Late results of removal of the loose posterior element (Gill's operation) in the treatment of lytic lumbar spondylolisthesis.

This study presents the late results of the Gill operation for the treatment of lytic lumbar spondylolisthesis in 75 patients. The observation time ranged for 5 to 20 years, averaging 12 years. Primary results were excellent, good or fair in 83 per cent at the end of 1 year. However, the figures dropped to 75 per cent when the cases were evaluated 5 or more years after operation. The worsening of the results during the observation time seems to depend on the degeneration of the intervertebral disk. Progression of olisthesis was observed in 27 per cent of the patients, usually in connection with progression of disk degeneration. This progression did not affect the clinical result of treatment. Nine patients had a lumbar disk herniation, 8 from a segment above the level of defect and 1 at that level. On 9 patients a fusion was later performed as a secondary operation. In these the late result was still unsatisfactory in all but 2. The operation is contraindicated in adolescents except in exceptional cases with signs of compression of the cauda equina. It is not recommended for patients below the age of 30 years. The main indication for the Gill operation is painful spondylolisthesis with nerve root symptoms in patients over 40 years of age.