Department of Orthopedic Surgery, Boston Children's Hospital, Boston, Massachusetts.
Department of Biomechanics, Medicine and Rehabilitation of the Locomotor System, Ribeirao Preto Medical School, University of Sao Paulo, Ribeirao Preto, Brazil.
J Bone Joint Surg Am. 2019 Feb 6;101(3):209-217. doi: 10.2106/JBJS.18.00440.
Femoral morphology may influence the etiology of slipped capital femoral epiphysis (SCFE). We investigated whether radiographic parameters of femoral head-neck morphology are associated with a subsequent contralateral slip in patients presenting with unilateral SCFE.
We evaluated 318 patients treated for unilateral SCFE between 2000 and 2017. There were 145 males (46%), and the mean age in the series was 12.4 ± 1.7 years. The patients were followed for a minimum of 18 months or until the development of a contralateral slip (70 patients, 22%). We measured the epiphyseal tilt, epiphyseal extension ratio, alpha angle, and epiphyseal angle of the uninvolved, contralateral hip at initial presentation. Multivariable logistic regression analysis was used to assess whether femoral measurements were associated with the occurrence of a contralateral slip. Receiver operating characteristic (ROC) curves were used to determine optimal thresholds of radiographic measures to determine an increased risk of a contralateral slip. A number-needed-to-treat (NNT) analysis was conducted to evaluate the effectiveness of the femoral measurement thresholds in preventing a contralateral slip.
Multivariable analysis, controlling for triradiate cartilage status, identified the lateral tilt angle and the superior epiphyseal extension ratio as independent factors associated with the likelihood of a contralateral slip. For each additional degree of posterior tilt, the odds of a contralateral slip increase by 8% (odds ratio [OR] = 1.08; 95% confidence interval [CI] = 1.02 to 1.14; p = 0.008), and for each 0.01 increase in the superior epiphyseal extension ratio, the odds of a contralateral slip decrease by 6% (OR = 0.94; 95% CI = 0.88 to 0.99; p = 0.03). A threshold for the epiphyseal tilt of 10° corresponded to a predicted probability of a contralateral slip of 54% in patients with open triradiate cartilage and an NNT of 3.3.
In patients presenting with unilateral SCFE, a higher posterior tilt of the epiphysis increases the risk while an increased superior extension of the epiphysis reduces the risk of a contralateral slip. Our findings may assist the discussion about contralateral prophylactic pinning in patients with unilateral SCFE.
Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.
股骨形态可能会影响股骨颈骨骺滑脱（SCFE）的病因。我们研究了在单侧 SCFE 患者中，股骨头颈形态的放射学参数是否与随后的对侧滑脱有关。
我们评估了 2000 年至 2017 年间接受单侧 SCFE 治疗的 318 名患者。其中男性 145 名（46%），系列平均年龄为 12.4±1.7 岁。所有患者的随访时间至少为 18 个月，或直到出现对侧滑脱（70 名患者，22%）。我们在初次就诊时测量了未受累、对侧髋关节的骺倾斜角、骺延伸率、α角和骺角。多变量逻辑回归分析用于评估股骨测量值与对侧滑脱发生的关系。接收者操作特征（ROC）曲线用于确定放射学测量值的最佳阈值，以确定对侧滑脱的风险增加。进行了需要治疗的人数（NNT）分析，以评估股骨测量阈值在预防对侧滑脱方面的有效性。
多变量分析，控制三射线软骨状态，确定外侧倾斜角和骺上延伸率为与对侧滑脱可能性相关的独立因素。后倾角度每增加 1 度，对侧滑脱的几率增加 8%（比值比[OR] = 1.08；95%置信区间[CI] = 1.02 至 1.14；p = 0.008），骺上延伸率每增加 0.01，对侧滑脱的几率降低 6%（OR = 0.94；95%CI = 0.88 至 0.99；p = 0.03）。骺倾斜角的阈值为 10°，在三射线软骨开放的患者中对应于对侧滑脱的预测概率为 54%，NNT 为 3.3。
在单侧 SCFE 患者中，骺后倾增加会增加对侧滑脱的风险，而骺上延伸增加会降低对侧滑脱的风险。我们的发现可能有助于讨论单侧 SCFE 患者的对侧预防性钉扎。
预后 IV 级。请参阅作者说明，以获取完整的证据水平描述。
