Raj Rahul Yogendra, Srivastava Amit, Aggarwal Aditya Nath, Haq Rehan Ul
Department of Orthopaedics, University College of Medical Sciences and Guru Teg Bahadur Hospital, Delhi, 110095 India.
Department of Orthopaedics, AIIMS, Bhopal, Madhya Pradesh India.
Indian J Orthop. 2021 Oct 3;56(3):392-398. doi: 10.1007/s43465-021-00522-2. eCollection 2022 Mar.
The sliding hip screw (SHS) is the gold standard for the management of stable intertrochanteric (IT) fractures. However, intramedullary implants are now being increasingly used for management of unstable IT fractures especially those with a compromised or vulnerable lateral wall. Therefore, accurate classification of fracture is important to ensure proper surgical planning and choice of implant. The AO classification for IT fractures is based on plain radiographs alone and many authors have reported it to have poor inter- and intra-observer agreement. Therefore, the objectives of the study were to assess the improvement in inter- and intra-observer agreement of the AO classification after addition of CT scan to plain radiographs, to assess the change in pattern of AO classification on addition of CT scan to plain radiographs and to assess percentage of times, stable lateral wall seen on plain radiographs is classified as unstable or broken on CT scans.
Fifty-four patients of intertrochanteric fracture were included in study. Plain radiographs of patients were shown to three orthopedic surgeons. They were asked to document the AO classification of the fracture, and comment on the integrity of the lateral wall. Then, CT scans with 3D reconstructions of the same patients were provided along with the radiographs and they were asked to classify the fracture again. Inter- and intra-observer agreement of the AO classification based on plain radiographs alone and once CT scan with 3D reconstruction was added to the plain radiographs was determined using Kappa coefficients. Pattern of change in classification on addition of CT scan to plain radiographs was also assessed.
The mean kappa value for inter- and intra-observer agreement for AO classification on plain radiographs alone were 0.58 (moderate) and 0.66 (substantial), respectively. Upon addition of CT scan to plain radiographs, both improved to 0.70 (substantial) and 0.77 (substantial), respectively. The AO classification of the fracture changed 28.70% times (93 of 324 observations) upon addition of CT scan to plain radiographs. 96.77% times (90 of 93 observations) the classification was upgraded to higher group, while it was downgraded in only 3.22% times (3 of 93). 55.91% times this change was observed in AO 31 A 2 group (52 of 93 observations). In 17.59% cases (57 of 324 observations), fractures which were classified as stable (A1.1-A2.1) on radiographs alone, were reclassified as unstable (A2.2-3.3) upon addition of CT scan to plain radiographs. In 11.4% cases (37 of 324 observations), the lateral wall was classified as vulnerable or broken on CT scans where it was classified intact on plain radiographs.
Addition of CT scans with 3D reconstructions to plain radiographs improves the intra- and inter-observer agreement of the AO classification. Addition of CT scan results in change in classification of the fracture in about one out of three cases. This most commonly happens in the AO 31 A 2 group. Most of the times, this results in the classification of fracture being upgraded. Many fractures which are initially classified as stable (A1.1-A2.1) on radiographs are reclassified as unstable (A2.2-3.3) on addition of CT scans. The lateral wall is also classified as vulnerable or broken more number of times on CT scans than plain radiographs alone. Therefore, we conclude that CT scan with 3 D reconstructions definitely helps in better pre-operative classification of intertrochanteric fractures especially in select group of fractures (AO 31 A 2) where stability and integrity of lateral wall is difficult to assess.
滑动髋螺钉（SHS）是治疗稳定型股骨转子间（IT）骨折的金标准。然而，髓内植入物目前越来越多地用于治疗不稳定型IT骨折，尤其是那些外侧壁受损或脆弱的骨折。因此，准确的骨折分类对于确保正确的手术规划和植入物选择很重要。IT骨折的AO分类仅基于平片，许多作者报告其观察者间和观察者内一致性较差。因此，本研究的目的是评估在平片基础上增加CT扫描后AO分类的观察者间和观察者内一致性的改善情况，评估在平片基础上增加CT扫描后AO分类模式的变化，以及评估平片上显示为稳定的外侧壁在CT扫描上被分类为不稳定或破损的次数百分比。
54例股骨转子间骨折患者纳入研究。将患者的平片展示给三位骨科医生。要求他们记录骨折的AO分类，并对外侧壁的完整性进行评价。然后，将同一患者的CT扫描三维重建图像与平片一起提供给他们，要求他们再次对骨折进行分类。使用Kappa系数确定仅基于平片以及在平片基础上增加CT扫描三维重建后的AO分类的观察者间和观察者内一致性。还评估了在平片基础上增加CT扫描后分类的变化模式。
仅基于平片的AO分类的观察者间和观察者内一致性的平均Kappa值分别为0.58（中等）和0.66（实质性）。在平片基础上增加CT扫描后，两者分别提高到0.70（实质性）和0.77（实质性）。在平片基础上增加CT扫描后，骨折的AO分类有28.70%（324次观察中的93次）发生了变化。96.77%（93次观察中的90次）的分类被升级到更高组，而只有3.22%（93次中的3次）被降级。在AO 31 A 2组中观察到这种变化的次数为55.91%（93次观察中的52次）。在17.59%的病例（324次观察中的57次）中，仅平片上分类为稳定（A1.1 - A2.1）的骨折在平片基础上增加CT扫描后被重新分类为不稳定（A2.2 - 3.3）。在11.4%的病例（324次观察中的37次）中，平片上分类为完整的外侧壁在CT扫描上被分类为脆弱或破损。
在平片基础上增加CT扫描三维重建可提高AO分类的观察者内和观察者间一致性。增加CT扫描导致约三分之一的病例骨折分类发生变化。这最常发生在AO 31 A 2组。大多数情况下，这导致骨折分类被升级。许多最初在平片上分类为稳定（A1.1 - A2.1）的骨折在增加CT扫描后被重新分类为不稳定（A2.2 - 3.3）。与仅平片相比，CT扫描上外侧壁被分类为脆弱或破损的次数也更多。因此，我们得出结论，CT扫描三维重建肯定有助于更好地进行股骨转子间骨折的术前分类，特别是在外侧壁稳定性和完整性难以评估的特定骨折组（AO 31 A 2）中。
