Department of Orthopaedic Medical Engineering, Osaka University Graduate School of Medicine, Osaka, Japan.
Department of Orthopaedic Surgery, Osaka University Graduate School of Medicine, Osaka, Japan.
Clin Orthop Relat Res. 2023 Jan 1;481(1):51-59. doi: 10.1097/CORR.0000000000002363. Epub 2022 Aug 29.
Osteonecrosis of the femoral head (ONFH) classification systems are based on the size, volume, and location of necrotic lesions. Often-but not always-ONFH results in femoral head collapse. Because acetabular coverage is associated with mechanical stress on the femoral head, it might also be associated with femoral head collapse in patients with ONFH. However, the association between acetabular coverage and femoral head collapse in these patients has not been established.
QUESTIONS/PURPOSES: (1) Is femoral head collapse associated with acetabular coverage or pelvic incidence (PI) in patients with ONFH? (2) Are established predictors of femoral head collapse in ONFH classification systems associated with acetabular coverage?
Between 2008 and 2018, we evaluated 343 hips in 218 patients with ONFH. We considered all patients with ONFH except for those with a traumatic etiology, a history of surgical treatment before collapse, or those with collapse at initial presentation as potentially eligible for this study. Of those, 101 hips with ONFH (50% [50] were in males with a mean age of 44 ± 15 years) met our inclusion criteria. These patients were subsequently divided into two groups: those with femoral head collapse within 12 months (collapse group, 35 hips) and those without femoral head collapse (noncollapse group, 66 hips). No differences in patient demographics were observed between the two groups. CT images were used to measure the PI and acetabular coverage in three planes: the lateral center-edge angle (LCEA) in the coronal plane, the anterior and posterior center-edge angle in the sagittal plane, and the anterior and posterior acetabular sector angle in the axial plane; in addition, the difference between these parameters was investigated between the groups. The thresholds for femoral head collapse in the parameters that showed differences were investigated. Necrotic location and size were evaluated using the Japanese Investigation Committee (JIC) classification and the Steinberg grade classification, respectively. We examined the relationship between these parameters and classifications.
The mean LCEA was slightly greater in the noncollapse group than in the collapse group (32° ± 6° versus 28° ± 7°; mean difference 4° [95% CI 1.15° to 6.46°]; p = 0.005); the clinical importance of this small difference is uncertain. There were no differences in PI between the two groups. After accounting for sex, age, BMI, and etiology as confounding factors, as well as acetabular coverage parameters and PI, we found a lower LCEA to be independently associated with increased odds of collapse, although the effect size is small and of questionable importance (OR 1.18 [95% CI 1.06 to 1.33]; p = 0.001). The threshold of LCEA for femoral head collapse was 28° (sensitivity = 0.79, specificity = 0.60, area under the curve = 0.73). The percentage of patients with an LCEA less than 28° was larger in JIC Type C1 (OR 6.52 [95% CI 1.64 to 43.83]; p = 0.006) and C2 (OR 9.84 [95% CI 2.34 to 68.38]; p = 0.001) than in patients with both Type A and Type B. The acetabular coverage data for the excluded patients did not differ from those of the patients included in the analysis.
Our findings suggest that acetabular coverage appears to have little, if any, association with the likelihood of collapse in patients with ONFH. We found a small association between a lower LCEA and a higher odds of collapse, but the effect size may not be clinically important. Factors other than acetabular coverage need to be considered, and if our findings are verified by other investigators, osteotomy is unlikely to have a protective role. As the patients in our study were fairly homogeneous in terms of ethnicity and BMI, these factors need to be further investigated to determine whether they are associated with femoral head collapse in ONFH.
Level III, prognostic study.
股骨头坏死（ONFH）分类系统基于坏死病变的大小、体积和位置。ONFH 通常会导致股骨头塌陷，但并非总是如此。由于髋臼覆盖与股骨头的机械应力有关，因此它也可能与 ONFH 患者的股骨头塌陷有关。然而，在这些患者中，髋臼覆盖与股骨头塌陷之间的关系尚未确定。
问题/目的：（1）在患有 ONFH 的患者中，股骨头塌陷与髋臼覆盖或骨盆入射角（PI）相关吗？（2）在 ONFH 分类系统中，股骨头塌陷的既定预测因子是否与髋臼覆盖相关？
在 2008 年至 2018 年期间，我们评估了 218 例患者的 343 髋患有 ONFH 的患者。我们考虑了除创伤性病因、塌陷前手术治疗史或初次就诊时即发生塌陷的患者以外的所有患有 ONFH 的患者，这些患者都可能符合本研究的纳入标准。其中，101 髋患有 ONFH（50%[50]为男性，平均年龄 44 ± 15 岁）符合我们的纳入标准。这些患者随后分为两组：在 12 个月内发生股骨头塌陷的患者（塌陷组，35 髋）和未发生股骨头塌陷的患者（非塌陷组，66 髋）。两组患者的患者人口统计学特征无差异。使用 CT 图像测量三个平面的 PI 和髋臼覆盖：冠状位的外侧中心边缘角（LCEA）、矢状位的前、后中心边缘角和轴向位的前、后髋臼扇区角；此外，还研究了两组之间这些参数的差异。研究了在表现出差异的参数中，股骨头塌陷的阈值。使用日本调查委员会（JIC）分类和 Steinberg 分级分类评估坏死部位和大小。我们研究了这些参数和分类之间的关系。
非塌陷组的平均 LCEA 略大于塌陷组（32°±6°对 28°±7°；平均差异 4°[95%CI 1.15°至 6.46°]；p=0.005）；这种小差异的临床重要性尚不确定。两组之间的 PI 无差异。在考虑性别、年龄、BMI 和病因等混杂因素以及髋臼覆盖参数和 PI 后，我们发现 LCEA 较低与塌陷的几率增加独立相关，尽管效应大小较小且存在疑问（OR 1.18[95%CI 1.06 至 1.33]；p=0.001）。股骨头塌陷的 LCEA 阈值为 28°（敏感性=0.79，特异性=0.60，曲线下面积=0.73）。JIC 类型 C1（OR 6.52[95%CI 1.64 至 43.83]；p=0.006）和 C2（OR 9.84[95%CI 2.34 至 68.38]；p=0.001）患者的 LCEA 小于 28°的患者比例大于 A 型和 B 型患者。排除患者的髋臼覆盖数据与纳入分析的患者的数据没有差异。
我们的研究结果表明，髋臼覆盖与 ONFH 患者的塌陷可能性似乎没有关联，或者关联很小。我们发现 LCEA 较低与塌陷几率增加之间存在较小的关联，但效应大小可能没有临床意义。需要考虑髋臼覆盖以外的其他因素，如果我们的研究结果得到其他研究人员的验证，那么截骨术不太可能具有保护作用。由于我们研究中的患者在种族和 BMI 方面相当同质，因此需要进一步研究这些因素是否与 ONFH 中的股骨头塌陷有关。
III 级，预后研究。
