Obtaining an air physiogram improves visualization of the resected physis and allows the surgeon to assess whether a sufficient amount of growth plate has been removed during percutaneous drilling epiphysiodesis. From 2008 through 2011, the air physiogram technique was used in 37 percutaneous epiphysiodesis procedures about the knee (17 femora, 20 tibiae) in 31 children. Average follow-up was 41 months (range, 19-70 months). Thirty-six of 37 limb segments achieved radiographic fusion after the initial procedure. One tibia appeared to be partially fused and underwent revision epiphysiodesis. At final follow-up, all limb segments had successful epiphysiodesis and showed radiographic evidence of fusion.