Foot & Ankle International - July 2018 - 771

762113
research-article2018

FAIXXX10.1177/1071100718762113Foot & Ankle Internationalde Cesar Netto et al

Article

Correlation of Clinical Evaluation and
Radiographic Hindfoot Alignment in Stage II
Adult-Acquired Flatfoot Deformity

Foot & Ankle International®
2018, Vol. 39(7) 771-779
© The Author(s) 2018
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https://doi.org/10.1177/1071100718762113
DOI: 10.1177/1071100718762113
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Cesar de Cesar Netto, MD, PhD1 , Grace C. Kunas, BA1, Dylan Soukup, BS1,
Anca Marinescu, BA1, and Scott J. Ellis, MD1

Abstract
Background: Previous work has demonstrated that the amount of radiographic hindfoot correction required at the time
of adult-acquired flatfoot deformity (AAFD) operative treatment can be predicted by the amount of radiographic deformity
present before surgery. Successful outcomes after reconstruction are closely correlated with hindfoot valgus correction.
However, it is not clear if differences exist between clinical and radiographic assessment of hindfoot valgus. The purpose
of this study was to evaluate the correlation between radiographic and clinical evaluation of hindfoot alignment in patients
with stage II AAFD.
Methods: Twenty-nine patients (30 feet) with stage II AAFD, 17 men and 12 women, mean age of 51 (range, 20-71)
years, were prospectively recruited. In a controlled and standardized fashion, bilateral weightbearing radiographic hindfoot
alignment views were taken. Radiographic parameters were measured by 2 blinded and independent readers: hindfoot
alignment angle (HAA) and hindfoot moment arm (HMA). Clinical photographs of hindfoot alignment were taken in 3
different vertical camera angulations (0, 20, and 40 degrees). Pictures were assessed by the same readers for standing
tibiocalcaneal angle (STCA) and resting calcaneal stance position (RCSP). Intra- and interobserver reliability were assessed
by Pearson/Spearman's and intraclass correlation coefficient (ICC), respectively. Relationship between clinical and
radiographic hindfoot alignment was evaluated by a linear regression model. Comparison between the different angles
(RCSP, STCA, and HAA) was performed using the Wilcoxon rank-sum test. P values of less than .05 were considered
significant.
Results: We found overall almost perfect intraobserver (range, 0.91-0.99) and interobserver reliability (range, 0.740.98) for all measures. Mean value and confidence interval (CI) for RCSP and STCA were 10.8 degrees (CI, 10.1-11.5)
and 12.6 degrees (CI, 11.7-13.4), respectively. The position of the camera did not influence readings of clinical alignment
(P > .05). The mean HMA was 18.7 mm (CI, 16.3-21.1 mm), and the mean HAA was 23.5 degrees (CI, 21.1-26.0). Clinical
and radiographic hindfoot alignment were found to significantly correlate (P < .05). However, the radiographic HAA
demonstrated increased valgus compared to both clinical alignment measurements, with a mean difference of 12.8 degrees
from the RCSP (CI, 11.0-14.5, P < .0001) and 11.0 degrees from the STCA (CI, 9.2-12.8, P < .0001).
Conclusion: We found significant correlation between radiographic and clinical hindfoot alignment in patients with stage II
AAFD. However, radiographic measurements of HAA demonstrated significantly more pronounced valgus alignment than
the clinical evaluation. The results of our study suggest that clinical evaluation of hindfoot alignment in patients with AAFD
potentially underestimates the bony valgus deformity. One should consider these findings when using clinical evaluation in
the treatment algorithm of flatfoot patients.
Level of Evidence: Level II, prospective comparative study.
Keywords: adult-acquired flatfoot deformity, flatfoot, hindfoot alignment, hindfoot valgus, measurement reliability
Adult-acquired flatfoot deformity (AAFD) occurs most commonly secondary to combined dysfunction of the posterior
tibial tendon (PTT) and plantar ligaments of the foot. It is clinically characterized by symptomatic collapse of the medial longitudinal arch, forefoot abduction at the talonavicular joint,
and hindfoot valgus.5,15,24 The evaluation of the hindfoot

Hospital for Special Surgery, New York, NY, USA

Corresponding Author:
Scott J. Ellis, MD, Hospital for Special Surgery, 535 East 70th Street,
New York, NY 10021, USA.
Email: elliss@hss.edu

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