Data, results spark debate about anterior THA approach

Special techniques help surgeons teach, learn anterior THA

Total hip arthroplasty can be performed with several surgical approaches, including the posterior approach, the lateral approach, the anterolateral approach and the direct anterior approach. With emphasis in health care today being on improved patient outcomes and reducing costs, the choice of surgical approach used for THA has become particularly controversial, especially the use of the direct anterior approach.

“[The direct anterior approach] came to the forefront as a ‘less invasive’ approach,” Michael J. Taunton, MD, associate professor at Mayo Clinic in Rochester, Minnesota, told Orthopedics Today. “It came off the heels of the other ‘less invasive’ hip and knee procedures, which have been proven to demonstrate little or no long-term benefit. So, I think many surgeons were skeptical to begin with.”

Adoption of anterior approach

Source: Jenny Morris

Use of the direct anterior approach in THA has increased in the last 10 to 15 years, and William G. Hamilton, MD, of Anderson Orthopedic Research Institute, said surgeons are motivated to use it because it offers the promise of a recovery with less pain and faster functional return, as well as a lower rate of hip dislocation compared with other approaches.

“Even if these differences go away by 4 to 6 weeks, patients find the possibility of an improved early recovery appealing,” Hamilton said.

Direct anterior THA is also thought to be a more anatomic approach, one that may help avoid muscle and nerve damage during surgery, William J. Hozack, MD, the Walter H. Annenberg professor of joint replacement surgery at Sydney Kimmel Medical School at Thomas Jefferson University and Rothman Orthopaedic Institute, said.

A study by Taunton and his colleagues published in Clinical Orthopaedics and Related Research in 2018 showed patients randomly assigned to undergo THA with the direct anterior approach stopped using walkers and gait aids 5 and 7 days earlier, respectively, compared with patients who underwent the miniposterior approach for THA. The direct anterior approach group also walked about 1,800 steps a day more than the miniposterior approach group at the 2-week point.

“For early rehab, they performed early functional milestones about 1 week earlier, with no difference in complications at 2 months or 1 year,” Taunton said.

Another study by Taunton and his colleagues, which was published in The Journal of Arthroplasty, showed about 1% to 2% of patients who underwent THA with the direct anterior approach (n=1,573) required superficial irrigation and debridement for superficial wound dehiscence.

One possible advantage of the direct anterior approach is the belief that patients may not have to adhere to range of motion precautions after surgery, according to R. Michael Meneghini, MD.

“That, however, is a bit anecdotal because there are new studies out that show even if you have a posterior approach, you do not have to obey range of motion precautions,” Meneghini, associate professor of orthopedic surgery and director of the Indiana University Hip and Knee Center, said.

Limited advantages

The clinical advantages to the direct anterior approach seem to be limited, Meneghini said.

Taunton said his 2018 study showed the early advantages associated with the direct anterior approach were no different when the short- and long-term results of patients treated with the direct anterior or the miniposterior approach were compared.

“At 8 weeks, the functional recovery equalized. Then, at 1 year, there was also no difference in complications or function. There was no difference in any kind of radiographic outcome at short or long term,” Taunton said.

The direct anterior approach may be more costly and consume more resources than other THA approaches, according to Meneghini, who is an Orthopedics Today Editorial Board Member.

“Most surgeons use fluoroscopy, so they have to have fluoroscopy machines and technicians to run them in the room. In addition, most surgeons use a special table, called the Hana table, which is also expensive and space consuming,” Meneghini said.

Complications can occur with any approach. However, Meneghini said a higher femoral component loosening and femoral fracture rate, greater blood loss and longer operative times may occur more frequently with the direct anterior approach.

“It is safe to say that the complications that can occur with the direct anterior approach can be more devastating,” Meneghini said. “All surgical approaches have risks. However, I would choose one with a complication profile that is not as devastating, with minimal lasting effects.”

According to Hamilton, these reports of increased complications come as surgeons work through the learning curve. As surgeons who use the anterior approach have changed in the last 10 years from about 5% to about 40% now, based on data from an American Association of Hip and Knee Surgeons audience response survey, many surgeons have made their way through the learning curve as they changed their approach. In studying more than 5,000 THA cases performed with the anterior approach at three centers, Steven L. Barnett, MD, and his colleagues found rates of 0.9% for femur fracture, 0.4% for infection and 0.23% for dislocation, Hamilton noted.

Taunton said the published literature shows similar complication rates between all of the approaches.

“We found 30-day major complications [for] posterior approach was 3.4%, lateral was 5.3% and direct anterior was 2.7%, and minor complications [for] posterior was 8.3%, lateral was 13.5% and direct anterior was 5.8%,” Taunton said. “The 30-day complications were overall similar for all approaches.”

