Direct Anterior Hip Replacement

how long have you been teaching anterior THA?

Dr. Greenhow and Dr. Loucks started teaching in 2005. We would be considered very early adopters of the approach.

Are all patients potential candidates for an Anterior Hip Replacement?

Theoretically yes. In our practice, EVERY patient for the last ten years (and more) undergoing primary hip replacement has had a Direct Anterior THA. This includes many patients with unusual anatomy or what surgeons would consider technically more difficult replacements. This is in large part due to our tremendous experience with the approach and when we teach surgeons how to do the technique we DO NOT recommend performing the approach in ALL patients.

How about revisions or “repeat hip” surgeries? Can you perform Anterior Approach?

Yes. We perform about 95% of our hip revisions through the Direct Anterior Approach. Again, this relates to our experience with the approach and is something that most surgeons would not do unless they have developed tremendous experience with the Anterior technique. We have such extensive experience, we teach these techniques at Advanced Direct Anterior Courses for surgeons.

How long have you been teaching Anterior THA?

Dr Robert Greenhow and I started teaching in 2005. We have been fortunate enough to teach this technique all over the world. Our technique has evolved over the years as has the techniques that we teach. We have trained surgeons in the Anterior Approach without a table, with a special OR table and with a special leg holder.

Are there differences among these Anterior techniques?

Absolutely. Personally, our own technique has evolved significantly over the years so we understand the subtle, yet important differences that exist out there with respect to the Anterior Approach. It really boils down to Anatomy. A true, AMIS or Anterior Minimally Invasive Surgery does NOT cut ANY muscles or tendons around the hip joint during the replacement procedure. For a beginning surgeon, we find that there is often a need to cut muscles and tendons to get the case done. If surgeons start to cut these muscles and tendons then it starts to become a Posterior Approach done through an Anterior incision. Also, if you start cutting muscles and tendons it takes away from some of the advantages of the approach. We see these incredible benefits for our patients manifested by rapid recovery with fewer complications.

Are there complications with Direct Anterior Approach?

We feel that in our practice, there has been a reduction in technique related complications with the Anterior Approach. There are potential complications with any hip replacement surgery, however, lets break it down into generalized complications and then technical complications.

General risks or complications include things like an infection or blood clot, which is a risk regardless of the type of approach. All joint replacement surgeons have protocols in place to prevent infection and blood clot and our associations put out great guidelines to help develop our preventative treatment algorithms.

Technical complications are things like dislocations and leg length inequality. These are things that are often directly affected by our surgical techniques. They are two of the more common complications that surgeons work hard to avoid. They are also somewhat related to each other from a technical perspective. When we replace a hip joint we strive to reproduce the anatomy as close as we can, however, depending on the situation this may not always be possible. Posterior approach has one of the highest dislocation rates of all the hip approaches. This is because in the posterior approach surgeons cut the muscles, tendons and capsule at the back of the hip to get access to the joint. This creates a path of weakened tissues posterior or out the back, where the prosthetic hip can dislocate out of the socket. Now you add in the fact that people like to flex their hip up in their normal activities such as sitting in a chair, putting on shoes and socks and you risk dislocating your hip out the back. Often these posterior approach patients will have movement restrictions or “hip precautions” for a period of time while these tissues heal to prevent unwanted dislocations. Now here is how the leg lengths are related to the dislocation issue. During our surgical approach, if we cut these tissues that normally help stabilize the hip joint we can reduce the risk of dislocation by adding length to the hip. This will effectively tighten up the surrounding tissues and potentially reduce the risk of dislocation, however, you “rob Peter to pay Paul”. Sometimes adding unwanted length is necessary to gain adequate stability but too much and patients are not usually happy.

So, this is where Direct Anterior has made a huge difference in our hands. We collectively perform over 800 Anterior Hips per year. We have come to realize that if you don’t cut ANY muscle or tendon around the joint that it is incredibly stable. In addition, we use X-ray guidance to position the parts we put in the hip. This allows us to try and anatomically replace the hip while respecting leg length and offset without worrying about dislocation. Also, going in the front makes sense anatomically from a dislocation perspective.

