Mylène Jansen

224 Chapter 11 Table 4 : Relation between KIDA parameters and Kellgren-Lawrence grade B β P- value Bone density (all in mm Al eq) Femur mean lateral 0.164 0.034 0.564 Femur mean medial 1.218 0.227 <0.001 Tibia mean lateral 0.314 0.056 0.324 Tibia mean medial 0.608 0.113 0.053 JSW (all in mm) Mean -0.173 -0.142 0.015 Mean lateral -0.049 -0.023 0.697 Mean medial -0.298 -0.163 0.005 Minimum -0.299 -0.247 <0.001 Osteophytes (all in mm 2 ) Femur lateral 2.995 0.340 <0.001 Femur medial 4.917 0.488 <0.001 Tibia lateral 4.677 0.402 <0.001 Tibia medial 2.325 0.325 <0.001 Other (mm, mm, degrees) Eminence lateral 0.097 0.038 0.520 Eminence medial -0.016 -0.008 0.891 Joint angle -0.358 -0.096 0.100 Separate linear regressionmodels were used for all different parameters. β : standardized coefficient; B : unstandardized coefficient; mm Al eq: mm aluminum equivalent. Influence of severity on intra-observer difference The influence of the mean values and KL grade, both as a measure of severity, on the differences between measurements of severe radiographs reanalyzed within 1 month are shown in Table 5. Both medial osteophyte parameters and the lateral tibia osteophytes showed a statistically significant influence of the mean values and of the KL grade (all p< 0.02); in all cases more severe OA (higher values) corresponded with a larger difference between measurements. Additionally, the tibia medial bone density and minimum JSW showed a significant positive influence of their mean values (both p< 0.03), but not KL grade (both p> 0.32).