Background:Tumor-like distal femoral cortical irregularities (DFCIs) are a frequent incidental finding on knee magnetic resonance imaging (MRI) and are common in young competitive athletes.Purpose:To assess and compare the morphology and prevalence of DFCIs in competitive alpine skiers over 48 months during adolescence.Study Design:Case series; Level of evidence, 4.Methods:Adolescent competitive alpine skiers were prospectively recruited in 2018 and received bilateral 3-T MRI of the knee at baseline and after 48 months. All MRIs were evaluated for the presence and location of DFCIs, which were marked at 1 of 3 anatomic positions: (1) the femoral attachment of the medial head of the gastrocnemius muscle, (2) the lateral head of the gastrocnemius muscle, or (3) the attachment of the adductor magnus aponeurosis. The size of the DFCI was measured by 2 radiologists independently. The measurements were compared using the Wilcoxon signed-rank test, the interclass correlation coefficient (ICC), and Cohen Kappa.Results:A total of 63 athletes (mean age at follow-up, 19.6 ± 1.2 years; n = 25 female) were included in the study. At baseline, DFCIs were detected in 84 out of 126 knees (67%). At the 48-month follow-up, DFCIs were found in 88 out of 126 knees (70%), with multiple DFCIs in 3 knees and no significant difference between male and female patients (n = 24 male, n = 19 female; P = .71). No significant increase was detected for the number ( P = .21) and size of the DFCIs between the baseline and the 48-month follow-up (mean size: baseline, 3.7 ± 0.8 mm; 48-month follow-up: 3.6 ± 0.9 mm; P = .66). The interrater agreement for the mean size measurements of DFCIs was good to excellent (ICC 0.88).Conclusion:DFCIs remain a frequent finding on knee MRI in competitive alpine skiers after skeletal maturation and do not disappear during adolescence. The DFCI size was constant in athletes aged between 15 and 19 years. Moreover, DFCIs should not be mistaken for a pathologic finding.

中文翻译：

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青少年高山滑雪竞技运动员膝盖肿瘤样远端股骨皮质不规则：48 个月的纵向评估

背景：肿瘤样远端股骨皮质不规则（DFCI）是膝关节磁共振成像（MRI）中常见的偶然发现，在年轻竞技运动员中很常见。目的：评估和比较 DFCI 在竞技高山滑雪运动员中的形态和患病率青春期48个月。研究设计：案例系列；证据级别，4。方法：2018 年前瞻性招募青少年高山滑雪竞技运动员，并在基线时和 48 个月后接受双侧膝盖 3-T MRI。所有 MRI 均评估了 DFCI 的存在和位置，这些 DFCI 被标记在 3 个解剖位置中的 1 个：(1) 腓肠肌内侧头的股骨附着处，(2) 腓肠肌外侧头，或 ( 3）大收肌腱膜的附着。 DFCI 的大小由 2 名放射科医生独立测量。使用 Wilcoxon 符号秩检验、组间相关系数 (ICC) 和 Cohen Kappa 来比较测量结果。结果：共有 63 名运动员（随访时平均年龄为 19.6 ± 1.2 岁；n = 25 名女性）进行了研究纳入研究。基线时，126 个膝盖中有 84 个（67%）检测到 DFCI。在 48 个月的随访中，126 个膝关节中有 88 个膝关节发现了 DFCI（70%），其中 3 个膝关节存在多种 DFCI，男性和女性患者之间没有显着差异（n = 24 名男性，n = 19 名女性；P = .71）。在基线和 48 个月随访期间，未检测到 DFCI 的数量 (P = .21) 和大小有显着增加（平均大小：基线，3.7 ± 0.8 毫米；48 个月随访：3.6 ± 0.9 毫米；P = .66)。 DFCI 平均尺寸测量值的参与者间一致性为良好到极好（ICC 0.88）。结论：在骨骼成熟后，DFCI 仍然是高山滑雪竞技运动员在膝部 MRI 中常见的发现，并且在青春期不会消失。 15 至 19 岁运动员的 DFCI 大小保持不变。此外，DFCI 不应被误认为是病理结果。