Compare with the previous radiograph: loosening (progressive lucency ≥ 2 mm), osteolysis from particle disease, periprosthetic fracture, component malposition, dislocation — and for metal-on-metal hips, the pseudotumour on MARS MRI.
Orient first
- Lucency around a component is described by zones (Gruen for the femoral stem, DeLee–Charnley for the acetabulum).
- Progressive or ≥ 2 mm lucency suggests loosening; infection can look the same — aspiration decides.
- Metal artefact reduction (MARS) MRI or ultrasound shows adverse reaction to metal debris.
Acquire the study
- AP and lateral radiographs of the joint, compared with the immediate post-operative study.
The manoeuvre
- Radiograph: lucency at the bone–cement or bone–implant interface by zone; width in mm; progression.
- Component position: acetabular inclination in degrees; subsidence of the stem in mm.
- Osteolysis: scalloped lucency.
- Periprosthetic fracture; dislocation.
What confirms it
- Progressive lucency or migration compared with prior radiographs; aspiration for infection.
What licenses you to exclude it
- Stable non-progressive thin lines are normal findings after cemented arthroplasty.
The classic misread
- Calling stress shielding (proximal bone loss) loosening.