Posterior vs. anterior operative approaches to THA debated

Proponents of the anterolateral approach cite high dislocation rate with posterior method. Posterior approach advocates say the problem is solved.

Issue: May 2003

NEW ORLEANS — Improved visualization is the reason why John J. Callaghan, MD, advocates the posterior approach to total hip arthroplasty. Lester S. Borden, MD, used the posterior approach early in his practice, but a high dislocation rate persuaded him to switch to the anterolateral approach.

With each surgeon maintaining that his technique is superior, Callaghan and Borden debated the optimal operative approach for total hip arthroplasty (THA) here at the American Academy of Orthopaedic Surgeons 70th Annual Meeting.

Innovations to the posterior approach, particularly the posterior capsule repair, have reduced the risk of dislocation, according to Callaghan, an orthopedic surgeon at the University of Iowa. “I think that’s very different than what was done in the early days,” he said.

He said the high dislocation rate was seen in older studies before the posterior capsule repair was added to the technique. He cited a more recent study in which the posterior capsule repair reduced the dislocation rate from 2.3% to 0% and another study that yielded a dislocation rate of 0.8%. Callaghan himself reported only two dislocations in his last 200 hips with six-month follow-up.

His advocacy of the posterior approach stems from concerns about the anterolateral approach. “You can potentially get nerve damage going more than 5 cm above the greater trochanter from denervation of the superior gluteal nerve when you’re doing an anterolateral type of approach,” Callaghan said. “And putting back down that abductor can be somewhat problematic.”

His other concerns include limping and heterotopic ossification (HO). “I don’t like to see my patients limping after the first six months, and I don’t like to see HO. When I originally did this [anterolateral] approach, I had both,” Callaghan said.

With the posterior approach, “I get great exposure and the gluteus medius is preserved. With the posterior repair I’m using, and with the use of designs with better head-neck ratios, dislocations with the posterior approach are really approaching that of the anterolateral approach rates,” Callaghan said.

Anterolateral approach

Acknowledging Callaghan’s criticisms of the anterolateral approach, Borden, of the Cleveland Clinic, said the anterolateral approach has undergone innovation as well. Borden described Harding as “resurrecting” the direct lateral approach in 1982. Unlike his predecessors who detached all the abductors from the trochanter, Harding left the posterior medius on the trochanter.

Borden said he uses a modification of Harding’s approach in which he detaches and reattaches the gluteus medius to the trochanter.

“We kind of modified the approach realizing that the gluteus minimus is actually, on average, about 1.4 cm medial to the medius, and that it’s important to put it back there. If you pull it out with the medius and increase the resting length, there will be too much tension, the muscles will avulse and they’ll [go] limp,” Borden said. “Reattachment is important and you do have to do it anatomically.”

He added, “I think it provides excellent exposure. It does everything the posterior approach does; dislocations are rare and we have not seen more heterotopic ossification doing this technique, but you do have to do it correctly.”

Strengths and weaknesses

Moderator Daniel J. Berry, MD, of the Mayo Clinic in Rochester, Minn., highlighted the reasons why surgeons advocate one approach over the other. “Those who changed to an anterior approach got tired of seeing dislocations in the emergency room, and those who changed to a posterior approach got tired of seeing patients limping into the office within a year. Those are of course, admittedly, the problems we always have with each approach.”

He continued, “I think that it’s probably true to say that while we can make both of those complications much less frequent than they used to be, each approach probably still has its strengths and weaknesses.”

Borden acknowledged that with refinements to posterior capsule repair and the improvement in the head-neck ratios of the implants, he has fewer objections to the posterior approach.

Taking steps to avoid dislocations

Thomas S. Thornhill, MD, of Brigham and Women’s Hospital in Boston, who utilizes both approaches, agreed much has been done to reduce the rate of dislocation associated with the posterior approach. Nevertheless, he still has greater confidence that he can avoid a dislocation in the high-risk patient with the anterolateral approach.

“People with avascular necrosis, people who have good motion dislocate more, people with fractures, people with neuromuscular disorders, people who are really obese … I do those all through an anterolateral approach,” he said.

Another advocate of the posterior approach, Miguel E. Cabanela, MD, of the Mayo Clinic, also reserves the anterior approach for some cases. “You should select the anterior approach for some patients, perhaps the fracture patient, the patient with Parkinson’s disease, maybe the very obese patient,” he said. “I do about 95% of my hips with the posterior approach, but I do about 5% through an anterior approach.”

Thomas P. Sculco, MD, of the Hospital for Special Surgery in New York, who utilizes the posterior approach in all of his patients, disagreed. “I use the posterior approach in every patient, and the dislocation rate is 1%, and I looked at 3000 patients. You’ve got to repair the posterior capsule, you got to put your components in correctly; I think that’s the key thing,” Sculco said. “I think if you do that and restore the soft tissue stability, the dislocation rate is going to be about 1%.”

For your information:

Callaghan JJ. I prefer a posterior approach. Borden LS. I prefer an anterolateral approach. Both presented at the American Academy of Orthopaedic Surgeons 70th Annual Meeting. Feb. 5-9, 2003. New Orleans.