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DOS Kongressen 2017 ·
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A Comparison of Measurements of Center-Edge angle
between Supine-Pelvis Radiograph and Supine AP-Hip
Radiograph, Intra- and interobserver study
Haider Ghalib Majeed, Morten Homilius, Idar Bohnhorst, Else Merete Ebbens-
gaard , Ahmed Salam N. Kurmasha, Torben Bæk Hansen
Department of Orthopedic, Holstebro Hospital; Department of Orthopedic,
Holstebro Hospital; Department of Radiology, Holstebro Hospital; Department
of Radiology, Holstebro Hospital; Department of Orthopedic, Holstebro Hospi-
tal; Department of Orthopedic, Holstebro Hospital
Background:
DDH is one of the common causes of OA of the hip. Wiberg
worked out a radiographic measurement, the center-edge angle(CE).
Purpose / Aim of Study:
-To compare the reproducibility of CE measurements
using Supine AP-Pelvis or supine AP-hip computed radiography (CR) -To inves-
tigate intra- & interobserver reproducibility between radiologists & orthopaedic
surgeons.
Materials and Methods:
We selected CRs of 40 patients, under the age of 60
yrs with a mean age of 40,8. The pelvis & hip CRs of all patients were anony-
mized & given a random order so that hip and pelvis CRs won’t be recognized as
paired observations 2 radiologists & 3 orthpaedic surgeons measured CE-angle
of both pelvis & hip CRs without instruction/training. 2 weeks after the 1st
round all CRs were given a different random order & CE-angles measured again
Using Bland Altman Plots to compare the measurements of 1st & 2nd round,
and to compare the measurements in pelvis vs. hip CRs. We also measured cor-
relation coefficient for all observers & used Z-test to compare them.
Findings / Results:
By using Bland Altman Plots to compare the two rounds,
we found rather high limits of agreement (+/- 6-11°) with all observers in
angle measurements of both pelvis & hip CRs. The same variation in angle mea-
surements was found by using pelvis CRs or hip CRs. There was high correlation
coefficient in all observers between CE angle of pelvis & CE angle of hip CRs,
with range of (0,85-0,92), and no significant difference between observers
(P- value 0,14-0,47)
Conclusions:
There was low reproducibility of CE angle measurements regard-
less of using pelvis or hip CRs There was no difference in reproducibility between
radiologists and orthpaedic surgeons in measurements of CE angle So, CE angle
measurements must be interpreted with care, detailed instruction & training of
observers in angle measurements may be required.
No conflicts of interest reported
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