HIP SURGERY APPROACHES

OVERVIEW

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.

The direct anterior approach (DAA) has gained much publicity recently via those who are championing it. Much is available on the Internet and it is described as a ‘muscle sparing’ approach. It is very emotive, I often get asked if I ‘cut any muscle’ during the operation, as those who have Googled hip replacement will have come across this phrase. It gives the impression that other approaches (other than the DAA) slice across the belly or meat of muscle, a bit like chopping steak. This is not what happens! All approaches to the hip have to work around muscles, as the hip joint is surrounded by them. With my approach, a window is made in the gluteus maximus (with my finger) to expose the short rotators. I will detach tendon of the inferior gemellus and the proximal part of quadratus femoris as they insert onto the back of the femur (thigh bone). These get sutured back to the bone at the end of the operation, nothing has been sliced in two! I virtually always use a ‘piriformis sparing’ technique, meaning the tendon of the largest short rotators remains attached and untouched.

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.

Regarding the DAA, I have looked into using it, but the complication rate is higher than the posterior approach (see below). My perception having seen it on many 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 (as in quite traumatic!). Also, studies have not yet managed to show any significant advantages, and some have shown more persistent muscle damage post-operatively.

However, I am not completely closed to it, but I do need a bit more convincing before I start using it. My biggest concern are the higher complication rates, especially infection, peri-prosthetic fracture and re-operation rates, which are all about double depending on what you read. Approximately 30% of patients are left with a numb lateral thigh, as the lateral cutaneous nerve is often in the surgical field and regularly damaged.

As a result of the above, I generally use my piriformis sparing version of the posterior approach for THR, and have very good results from this. The standard posterior approach is the most common approach used by surgeons in the UK and worldwide. 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. (It is worth noting that Andy Murray’s hip replacement was performed via a standard posterior approach).

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. 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’!

More Detail

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 and many claims have been made about it online. 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. Some of the disadvantages of the anterior approach are that often a special table is needed, as is intra-operative x-ray (as you can’t see what you are doing very well). 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:

I recently came across a quote from an American surgeon, Dr Sweet, whom I feel puts it in perspective very well:

“During my fellowship training in joint replacement surgery at the New England Baptist Hospital in Boston, the anterior “Smith-Peterson” (DAA) hip approach was still popular in part due to the fact that Dr. Smith-Peterson had been a legendary New England surgeon in the pioneering days of early orthopedics. As a result I received considerable training in its use. It was around this time that the anterior approach lost favor with most joint replacement surgeons. The reasons for the demise of the anterior approach were many, and most are outlined above.

In summary, though, it was generally felt that risks and complications of the anterior approach outweighed any advantages. It has been clearly shown that there is no difference in recovery time between the two approaches. And with the advent of “large head” hip replacement systems, the single possible advantage of a lowered risk of hip dislocation has effectively been eliminated. As with many things, what is old becomes new as we constantly strive to both reinvent and improve tried and true procedures. Sometimes this leads to better methods of treating patients. And sometimes these “new” recycled methods work no better the second or third time around. What is really new in our modern medical world is the hype and marketing in the lay press of all things new before scientific proof of success is available.

My word of advice to patients remains this: Stay focused on the important issue – the long-term results. Pick your surgeon based on reputation, experience, and your feelings of trust and personal connection. Though it is important to discuss new procedures and technology, in the end let the surgeon in whom you place your trust pick what is best for you. All that is new is not necessarily better, and this is especially true of ideas that have that may have had a past history of problems or failures.”