髋臼后壁骨折——动态应力检查的价值

蔡鸿敏 | MilesStone  [e-mail]

河南省洛阳正骨医院（河南省骨科医院）髋中心

河南省骨科微创工程技术中心

原创声明：本文所有文字内容均100%原创。所有图表来自参考文献5，不做商业用途，版权归原著者。

髋臼后壁骨折——动态应力检查的价值

Posterior Wall fractures of the Acetabulun: the Value of the Dynamic Stress Examination

髋臼后壁骨折是最常见的髋臼骨折类型，占整个髋臼骨折比重的25%^[1]，其手术与否关联于诸多因素：①骨块的体积、②骨块的粉碎程度、③髋臼边缘是否有压缩骨折、④是否有髋关节脱位以及⑤髋关节的稳定性等等，其中髋关节稳定性至关重要。

Posterior wall (PW) fractures are the mostfrequently encountered acetabular fracture type, comprising approximately 25% ofall the acetabular fractures^[1]. Thetreatment of this type of fractures depends on many parameters such as the dimension,comminution, marginal impaction, dislocation or subluxation, and the stabilityof the hip joint. Of course, stability is the most determining factor.

髋关节稳定性有①静态和②动态之分。

    The stability of the hip can be grossly categorized asstatic or dynamic.

髋关节静态稳定性：髋关节处于伸直和旋转中立位（如存在脱位，则需先行闭合复位），在无应力刺激情况下的影像学检查（正位及Judet斜位X线片，CT扫描）所证实的头臼匹配。如果影像检查确定髋关节存在半脱位或脱位，则认为其不稳定。

The static stability can be perceived as the hipcongruency verified by using the pelvic anteroposterior and Judet radiographsas well as the CT scan with the hip in neutral rotation and full extensionwithout load. If the hip is dislocated, closed reduction should be done priorto the radiographic tests. When subluxation or dislocation is detected, the hipis referred as instable.

髋关节动态稳定性：髋关节在沿股骨长轴施加应力并被动活动情况下，影像检查证实髋关节仍保持头臼匹配。

The dynamic stability of the hip is made sure when jointcongruence is still preserved under passive motion combined with axial loadalong the femur.

一般来说，髋关节如动态稳定，则静态亦稳定。反之则不然。

Generally speaking, when the hip joint is dynamicallystabile, its static stability is also without question. However, staticstability can not be relied on to make a clear decision upon dynamic stability.

髋关节静态稳定的情况下，如何预估动态稳定与否？髋关节稳定性可以通过后壁骨块的体积而预判为三组^[2]：组①＜20%，稳定（stable）；组②≥20%且≤50%，不能确定（indeterminate）；③＞50%，不稳定（unstable）。后壁体积的测量方法：①Calkins法^[3]、②Keith法^[4]以及③Moed法（改良的Keith法）^[5]，其中方法③较为可靠，均不加以详述。但是，这只是依靠静态CT平扫图像的主管臆测，不能完全准确地预测髋关节的动态稳定性；＜20%的后壁骨折被认作稳定，却有不稳定的病例存在，同理，＞50的后壁骨折却有可能是稳定的^[3,4]（表1）。

Given the staticstability of the hip, how can the physician determine its dynamic stability? Stabilityof the hip can be predicted into three groups depending on the dimension of thePW^[2]. Group 1 (stable): fracturesinvolve less than 20% of the PW; Group 2(indeterminate): PW involvement is between 20% and 50%; Group 3 (instable): more than 50% of the PW is fractured. The measurementmethods for PW involvement are described clearly by Calkins et al.^[3], Keith et al.^[4], and Moed et al^[5], the latter of which is considered to be themost reliable. All these measurements are not introduced here in detail, butthe truth is they are subjective predictions relying on the CT scan and can notaccurately tell the dynamic stability of the hip. There are unstable hipfractures existing in Group 1 and stable hips in Group 3^[3,4](Table 1).

