SLR- November 2022- Zach Lind, DPM
Title: Measuring standing hindfoot alignment: reliability of different approaches in conventional x-ray and cone-beam CTReference: Brandenburg LS, Siegel M, Neubauer J, Merz J, Bode G, Kühle J. Measuring standing hindfoot alignment: reliability of different approaches in conventional x-ray and cone-beam CT. Arch Orthop Trauma Surg. 2022 Nov;142(11):3035-3043. doi: 10.1007/s00402-021-03904-1. Epub 2021 Apr 22. PMID: 33885961; PMCID: PMC9522738.
Reviewed By: Zach Lind, DPM
Residency Program: Ascension Milwaukee, Wisconsin
Podiatric Relevance: Hindfoot alignment is an essential portion of any flatfoot and cavus foot work up. Evaluating reliability of alignment measurements in both x-ray and cone-beam CT imaging may lead to improved treatment selection and outcomes for patient. This study aims to determine which anatomic structures and reference points reliability evaluate hindfoot alignment given different measurement tools.
Methods: A level IV prospective imaging study evaluating weightbearing x-rays and weightbearing cone-beam CT images over a three-year period. In total, 32 patients received both imaging modalities. Imaging and hindfoot alignment evaluation was performed using 7 different measurement methods, varying which anatomic structure or location of tangent line within that structure to determine alignment of the hindfoot.
Results: Statistical analysis and linear regression of measurement methods 1-7 showed marked variation in reliability between methods. Heel contact point as a basis for measuring hindfoot alignment and hindfoot moment arm was found to be most reliable. The method described by Saltzmann and El-khoury (method 1) measuring the translation between tibial shaft axis and the heel contact point, as well as the WB-CBCT evaluating center talus point translation to heel contact point(method 4), were found to be most reliable. In general, measurement methods using translation, rather than angular measurements or calcaneal contour, were found to have increased reliability. WB-CT (method 4) was found to have lower estimates of deformity than method 1, likely due to the talus having a less remarkable shift compared to the tibial shaft axis in hindfoot malalignment.
Conclusions: There is no consensus on which hindfoot alignment measurement leads to the highest reliability and estimation of deformity severity. This study shows that WB-CT that measures translation from reference lines from center of the talus and heel contact point were as reliable as standard view Saltzmann measurements. This study shows that the readily available standard Saltzmann radiographic view measurements are a reliable and cost-effective way to assess hindfoot alignment.