Uniplanar versus biplanar monolateral external fixator knee arthrodesis after end-stage failed infected total knee arthroplasty: a comparative study

Abstract

Background: External fixator knee arthrodesis is a salvage procedure used primarily in cases of end-stage infected total knee replacement (iTKR). Stable fixation combined with bone-end compression is essential to achieve knee fusion, but providing sufficient stability can be challenging in the presence of severe bone loss. Our hypothesis is that using an external fixation biplanar configuration would bring about a fusion rate superior to that of a monolateral frame.

Methods: This study compares outcomes of biplanar external fixator knee fusion due to non-revisable iTKR with those of a historical cohort control study with patients managed with a monoplanar configuration. Primary endpoints were fusion rate, time to achieve bone fusion and infection eradication rate. Limb-length discrepancy, pain level, patient satisfaction and health-related quality of life were evaluated.

Results: A total of 29 knee fusion cases were included. In the biplanar group, infection was eradicated in 100% of the patients and fusion was achieved in all cases within an average of 5.24 months. In comparison, in the monolateral group, infection was eradicated in 86% of the cases and fusion was achieved in 81% of the patients after a mean of 10.3 months (p < 0.05). In both groups, postoperative pain was mild and patients expressed a high degree of satisfaction once fusion was achieved.

Conclusions: According to our data, external fixation knee fusion is a useful limb-salvage procedure in end-stage cases of knee PJI. We conclude that a biplanar configuration can halve the time required to achieve solid bone fusion in such a complex scenario.

Keywords: Biplanar fixation; External fixator; Knee arthrodesis; Periprosthetic joint infection.