所以，后壁骨折的髋关节的稳定性需要动态检测加以确定，也就是麻醉下动态应力检查。具体步骤^[4]：①病人仰卧，患髋保持伸直及旋转中立位，逐渐被动屈曲超过90°，沿股骨长轴施加应力，拍摄骨盆正位及闭孔斜位X线片；②如果出现头臼匹配失常（半脱位），则认为是动态不稳定，则需要手术；③如果头臼匹配，则患髋需要附加轻度内收、内旋（约20°），再次摄片；④如仍头臼匹配，则认为是动态稳定，如匹配失常，则不稳定。需要注意的是，完全没有必要造成髋关节再次完全脱位，以免加重损伤。

Consequently, the verificationof the hip stability after PW fractures should only count on the dynamic stressexamination (DSE) under anesthesia. The procedures of the DSE are introduced indetail as follows: 1. The patient issupine with the affected hip in full extension and neutral rotation, the hip is then gradually flexed past 90 degreeswhereas progressive manual force is applied to the hip along the longitudinalaxis of the femur, simultaneously, fluoroscopic imaging of the hip in the APand obturator oblique projections is performed; 2. The loss of hip congruence (subluxation) is considered asinstability, thus, surgical intervention will be the correct option; 3. If the hip remains congruent on thisassessment, the examination is repeated with the addition of slight adductionand internal rotation (approximately 20 degrees), and the hip congruence isreevaluated by the fluoroscopy; 4. Ifthe congruence is maintained, the hip is dynamically stable, if not, theunstable fractures should be fixed. It must be noted that frank redislocation isneither required nor clinically desirable.

举例：一例40岁男性病例，摩托车事故导致髋臼后壁骨折。X线片及CT显示头臼匹配，即静态稳定性存在（图1）。髋关节CT平扫图像经Moed法测量结果显示后壁骨折占比38%，即髋关节稳定性不能确定（组②）（图2）。麻醉下进行动态应力检查，结果显示：①静态稳定（图3A）、②被动屈髋超90°未施加沿股骨干轴向应力情况下仍稳定（图3B）、③施加轴向应力后出现髋关节病脱位而不稳定（图3C）。因动态不稳定而进行复位固定手术（图4A）术后两年复查（图4B）。

Example: A 40-year-old male patient was injuredin a motorcycle accident, sustaining a PW acetabular fracture. Initialobturator oblique radiograph and CT section demonstrate hip congruence, thatis, static stability (Figure 1). PW involvement measured on CT section usingthe Moed technique is 38%, which means the hip stability is indeterminate(Group 2)(Figure 2). The DSE under anesthesia shows: 1. Static stability(Figure 3A); 2. Hipstability maintained with the hip in 90-degree flexion without axial load alongthe femur (Figure 3B); 3. Hip incongruence with axial load along the femur(Figure 3C). Internalfixation performed depending on dynamic instability (Figure 4A) and two-year follow-up (Figure 4B). 

图1. X线片及CT显示头臼匹配，即静态稳定性存在。

图2. 髋关节CT平扫图像经Moed法测量结果显示后壁骨折占比38%，即髋关节稳定性不能确定。

图3. 麻醉下进行动态应力检查，结果显示：①静态稳定（A）、②被动屈髋超90°未施加沿股骨干轴向应力情况下仍稳定（B）、③施加轴向应力后出现髋关节病脱位而不稳定（C）。

图4. 因动态不稳定而进行复位固定手术（A）术后两年复查（B）。

参考文献

1. Letournel E, Judet R. In: Elson RA, ed. and translator. Fractures of the Acetabulum. New York, NY: Springer; 1993: 565–581.

2. Calkins MS, Zych G, Latta L, et al. Computed tomography evaluation of stability in posterior fracture dislocation of the hip. Clin Orthop Relat Res. 1988; 227: 152–163.

3. Keith JE Jr, Brashear HR, Gullford WB. Stability of posterior fracture dislocations of the hip. Quantitative assessment using computed tomography. J Bone Joint Surg Am. 1988; 70: 711–714.

4. Vailas JC, Hurwitz S, Wiesel SW. Posterior acetabular fracturedislocations: fragment size, joint capsule, and stability. J Trauma. 1989; 29: 1494–1496.

5. Moed BR, Ajibade DA, Israel H. Computed tomography as a predictor of hip stability status in posterior wall fractures of the acetabulum. J Orthop Trauma. 2009; 23: 7–15.

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