The anterior approach has gained much publicity recently via the few who are championing it. Much is available on the Internet and it is described as a ‘muscle sparing’ approach. I have looked into using it, but the complication rate may be higher than the other two below. My perception having seen it on a few occasions being used by surgeons who are skilled at it is that the surgical view gained is not great and it may not be as ‘muscle sparing’ as advertised. A randomised study on the anterior versus the posterior approach has been performed at my NHS hospital, and this has not yet managed to show any advantages. As a result, I am not completely closed to it, but I do need a bit more convincing before I start using it.
Other approaches used by many surgeons are the lateral (or Hardinge) and the posterior. The Hardinge approach was once the commonest approach for THR, but the issues with it are that it can damage the hip abductors, which can leave the patient with a persistent limp.
As a result of the above, I generally use a posterior approach for THR. This (or variations of it) is now the most common approach used by surgeons in the UK. The benefits are that the surgeon can gain excellent exposure (which makes correct component positioning much easier), and this can be done through a small incision if the patient is suitable. I always promise that I will do the procedure properly through the smallest incision possible, with the least muscle trauma, to perform surgery safely. In some this can be 10cm, in others though it may need to be larger.
Hip replacement surgery has been sucessfully performed for over 50 years. Throughout this time, surgeons have used various different ways to get into the hip,which we term the ‘approach’. They all have pros and cons, and virtually all surgeons feel that the way that they do it is the best! In reality, and despite what is written on the internet by companies or other surgeons, all approaches are generally safe and yield good results during the operation and afterwards. The most important thing is to choose a surgeon who you communicate well with and trust.
Currently, the widest utilised approach for a hip replacement in the US and UK is the ‘posterior’ or ‘posterolateral’ (which I use). The reason for this is that the surgeon can gain excellent, clear access to the joint. In skilled hands it can be performed through reasonably small incisions (10cm in thinner patients). However, the great bonus of this approach is that should the surgeon encounter unexpected difficulties, the approach is easily and safely extendable (can be made larger) allowing them to deal with these effectively. This is one of the first principles of surgery, ‘always use an approach which is easily extendable should you encounter the unexpected’!
My results using this approach are very good. Intra-operative blood loss is usually around 200 ml (less than a can of cola). Patients get up out of bed on the same day following surgery, and only need to stay in one to two nights. My intra-operative complications are also very low, these being nerve injury, infection, leg length discrepancy (defined as +/- 1 cm), and fracture (bone crack) all being less that 1% each. As the surgery is not unduly prolonged and we get patients up quickly following their operation, our rate of blood clots such as deep vein thrombosis (DVT) in my patients is also less than 1%.
Historically, however, the posterior approaches were criticised for having a higher post-operative dislocation rate than the others. Certainly, thirty years ago this was true, but the approach was performed differently then and the surgeons did not repair the joint capsule, which was the major issue. We all do this now, and all high volume hip surgeons who use the posterior approach can quote a dislocation rate of less than 1% for a primary (first-time) hip replacement. (Currently, mine is about 0.5% at the time of writing).
The Direct Anterior Approach (DAA) has gained a lot of interest recently and many claims have been made about it online. Many of these are quite emotive, such as being ‘muscle-sparing’ and ‘minimally invasive’ etc. There are also claims that the post-operative dislocation rates are lower than other approaches. As a patient, I can understand why this kind of marketing is effective and why patients are led to think that it is the best approach for hip replacements.
In reality, the vast majority of the claims made about DAA are untrue or unproven. The claims that have been made is that it’s tissue sparing, there is less pain, and faster recovery. However, there is little evidence to support these.
The disadvantages of the anterior approach are that often a special table is needed, as is intra-operative x-ray. The femoral exposure can be difficult (particularly in male and heavyset patients); it also increases operating time.
In a study of the anterior versus the posterior approach (Meneghini, CORR, 2006) the researchers found muscle damage with both approaches. The muscle damage in the anterior approach was significantly more than posterior. A different study by Pilot (Injury, 2006) looked at another way to look at muscle damage, H-FABP (heart-type fatty acid binding protein), which is a muscle protein. You can evaluate the levels of muscle damage based on the levels of this protein. There was no difference in the posterolateral versus the anterior approach. Post-operative MRI has also failed to show any reduced muscle damage following DAA compared to posterior approaches.
Complications are higher with DAA. Regarding dislocation, several large series of anterior approaches to the hip showed roughly the same thing: 0.96% (Siguier), 0.61% (Matta), 1.3% (Kennon), 1.5% (Sariali). As mentioned above, these are all (at best) comparable or higher than mine using the posterolateral approach. Joel Matta is the biggest advocate of the DAA in the U.S. He has quoted a 2.4 % fracture rate with the anterior approach, which is much greater than we see with the posterior approach.
The anterior approach is also associated with lateral femoral cutaneous nerve injury. In a paper by Goulding (CORR, 2010) 80% of the patients noted numbness in the distribution of that nerve. And not all of those patients fully recovered. In a paper by Woolson (Journal of Arthroplasty, 2009) looking at surgeons using this technique the complication rate was 9% and the surgical time was at least two thirds more that of the posterolateral approach.
Below is a comparison table to look at: