近期看到關于髖臼方向不同應用場景下的不同定義，覺得特別有意思，但是，原文是影印本，不太方便實用屏幕取詞翻譯，且一些專業術語也不太好理解。
因此，我將原文和翻譯整理了一些，不對的地方，敬請指出！

Operative definitions: Acetabular components are frequently positioned with jigs, and these usually have two rods perpendicular to each other.
The inclination of the component is set by placing one of these rods parallel to the transverse axis of the patient and the other parallel to the longitudinal axis (McKee 1970; Charnley 1979; Harris 1980).
Anteversion is achieved by rotating the longitudinal rod about the transverse axis — a movement akin to hip flexion (McKee 1970; Harris 1980).
The anteversion angle is that through which the longitudinal rod is swung, and is measured in the sagittal plane.
The operative anteversion (OA) is thus the angle between the longitudinal axis of the patient and the acetabular axis as projected onto the sagittal plane (see Fig. 1).
This is sometimes called the phi angle

髖臼假體通常通過定位夾具（jigs）進行安置，而這些夾具通常具有兩根相互垂直的桿。
假體的**傾斜角（inclination）通過將其中一根桿與患者的橫軸（transverse axis）平行，另一根桿與縱軸（longitudinal axis）**平行來設定（McKee 1970；Charnley 1979；Harris 1980）。

前傾角（anteversion）則是通過將縱向桿繞橫軸旋轉實現的，這種運動類似于髖關節的屈曲（flexion）（McKee 1970；Harris 1980）。

前傾角是指這根縱向桿擺動的角度，并在**矢狀面（sagittal plane）**中進行測量。

因此，所謂的術中前傾角（operative anteversion, OA），是指患者的縱軸與髖臼軸（acetabular axis）在矢狀面上的投影之間的夾角（見圖1）。

The inclination preset by the jig is the angle between the acetabular axis and the longitudinal rod.
When the prosthesis is anteverted, the longitudinal rod remains in the sagittal plane, and the preset inclination remains the same, being the angle between the acetabular axis and the sagittal plane.
The operative inclination (OI) is therefore the angle between the acetabular axis and the sagittal plane (Fig 1).
It is the angle of abduction of the acetabular axis.

當使用夾具時，預設的傾斜角（inclination）是**髖臼軸（acetabular axis）與縱向桿（longitudinal rod）**之間的夾角。
當假體前傾（anteverted）時，縱向桿仍位于矢狀面（sagittal plane）中，因此預設的傾斜角不會改變，此時它是髖臼軸與矢狀面之間的夾角。
因此，術中傾斜角（OI）指的是髖臼軸與矢狀面之間的夾角（見圖1）。
它也可以看作是髖臼軸的外展角度（abduction angle）。

Radiographic definitions.
The orientation of the acetabular component can be determined postoperatively on anteroposterior radiograph from the alignment of radio-opaque markers (with correction for distortion caused by X-ray beam divergence and pelvic rotation) (Goerge and Resnick 1977; Sellers, Lyles and Dorr 1988).

The inclination is the angle between the face of the cup and the transverse axis (Lewinnek et al 1978; Woo and Morrey 1982; Ackland et al 1986; Sarmiento et al 1990), which is the same as the angle between the longitudinal axis and the acetabular axis when this is projected onto the radiograph.

The radiographic inclination (RI) is therefore defined as the angle between the longitudinal axis and the acetabular axis when this is projected onto the coronal plane (Fig. 2).

It is sometimes called the “projected inclination” or “theta angle” (Lewinnek et al 1978; Herrlin et al).

