Granulomas and wear seen decades after noncemented acetabular procedures

Investigator finds 25% incidence of retroacetabular osteolysis in active patients up to 18 years postop.

Osteolysis and wear may pose long-term problems for young and active patients following cementless acetabular reconstruction.

Cementless acetabular components work well up until the second decade of use, said Richard A. Berger, MD, of Chicago. “However, there are some problems and potential long-term failure mechanisms of progressive granuloma invasion, either along the rim or through the screw holes, whether they had screws in them or not,” he said.

Berger said massive retroacetabular pelvic lesions could develop around the screw holes, regardless of screw usage. His comments came during a presentation at the annual Insall Scott Kelly symposium.

In his study of over 200 cementless acetabular reconstructions, Berger and Craig J. Della Valle, MD, found a 99% survivorship for loosening and nearly 93% survivorship for revision after 15 years. Yet, radiographs detected a 25% incidence of peripheral and retroacetabular osteolysis at 18-year follow-up. “We actually found that most of our problems occur in our young and more active patients,” Berger said.

He noted that patients younger than 50 at the time of arthroplasty had three times the rate of osteolysis and 50% greater wear rates than patients that underwent the procedure after 50.

“The long-term problem is wear and osteolysis," Berger said. "It's not loss of fixation, at least not yet up to 20 years.”

Berger cited a retrieval study performed by Robert Urban and colleagues at Rush University Medical Center, which found large granulomas in well-functioning hips in situ from 2 to 157 months. In their study of 28 HG-1 and HG-2 cups implanted in patients at a mean age of 65, the researchers discovered an average bone ingrowth of 35%, Berger said.

“But patients with implants in situ for more than 5 years were more likely to demonstrate expansile granulomas contiguous with screw holes with particulate debris within the granulomas,” he said.

The researchers also found that retroacetabular granulomas occurred at the screw holes and expanded over time.

“The deepest penetration was around not just screw holes, but screws allowing particulates to travel up into that periprosthetic bone,” Berger said. “And the pathway was the screw holes, whether or not it had screws in it.”

The investigators also discovered many pelvic granulations, which also increased over time. Yet, even good radiographs didn't prevent investigators from underestimating the severity of these lesions, Berger said.

“Cementless fixation is quite consistent and predictable,” he said. “However, I think it’s important to start using wear-resistant articular surfaces ... to prevent some of these long-term problems or at least minimize them.”

Berger also said that new technologies, such as crosslinked polyethylene or alternative bearings, are crucial for the longevity of implants in young and active patients.

For more information:
Berger RA, Long-term results of cementless hemispherical acetabular components. Presented at the Ninth Annual Insall Scott Kelly Institute Sports Medicine and Total Knee & Hip Symposium. Sept. 15-17, 2006. New York.
Della Valle RM, Berger RA, Rosenberg AG, et al. Primary total hip arthroplasty with a porous-coated acetabular component: A follow-up note at 15 to 18 years. J Bone Joint Surgery Am. 86:1217-22,204.
Urban RM, Jacobs JJ, Sapienza CI, et al. Polyethylene wear and interface tissues in intermediate and long-term modular porous-coated acetabular components retrieved postmortem. Trans ORS. 27:25, 2002.
Richard A. Berger, MD, is an orthopedist at Rush University Medical Center, 1725 West Harrison Street, Suite 1063, Chicago IL 60612. He can be reached at 312-243-4244 or rberger@ortho4.pro.rpslmc.edu.