Porous tantalum cones show short-term efficacy in large tibial defects during revision TKA

SAN FRANCISCO — Porous tantalum cones appear to offer an effective alternative option to bone graft for reconstructing large tibial defects during revision total knee arthroplasty, according to short-term results of a small study presented here.

"These are promising results at this early stage. We have no cases of loosening, migration or subsidence. And [we have] evidence of stable osteointegration," said William Long, MD, at the American Academy of Orthopaedic Surgeons 75th Annual Meeting. Also, "We have no new complications associated with this new reconstructive tool noted in this study," he said.

Long and colleague Giles R. Scuderi, MD, reviewed prospectively collected data for 13 revision TKAs performed on 12 patients. All cases were reconstructed using porous tantalum cones for Anderson Orthopedic Research Institute (AORI) Type T2 or greater lesions. Specifically, two cases had type T2B lesions, four had type T3A and seven had type T3B, according to the study.

Patients averaged just younger than 70 years at the time of revision. Of the 13 knees, 10 cases were revised for aseptic loosening and three cases underwent staged reimplantation for infection.

All patients were followed for a minimum of 2 years, Long noted.

The surgeon implanted cemented stems in two cases and used hybrid fixation in nine, which included "a number" of offset stems, he said.

Seven tibial augments were placed on top of the trabecular metal cone; six medially and one laterally. A constrained polyethylene insert was also used in all cases, he said.

Two cases developed recurrent infection — one at 3 months and one at 8 months follow-up. However, bone ingrowth was noted at the time of resection in both cases, Long said.

At 30-months mean follow-up, none of the remaining 11 cases required additional surgery, and range of motion averaged from 0° to 108°.

"There was one case of inflammatory arthritis, where the patient had some mild pain and swelling," Long said. However, there was no evidence of a deep infection, he noted.

Regarding radiographic outcomes, also for these 11 non-infected cases, alignment averaged 5.6° of valgus, with stable osteointegration and no migration, subsidence or osteolysis, he said.

"In terms of clinical application, this can be applied and used with any revision system; there are multiple sizes and dimensions that can be used. It eliminates concerns traditionally associated with bone graft, including reabsorbtion, disease transmission, graft fracture [and] size and shape mismatches," Long added.

For more information:
Long W, Scuderi GR. Porous tantalum cones for large tibial defects in revision TKA: Minimum 2 year follow-up. Paper #450. Presented at the American Academy of Orthopaedic Surgeons 75th Annual Meeting. March 5-9, 2008. San Francisco.