Abstract
Introduction: Nonsteroidal anti-inflammatory medications such as Ibuprofen are commonly used to aid in the management of chronic pain in both children and adults. These medications are known to retard fracture consolidation and inhibit the formation of heterotopic bone in susceptible patients. We wished to determine the deleterious effects, if any, of the administration of therapeutic doses of Ibuprofen on the strength of regenerate bone in a caprine model.
Method: Twelve skeletally immature cross-bred goats were divided into two groups. In both groups, a standard four-ring, 6-wire Ilizarov apparatus was fixed to the tibia of one hindlimb and mid-diaphyseal corticotomy performed. After a five-day latency period, the operated tibiae were lengthened to 20% of their original length at rate and rhythm of 0.25mm TID. Consolidation time was standardized at 80 days. Group I received Ibuprofen at a dose of 20mg/kg BID PO during the entire postoperative period. Group II received no additional medication, and served as the control group. The animals were monitored for gatrointestinal intolerance, blood dyscrasias, and blood levels of Ibuprofen throughout the experiment. At the end of consolidation, the twelve lengthened tibiae and the contralateral tibiae were harvested for mechanical testing.
Results: In the medicated group, no adverse affects on the gastrointestinal or hematopoietic organ systems were identified. Blood Ibuprofen levels remained in the low therapeutic range during the course of the experiment (average levels 28.9 ug/ml at 1.5 hrs, 15.1ug/ml at 4 hrs., and 2.6 ug/ml at 8 hrs., after oral administration of Ibuprofen) .
One nonunion developed in each of the two treatment groups, and was unsuitable for mechanical testing. The remaining 22 tibiae (10 lengthened, and 12 contralateral unoperated, tibiae) were torqued to failure on the MTS testing machine. There were no significant differences between the unoperated tibiae of the Ibu-profen group and the unmedicated group measuring torsional toughness, stiffness, and strength. Similarly, there were no differences detected using these parameters between the lengthened tibiae of the medicated and unmedicated groups.
No adverse systemic affects were noted during the course of this experiment, in which low therapeutic levels of Ibuprofen were maintained for an average of 120 days. No affect on the torsional strength of the unoperated tibia was detected. No adverse affect on the torsional strength, stiffness, or toughness of the regenerate of the medicated group was noted compared to the control group.
Conclusions: The chronic administration of Ibuprofen was well-tolerated and did not adversely affect the strength of untreated or lengthened tibiae in this model.
The abstracts were prepared by Professor Jegan Krishnan. Correspondence should be addressed to him at the Flinders Medical Centre, Bedford Park 5047, Australia.
