Worrall Douglas, Smith-Whitley Kim, Wells Lawrence
The Children's Hospital of Philadelphia, Philadelphia, PA.
J Pediatr Orthop. 2016 Mar;36(2):139-44. doi: 10.1097/BPO.0000000000000409.
Femoral head osteonecrosis (ON) secondary to sickle cell disease (SCD) often progresses to femoral head collapse, requiring total hip arthroplasty. However, this treatment has a limited durability and patients with SCD have higher rates of complications, requiring multiple revision operations. Identifying risk factors linked to ON in SCD can facilitate earlier precollapse diagnosis and surgical treatment aimed at preservation of the native hip joint.
Fifty-nine children treated at our institution between January 2001 and April 2012 with SCD and ON, as diagnosed by magnetic resonance imaging or radiographic imaging, were compared with age-matched and sickle cell phenotype-matched (SS, SC, Sβ, Sβ) controls with no evidence of ON. Two sided t-tests assuming unequal variances determined statistically risk factors and threshold values were assigned to calculate odds ratios.
Systolic blood pressure (P=1.2×10, OR=3.68), diastolic blood pressure (P=0.0084, OR=1.41), weight in the SCD-SS population (P=0.04, OR=1.85), and hemoglobin (Hb) in the SCD-SS population (P=0.036, OR=2.56) were elevated in cases. Curiously, dividing the Hb by the hematocrit to serve as a clinical proxy for the mean corpuscular Hb concentration (MCHC) produced an excellent predictor of ON (P=2.06×10, OR=5.17), which was especially pronounced in the SCD-SS subpopulation (P=2.28×10, OR=8.65). Among children with SCD, the overall prevalence of ON was 9% (59/658) and the phenotype with the highest prevalence of ON was Sβ thalassemia with an ON prevalence of 11.1%. There was no observed correlation between ON and height, body mass index, cholesterol, mean corpuscular volume, hematocrit, or glucocorticoid use.
These data support a novel clinical marker, the MCHC proxy, as the strongest predictor of ON in children with SCD. High-risk children should receive hip magnetic resonance imaging to diagnose early ON and facilitate interventions focused on hip preservation, forestalling, or possibly preventing, the need for total hip arthroplasty.
镰状细胞病（SCD）继发的股骨头坏死（ON）常进展为股骨头塌陷，需要进行全髋关节置换术。然而，这种治疗的耐久性有限，且SCD患者的并发症发生率较高，需要多次翻修手术。识别与SCD中ON相关的危险因素有助于更早地在塌陷前进行诊断，并开展旨在保留天然髋关节的手术治疗。
将2001年1月至2012年4月期间在我们机构接受治疗的59例经磁共振成像或放射成像诊断为SCD和ON的儿童，与年龄匹配且镰状细胞表型匹配（SS、SC、Sβ、Sβ）且无ON证据的对照组进行比较。采用假设方差不等的双侧t检验确定统计学危险因素，并指定阈值以计算比值比。
病例组的收缩压（P = 1.2×10，OR = 3.68）、舒张压（P = 0.0084，OR = 1.41）、SCD - SS人群的体重（P = 0.04，OR = 1.85）以及SCD - SS人群的血红蛋白（Hb）（P = 0.036，OR = 2.56）升高。奇怪的是，将Hb除以血细胞比容作为平均红细胞血红蛋白浓度（MCHC）的临床替代指标，可出色地预测ON（P = 2.06×10，OR = 5.17），这在SCD - SS亚组中尤为明显（P = 2.28×10，OR = 8.65）。在SCD儿童中，ON的总体患病率为9%（59/658），ON患病率最高的表型是Sβ地中海贫血，ON患病率为11.1%。未观察到ON与身高、体重指数、胆固醇、平均红细胞体积、血细胞比容或糖皮质激素使用之间存在相关性。
这些数据支持一种新的临床标志物，即MCHC替代指标，作为SCD儿童ON的最强预测指标。高危儿童应接受髋关节磁共振成像检查，以早期诊断ON，并促进针对保留髋关节的干预措施，从而避免或可能预防全髋关节置换术的需求。
