We asked whether radiographic angles and signs of hip osteoarthrosis differ between radiographs of the pelvis taken in standing
and supine positions. We retrospectively reviewed the radiographs of 61 patients (72 hips) with developmental dislocation
of the hip. The minimum followup after closed reduction was 15 years (mean, 44 years; range, 15–64 years). We used pelvic
radiographs in supine and standing positions taken at the same time and determined the following parameters: minimal joint
space width, acetabular roof obliquity (AC angle), depth of the acetabulum (ACM angle), and center-edge angle. Osteoarthrosis
was assessed according to Kellgren and Lawrence. Two independent observers measured all radiographs manually with a goniometer.
AC angle, center-edge angle, and minimum joint space width differed between the radiographs taken in supine and standing positions
at followup, whereas osteoarthrosis grading and the ACM angle did not. The AC angle depended on patient position and predicted
development of osteoarthrosis. The minimum joint space width was influenced by the radiographic position with greater values
in the supine position. ACM angle and the osteoarthrosis grade according to Kellgren and Lawrence were unaffected by the patient’s
position.
Level of Evidence: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.
Each author certifies that he or she has no commercial associations (eg, consultancies, stock ownership, equity interest,
patent/licensing arrangements, etc) that might pose a conflict of interest in connection with the submitted article.
Each author certifies that his or her institution has approved the human protocol for this investigation, that all investigations
were conducted in conformity with ethical principles of research, and that informed consent was obtained.