Evaluation of analgesic effect of local administration of morphine after iliac crest bone graft harvesting: A double blind study

BACKGROUND AND OBJECTIVE: Pain is a complex process influenced by both physiological and psychological factors. In spite of an armamentarium of analgesic drugs and techniques available to combat post-operative pain, appropriate selection, and effective management for relief of post-operative pain still poses unique challenges. The discovery of peripheral opioid receptors has led to growing interest in the use of locally applied opioids (intra-articular, intra-pleural, intra-peritoneal, and perineural) for managing acute pain. As bone graft harvesting is associated with significant post-operative pain and there is a paucity of literature on the use of peripheral opioids at the iliac crest bone harvesting site, the present study was planned to evaluate the analgesic efficacy of local administration of morphine after iliac crest bone graft harvesting. MATERIALS AND METHODS: A total of 60 patients, 20-50 years of age scheduled to undergo elective surgery for delayed and non-union fracture both bone leg with bone grafting under general anaesthesia (GA) were randomly assigned to one of the four groups of 15 patients each: group 1: 2.5 ml normal saline (NS) +2.5 ml NS infiltrated into the harvest site at 2 sites + 1 ml NS intramuscularly (i/m); Group 2: 2.5 ml NS + 2.5 ml NS infiltrated into the harvest site at 2 sites + 5 mg morphine in 1 ml i/m.; Group 3: 2.5 mg (2.5 ml) morphine + 2.5 mg (2.5 ml) morphine infiltrated into the harvest site at 2 sites + 1 ml NS i/m; Group 4: 0.5 mg naloxone (2.5 ml) +5 mg (2.5 ml) morphine infiltrated into the harvest site at 2 sites + 1 ml NS i/m. Pain from the bone graft site and operative site was assessed for 24 h post-operatively. RESULTS: The patients who had received morphine infiltration (Group 3) had significantly less pain scores at the graft site at 4, 6, and 10 post-operative hours. They also had significantly less morphine consumption and overall better pain relief as compared to the other groups. CONCLUSIONS: Morphine administered peripherally provided better analgesia as compared to that given systemically and this effect was noticeable after 4 h post-operatively.