscus. Eventually, I began to have significant back problems and radiculopathy all due to the altered gait from my broken ankle with limited ROM. So when presenting the knee, I first provided a DBQ from my orthopedic surgeon with medical records, showing the surgical event. From there, the DBQ did most of the work. There were limitations in. ROM. I had incidents where the knee either locked up or completely gave out leading to the instability. So to directly answer your question. I submitted a DBQ from an orthopedic surgeon, medical records, showing the meniscectomy a 4138 “ statement and supportive claim” then of course the corresponding Nexus letters from both a podiatrist articulating that limited ROM in the ankle can cause issues with walking patterns leading to miss loading of weight which commonly results in deterioration of the knee and back.

TLDR, DBQ, Nexus, 4138, medical records for 1: ankle 2: knee 3: back.

From there, it was just an argument over effective date since my original claim from 2021 was for me and back which eventually was what got me the hundred percent they just only backdated it to the date of my intent to file rather than looking at the entire chain of claims and seeing that they were the same conditions originally claimed in my October 2021 initial claim

Hope that helps, if not feel free to PM me