Objective: To assess the clinical effectiveness of dexamethasone wound infiltration post lumbar discectomy.

Design: A prospective, double blind, randomised study comparing morphine consumption in two groups of patients in elective lumbar spine surgery via the posterior approach.

Subjects: There were forty patients divided into two randomly selected groups, one received postoperative wound infiltration with dexamethasone, the other with saline. Their morphine usage was measured.

Outcome measures: These included levels of morphine use postoperatively, pain scores and length of hospital stay.

Results: There was no statistically significant difference between postoperative morphine consumption in the two groups or in the length of hospital stay. There appeared to be improvement in pain scores with dexamethasone. There were no complications.

Conclusion: Postoperative wound infiltration with dexamethasone may result in some subjective improvement in pain, but none in analgesic consumption. Despite the lack of complications the subjective benefits do not outweigh the risks in the absence of objective improvement in pain.