• 放射學定義（Radiographic definitions）

髖臼假體的方向可以通過術后的**前后位X線片（anteroposterior radiograph）來確定，通常通過觀察顯影標記（radio-opaque markers）**的排列實現（同時需校正因X射線束發散和骨盆旋轉引起的畸變）（Goerge 和 Resnick 1977；Sellers、Lyles 和 Dorr 1988）。

所謂的“傾斜角”（inclination）是指髖臼杯面與人體橫軸（transverse axis）之間的夾角（Lewinnek 等，1978；Woo 和 Morrey 1982；Ackland 等，1986；Sarmiento 等，1990）。這個角度也等同于：縱軸（longitudinal axis）與髖臼軸（acetabular axis）在X線片上的投影之間的夾角。

因此，**放射學傾斜角（Radiographic Inclination, RI）**被定義為：縱軸與髖臼軸在冠狀面（coronal plane）投影下的夾角（見圖2）。

它有時也被稱為**“投影傾斜角（projected inclination）”或“ theta 角度”**（Lewinnek 等 1978；Herrlin 等）。

The technique for assessing acetabular anteversion depends on the type of radio-opaque marker.
When this is an encircling wire, which is projected radiographically as an ellipse, anteversion is calculated from the relative sizes of the major and minor diameters of the ellipse (McLaren 1973; Lewinnek et al 1978; Ackland et al 1986).

The result of these calculations gives the angle between the axis of the acetabulum and the coronal plane.

The radiographic anteversion (RA) is therefore defined as the angle between the acetabular axis and the coronal plane (Fig. 2).

This is sometimes called the planar anteversion or the α angle, and can also be determined approximately from lateral radiographs (Lewinnek et al 1978; Woo and Morrey 1982; Herrlin et al 1988).

評估髖臼前傾角的方法取決于顯影標記的類型。
當使用的是一個環狀的金屬絲時，它在X線片上的投影為一個橢圓形。此時可以通過橢圓的長軸與短軸之比來計算前傾角（McLaren 1973；Lewinnek 等 1978；Ackland 等 1986）。

通過這些計算，所得到的是髖臼軸與冠狀面之間的夾角。

因此，**放射學前傾角（Radiographic Anteversion, RA）**被定義為：髖臼軸與冠狀面之間的夾角（見圖2）。

它有時也被稱為**“平面前傾角（planar anteversion）”或“α角”，也可以通過側位X線片**進行近似測量（Lewinnek 等 1978；Woo 和 Morrey 1982；Herrlin 等 1988）。

Anatomical definitions.
In anatomical studies of both normal and dysplastic hips, the angle between the plane of the face of the acetabulum and the transverse plane is considered to be the inclination of the acetabulum (Walker 1977; T?nnis 1987).

This is equivalent to the angle between the acetabular axis and the longitudinal axis.

The anatomical inclination (AI) is therefore defined as the angle between the acetabular axis and the longitudinal axis (Fig. 3).

Anteversion is the angle between the acetabular axis and the coronal plane when viewed in a cranio-caudal direction (McKibbin 1970; Walker 1977; Calandruccio 1987).

The anatomical anteversion (AA) is therefore defined as the angle between the transverse axis and the acetabular axis when this is projected onto the transverse plane (Fig. 3).

It is similar to internal rotation of the acetabulum about a longitudinal body axis.

Anatomical inclination and anteversion are occasionally referred to as true or three-dimensional inclination and anteversion (Herrlin et al 1986, 1988).

解剖學定義：
在正常髖關節和發育不良髖關節的解剖研究中，髖臼面與人體橫斷面之間的夾角被認為是髖臼的傾斜角（inclination）（Walker 1977；T?nnis 1987）。

這等價于髖臼軸線與人體縱軸之間的夾角。

因此，**解剖學傾斜角（AI, Anatomical Inclination）**被定義為：髖臼軸與人體縱軸之間的夾角（見圖3）。

前傾角（anteversion）則是髖臼軸與人體冠狀面之間的夾角，從頭向腳方向（即顱尾方向）觀察得到（McKibbin 1970；Walker 1977；Calandruccio 1987）。

因此，**解剖學前傾角（AA, Anatomical Anteversion）**被定義為：將髖臼軸投影到橫斷面上時，其與人體橫軸之間的夾角（見圖3）。

它可以類比為：髖臼圍繞縱軸發生的內旋。

有時，解剖學傾斜角與前傾角也被稱為真實的或三維的（true or 3D）傾斜角與前傾角（Herrlin 等 1986, 1988）。