Risk of nerve injury

Meneghini said the direct anterior approach can lead to nerve injuries. The incidence of femoral nerve palsy in a 2018 study by Andrew N. Fleischman, MD,and his colleagues was 14 times higher with the direct anterior approach compared with the posterior approach, Meneghini noted.

However, Hamilton said that when approaching the hip from a non-anterior-based approach, the rate of sciatic or common peroneal nerve palsy increases to a similar frequency. This is rare with the anterior approach and, regardless of approach, there is a low rate of major nerve palsy.

A 2019 study by Ryan S. Patton, MD, and his colleagues in The Journal of Arthroplasty showed that, within 2 years after surgery, 24% of 680 patients who underwent THA via the direct anterior approach had positive Douleur Neuropathique 4-Interview scores for continued neuropathic symptoms to the lateral femoral cutaneous nerve. Although the percentage decreased the further out from surgery the patients were, researchers found 11% of patients were positive for continued neuropathic symptoms 6 to 8 years after surgery. Numbness of the lateral femoral cutaneous nerve was the most common symptom reported.

“[The lateral femoral cutaneous nerve] does not influence function, so it would not cause disability in any way, but patients may have numbness in the thigh,” Hamilton, who is an Orthopedics Today Editorial Board Member, said. “That is typically transient, meaning it will go away over time, but there will be a small percentage of patients who may complain of permanent thigh numbness.” 

Continued improvements

As the use of the direct anterior approach in THA gained popularity in the mid-2000s, Hamilton noted industry-led educational programs related to the technique developed, allowing more surgeons to learn to perform the direct anterior approach. Hamilton believes these educational programs have improved over time and innovation in industry has helped, as well. He said technological advancements have included “the development of special instruments, techniques and implants. Also, other modalities have been developed to improve accuracy of implant positioning and equalizing leg lengths.”

“All these techniques, have evolved over time, making it easier for us to teach the technique,” Hamilton told Orthopedics Today.

Hozack said this collective learning experience of the direct anterior approach among surgeons has improved the quality of the operation. According to him, surgeons who have extensive experience with the direct anterior approach will have complications at the same low frequency as surgery done by any other surgical approach.

Despite the advancements that have been made regarding the direct anterior approach, Taunton said long-term outcomes about this THA approach are needed.

Currently, one focus is on whether a specific prosthetic design may help surgeons perform the direct anterior approach, according to Hozack.

Hamilton believes the advent of the American Joint Replacement Registry provides an opportunity to use large data to objectively evaluate the direct anterior THA approach.

“Much of the data that we have had so far have been smaller datasets from single institutions, sometimes from surgeon experts, sometimes from surgeon detractors, and that leads to significant bias in the data,” Hamilton said. “I think that as the American Joint Replacement Registry matures, we will be able to get a more accurate measure of outcomes [and] complication rates, as well as learn the relative value of these approaches.”

High patient demand

Despite limited data on the direct anterior approach, some surgeons and hospitals have begun to market it as a way to achieve better results, a tactic that Lawrence D. Dorr, MD, said has been bad for THA and for physician/patient relationships.

“When the data show there is not any difference, then it is unfair to patients, it is unfair to our profession and it is unfair to society to go out and brag that one way is better than another way,” Dorr, of Dorr Institute for Research and Education, told Orthopedics Today.

Hamilton believes patient demand for the direct anterior approach would be high regardless of whether the approach was marketed to patients.

“[Patient] demand has been the driving force behind the growth of this approach over the last 15 years. There have been surgeons who have marketed the approach using the internet, but there have been innumerable fads marketed by surgeons in recent years. Those that stand the test of time do so as patient testimony spreads and the thousands of patients who have had the approach tell their friends and community how well they did,” he said. “If there really was no difference or if the complication rate was as bad as the detractors say, this [approach] would have died years ago. Instead, it continues to grow every year.”

Learning curve

Dorr noted it is rare for surgeons to be able to switch between approaches, so it is important for orthopedic surgery residents and fellows to be exposed to both direct anterior and posterior approaches during their training program. This kind of exposure lets them decide which approach works best for them.

“If you are a young surgeon at training level, that is the time that most people decide what their approach is going to be, whether they like this approach or that approach,” Dorr said. “Frankly, that usually depends upon what their teachers do. If they are in a program where the anterior approach is done, that is probably what they are going to go out and do. If they are in a program where the posterior approach is done, that is probably what they are going to go and do.”

The direct anterior approach may have a higher learning curve compared with the posterior approach, according to Dorr.

