Validation of an Intraoperative Visual Assessment System Based on Bone Mechanical Properties for Selection of...

Background/Objectives: Successful cementless total knee arthroplasty (TKA) requires adequate bone quality. However, reliable tools for intraoperative assessment remain limited. This study aimed to introduce a novel visual grading system for evaluating femoral bone during surgery and to assess its correlation with actual bone mechanical properties and suitability for cementless fixation. Methods: We prospectively recruited 193 patients receiving posterior-stabilized TKA. Intraoperatively, femoral cutting surfaces were classified into four visual grades (Excellent, Good, Fair, Poor) considering pore appearance and contour integrity. Femoral bone specimens were harvested during box preparation, and bone mechanical properties were measured through indentation testing. Spearman correlation was used to evaluate the relationship between visual grades and bone mechanical properties. Fisher's exact test was used to evaluate the distribution pattern of cementless suitable and cemented mandatory classifications across visual grading. Receiver operating characteristic (ROC) analysis was used to evaluate diagnostic accuracy for each visual grade cutoff. Results: Visual grade strongly correlated with bone mechanical properties (Spearman's ρ = 0.881, p < 0.01). Cementless suitable cases were predominantly distributed in Good/Excellent visual grades, while cemented mandatory cases were mostly found in Fair/Poor grades. However, 8% of Good visual grade specimens exhibited strength warranting cemented fixation, and 18% of Fair visual grade specimens demonstrated adequate mechanical properties for cementless fixation. Using the Good visual grade as a cutoff threshold, ROC analysis showed excellent diagnostic accuracy (AUC = 0.941) with high sensitivity (89%) and specificity (94%). Conclusions: The authors' novel intraoperative visual assessment system demonstrated significant correspondence to measured bone mechanical properties in the distal femur and showed high accuracy in determining suitability for cementless TKA in Asian individuals. Given the ethnic homogeneity of this cohort, further validation in diverse populations is required to generalize these findings.