Abstract
There are numerous examples in medicine where “eminence trumps evidence.” The direct anterior approach (DA) is no exception. Its meteoric rise has largely been driven by industry and surgeon promotion. This surgical approach continues to garner interest, but this interest is largely for marketing purposes, as emerging data would suggest a high risk, low reward operation. In addition, factors such as selection bias and impact bias, have substantially swayed peoples interest into making an inferior operation look better.
There are several factors related to the direct anterior approach that should give us pause. Those include the surgeon learning curve, limited functional benefit and increased complications. There is no question the DA approach for total hip arthroplasty (THA) has a long and steep learning curve. The majority of studies would suggest at minimum, 50–100 cases before a surgeon is comfortable with this approach and some studies would suggest the technical difficulties of this approach remain an issue even with increasing experience. This proves difficult with an attempted rapid adoption of this technique by a surgeon who may perform less than 50 THAs per year but feel the need to offer this approach to their patients for marketing purposes.
One of the many touted benefits of the DA approach is the perception of improved functional outcomes. Many of the early studies showed early improvement in gait, pain and mobility. However, these studies compared the DA approach to an anterolateral approach. Even when compared to the anterolateral approach, considered the most invasive and least muscle sparing, the benefits of the DA approach were only short term (6 weeks). The majority of retrospective studies, prospective randomised studies and meta-analyses comparing DA to a posterior approach show little, if any, benefit of one approach over another with regards to functional benefit. Another touted benefit includes a low or no dislocation risk associated with the posterior approach. On the contrary many studies have failed to demonstrate lower dislocation rates with the DA approach compared to a contemporary posterior approach. A recent registry study from the Michigan Arthroplasty Registry Quality Initiative (MARQI) showed equal dislocation rates between the DA and posterior approach.
Concerns have also been raised regarding unique and more frequent complications with the DA approach compared to other surgical approaches for total hip arthroplasty. Unique complications such as ankle fractures and a high incidence of nerve injury, especially damage to the lateral femoral cutaneous nerve, have been reported. In addition, the data now clearly show a higher incidence of complications on the femoral side, including early loosening and periprosthetic fracture.
As responsible surgeons, if we want to say the DA approach is different, then fine, we can say it's different. Claims of superiority of one approach over another have not been born our in the literature and in fact much of the data would suggest a high risk no reward operation for the DA approach compared to other surgical approaches for total hip arthroplasty.
