Radiographic joint-space narrowing

Method

Reduction over a stated interval in the minimum radiographic distance between the femoral and tibial articular surfaces on standardised weight-bearing knee radiographs, reported as the amount of narrowing.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

SIGN INVERSION HAZARD against joint space width change, derived from the identical radiographic distance on the identical film: NARROWING improves by getting SMALLER and WIDTH improves by getting LARGER. Papers switch between the two conventions without flagging it, so confirm which the source used before creating an edge. Also distinct from WOMAC pain and function subscales, which are symptom scales and dissociate from structural progression.