LON, lengthening over nail, still requires frames. Once lengthening is completed, the nail that was inserted in the first surgery is locked in place, then the frame is removed.
When we say internal lengthening, it means no frames. Devices like the Precice nail is lengthened via an external controller which activates a magnet inside the nail. This does indeed cost more, but you're paying for much improved patient comfort, especially for femurs.