股骨头缺血性坏死的磁共振影像与骨小梁强度分析

Magnetic resonance imaging with multiplane histomorphometry in avascular necrosis of femoral head:analysis of trabeculae

目的了解直接反映股骨头的机械强度并且可预测股骨头塌陷的骨小梁结构改变，在磁共振高低信号之间的差异。方法采用全髋关节置换术后完整股骨头坏死标本，进行磁共振扫描，并按扫描线精确定位、连续切片、多平面取样，并将磁共振影像与病理切片完全重叠对应，对平均骨小梁宽度、平均骨小梁板间隙。进行骨组织计量学分析。结果（１）低信号区平均骨小梁宽度明显低于高信号区。（２）低信号区骨小梁板间隙较高信号区离散程度大。结论低信号区单位体积内骨量下降，机械强度低，提示低信号区较高信号区易发生骨折和塌陷。

Objective To distinguish the differences of changes of bone trabecular structure between high and low signal area which could directly reflect the mechanical strength and estimate the risk of collapse in avascular necrosis of femoral head (ANFH). Methods After total hip replacement, the specimen of ANFH was scanned by MR imaging. Accurate localization,consecutive slicing, multiplane histomorphometry, correspondence of MR images with slices were used. Mean trabecular width (MTW μm) and mean trabecular space (MTS μm) were selected as observation indexes. Results MTW in the low signal area was lower than that in the high signal area. MTS in the low signal area was higher than that in the high signal area. The results indicated that the dispersive degree of bone trabeculae was higher in the low signal area. Conclusion Bone trabeculae in the low signal area necrosed and atrophied so that the bone volume and mechanical strength of trabeculae declined and bone trabeculae in the low signal area were liable to microfracture and collapse.