Effect of Arterial Deprivation on Growing Femoral Epiphysis: Quantitative Magnetic Resonance Imaging Using a Piglet Model

OBJECTIVE: To investigate the usefulness of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion MRI for the evaluation of femoral head ischemia. MATERIALS AND METHODS: Unilateral femoral head ischemia was induced by selective embolization of the medial circumflex femoral artery in 10 piglets. All MRIs were performed immediately (1 hour) and after embolization (1, 2, and 4 weeks). Apparent diffusion coefficients (ADCs) were calculated for the femoral head. The estimated pharmacokinetic parameters (Kep and Ve from two-compartment model) and semi-quantitative parameters including peak enhancement, time-to-peak (TTP), and contrast washout were evaluated. RESULTS: The epiphyseal ADC values of the ischemic hip decreased immediately (1 hour) after embolization. However, they increased rapidly at 1 week after embolization and remained elevated until 4 weeks after embolization. Perfusion MRI of ischemic hips showed decreased epiphyseal perfusion with decreased Kep immediately after embolization. Signal intensity-time curves showed delayed TTP with limited contrast washout immediately post-embolization. At 1-2 weeks after embolization, spontaneous reperfusion was observed in ischemic epiphyses. The change of ADC (p = 0.043) and Kep (p = 0.043) were significantly different between immediate (1 hour) after embolization and 1 week post-embolization. CONCLUSION: Diffusion MRI and pharmacokinetic model obtained from the DCE-MRI are useful in depicting early changes of perfusion and tissue damage using the model of femoral head ischemia in skeletally immature piglets.

Effects of Multiple Drilling on the Ischemic Capital Femoral Epiphysis of Immature Piglets

PURPOSE: This study investigated the effects of multiple drilling on the immature capital femoral epiphysis following ischemic injury in a piglet model. MATERIALS AND METHODS: Ischemic necrosis of capital femoral epiphysis was induced bilaterally in 12 piglets using a cervical ligation method. Three weeks later, medial, central, and lateral 3 drill holes were made on the left femoral head using 0.062" K-wire. At 3, 6, 9, and 12 weeks following the multiple drilling, femoral heads were harvested from each three piglets. On histologic examination, percent of revascularization, percent of osteoblast surface, capital femoral epiphyseal quotient and proximal femoral growth plate height were evaluated. Untreated right femoral heads served as control. RESULTS: While percent of revascularization of left capital femoral epiphysis with multiple drilling was significantly higher than untreated control side (p<0.001), percent of osteoblast surface, capital femoral epiphyseal quotient and proximal femoral growth plate height showed no significant difference. CONCLUSION: This study indicates that multiple drilling could promote revascularization of ischemic capital femoral epiphysis, and multiple drilling does not appear to produce bony physeal bars at short-term, if using small diameter drill. However, multiple drilling alone does not seem to prevent femoral head deformity or to promote new bone formation.

Estudo comparativo da influência da osteotomia do ilíaco e da osteotomia subtrocantérica do fémur na circulaçäo sangüinea da epífise femoral proximal em coelhos / Compative study on the influence of iliac osteotomy and femoral subtrochanter osteotomy in the proximal femoral epiphysis blood flow in rabbits

Resumo: O efeito causado pela osteotomia de ilíaco e pela osteotomia femoral subtraocantérica sobre a circulaçäo sangüinea da ep1fise femoral proximal é estudado em coelhos, através de cintilografia óssea e de estudo histomorfométrico. a cintilografia demonstrou aumento na captaçäo do radiofármaco da cabeça femoral após a realizaçäo da osteotomia femoral, näo sendo observado esse fenômeno após a osteotomia do ilíaco. Na cabeça femoral ipsilateral à osteotomia subtrocantérica, o número de vasos e sua densidade de volume foram maiores do que no lado näo operado, näo sendo demonstradas mudanças na vascularizaçäo óssea após a cirurgia do ilíaco. O autor conclui que a cirulaçäo sangüinea da cabeça femoral aumenta após a osteotomia subtrocantérica do fêmur, näo ocorrendo o mesmo fenômeno após a osteotomia do ilíaco em coelhos.

Vascularizaçäo da epífise proximal da fíbula em fetos / Vascularization of the proximal epiphysis of the fibula in fetuses

A vascularizaçäo da epífise proximal da fíbula foi estudada pelos autores em 30 fetos humanos após injeçäo de uma mistura de látex e óxido de chumbo. Foi realizado estudo radiológico e de dissecçäo, sendo encontrada grande variaçäo para a origem dos ramos arteriais que provêm a vascularizaçäo da epífise. As maiores variaçöes foram observadas na origem da artéria posterior do colo da fíbula, embora nenhuma das artérias tenha se apresentado como constante, diferentemente do que consta na literatura