"Is every revision the same?" definition of complexity in knee revision surgery.

Purpose: The purpose of this paper is to define a subset of complex rTKA in terms of preoperative, intraoperative, and postoperative outcomes and complications. The secondary outcome of the authors is to propose a simple and easy-to-use guide for clinical network in rTKA management.

Methods: Complex rTKAs were defined according to the presence of at least two of the following features: periprosthetic joint infection, re- revision, femoral and/or tibial massive bone defects, soft tissue impairment, stiffness, fracture requiring fixed component revision.

Results: Twenty-six patients underwent a standard rTKA (group A) while 24 had a complex rTKA (group B). The mean follow-up was 50.2 ± 16.4 months in group A and 49.5 ± 16.8 in group B (p = 0.44). The operative time was longer in group B (200.4 ± 131.4 min vs 110.2 ± 59.8 min). A greater intraoperative total blood loss (3014.2 ± 740.0 vs 2328.5 ± 620.6 ml, p < 0.001), intra and postoperative blood infusion (3.6 ± 1.2 vs 2.1 ± 1.2 units, p < 0.001) was reported in group B. Significant difference was obtained for global complication rate (11.5% group A vs 37.5% group B, p = 0.04), reoperation (7.7% group A vs 33.3% group B, p = p = 0.03) and re-revision (3.8% group A vs 25% group B, p = p = 0.04).

Conclusion: This study describes a specific entity of rTKA that require higher surgical effort and increased surgical challenge (measured as increased surgical time, need of transfusions and complications). The proposed classification could provide an easy-to-use tool for quick grading of complexity in rTKA.