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. 2023 May 22;4(5):363-369.
doi: 10.1302/2633-1462.45.BJO-2023-0031.R1.

Measuring hip migration percentage in cerebral palsy using the HipScreen app

John Amen  1   2 , Oliver Perkins  2 , Jill Cadwgan  2 , Stephen J Cooke  3 , Konstantinos Kafchitsas  4 , Michail Kokkinakis  2   5
Affiliations

Measuring hip migration percentage in cerebral palsy using the HipScreen app

John Amen et al. Bone Jt Open. .

Abstract

Aims: Reimers migration percentage (MP) is a key measure to inform decision-making around the management of hip displacement in cerebral palsy (CP). The aim of this study is to assess validity and inter- and intra-rater reliability of a novel method of measuring MP using a smart phone app (HipScreen (HS) app).

Methods: A total of 20 pelvis radiographs (40 hips) were used to measure MP by using the HS app. Measurements were performed by five different members of the multidisciplinary team, with varying levels of expertise in MP measurement. The same measurements were repeated two weeks later. A senior orthopaedic surgeon measured the MP on picture archiving and communication system (PACS) as the gold standard and repeated the measurements using HS app. Pearson's correlation coefficient (r) was used to compare PACS measurements and all HS app measurements and assess validity. Intraclass correlation coefficient (ICC) was used to assess intra- and inter-rater reliability.

Results: All HS app measurements (from 5 raters at week 0 and week 2 and PACS rater) showed highly significant correlation with the PACS measurements (p < 0.001). Pearson's correlation coefficient (r) was constantly over 0.9, suggesting high validity. Correlation of all HS app measures from different raters to each other was significant with r > 0.874 and p < 0.001, which also confirms high validity. Both inter- and intra-rater reliability were excellent with ICC > 0.9. In a 95% confidence interval for repeated measurements, the deviation of each specific measurement was less than 4% MP for single measurer and 5% for different measurers.

Conclusion: The HS app provides a valid method to measure hip MP in CP, with excellent inter- and intra-rater reliability across different medical and allied health specialties. This can be used in hip surveillance programmes by interdisciplinary measurers.

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Conflict of interest statement

None declared.

Figures

Fig. 1
Fig. 1
Anteroposterior radiograph of right hip. Red arrow indicates the lateral edge of the sourcil used in the modified method, while the blue arrow indicates the lateral edge of the acetabulum used in the classic method.
Fig. 2
Fig. 2
a) Home screen of the HipScreen app, with red arrow pointing to the ruler function. b) Ruler with the red line indicating 30% migration percentage. c) Rotate function to correct pelvic obliquity; in this radiograph counter-clockwise (CCW) is needed (red curved arrow). CW, clockwise.
See this image and copyright information in PMC

References

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