Do Weight-Bearing Knee Digital Radiographs Help to Track the Severity of OA?

Objective: Weight-bearing radiographs are preferred for joint space width (JSW) assessment in OA, sometimes non-weight-bearing radiographs are also done. This study aims to evaluate (1) The knee JSW in weight-bearing (WB) and non-weight-bearing (NWB) X-ray images. (2) Quadriceps angle (Q angle) at weight-bearing and non-weight-bearing positions. Materials and
Methods: Patients above 50 years old with symptoms (knee pain, functional limitations, and crepitus) from April 2019 to November 2019 were included in the study. Expert exclude patients with post-surgical evaluation, trauma, and infection. JSW and Q angle measurements with respect to weight-bearing and non-weight-bearing positions were made by the same medical expert to avoid inter-observer variation.
Results: Medial knee JSW varies from 0.49 to 5.75 mm in weight-bearing radiograph and 0.53 mm to 6.16 mm in non-weight-bearing radiograph. Q angle varies from 8.72° to 14.58° in weight-bearing position and 10.13° to 14.92° in non-weight-bearing position. Q angle (< 11.72°) and medial JSW (< 3.725 mm) were found to be significantly associated with the rapid progression of knee varus OA (p < 0.001).
Conclusion: NWB digital X-ray images overestimate early and underestimate severe OA. There is a possibility of increasing tibia internal rotation and reduction of joint space width in a standing position (WB) as the phase of knee OA diagnosis. These findings show that weight-bearing knee joint radiographs are helpful to track the progression of knee varus OA and have strong clinical usage than non-weight-bearing radiographs. Patients whose Q angle and knee JSW measures are below the limitations need more attention. © Indian Orthopaedics Association 2021.