Source : Webster's Revised Unabridged Dictionary (1913)

Diastasis \Di*as"ta*sis\, n. [NL. See {Diastase}.] (Surg.)
   A forcible of bones without fracture.

Source : WordNet®

diastasis
     n : separation of an epiphysis from the long bone to which it is
         normally attached without fracture of the bone
     [also: {diastases} (pl)]