The Journal of Bone and Joint Surgery, Vol 75, Issue 2 162-167, Copyright © 1993 by Journal of Bone and Joint Surgery, Inc
Early failure of short-segment pedicle instrumentation for thoracolumbar fractures. A preliminary report
RF McLain, E Sparling and DR Benson
Department of Orthopaedic Surgery, University of California, Davis 95817.
The results after treatment of fifty-two lumbar and thoracolumbar fractures
with Cotrel-Dubousset instrumentation were reviewed as part of an ongoing
study. Nineteen patients (average duration of follow-up, fifteen months)
had been managed with short-segment pedicle-screw instrumentation. This
preliminary report outlines the complications and pitfalls identified
during the initial healing phase in this subgroup of patients. There were
no neurological or vascular injuries due to placement of the pedicle
screws, but ten patients had some form of failure of the fixation during
the early period of healing. Failure of the fixation was manifested in
three ways: progressive kyphosis secondary to the bending of screws (six
patients), kyphosis secondary to osseous collapse or vertebral translation
without bending of the hardware (three patients), and segmental kyphosis
after a caudad screw in the lumbar construct broke (one patient, who had
had a combined instrumentation for multiple fractures). Untreated anterior
instability, and pre-stressing of the screws when the rods were contoured
in situ, resulted in a high rate of failure. The high rate of failure of
the hardware associated with this fixation construct suggests that
posterior screw fixation alone may not be adequate when Cotrel-Dubousset
instrumentation is used for short-segment lumbar arthrodeses. Bent screws
or measurable kyphosis did not always herald a clinical failure, but
patients who had progressive kyphosis of more than 10 degrees had
substantially more pain than did those who had little or no progression.
The results reported here are preliminary, and speculation as to the
importance of these findings and as to the long-term outcome in these
patients would be premature.(ABSTRACT TRUNCATED AT 250 WORDS)