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September 02, 2021
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Fusion, amputation are worthwhile options for chronic knee periprosthetic joint infection

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SAN DIEGO — A study presented here showed similar complication and reoperation rates, as well as Knee Society Scores, for knee fusion and above knee amputation in complex cases of knee periprosthetic joint infection.

At the American Academy of Orthopaedic Surgeons Annual Meeting, Alexandra I. Stavrakis, MD, of UCLA Health, presented the study findings. She said, “We specifically looked at index hospitalization complications, both medical and surgical complications, as well as overall reoperation rate — there was no difference. However, when we looked specifically at reoperation rate for various indications, we do see that the patients in the fusion group had a slightly higher percentage of reoperations specifically for reinfection. Within the amputation group, there was a higher reoperation rate specifically for wound complications.”

Alexandra I. Stavrakis

The single-center retrospective review Stavrakis and her colleagues performed included 93 patients who underwent fusion or amputation between 2011 and 2018 and had 1-year minimum follow-up. Patients previously failed either a two-stage exchange or had persistent infection despite placement of an antibiotic cement spacer, she said.

There were 67 patients in the fusion group and 26 patients in the amputation group.

“A single, cemented, modular arthrodesis system was used for all patients in the fusion group,” Stavrakis said.

Researchers evaluated patients by age, gender and McPherson host type, as well as by preoperative and 1-year postoperative clinical and functional Knee Society Scores (KSS).

Results showed the groups did not differ by age or gender.

“As far as the McPherson classification system comparing the two groups, within the amputation group, there was a higher percentage of patients who were type C hosts and had a type 3 extremity, and all patients in both groups had a chronic infection, type 3 infection,” Stavrakis said.

McPherson staging for the fusion group was 11 A hosts, 36 B hosts and 20 C hosts. One patient had a limb score of 1; 31 patients had a score of 2; and 35 patients had a score of 3.

Staging for the amputation group was 0 A hosts, 12 B hosts and 14 C hosts. No patients had a limb score of 1; six patients had a score of 2; and 20 patients had a score of 3, according to the abstract.

The failed two-stage reimplantation rate for the fusion group was 82.1%, and 17.9% of patients within the fusion group underwent fusion for reinfection of a spacer, Stavrakis said.

According to the abstract, the most common infecting organism in the fusion group was Staphylococcus epidermidis (27%). In the amputation group, it was Staphylococcus aureus (31%).

“There is no significant difference for either clinical KSS scores or functional KSS scores between the two groups; however, it’s important to note that only 38% of patients within the above-knee amputation group eventually ambulated with a prosthesis by 1 year,” Stavrakis said.

“We need to evaluate long-term follow-up to evaluate reinfection of the fusion cohort, as well as long-term survival of the fusion cohort as far as aseptic loosening,” she said.