This week’s Orthopaedic Crossfire® debate was part of the Annual Current Concepts in Joint Replacement® (CCJR), Winter meeting, which took place in Orlando. This week’s topic is “The Anterior Approach: Better, Faster, Safer.” For is Jose A. Rodriguez, M.D., Hospital for Special Surgery, New York, New York. Opposing is Bryan D. Springer, M.D., OrthoCarolina Hip & Knee Center, Charlotte, North Carolina. Moderating is Thomas S. Thornhill, M.D., Harvard Medical School, Boston, Massachusetts.
Dr. Rodriguez: So better, faster, safer…in my hands. I don’t know about you guys, but my decision making is limbic. How we perceive data is how we feel, but how we feel influences how we perceive the data.
I have presented this data from this podium previously on comparing anterior and posterior approaches by two very good surgeons (Clin Orthop Relat Res, 2014), using the objective measures of the Timed-up and Go (TUG) test, Functional Independence Measures, as well as a milestone diary.
We found that in the hospital there was a significant improvement in total score in the Functional Independence Measures and the time to achieve that peak score with the anterior approach. The TUG test was better with the anterior approach.
There was no difference in this study in the length of stay.
By two weeks, most of those measures had normalized. The TUG test remained significantly better for the anterior approach and by six weeks everything was basically the same.
More recently a much better study was presented by the folks at Mayo Clinic (Taunton et al., AAHKS 2016); 100 patients came to all surgeons; they were then randomized to go to either an anterior surgeon or a posterior surgeon, with similar in-hospital assessments.
In all the assessments that were made—discontinued walker, discontinued gait aids, opioids, stairs and walking six blocks, there was a marked improvement in the anterior group. They concluded, obviously in a familiar way, that both approaches provided excellent recovery. The anterior approach was faster at two weeks. How that matters? That’s up to you.
What about gait? We looked at gait analysis in two cohorts pre-operatively and at six months (J Arthroplasty, 2014). Of all the variables that we measured, the only difference that we found was in the range of motion during the gait cycle.
Both groups significantly improved in the frontal and sagittal planes, but there was no improvement with the posterior approach in the transverse plane. That is the amount of internal and external rotation that occurs during gait. This is not surprising given the dislocation precautions we had imposed on these people.
What about muscle strength? We measured muscle strength in the two cohorts using a technique that’s well published (Thorborg et al., Scan J Sci Sports, 2010). And we found that between pre-op and six weeks, the posterior group had a significant external rotation weakness and the anterior group had a notable flexion weakness. By three months, the flexion weakness had resolved in the anterior group. The external rotation weakness had improved with the posterior group, but there were still some clear measurable changes.
Precision. Looking at acetabular component anteversion for my anterior group patients — as I critically analyze my X-rays– I got better. I only had two dislocations within the first 100 cases. We then measured muscle volumes.
What we found was that there was relative comparability between the two cohorts in terms of anterior and posterior muscle volumes. For the anterior group, all the muscle volumes improved except for the obturator internus which we routinely release during the procedure. With the posterior approach, in addition to the obturator internus, there was also the obturator externus, piriformis and quadratus, a drop which is sustained post-operatively in the muscle volumes. All other volumes improved.
