Improving the Reliability of a Novel Baldini Classification for Revision Total Knee Arthroplasty: The Development and Validation of the Modified Grading System.

Abstract

The concept of zonal fixation has revolutionized our approach to bone loss in revision total knee arthroplasty (rTKA). Recently a quantitative grading system for each zone has been introduced, which allows for independent grading for the epiphysis, metaphysis, and diaphysis. The current study reports on the intra- and interobserver reliability of this scoring system in a non-selected patient cohort. Pre- and postoperative radiographs of 250 rTKA cases with stemmed prostheses were evaluated using the grading system published by d´Amato et al. To potentially improve the reliability of diaphyseal scoring, the grading schema for the diaphysis was modified to include the Scuderi and Weinberg diaphysis bone defect classification. There were three independent reviewers who evaluated each case separately with both the original scoring method and the modified score in two grading sessions. Inter- and intraobserver reliability was calculated with the intraclass correlation coefficient (ICC). The ICC for the original grading system with respect to the diaphysis showed poor overall reliability for the femur (Epiphysis: 0.48; Metaphysis: 0.67; Diaphysis: 0.34, Total: 0.35) and tibia (Epiphysis: 0.51; Metaphysis: 0.68; Diaphysis: 0.28, Total: 0.28). The modified grading system showed improved results in the revised diaphyseal zonal grading in both the femur (epiphysis: 0.67; metaphysis: 0.81; diaphysis: 0.84; total: 0.84) and tibia (epiphysis: 0.87; metaphysis: 0.72; diaphysis: 0.78; total: 0.73). Incorporating the Scuderi and Weinberg diaphyseal bone defect classification increases the accuracy of the grading of implant fixation in the diaphysis. While some variability exists in the grading, the study confirms the overall feasibility of the grading system and supports using it for long-term studies evaluating implant fixation.