Benjamin F, Fritz J, Fucentese SF, et al. - A detailed quantification of the femorotibial joint space and the impact of knee alignment on joint space width (JSW) can be accomplished by integrating weight-bearing cone beam CT (WB-CT) with 3D-based assessment. On WB-CT, significantly more bone-on-bone appositions were identified, which were underestimated or even undetectable on non-weight-bearing multi-detector CT (NWB-CT) and weight-bearing conventional radiographs (WB-XR).

• In this study of 26 participants who prospectively underwent NWB-CT, WB-CT, and WB-XR of the knee, the goal was to compare computer-based 3D-analysis for quantification of the femorotibial JSW using WB-CT, NWB-CT, and WB-XR.

• Average medial and lateral JSW differed significantly between WB-CT and NWB-CT (medial: 4.7 vs 5.1 mm, lateral: 6.3 vs 6.8mm).

• Significantly wider minimal JSW was evident on WB-XR (medial: 3.1 mm, lateral: 5.8 mm) vs WB-CT and NWB-CT (both medial: 1.8 mm, lateral: 2.9 mm), but did not differ significantly between WB-CT and NWB-CT.

• In those having varus knee alignment, significant differences for the average and the minimal medial JSW were found between WB-CT and NWB-CT.

• In participants with valgus alignment, there were significant differences between WB-CT and NWB-CT for the average lateral JSW.

• WB-CT revealed bone-on-bone apposition in 25% of the femorotibial compartments, which was significantly higher vs NWB-CT (10%) and WB-XR (8%).