Focusing on Direct Anterior Approach (DAA): an Interview with Dr Hu Yihe
The American Academy of Orthopaedic Surgeons 2017 Annual Meeting (AAOS 2017) was held at the San Diego Convention Center, California's second-largest city, at 3.14 to 3.18 in U.S. time. As the honored guests, Prof. Hu Yihu, director of Department of Orthopaedics from Xiangya Hospital of Central South University made a brief introduction of the DAA of total hip replacement. Let's see what he said!
The strength and characteristics of DAA
In general, hip replacement surgery are mainly done with lateral, posterolateral approach in China. However, more or less, this approach have to cut some of the muscles affecting the joint stability and strength. The word "direct" in DAA, refers to the entrance from the front of the intermuscular interval without damage the muscles. For the reason why this approach is becoming increasingly favored by joint surgeons, I think there are three main answers. Firstly, it does not hurt the muscle. The second, hip dislocation rate using the DAA is quite low. The last but not least, it is involved in fast track recovery programme.
Direct anterior approach VS posterolateral approach
Posterolateral approach is still the first choice of the majority of orthopaedic surgeons when handling a primary hip replacement. Its applicatoin is broader because of easier handling than DAA. Aside from its obvious advantages, direct anterior approach has its own drawbacks. It can not be used to handle complicated hip surgery such as DDH (Developmental Hip Dysplasia) or revision surgery. Therefore, primary hip replacement in relatively simple case is the major application area for DAA.
What are the advantages of posterior lateral approach? Surgical approach do affect the rate of prosthesis aseptic loosening. In direct anterior approach, surgeons get limited filed to determine the suitable prosthesis size and position, which may increases the rate of aseptic loosening of the prosthesis. However, from posterior lateral approch, surgeons can directly see that prosthesis, so the complication rate is relatively low. This requires the surgeons to carefully scan and test primary stability and prosthesis positions under fluoroscopy.
The future premise of DAA
The first concern is so-called the learning curve. Any operation could be in trouble without full understanding of the underlying mechanism and tactics through learning. How to obtain effective learning is the next issue. The easiest way to train young surgeons starts with the cadaver study. The second is to learn DAA in operation room from the experienced surgeons. As Professor Hu added at last, never forget to choose easy and typical cases at the beginning, which will help you learning the skill with lower risk and building up your own confidence.
原文题目：AAOS 2017：胡懿郃教授谈直接前入路全髋关节置换
美国骨科医师学会年会 2017 年会（AAOS 2017）于美国时间 3.14～3.18 在加利福尼亚州第二大城市圣地亚哥会议中心隆重召开。
作为此次的参会嘉宾，来自中南大学湘雅医院的骨科主任胡懿郃教授，就直接前入路全髋关节置换做了简要介绍，让我们一起来学习一下！
直接前入路的定义及特色
一般来讲髋关节置换术式主要有后外侧入路、前方入路和直接前入路等，但总的来讲这些入路都要从外侧进入。直接前入路有两个字「直接」，也就是从前方的肌间隙进去，一般不会损伤肌肉，术后康复快。
直接前入路之所以受到很多医师的青睐，主要有三个方面的原因，第一不损伤肌肉，第二脱位发生率低，第三康复快。现在对术后快速康复重视度高，因此直接前入路也就受到更多医生的青睐。
直接前入路 PK 后外侧入路
后外侧入路是比较经典的入路，这个入路可以做从初次到翻修的所有髋关节手术。而直接前入路有自己的缺陷，它不能做一些复杂的髋关节手术，比如 DDH（发育性髋关节发育不良）及翻修手术。所以直接前入路一般对初次髋关节置换这种比较简单的手术来说是非常方便的。
手术入路之于假体无菌性松动
熟练掌握直接前入路才能在安放假体时找到非常合适的假体；假如你不熟练，或者学习曲线不够，就会出现假体大小不合适的可能，也就会导致假体的松动。
所以要做好直接前入路，一定要从尸体操作等开始，慢慢学习，一步步掌握。不熟练的情况下，一定要在透视下做，并将假体非常合适地放进去，从而预防术后假体无菌性松动。假体的初始稳定性很重要，如果不稳定，发生无菌性松动的风险就比别人更早。
后外侧入路有什么优点呢？首先就是可以直接看到，手术当中基本上也可以直接测试，所以并发症相对比较少。无菌性松动一般来说不容易出现，因为做后外侧入路同样要试好假体大小，按照试模大小放置假体，所以早期一般不容易出现无菌性松动。
实施直接前入路 THA 的前提
首先是要学习。每一个入路，每一个手术方式，不经过学习的话就会出现问题。那怎么样学习呢？
一是培训，要从尸体解剖练习开始；二是开始做直接前入路时要在有经验医生的指导下进行，然后慢慢积累。胡教授认为学习曲线要达到 50 例才有才会有能力完成直接前入路手术；三是在选择病例的时候不要选择复杂病例，要选择有意义、典型的手术，让自己的入路得到很好的培训。
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