External fixation as a test for instability after spinal fusion L 4-S 1. A case report

A case presented with severe backache after fusion of the L 4-S 1 levels; the patient became immediately painfree after external transpedicular fixation between L 4 and the sacrum. The device was kept in place for 10 weeks. After an additional 4 weeks the patient was able to return to his work after several years of sick-leave. The case indicates instability as a cause of backache. Painful nonunion of a fusion can be present in spite of signs of healing on radiographs and CT-scan. External transpedicular fixation may be a good tool in assessing instability of the lower lumbar spine.