So the short answer after this long explanation is that in our experience, Anterior Approach has reduced some of the more common technical complications with Total Hip Replacement.

However, we do see some unique issues with Anterior Approach. For example, patients may experience some transient numbness in the lateral thigh, which is related to a skin nerve called the Lateral Femoral Cutaneous Nerve. This nerve sits under the skin close to our incision and small branches of it may get cut during the approach. The skin numbness is usually NOT an issue for patients and often resolves without ANY issues. It DOES NOT innervate any muscles so there is no muscle weakness or functional issues, only potentially a patch of numb skin. The other thing we see is occasional hip flexor “tendonitis”. This relates to the anatomy of the Anterior Approach and activities of daily living. During an Anterior approach, the “hip flexors” get pushed aside, however, will often get irritated by retractors, bleeding and inflammation created by the surgery. Then the patient spends a fair amount of time in a hip flexed position (for example sitting and sleeping) and these irritated and inflamed muscles will often tend to contract and shorten. Then when the patient transitions to a full stride gait pattern they experience hip flexor discomfort with hip extension. An easy way for us to prevent and treat this is to educate both patients and physical therapists to do regular stretches of these “hip flexors” during the rehabilitation phase.

Has the Anterior Approach shortened the patient’s recovery?

Absolutely. In fact, we are now doing a number of these total hips as Outpatients. This is a relatively newer concept and we are developing teaching programs and patient care pathways to make sure that these are appropriate cases done in a safe environment. High quality care and patient safety are of paramount importance. In 2014 we performed approximately 100 hips as an outpatient where 95 patients went home the SAME day of surgery and 5 patients went home within 23 hours. Patients report less pain and faster return to work and activities. We use special anesthesia techniques and medicines that allow patients to walk the day of surgery, often requiring very little narcotic pain medication. By 2 weeks most of our patients are walking without any aids (for example cane or crutch) and could potentially return to sedentary work. We have had hundreds of patients skiing and golfing by 7 weeks post-op and these patients frequently send us videos to prove it! Also, people can return to regular exercise, including Yoga and Pilates much faster because the hip is stable and we do not impose dislocation precautions or movement restrictions. We have many Yoga and Pilates instructors, as well as professional athletes and ballerinas as patients who have put this to the test.

Are there special exercises or physical therapy that is required after an Anterior Approach?

A good stretching program combined with normal walking is often all that is needed. If patients have developed bad gait patterns as a result of their diseased hip they may need some professional treatment with a physical therapist. The key is stretching especially the hip flexor group of muscles to prevent shortening and tendonitis.

Are there any restrictions after an Anterior Approach Total Hip?

Preservation of the muscles and tendons, along with proper hardware placement results in a very stable hip replacement and as such we do NOT impose hip “precautions” or restrict any motion after an AMIS Total Hip. However, the biology of the “press-fit” implant does require some modification of activities for at least the first 6 weeks. A press-fit cup and stem is most common and this means that the surgeon implants the metallic prosthesis very firmly into the bone with a “scratch fit” that holds it into the bone. Over the next 6 to 8 weeks the bone will grow around the prosthesis and create a solid bond that can react to the dynamic stresses that are placed on the metal-bone interface. During this 6-8 week period of bone ingrowth, we recommend non-impact, lighter exercise with no heavy resistance loads. Once we see follow-up X-rays around the 6-8 week mark we can usually clear patients for more strenuous activity. In general, our patients return to VERY active lifestyles, however, we educate patients about lower impact activities to prevent accelerated wear on the artificial bearing surfaces. We allow patients to ski, hike, bike, golf, play tennis and hockey and many other sports, however, we recommend against regular running or higher impact exercises. Exercise programs like yoga and pilates are fantastic and lower impact cardio routines such as stationary bike, elliptical trainer, swimming and rowing are great ways to burn calories without putting undue impact of the new joint replacement.