ULTRASONOGRAPHY OF POSTOSTEOTOMY CYSTS

Three patients with postosteotomy ''cysts'' complicating limb-lengthen ing procedures are described. In all of the patients serial radiograph s after distraction failed to show new bone formation, but the cause o f the delay was not obvious from these images. Ultrasonography (US) re vealed a well-defined fluid collection as the factor responsible for d elayed consolidation. In one of the patients the fluid collection recu rred, in spite of several attempts at US-guided percutaneous aspiratio n. In all three patients compression of the bone ends followed by redi straction failed to yield any new bone at the distraction site. Two of the patients subsequently underwent bone grafting at the site of oste otomy. Postosteotomy ''cysts'' (which are not true cysts) constitute a n avoidable complication of distraction osteotomy resulting from inade quately supervised or too-rapid distraction. US is the imaging modalit y of choice for early detection of this complication.