Abstract：
OBJECTIVE: Although some patients may experience collapse progression while others may not in post-collapse osteonecrosis of the femoral head (ONFH) with a necrotic lesion located within the weight-bearing part of the acetabulum (Type B/C1), few studies have focused on the natural course after collapse. This study aimed to clarify the correlation between necrotic volume (NV) and necrotic depth (ND) in predicting collapse progression in patients with post-collapse ONFH Type B/C1.
METHODS: We retrospectively reviewed 54 hips with post-collapse ONFH Type B/C1 from 52 consecutive patients who were conservatively followed up for more than 1 year. We measured the amount of femoral head collapse using biplane radiographs at each follow-up period, and produced Kaplan-Meier survival curves with collapse progression (≥ 1 mm) as the endpoint. We compared NV and ND, which were calculated as the ratio of the distance from the articular surface of the femoral head to the deepest point of a necrotic lesion to the femoral head diameter in the mid-coronal slice of T1-weighted magnetic resonance imaging (MRI).
RESULTS: We observed collapse progression in 31 hips (57.4%). The NV and ND were significantly greater in hips with collapse progression than in those without collapse progression (p = 0.0127 and 0.0047, respectively). Necrotic volume was significantly correlated with ND (rs = 0.56, p < 0.0001).
CONCLUSIONS: This study suggests that necrotic depth on the mid-coronal slice of T1-weighted MRI can be a substitute for necrotic volume to predict collapse progression in ONFH Type B/C1.
METHODS: We retrospectively reviewed 54 hips with post-collapse ONFH Type B/C1 from 52 consecutive patients who were conservatively followed up for more than 1 year. We measured the amount of femoral head collapse using biplane radiographs at each follow-up period, and produced Kaplan-Meier survival curves with collapse progression (≥ 1 mm) as the endpoint. We compared NV and ND, which were calculated as the ratio of the distance from the articular surface of the femoral head to the deepest point of a necrotic lesion to the femoral head diameter in the mid-coronal slice of T1-weighted magnetic resonance imaging (MRI).
RESULTS: We observed collapse progression in 31 hips (57.4%). The NV and ND were significantly greater in hips with collapse progression than in those without collapse progression (p = 0.0127 and 0.0047, respectively). Necrotic volume was significantly correlated with ND (rs = 0.56, p < 0.0001).
CONCLUSIONS: This study suggests that necrotic depth on the mid-coronal slice of T1-weighted MRI can be a substitute for necrotic volume to predict collapse progression in ONFH Type B/C1.
摘要：
目的：尽管有些患者可能会出现塌陷进展，而另一些患者可能不会出现塌陷后股骨头坏死（ONFH），坏死病变位于髋臼负重部位（B型/C1型），很少有研究关注崩溃后的自然过程。这项研究旨在阐明坏死体积（NV）和坏死深度（ND）之间的相关性，以预测塌陷后ONFHB型/C1型患者的塌陷进展。
方法：我们回顾性分析了52例连续保守随访1年以上的患者中54例合并塌陷后ONFHB型/C1型的髋关节。我们在每个随访期间使用双平面X光片测量股骨头塌陷的数量，并产生Kaplan-Meier存活曲线,以塌陷进展(≥1mm)为终点。我们比较了NV和ND,计算为T1加权磁共振成像（MRI）中冠状层中从股骨头关节面到坏死病变最深点的距离与股骨头直径之比。
结果：我们观察到31髋塌陷进展（57.4%）。与无塌陷进展的臀部相比，塌陷进展的臀部的NV和ND明显更大（分别为p=0.0127和0.0047）。坏死体积与ND显著相关(rs=0.56,p<0.0001)。
结论：这项研究表明，T1加权MRI中冠状切片的坏死深度可以替代坏死体积来预测ONFHB型/C1型的塌陷进展。
方法：我们回顾性分析了52例连续保守随访1年以上的患者中54例合并塌陷后ONFHB型/C1型的髋关节。我们在每个随访期间使用双平面X光片测量股骨头塌陷的数量，并产生Kaplan-Meier存活曲线,以塌陷进展(≥1mm)为终点。我们比较了NV和ND,计算为T1加权磁共振成像（MRI）中冠状层中从股骨头关节面到坏死病变最深点的距离与股骨头直径之比。
结果：我们观察到31髋塌陷进展（57.4%）。与无塌陷进展的臀部相比，塌陷进展的臀部的NV和ND明显更大（分别为p=0.0127和0.0047）。坏死体积与ND显著相关(rs=0.56,p<0.0001)。
结论：这项研究表明，T1加权MRI中冠状切片的坏死深度可以替代坏死体积来预测ONFHB型/C1型的塌陷进展。
