Dorr v. Taunton: The Mini-Posterior Approach: Evidence Over Eminence

We gave the patients a home diary to record their daily functional milestones at home. We also used the proprietary ambulatory activity monitors preoperatively, at two and eight weeks, and one year. This allowed an objective evaluation of physical activity over a course of five days and in the daily living environment at those time points.

The direct anterior approach patients used less pain medication, overall had less pain, and were able to walk further with physical therapy in their first PT session. Looking further at early functional recovery, we saw that the direct anterior approach patients were able to discontinue their gait aids a week before the posterior approach patients. They were also able to discontinue their walker and narcotics, able to ascend stairs and walk six blocks—all about five days earlier. Looking at the steps per day at two weeks, there was a significant difference: 1,800 steps more per day for the direct anterior patients than the posterior approach patients. There was no difference at eight weeks or one year.

There was no difference in radiographic outcomes between the two groups. The overall complication rate for the posterior approach was 10% with one dislocation, one wound problem, two calcar fractures, and a deep vein thrombosis (DVT). For the anterior approach there was one dislocation, two wound dehiscence, and one fall resulting in a pubic rami fracture. This randomized controlled trial had a well-matched cohort with a unique surgeon crossover design that focused surgical expertise and decreased bias in the rehab phase.

As for longer term outcomes, I will point you to a couple of registry studies.

The Kaiser group had 118,000 patients with an average follow-up of three years: no difference in revision (septic or aseptic) or dislocation rate (Sheth et al, CORR2015). Recently, the Dutch Arthroplasty Register reported an overall dislocation rate for the posterior approach at 1%, and dislocation for the anterior approach at 0.59% (Zijlistra et al, Acta Orthopaedica2017). There was no difference in the overall revision rate.

In conclusion, both the direct anterior and the posterior approach really did provide excellent early postoperative recovery with a low complication rate. However, the direct anterior approach patients had an objectively faster recovery as measured by shorter times to achieve a number of functional milestones, and by quantitative activity monitoring at two weeks. Additionally, some new long-term studies are showing a reduced long-term dislocation rate..

Moderator Trousdale: Can we agree, Larry and Michael, that done well, both the direct anterior approach and the mini posterior approach do well for our patients?  Is that a true statement?

Dr. Dorr: That was my opening conclusion and my closure is that I don’t care what you do as long as you do it well. Unfortunately, I think there’s too many people not doing the anterior approach well because there are too many complications.

Moderator Trousdale: Michael, you showed a graph projecting that the direct anterior approach will overcome the posterior approach. How much of that do you think is marketing versus it will take over because it is really a better approach in the short and long-term?

Dr. Taunton: I think the answer is “yes” to both. There is patient pressure due to marketing. It’s certainly out there. I do think that part of the growth will be as there are surgeons in fellowship training programs that are performing the direct anterior approach, and then taking that approach into their practice.