Background

To reduce the rate of correction loss in hallux valgus surgery, a proximal to distal phalangeal articular angle (PDPAA) of the proximal phalanx of the greater toe of> 8° is considered an indication for a combined Akin and Chevron osteotomy. The PDPAA is measured between the articular surfaces of the proximal phalanx of the greater toe. Viewed from a sagittal perspective, the joint surfaces are not perpendicular aligned to the phalanx axis. Therefore, the PDPAA might be confounded by pronation. This study aims to, first, evaluate the intra- and interobserver reliability of the PDPAA and, second, to analyze the correlation to first ray pronation.

Methods

In a consecutive series of 59 feet who underwent hallux valgus (HV) surgery, PDPAA, round sign and other angles were measured on weight-bearing radiographs pre- and postoperatively. After power analysis, the intraclass correlation coefficient (ICC) was used to calculate the intra- and interobserver reliability. The correlation of PDPAA with the round sign as well as angles defining the HV and the Hallux valgus interphalangeus (HVI) were evaluated.

Results

The PDPAA showed an excellent intra- and interobserver reliability (ICC 0.92 and 0.89, p < 0.05). The round sign did not correlate significantly with the PDPAA (p = 0.51). However, the PDPAA showed a moderate correlation with the interphalangeal angle (r = 0.51, p < 0.05) and fair inversely with the intermetatarsal angle (r = −0.45, p < 0.05).

Conclusion

First, measurement of PDPAA is reliable. Second, PDPAA is not associated with first ray pronation, but a false low PDPAA is geometrically possible. A high PDPAA correlates with a relevant HVI and inversely correlates with the HV like the HVI. Hence, first ray pronation should be treated first and a remaining PDPAA of> 8° after intraoperatively reevaluation separately.

中文翻译：

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第一近端指骨的近端至远端指骨关节角：可靠性和与圆形标志的相关性

背景

为了降低拇外翻手术中的矫正损失率，大脚趾近端指骨的近端至远端指骨关节角 (PDPAA) > 8° 被认为是 Akin 和 Chevron 联合截骨术的指征。PDPAA 是在大脚趾近节指骨的关节面从矢状面看，关节面不垂直于指骨轴。因此，PDPAA 可能会被旋前混淆。本研究旨在首先评估 PDPAA 的观察者内和观察者间可靠性，其次分析与第一射线旋前的相关性。

方法

在接受拇外翻 (HV) 手术的连续 59 只脚中，PDPAA、圆征和其他角度在术前和术后的负重 X 光片上进行了测量。功效分析后，组内相关系数 (ICC) 用于计算观察者内和观察者间的可靠性。评估了 PDPAA 与圆形征的相关性以及定义 HV 和拇趾外翻指间肌 (HVI) 的角度。

结果

PDPAA 显示出出色的观察者内部和观察者间可靠性（ICC 0.92 和 0.89，p < 0.05）。圆形标志与 PDPAA 无显着相关性 (p = 0.51)。然而，PDPAA 与指间角呈中度相关（r = 0.51，p < 0.05），与跖骨间角成反比（r = -0.45，p < 0.05）。

结论

首先，PDPAA 的测量是可靠的。其次，PDPAA 与第一射线旋前无关，但假低 PDPAA 在几何学上是可能的。高 PDPAA 与相关的 HVI 相关，并且与 HV（如 HVI）呈负相关。因此，应首先治疗第一线旋前，并在术中重新评估后单独治疗剩余的 PDPAA > 8°。