Tantalum revision cups show good stability at two years

Although 5.2% of cases did require additional revision for instability, hematoma or wire removal, none exhibited cup migration.

Radiograph of a patient who underwent bilateral acetabular cup revisions with tantalum implants. Both arthroplasties remained stable with good anatomical reconstruction at short-term follow-up.

COURTESY OF RODRIGO M. MARDONES

WASHINGTON — Implanting revision acetabular cups made from highly porous tantalum can yield low rates of secondary revision procedures at a minimum two years postop, suggest results of a new study presented here.

Researchers at the Mayo Clinic in Rochester, Minn., evaluated the early postoperative outcomes of 114 consecutive acetabular revisions performed on 111 total hip arthroplasty patients.

Roughly half the acetabula included (49%) had deficits classified as type 2C, 3 or 3B based on the Paprosky system for defect classification. The study excluded patients with pelvic discontinuity or infection, and all patients had at least two years follow-up.

In all cases, surgeons implanted the Trabecular Metal Modular Acetabular System (Zimmer), a porous tantalum revision acetabular cup fitted with a modular polyethylene liner, which was cemented in place. The implant includes an elliptical-shaped cup and has a periphery 2 mm in diameter larger than the bone reamed to receive it, which provides an interference fit that improves bone contact and stability. It also has been shown to support intensive bone ingrowth, according to Rodrigo M. Mardones, MD, an orthopedic surgeon from Santiago, Chile.

Mardones presented the results of the study here at the American Academy of Orthopaedic Surgeons 72nd Annual Meeting.

“Most of the patients required bone grafting, typically autologous or allograft morselized cancellous bone impacted with a reverse reamer,” Mardones said.

At two years follow-up, the researchers found that 86% of patients attained an anatomical reconstruction with the cup’s center of rotation in Ranawat zone 1. Radiographic analysis showed no radiolucencies in 86% of cases and incomplete radiolucencies in the remaining 14% of cases.

Although 5.2% of cases did require additional revision for instability, hematoma or wire removal, no cases exhibited cup migration, he said.

For more information:

Mardones RM, Talac R, Hanssen AD, et al. Use of a porous tantalum revision shell in revision total hip arthroplasty. #277. Presented at the American Academy of Orthopaedic Surgeons 72nd Annual Meeting. Feb. 23-27, 2005. Washington.