Results and complications after posterior lumbar spondylodesis with the "Variable Screw Placement Spinal Fixation System".

Between March 1988 and March 1990, 45 patients underwent a spondylodesis using transpedicular screws and plates of the "Variable Screw Placement Spinal Fixation System". The indications for operation were spondylolisthesis (13), spondylolisthesis plus discopathy at the adjacent level (4), degenerative discopathy (13), pseudarthrosis after interbody fusion (7), disc herniations (4) and disc herniations plus degenerative discopathy of the adjacent segment (4). In 1992, 43 patients were available for follow-up. The mean follow-up was 3.85 years. Side effects or complications of a more permanent character were seen 25 times in 43 patients. Eight patients had evidence of screw failure: loosening (5), fracture (2), and malposition (1). Complications, screw failure and reoperation all adversely affected clinical outcome. Overall only 60% of the patients reported a positive clinical outcome at follow-up. In our opinion transpedicular instrumentation is a logical system to provide rigid stabilisation, but it has a high learning curve. The original V.S.P. system with its bulky plates and screws appears to be particularly prone to giving a high rate of unwanted side effects not offset by a high clinical success rate.