In the literature, the reported learning curve for the direct anterior approach involves the first 50 to 100 patients, according to Meneghini.

“The anterior approach will have a higher learning curve than the posterior approach because it is a little more complicated,” Dorr said. “Particularly with the anterior approach, the difficulty has always been the visualization of the femur and being able to get the femoral implant in easily and without breaking the femur.”

Hozack noted residents and fellows master the anterior approach in the same amount of time as they do other approaches.

“I do not see [the direct anterior approach being] inherently more difficult to teach nor more difficult to learn,” he said. “You need to have proper supervision, just like the posterior approach. If you are not supervised in how to do it properly, there is a higher risk of complications, such as nerve injuries, bone fractures and dislocations.”

Considerations for approach

Whether a learning curve exists, established surgeons may still find it difficult to start using the direct anterior approach without formal training, Hozack said.

Before experienced surgeons switch to any new approach, he said they should evaluate their reasons for switching. Surgeons should not change approaches solely to obtain more patients because, in doing so, they could potentially increase their risk of complications, Hozack said.

Dorr said surgeons who encounter complications with one approach should not switch to a different THA approach as the solution.

“[They are] better off trying to become more skilled and understand more of the approach [they are] using,” he said. “To switch to another approach is probably just going to trade one set of complications for another set of complications.”

Taunton said surgeons who are interested in learning the direct anterior approach should attend multiple cadaver training courses and then consider either a site visitation or a reverse visitation with a surgeon who performs the direct anterior approach.

“Established surgeons transitioning approaches in practice have to recognize there will be a learning curve, that their early cases will take a little longer, but that does not mean there has to be a higher complication rate,” Hamilton said. “Also, the fellows I have the opportunity to train over months at a time have a much easier time adopting the approach than I did trying to learn it myself.”

Use what you know

Although experienced surgeons should be familiar with more than one THA approach, Hamilton said it is best to use one approach most of the time because it improves surgical quality and efficiency.

According to Dorr, surgeons need to “keep the perspective of what the approach does” in mind because the approach does not “determine the outcome for the operation.”

“The approach to the hip is just that. It is a way to get into the hip joint to do the operation and what is most important is that if once you are in the hip you do not do the operation correctly, it does not matter how you did the approach,” Dorr said.

Instead of focusing on the THA approach, Dorr said surgeons should focus on providing the best outcome for their patients.

“A surgeon should do the approach that they are good at. If you are good at an anterior approach, do it,” Dorr said. “If you are good at a posterior approach, do it. But this debate has been going on for at least 10 years now and there are not any data that say that one approach is superior to another.” – by Casey Tingle

• References:
• Barnett SL, et al. J Arthroplasty. 2016;doi:10.1016/j.arth.2015.07.008.
• Fleischman AN, et al. J Arthroplasty. 2018;doi:10.1016/j.arth.2017.10.050.
• Galakatos GR. Mo Med. 2018;115:537-541.
• Hart A, et al. J Arthroplasty. 2019;doi:10.1016/j.arth.2019.06.046.
• Patel NN, et al. J Arthroplasty. 2019;doi:10.1016/j.arth.2019.04.025.
• Patton RS, et al. J Arthroplasty. 2019;doi:10.1016/j.arth.2018.04.032.
• Statz JM, et al. J Arthroplasty. 2019;doi:10.1016/j.arth.2019.03.020.
• Taunton MJ, et al. Clin Orthop Relat Res. 2018;doi:10.1007/s11999.0000000000000112.
• Trousdale WH, et al. J Arthroplasty. 2017;doi:10.1016/j.arth.2016.10.006.

• For more information:
• Lawrence D. Dorr, MD, can be reached at 671 Bellefontaine St., Pasadena, CA 91105; email: drdorr@me.com.
• William G. Hamilton, MD, can be reached at 2501 Parkers Lane, #200, Alexandria, VA 22306; email: billhamilton@cox.net.
• William J. Hozack, MD, can be reached at 925 Chestnut St., 5th Fl., Philadelphia, PA 19107; email: tim.jones@rothmanortho.com.
• R. Michael Meneghini, MD, can be reached at 13000 E. 136th St., Suite 2000, Fishers, IN 46037; email: rm_meneghini@yahoo.com.
• Michael J. Taunton, MD, can be reached at 200 1st St. SW, Rochester, MN 55905; email: madson.rhoda@mayo.edu.

Disclosures: Hamilton reports he is a consultant, does product development and teaches the anterior approach for DePuy Synthes. Hozack reports he is a consultant for and receives royalties from Stryker. Meneghini reports he is a consultant for DJO Global. Taunton reports he is developing a total hip system with DJO Global. Dorr reports no relevant financial disclosures.

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