Foot & Ankle International - June 2017 - 690

695361

FAIXXX10.1177/1071100717695361Foot & Ankle InternationalMiller et al

research-article2017

Article

High Variability of Observed
Weight Bearing During Standing
Foot and Ankle Radiographs

Foot & Ankle International®
2017, Vol. 38(6) 690-693
© The Author(s) 2017
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https://doi.org/10.1177/1071100717695361
DOI: 10.1177/1071100717695361
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Christopher P. Miller, MD1, Mohammad Ghorbanhoseini, MD1,
Lauren K. Ehrlichman, MD2, Kempland C. Walley, BSc1, Azadeh Ghaheri, MSc3,
and John Y. Kwon, MD1

Abstract
Background: Weight-bearing radiographs are a critical component of evaluating foot and ankle pathology. An underlying
assumption is that patients are placing 50% of their body weight on the affected foot during image acquisition. The accuracy
of weight bearing during radiographs is unknown and, presumably, variable, which may result in uncertain ability of the
resultant radiographs to appropriately portray the pathology of interest.
Methods: Fifty subjects were tested. The percentage body weight through the foot of interest was measured at the
moment of radiographic image acquisition. The subject was then instructed to bear "half [their] weight" prior to the next
radiograph. The percentage body weight was calculated and compared to ideal 50% weight bearing.
Results: The mean percentage body weight in trial 1 and 2 was 45.7% ± 3.2% (P = .012 compared to the 50% mark)
and 49.2% ± 2.4%, respectively (P = .428 compared to 50%). The mean absolute difference in percentage weight bearing
compared to 50% in trials 1 and 2 was 9.3% ± 2.3% and 5.8% ± 1.8%, respectively (P = .005). For trial 1, 18/50 subjects were
within the "ideal" (45%-55%) range for weight bearing compared to 32/50 on trial 2 (P = .005). In trial 1, 24/50 subjects had
"appropriate" (>45%) weight bearing compared to 39/50 on trial 2 (P = .002).
Conclusions: There was substantial variability in the weight applied during radiograph acquisition. This study raises
questions regarding the assumptions, reliability, and interpretation when evaluating weight-bearing radiographs.
Level of Evidence: Level III, comparative study.
Keywords: weight bearing, reliability, foot and ankle, radiographs

Introduction
The diagnosis and treatment of foot and ankle pathology
often depends upon radiographs obtained with physiologic
load on the affected limb. Although routinely obtained for
most foot and ankle conditions, weight-bearing radiographs
are of particular importance when assessing hallux valgus,
midfoot instability, pes planus, fractures, and arthritic conditions of the hindfoot.2-4,7,8,12 Furthermore, weight-bearing
radiographs are commonly used when calculating measurements such as the Meary angle and the first/second intermetatarsal angle, which often determine the need for
operative treatment.
An underlying assumption when assessing weightbearing radiographs is that the image represents the radiographic alignment of the foot when one-half of the patient's
body weight is applied. Although surgeons and radiology
technicians may instruct patients to approximate "normal"
weight bearing when obtaining radiographs, such estimations are likely highly inaccurate and as of now undescribed.

As such, the diagnostic value of the radiograph and our ability to accurately interpret standing bony alignment is called
into question. This may be particularly true if a patient were
placing inadequate weight, whether due to pain or poor
instruction, yet the physician assumed they were weight
bearing appropriately when the radiograph was obtained.
As the accurate assessment of osseous alignment is
based on the magnitude of weight that a patient applies at
the time of image acquisition, the purpose of this study was
to prospectively assess how much weight patients actually
1

Beth Israel Deaconess Medical Center, Harvard Medical School, Boston,
MA, USA
2
Naval Hospital Beaufort, Beaufort, SC, USA
3
Royan Institute for Reproductive Biomedicine, ACECR, Tehran, Iran
Corresponding Author:
Mohammad Ghorbanhoseini, MD, Carl J. Shapiro Department of
Orthopaedics, Beth Israel Deaconess Medical Center, Harvard Medical
School, 330 Brookline Avenue Boston, MA 02215, USA.
Email: mghorban@bidmc.harvard.edu

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