The causes of failure of lumbar transpedicular spinal instrumentation and fusion - A prospective study

A prospective study was made of 101 patients who underwent transpedicular spinal instrumentation and fusion of the lumbar spine. All were reviewed by art independent observer: The objectives were to determine the causes of clinical failure and to recommend preventive measures. Forty-two primary and 59 revision operations were performed. The average age was 46 years and follow up 4 years. The variable screw placement and Cotrel-Dubousset systems were used Posterior lumbar interbody fusion was carried out in 24 patients. The outcome was satisfactory after primary operations in 67% and after revisions in 46%. Nerve root injuries due to screw placement occurred in 4% (2% permanent and 2% transient). Instrumentation-induced foraminal stenosis developed in 2%. Proper surgical technique can avoid these complications. Predictive factors for failure are: abnormal psychology, symptomatic epidural fibrosis, inadequate decompression of lateral stenosis, surgical complications and the use of allografts.