Ha Yong-Chan, Jung Woon Hwa, Kim Jang-Rak, Seong Nak Hoon, Kim Shin-Yoon, Koo Kyung-Hoi
J Bone Joint Surg Am. 2006 Nov;88 Suppl 3:35-40. doi: 10.2106/JBJS.F.00535.
The hypothesis that the combined necrotic angle measurement from magnetic resonance imaging scans predicts the subsequent risk of collapse in hips with femoral head necrosis was tested.
Thirty-seven hips with early stage osteonecrosis in thirty-three consecutive patients were investigated. With use of the modified method of Kerboul et al., we measured the arc of the femoral surface involved by necrosis on a midcoronal as well as a midsagittal magnetic resonance image (rather than an anteroposterior and a lateral radiograph) and then calculated the sum of the angles. On the basis of the magnitude of the resulting combined angle, hips were classified into four categories: grade 1 (<200 degrees), grade 2 (200 degrees to 249 degrees), grade 3 (250 degrees to 299 degrees), and grade 4 (>/=300 degrees). After the initial evaluations, the hips were randomly assigned to a core decompression group or a nonoperative group. Patients underwent regular follow-up until femoral head collapse or for a minimum of five years.
Seven grade-4 hips and sixteen grade-3 hips had development of femoral head collapse by thirty-six months. Six of the nine grade-2 hips and none of the five grade-1 hips collapsed (log-rank test, p < 0.01). None of the four hips with a combined necrotic angle of </=190 degrees (the low-risk group) collapsed, all twenty-five hips with a combined necrotic angle of >/=240 degrees (the high-risk group) collapsed, and four (50%) of the eight hips with a combined necrotic angle between 190 degrees and 240 degrees (the moderate-risk group) collapsed during the study period.
The Kerboul combined necrotic angle, as ascertained with use of magnetic resonance imaging scans instead of radiographs, is a good method to assess future collapse in hips with femoral head osteonecrosis.
Prognostic Level I. See Instructions to Authors on jbjs.org for a complete description of levels of evidence.
对磁共振成像扫描所测得的坏死角总和能否预测股骨头坏死髋关节随后发生塌陷风险的假说进行了验证。
对连续33例患者的37个早期骨坏死髋关节进行了研究。采用Kerboul等人的改良方法，在矢状面及冠状面磁共振图像（而非前后位和侧位X线片）上测量坏死累及的股骨表面弧度，然后计算角度总和。根据所得坏死角总和的大小，将髋关节分为四类：1级（<200度）、2级（200度至249度）、3级（250度至299度）和4级（≥300度）。初始评估后，将髋关节随机分为髓芯减压组或非手术组。患者接受定期随访，直至股骨头塌陷或至少随访5年。
7个4级髋关节和16个3级髋关节在36个月时发生了股骨头塌陷。9个2级髋关节中有6个塌陷，5个1级髋关节均未塌陷（对数秩检验，p<0.01）。坏死角总和≤190度的4个髋关节（低风险组）均未塌陷，坏死角总和≥240度的25个髋关节（高风险组）均塌陷，坏死角总和在190度至240度之间的8个髋关节中有4个（50%）在研究期间塌陷。
采用磁共振成像扫描而非X线片测定的Kerboul坏死角总和，是评估股骨头坏死髋关节未来塌陷情况的一种良好方法。
预后I级。有关证据水平的完整描述，请参见jbjs.org上的作者须知。
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