Measuring standing hindfoot alignment: reliability of different approaches in conventional x-ray and cone-beam CT

Abstract

Introduction Currently there is no consensus how hindfoot alignment (HA) should be assessed in CBCT scans. The aim of this study is to investigate how the reliability is affected by the anatomical structures chosen for the measurement. Materials and methods Datasets consisting of a Saltzman View (SV) and a CBCT of the same foot were acquired prospectively and independently assessed by five raters regarding HA. In SVs the HA was estimated as follows: transversal shift between tibial shaft axis and heel contact point (1); angle between tibial shaft axis and a tangent at the medial (2) or lateral (3) calcaneal wall. In CBCT the HA was estimated as follows: transversal shift between the centre of the talus and the heel contact point (4); angle between a perpendicular line and a tangent at the medial (5) or lateral (6) calcaneal wall; angle between the distal tibial surface and a tangent at the medial calcaneal wall (7). Intraclass correlation coefficients (ICC) were calculated to assess inter-rater reliability. A linear regression was performed to compare the different measurement regarding their correlation. Results 32 patients were included in the study. The ICCs for the measurements 1–7 were as follows: (1) 0.924 [95% CI 0.876–0.959] (2) 0.533 [95% CI 0.377–0.692], (3) 0.553 [95% CI 0.399–0.708], (4) 0.930 [95% CI 0.866–0.962], (5) 0.00 [95% CI − 0.111 to 0.096], (6) 0.00 [95% CI − 0.103 to 0.111], (7) 0.152 [95% CI 0.027–0.330]. A linear regression between measurement 1 and 4 showed a correlation of 0.272 (p = 0.036). Conclusions It could be shown that reliability of measuring HA depends on the investigated anatomical structure. Placing a tangent along the calcaneus (2, 3, 5, 6, 7) was shown to be unreliable, whereas determining the weight-bearing heel point (1, 4) appeared to be a reliable approach. The correlation of the measurement workflows is significant (p = 0.036), but too weak (0.272) to be used clinically.

3D measurement techniques for the hindfoot alignment angle from weight-bearing CT in a clinical population

“…Acquired adult flatfoot, more recently defined as ‘progressive collapsing foot deformity’ 1 , implies multiple, complex and combined three-dimensional (3D) deformities, including flattening of the medial longitudinal arch, abduction of the forefoot and, in particular, valgus of the hindfoot 1 – 4 . In support to the standard clinical assessments 1 , 5 , accurate measurements on foot bones should be established 6 – 11 to evaluate the severity of the deformities, to plan for possible correction procedures and to assess the outcomes. Unfortunately, simple foot bone alignments in weight-bearing are usually assessed based on X-ray pictures with the subject in upright postures 6 , 12 , thus missing essential 3D observations and suffering of bones’ superimposition and reproducibility, particularly for the analysis of the subtalar joint 13 .…”

A comparison between the Bluman et al. and the progressive collapsing foot deformity classifications for flatfeet assessment

“…Multiplanar weight-bearing CT has already proven its superiority in assessing subtalar joint subluxation [29][30][31][32], and subfibular impingement [16,33]. Adding a weight-bearing CT assessment in our readings may improve the reliability of this class [18,[34][35][36][37][38]. In the original PCFD publication [13], it is also unclear whether the presence of sinus tarsi impingement should be considered as peritalar subluxation (Class D) or midfoot abduction (Class B) sign.…”

Early results and complication rate of the LapiCotton procedure in the treatment of medial longitudinal arch collapse: a prospective cohort study

“…In contrast, our cohort presented with two patients (9%) that did not demonstrate complete healing after 3 months of surgery. The main difference is that our assessment was performed with WBCT imaging rather than conventional radiographs, increasing the sensitivity for the diagnosis of delayed healing/non-union [ 49 – 51 ]. The rate of radiographic non-unions in these other reported cohorts could potentially be higher if computed tomography (CT) imaging was used for assessment.…”