The lower radial epiphysis unites at about twenty years. Separation of this epiphysis, therefore, is seen prior to this time. The trauma which produces this injury is identical with that which produces a Colles' fracture in an older individual.
There are several essential differences between the Colles' fracture and separation of the lower radial epiphysis:
(a) In fully 50 per cent, of Colles' fractures, the styloid of the ulna is broken. In separation of the epiphysis, the ulna is commonly broken, but generally at a higher level. There is usually no displacement of the ulnar fragment.
(b) In Colles' fracture there is commonly radial deviation of the lower fragment, which may be very difficult to correct, and which may produce the end-result of radial deviation of the hand in spite of active attempts to prevent this occurrence. This is probably dependent on crushing of the fine bony structure at the
ISADORE ZADEK. TREATMENT OF EPIPHYSEAL SEPARATION OF THE LOWER END OF THE RADIUS. Arch Surg. 1925;10(3):969–982. doi:10.1001/archsurg.1925.01120120157006