To The Editor:I read with interest the article "Relationship Between Polyethylene
Wear and Osteolysis in Hips with a Second-Generation Porous-Coated Cementless
Cup After Seven Years of Follow-up" (2003;85:1095-9), by Orishimo et al.
However, the study methodology and the interpretation of the results are
questionable.First, the study design analyzes retrospective radiographs, which
presumably were not performed as part of the current study and may not have
been sufficiently controlled to provide standardized projections. I am part of
a team involved in radiographic assessment of total hip replacements, and one
problem that we encountered when attempting to measure cup wear was the
apparent alteration in cup inclination due to minor differences in patient
positioning, which produced apparent differences in polyethylene wear. It
seems that, even with the most exact measuring equipment, if radiographs are
not standardized, then inconsistencies will occur.