Da Silva Tomas, Barkow Ronja-Patricia, Richter Martin, Koja Sara, Zumbansen Vivien Yvonne, Knop Christian, Merkle Tobias Peter
Klinikum Stuttgart, Stuttgart, Germany.
Eur J Orthop Surg Traumatol. 2025 Jun 9;35(1):240. doi: 10.1007/s00590-025-04307-3.
The Deltoid Tuberosity Index (DTI) is a radiographic parameter proposed as an indirect measure of bone mineral density in the humerus, potentially useful in assessing proximal humerus fractures. Despite suggestions that lower DTI values may predict osteosynthesis failure linked to osteopenia, the reliability of DTI measurements-particularly regarding intra- and interobserver variability and the influence of humeral rotation- has not yet been comprehensively validated.
This study evaluated the reliability of DTI measurements in four parts, involving a total of 1448 measurements performed by seven observers. Interobserver variability was assessed by having seven trauma surgeons measure the DTI on 100 anteroposterior (AP) radiographs of proximal humerus fractures. Intraobserver variability was evaluated by having four observers measure the DTI on three selected radiographs ten times each on different occasions. The impact of humeral internal rotation on DTI measurements was examined using a synthetic humerus model at varying degrees of rotation (0°-90° in 10° increments), with repeated measurements to assess the impact of rotation. Cortical variation in the proximal humerus was assessed using computed tomography (CT) imaging in 10 patients, with DTI measurements conducted at different simulated internal rotation angles to evaluate consistency and compare with radiographic measurements. Finally, the clinical relevance of DTI was evaluated by correlating DTI values with the incidence of screw cutout or secondary displacement in 100 patients treated with PHILOS plates.
Interobserver variability was moderate (ICC = 0.55), with significant differences in DTI measurements across observers (p = 0.0079). Experience level had no significant impact (p = 0.71). Intraobserver variability was low, with a mean coefficient of variation of 3.45%, indicating high consistency within individual observers. Humeral rotation significantly influenced DTI measurements in the synthetic bone model (p < 0.01); however, in patient CT scans, DTI measurements showed minimal variation across rotation angles and correlated strongly with radiographic measurements (r = 0.82-0.89, p < 0.001). No significant correlation was found between DTI values and screw cutout incidence in the overall population. In the subgroup aged 65 to 80 years, only two of the seven observers found a significant correlation between lower DTI values and screw cutout.
This comprehensive study, involving 1448 DTI measurements, revealed not only considerable interobserver variability but also a significant sensitivity to humeral rotation, raising concerns about the DTI's reliability in clinical practice. The inconsistent correlation between DTI and clinical outcomes like screw cutout suggests that the DTI may have limited utility as a predictive tool in managing proximal humerus fractures.
Level III.
三角肌粗隆指数（DTI）是一种影像学参数，被提议作为肱骨骨密度的间接测量指标，可能有助于评估肱骨近端骨折。尽管有观点认为较低的DTI值可能预示与骨质减少相关的骨合成失败，但DTI测量的可靠性——特别是关于观察者内和观察者间的变异性以及肱骨旋转的影响——尚未得到全面验证。
本研究分四个部分评估DTI测量的可靠性，共进行了1448次测量，由七名观察者完成。通过让七名创伤外科医生在100张肱骨近端骨折的前后位（AP）X线片上测量DTI来评估观察者间的变异性。通过让四名观察者在三张选定的X线片上不同时间各测量十次来评估观察者内的变异性。使用合成肱骨模型在不同旋转角度（0°至90°，以10°递增）下检查肱骨内旋对DTI测量的影响，并进行重复测量以评估旋转的影响。使用计算机断层扫描（CT）成像评估10名患者肱骨近端的皮质变化，并在不同的模拟内旋角度进行DTI测量，以评估一致性并与X线测量结果进行比较。最后，通过将DTI值与100例接受PHILOS钢板治疗患者的螺钉穿出或二次移位发生率进行相关性分析，评估DTI的临床相关性。
观察者间的变异性为中等（ICC = 0.55），观察者之间的DTI测量存在显著差异（p = 0.0079）。经验水平没有显著影响（p = 0.71）。观察者内的变异性较低，平均变异系数为3.45%，表明个体观察者内部具有高度一致性。肱骨旋转在合成骨模型中对DTI测量有显著影响（p < 0.01）；然而，在患者的CT扫描中，DTI测量在不同旋转角度下变化最小，并且与X线测量结果高度相关（r = 0.82 - 0.89，p < 0.001）。在总体人群中，未发现DTI值与螺钉穿出发生率之间存在显著相关性。在65至80岁的亚组中，七名观察者中只有两名发现较低的DTI值与螺钉穿出之间存在显著相关性。
这项涉及1448次DTI测量的综合研究不仅揭示了观察者间存在相当大的变异性，而且对肱骨旋转具有显著敏感性这一问题，引发了对DTI在临床实践中可靠性的担忧。DTI与螺钉穿出等临床结果之间不一致的相关性表明，DTI作为肱骨近端骨折管理中的预测工具，其效用可能有限。
三级。
