Abstract
Background
Distraction Osteogenesis can be complicated by regenerate insufficiency resulting in prolonged implant usage or regenerate failure with malalignment or fracture. Experimental evidence has demonstrated that bisphosphonates may mediate improved local limb BMD and regenerate strength.
Methods
A prospective series of 14 patients over 5 years. One cohort (Group A) of these cases presented with established regenerate insufficiency leading to consideration for surgical intervention. Patients received a therapeutic regime of intravenous bisphosphonate A further cohort (Group B) of 7 patients was commenced on bisphosphonate therapy at an earlier stage, prior to the regenerate maturation phase.
Results
Mean age at primary surgery was 11.6 years (3-17 yrs) with a minimum follow-up of 12 months after fixator removal. The sites of regenerate insufficiency were tibia (12) and distal femur (3), with 1 patient undergoing both femoral and tibial lengthening. Mean fixator time was 108 days prior to treatment for a mean lengthening of 5.3 cm. At time of treatment measurements demonstrated a reduced BMD in the bone, mean 44% (39-58%) of the normal limb, the primary consolidation index was high at 40.5 (46-68) days/cm, reflecting observed regenerate insufficiency. Significant increase in regenerate bone mass and mineral density was observed after the first dose of intravenous bisphosphonate. No significant systemic complications were encountered. After a mean 130 days (range 103-231 days) of therapy the bone consolidated to unencumbered full weight bearing, final healing index of 82 days/cm (Range 67-108days/cm). Cases demonstrated a rapid and sustained improvement in local BMD (increasing to mean 78% of the normal side). Remodelling was seen radiologically from 12 months post-therapy. However, subsequently, one femoral regenerate fractured and required intramedullary nail stabilisation.
Conclusion
This is early clinical evidence that Bisphosphonate therapy has potential therapeutic benefit in managing regenerate insufficiency and counteracting local osteopenia in distraction osteogenesis.
