Anatomical axis validation of lower extremity for different deformities: A radiological study.

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Unal M., ERCAN S., Budeyri A., Toprak U., Salkaci A.

SAGE open medicine, vol.8, 2020 (ESCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 8
  • Publication Date: 2020
  • Doi Number: 10.1177/2050312120923822
  • Journal Name: SAGE open medicine
  • Journal Indexes: Emerging Sources Citation Index (ESCI), Scopus
  • Keywords: Lower extremity alignment, knee deformity, orthoroentgenogram, knee axis, knee radiograph, KNEE ALIGNMENT, OSTEOARTHRITIS
  • Eskisehir Osmangazi University Affiliated: Yes


Aim: The aim of this study was to derive a pure, unbiased, reliable and accurate objective relationship between the local knee axis measurements through a short knee anteroposterior roentgenogram and the lower limb axis measurement through an orthoroentgenogram. Patients and Methods: Radiographs of 114 patients (114 knees) were evaluated by two independent raters for measurement of lower limb axis on an orthoroentgenogram and the local knee axis on short knee anteroposterior X-ray, which was derived by cropping the orthoroentgenogram by a blinded radiology assistant. The raters measured at two different time-points separated by an interval of 30-day period. Intra-rater and inter-rater reliabilities were calculated by intra-class correlation coefficients and three models were built to establish the relationships of X-ray anatomical axis with orthoroentgenogram anatomical axis, orthoroentgenogram anatomical axis with orthoroentgenogram mechanical axis and X-ray anatomical axis with orthoroentgenogram mechanical axis. Results: For three different measurements, intra-class correlation coefficients of Rater 2 were higher than 0.90 which shows perfect reliability, while that for Rater 1 was low. Furthermore, first measurements were more consistent than the second measurement. There was a strong positive correlation in all the three models except for varus cases in the last. Conclusion: The standardized correlation derived between the two different techniques for measuring knee alignment is fairly comparable with the studies in the past and would serve as a reliable template for future studies concerning relationships between the two, in addition to helping knee surgeons make more reliable and accurate interpretations through local knee axis measurements.