My 17 Year Old Son Had A Partial Menisectomy In

My 17 year old son had a partial menisectomy in January - they also removed a lot of brown tissue the ortho felt was PVNS. The lab says it was a hemangioma. He is still swollen and having pain. We've been to a rheumatologist who knew nothing about PVNS, but the bloodwork came back good and a contrast MRI was inconclusive. Our ortho wants to do a biopsy removing more tissue and has discussed a full synovectomy ... I trust this guy (this was the second meniscus tear, and right now he's treating my son for a boxer's fracture), but I'm a little scared ...