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

Area of Science:

• Radiology
• Orthopedics
• Biomedical Imaging

Background:

• Weight-bearing (WB) radiographs are standard for assessing knee osteoarthritis (OA) joint space width (JSW).
• Non-weight-bearing (NWB) radiographs are sometimes used, but their accuracy in OA assessment is debated.
• The quadriceps angle (Q angle) is another parameter evaluated in knee OA studies.

Purpose of the Study:

• To compare knee joint space width (JSW) measurements between weight-bearing (WB) and non-weight-bearing (NWB) X-ray images.
• To evaluate the quadriceps angle (Q angle) in both WB and NWB positions.
• To determine the association between these measurements and the progression of knee varus OA.

Main Methods:

• Included patients over 50 years old with knee OA symptoms.
• Excluded patients with a history of trauma, infection, or post-surgical evaluation.
• Measurements of JSW and Q angle were performed by a single expert for both WB and NWB positions to ensure consistency.

Main Results:

• Medial knee JSW ranged from 0.49–5.75 mm (WB) and 0.53–6.16 mm (NWB).
• Q angle ranged from 8.72°–14.58° (WB) and 10.13°–14.92° (NWB).
• A Q angle < 11.72° and medial JSW < 3.725 mm were significantly associated with rapid knee varus OA progression (p < 0.001).

Conclusions:

• NWB radiographs may overestimate early and underestimate severe knee OA.
• WB knee radiographs are more clinically valuable for tracking OA progression.
• Patients with lower Q angles and JSW require increased attention due to higher risk of rapid OA progression.