RESUMEN
Low-intensity pulsed ultrasound has been reported to have a positive effect when applied during the consolidation phase of distraction osteogenesis and bone transportation, but the optimal application time has not been determined. We used a rabbit model to determine whether low-intensity pulsed ultrasound applied during the distraction and early consolidation phases of tibial lengthening would have a positive effect on regenerated bone formation. Radiographic analysis showed no differences in regenerated callus area or in percent of callus mineralization between treated and control tibias immediately after distraction or at 1, 2, or 3 weeks after distraction. Similarly, we observed no differences in structural stiffness or maximal torque to failure at 1.5 or 3 weeks after distraction. We detected no differences in bone mineral appositional rates or percent tissue composition measured histologically between groups. Our data do not support the application of low-intensity pulsed ultrasound to regenerated bone during distraction osteogenesis.
Asunto(s)
Callo Óseo/efectos de la radiación , Osteogénesis por Distracción/métodos , Osteogénesis/efectos de la radiación , Tibia/efectos de la radiación , Terapia por Ultrasonido/métodos , Animales , Callo Óseo/diagnóstico por imagen , Callo Óseo/fisiopatología , Osteogénesis/fisiología , Conejos , Radiografía , Tibia/fisiopatología , Tibia/cirugía , Soporte de PesoRESUMEN
To study the effect of applying pulsed electromagnetic fields (PEMF) during the consolidation phase of limb lengthening, a mid-tibial osteotomy was performed in 18 adult New Zealand White rabbits and an external fixator was applied anteromedially. Animals were randomly assigned to treatment and control groups. After a 7-day latency period, the tibiae were distracted 0.5 mm every 12 h for 10 days. The treatment group received a 20-day course of PEMF for 60 min daily, coinciding with initiation of the consolidation phase. The control group received sham PEMF. Radiographs were performed weekly after distraction. Animals were euthanized 3 weeks after the end of distraction. Radiographic analysis revealed no significant difference in regenerate callus area between treatment and control tibiae immediately after distraction, at 1 week, 2 weeks, or 3 weeks after distraction ( p = 0.71, 0.22, 0.44, and 0.50, respectively). There was also no significant difference in percent callus mineralization ( p = 0.96, 0.69, 0.99, and 0.99, respectively). There was no significant difference between groups with respect to structural stiffness ( p = 0.80) or maximal torque to failure ( p = 0.62). However, there was a significant positive difference in mineral apposition rate between groups during the interval 1-2 weeks post-distraction ( p < 0.05). This difference was no longer evident by the interval 2-3 weeks post-distraction. While PEMF applied during the consolidation phase of limb lengthening did not appear to have a positive effect on bone regenerate, it increased osteoblastic activity in the cortical bone adjacent to the distraction site. Since the same PEMF signal was reported to be beneficial in the rabbit distraction osteogenesis when applied during distraction phase and consolidation phase, application of PEMF in the early phase may be more effective. Further work is necessary to determine optimal timing of the PEMF stimulation during distraction osteogenesis.
Asunto(s)
Regeneración Ósea/efectos de la radiación , Campos Electromagnéticos , Osteogénesis por Distracción , Animales , Conejos , Tibia/crecimiento & desarrolloRESUMEN
BACKGROUND: Autogenous bone grafting is considered the standard in management of bony defects but has some disadvantages, including limited source of graft material, especially in children. This study represents an attempt to regenerate bone at the donor site of iliac bone grafts using the guided bone regeneration principle for future use in multistage bone reconstruction by grafting. METHODS: Critical size defects were created in 24 iliac bones of 12 skeletally mature New Zealand White rabbits. Defects in group 1 (n = 12) were covered with inverted U-shaped resorbable mesh (space maintainer) and polytetrafluoroethylene membranes underneath the periosteum. In group 2 (n = 6), inverted U-shaped resorbable mesh was used alone (positive control). In group 3 (n = 6), neither resorbable mesh nor polytetrafluoroethylene membranes were used (negative control). An unpaired t test was used for comparison between each two groups. RESULTS: Plain radiographs and contact microradiographic studies showed that bone regeneration was significantly higher in group 1 and group 2 than in group 3 (p < 0.001). There was no significant difference between group 1 and group 2 regarding density. CONCLUSIONS: The periosteum acted as an ideal membrane for guided bone regeneration so that the polytetrafluoroethylene membranes could be used only to compensate for the deficient periosteum. Space maintenance was essential for bone regeneration.
Asunto(s)
Regeneración Ósea , Trasplante Óseo , Ilion/trasplante , Periostio/fisiología , Animales , Membranas Artificiales , Conejos , Trasplante AutólogoRESUMEN
Distraction osteogenesis is a powerful tool for addressing segmental defects and limb-length discrepancies. Guidelines for the rate and rhythm of distraction have been described. The possibilities of early consolidation or nonunion threaten clinical success. A quantifiable method for monitoring the distraction gap would be useful. Previous methods to measure regenerate callus stiffness have not gained widespread clinical acceptance, largely because of cumbersome instrumentation. A rabbit tibial lengthening model was used to show the clinical utility of a digital torque wrench in monitoring axial stiffness of the regenerate bone callus during distraction osteogenesis. We confirmed the linear increase in peak torsional stiffness with time, which has been reported by others. This relationship may prove to be a useful clinical adjunct in guiding the rate and rhythm of distraction during limb lengthening.