Preliminary findings show 95% survivorship with STAR prosthesis at 8 years postop

Researcher called the 78% rate — using second operation as an endpoint — favorable.

Issue: October 2006

Early results with the Scandinavian Total Ankle Replacement indicate good survivorship rates for revision and reoperation.

Researchers studying 80 patients who received the Scandinavian Total Ankle Replacement (STAR) found an almost 95% survivorship for revision or removal at 8.3 years postop. When they used second operation as an endpoint, investigators discovered a 78% survivorship rate during the same period.

Satisfactory results

"The take-home message is the fact that the STAR prosthesis, in a very carefully controlled clinical study, seems to be producing satisfactory results, having an average follow-up of 6.5 years with up to 8 years with some of the patients," Roger A. Mann, MD, the study's author and director of the American Orthopaedic Foot and Ankle Society's Foot and Ankle Fellowship Program, told Orthopedics Today. Mann's co-investigator, Eric R. Horton, MD, presented the study at the society's 22nd annual summer meeting.

The study included patients who underwent total ankle replacement using the STAR between 1998 and 2000. The cohort had an average age of 61.7 at the time of surgery, and 51% were men. The patients had preoperative diagnoses of post-traumatic arthrosis, osteoarthritis, rheumatoid arthritis or hemochromatosis, the researchers wrote in their abstract.

In addition to reviewing patient records, the investigators contacted the cohort for postoperative analysis. The researchers located 77 living patients and gathered medical information for three patients. They conducted follow-up between 5.7 and 8.3 years after implantation.

Intraoperative results revealed four cases of malleolar fractures, which were treated with open reduction and internal fixation (ORIF). The researchers also noted seven early postoperative cases of wound and skin complications. While three cases healed with irrigation and debridement, two patients required skin flaps.

"We had some problems with getting the skin to heal over the anterior aspect of the ankle," Mann told Orthopedics Today. At 6 and 10 weeks postoperatively, the researchers found that two patients had medial malleolar fractures. "These were treated with ORIF, with successful healing in both cases," they wrote.

During longer follow-up, the researchers found that most of the implants remained intact or functioning at the time of death. They discovered that only four patients in the cohort underwent implant revision or removal. Of these, two patients received fusion for aseptic loosening. One patient had a revision for talar component loosening, while another underwent revision for pain.

Second analysis

A second analysis using additional surgery as an indication of implant failure showed a 78% survivorship. Only 15 patients in the study underwent a second operation, such as osteotomy or ligament reconstruction, the researchers wrote. Mann told Orthopedics Today that this outcome was "quite favorable" compared to that of other prostheses.

Despite the good results, Mann noted that the Class III device is still under FDA study.

"The main indication would be endstage arthrosis of the ankle joint in the patient who is usually over the age of 60, who has adequate skin coverage over the ankle [and] does not have a significant degree of arthritis of the remainder of the foot," he said.

For more information:
Horton ER, RA Mann, J Mann. Medium term survivorship of the Scandinavian Total Ankle Replacement. Presented at the American Orthopaedic Foot and Ankle Society 22nd Annual Summer Meeting. July 14-16, 2006. La Jolla, Calif.
Orthopedics Today was unable to determine whether Drs. Mann or Horton have a direct financial interest in the product discussed in this article or if they are paid consultants for any companies mentioned.