Jentzsch Thorsten, Hasler Anita, Renner Niklas, Peterhans Manuel, Sutter Reto, Espinosa Norman, Wirth Stephan H
Department of Orthopaedics, Balgrist University Hospital, University of Zurich, Forchstrasse 340, 8008, Zurich, Switzerland.
Department of Orthopaedics, Kantonsspital Aarau, Aarau, Switzerland.
BMC Musculoskelet Disord. 2017 Jul 3;18(1):284. doi: 10.1186/s12891-017-1642-x.
Lateral talar process fractures (LTPF) are often missed on conventional radiographs. A positive V sign is an interruption of the contour of the LTP. It has been suggested, but not proven to be pathognomonic for LTPF. The objective was to study whether the V sign is pathognomonic for LTPF and if it can be properly assessed in different ankle positions and varying fracture types.
An experimental study was conducted. Two investigators assessed lateral radiographs (n = 108) of a foot and ankle model. The exposure variables were different ankle positions and fracture types. The primary outcome was the correct detection of a V sign. The secondary outcomes were the detection of the V sign depending on ankle position and fracture type as well as the uncertainty.
The interobserver agreement on the V sign and type of fracture were fair (κ = 0.35, 95% CI 0.18-0.53, p < 0.001 and κ = 0.37, 95% CI 0.26-0.48, p < 0.001). The mean sensitivity, specificity, PPV, NPV, and likelihood ratio for the detection of the V sign were 77% (95% CI 67-86%), 59% (95% CI 39-78%), 85% (95% CI 75-92%), 46% (95% CI 29-63%), and 2. The mean uncertainty in the V sign detection was 38%. The V sign identification stratified by ankle position and fracture type showed significant better results with increasing inversion (p = 0.035 and p = 0.011) and type B fractures (p = 0.001 and p = 0.013).
The V sign may not be pathognomonic and is not recommended as the only modality for the detection of LTPF. It is better visualized with inversion, but does not depend on plantar flexion or internal rotation. It is also better seen in type B fractures. It is difficult to detect and investigator-dependent. It may be helpful in a clinical setting to point into a direction, but a CT scan may be used if in doubt about a LTPF.
距骨外侧突骨折（LTPF）在传统X线片上常被漏诊。阳性V征是距骨外侧突轮廓的中断。有人提出该征对LTPF具有诊断意义，但尚未得到证实。本研究的目的是探讨V征对LTPF是否具有诊断意义，以及能否在不同踝关节位置和不同骨折类型中准确评估该征。
进行一项实验研究。两名研究者评估了足踝模型的外侧X线片（n = 108）。暴露变量为不同的踝关节位置和骨折类型。主要结局是正确检测到V征。次要结局是根据踝关节位置和骨折类型检测V征以及不确定性。
观察者间对V征和骨折类型的一致性一般（κ = 0.35，95%CI 0.18 - 0.53，p < 0.001；κ = 0.37，95%CI 0.26 - 0.48，p < 0.001）。检测V征的平均灵敏度、特异度、阳性预测值、阴性预测值和似然比分别为77%（95%CI 67 - 86%）、59%（95%CI 39 - 78%）、85%（95%CI 75 - 92%）、46%（95%CI 29 - 63%）和2。V征检测的平均不确定性为38%。按踝关节位置和骨折类型分层的V征识别结果显示，随着内翻增加（p = 0.035和p = 0.011）以及B型骨折（p = 0.001和p = 0.013），结果明显更好。
V征可能不具有诊断意义，不建议将其作为检测LTPF的唯一方法。内翻时该征显示更佳，但不依赖于跖屈或内旋。在B型骨折中也更易观察到。该征难以检测且依赖观察者。在临床环境中它可能有助于指明方向，但如果对LTPF存在疑问，可使用CT扫描。
