Angular and linear measurements of adult flexible flatfoot via weight-bearing CT scans and 3D bone reconstruction tools

Ortolani, Maurizio; Leardini, Alberto; Pavani, Chiara; Scicolone, Silvia; Girolami, Mauro; Bevoni, Roberto; Lullini, Giada; Durante, Stefano; Berti, Lisa; Belvedere, Claudio

doi:10.1038/s41598-021-95708-x

Cited by 39 publications

(35 citation statements)

References 65 publications

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“…Furthermore, the reliability of the software algorithm we describe has been previously reported in 2 studies, and we found that it was excellent in our analysis as well. 18,28 A number of authors have used similar techniques and the same software with reproducible results, and we included a control group (normal feet) where there was no difference from conventional manual methods, suggesting the technique is reproducible. This study cannot ascertain the cause for the differences seen, nor prove that rotation is responsible and further work with larger sample sizes is required looking at coronal plane deformities and how they relate to sagittal and axial deformities.…”

Section: Discussionmentioning

confidence: 99%

2D Manual vs 3D Automated Assessment of Alignment in Normal and Charcot-Marie-Tooth Cavovarus Feet Using Weightbearing CT

et al. 2022

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Background: The complex deformities in cavovarus feet may be difficult to assess and understand. Weightbearing computed tomography (WBCT) is increasingly used in evaluating complex deformities. However, the bone axes may be difficult to calculate in the setting of severe deformity. Computer-assisted 3D axis calculation is a novel approach that may allow for more accurate assessment of foot alignment or deformity. This study aimed to assess differences in measurements done manually on 2D slices of WBCT vs 3D computer models in normal and cavus feet. Methods: We retrospectively analyzed WBCT scans from 16 normal and 16 cavus feet in patients with Charcot-Marie-Tooth disease. Six measurements were assessed: talar–first metatarsal angle (axial plane), forefoot arch angle (coronal plane), and Meary angle, calcaneal pitch, and cuneiform and navicular to floor distances (sagittal plane). 2D measurements were performed manually and 3D measurements were performed using specialized software (Bonelogic, DISIOR). Bland-Altman plots and linear regression were used to analyze differences. Results: There were no significant biases in measured variables in normal feet. In the cavovarus group, automated assessment calculated increased sagittal plane deformity (fixed bias 7.31 degrees for Meary angle, 2.39 degrees for calcaneal pitch) and less axial plane deformity (fixed bias 10.61 degrees for axial talar–first metatarsal angle). The latter also demonstrated proportional bias indicating greater discrepancy with increasing adduction. Conclusion: Measurements were comparable in normal feet suggesting automated techniques can reliably assess the alignment of bony axes. However, automated calculations show greater sagittal and less axial deformity in cavovarus feet than measured by manual techniques. This discrepancy may relate to rotational deformity seen in cavovarus feet, which may not be easily assessed manually. 3D automated measurements may therefore play a role in better assessing and classifying the cavovarus foot, which may ultimately inform treatment algorithms. Level of Evidence: Level III, retrospective comparative study.

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Section: Discussionmentioning

confidence: 99%

2D Manual vs 3D Automated Assessment of Alignment in Normal and Charcot-Marie-Tooth Cavovarus Feet Using Weightbearing CT

et al. 2022

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“…The automated software has been validated against measurements on conventional radiographs in previous foot and ankle studies and further verified in this study by post hoc surgeon review for all the parameters analyzed. 10,13 Finally, we recognize that the WBCT is a static radiologic representation of osseous structures and direct application to clinical management may be limited. Further studies are needed to compare pre- and postoperative WBCT to determine the true effect of TN soft tissue release with or without bony procedures.…”

Section: Discussionmentioning

confidence: 99%

“…FDA-approved clinical software for 3D anatomic modeling (Disior Bonelogic, version 2.0) allowed for precise, automated multisegment volume and surface area rendering, previously validated in the foot and ankle literature. 10,13 The axial plane anterior-posterior axis was determined from principal components analysis of the distal tibial plafond. Similar calculation for the anatomic axes of the calcaneus, talar body, talar head, navicular, medial cuneiform, and first metatarsal were compared to the reference anterior-posterior axis.…”

Section: Methodsmentioning

confidence: 99%

Cavovarus With a Twist: Midfoot Coronal and Axial Plane Rotational Deformity in Charcot-Marie-Tooth Disease

Haupt

Michalski

et al. 2022

Foot Ankle Int.

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Background: The cavovarus deformity of Charcot-Marie-Tooth (CMT) disease is often characterized by a paradoxical relationship of hindfoot varus and forefoot valgus. The configuration of the midfoot, which links these deformities, is poorly understood. Accurate assessment of 3-dimensional alignment under physiologic loadbearing conditions is possible using weightbearing computed tomography (WBCT). This is the first study to examine the rotational deformity in the midfoot of CMT patients and, thus, provide key insights to successful correction of CMT cavovarus foot. Methods: A total of 27 WBCT scans from 21 CMT patients were compared to control WBCTs from 20 healthy unmatched adults. CMT patients with a history of bony surgery, severe degenerative joint disease, or open physes in the foot were excluded. Scans were analyzed using 3-dimensional software. Anatomic alignment of the tarsal bones was calculated relative to the anterior-posterior axis of the tibial plafond in the axial plane, and weightbearing surface in the coronal plane. Results: Maximal rotational deformity in CMT patients occurred at the transverse tarsal joints, averaging 61 degrees of external rotation (supination), compared to 34 degrees among controls ( P < .01). The talonavicular joint was also the site of peak adduction deformity in the midfoot, with an average talonavicular coverage angle measuring 12 degrees compared with −11 degrees in controls ( P < .01). Conclusion: This 3-dimensional WBCT analysis is the first to isolate and quantify the multiplanar rotational deformity in the midfoot of CMT patients. Compared with healthy unmatched control cases, CMT patients demonstrated increased axial plane adduction and coronal plane rotation at the talonavicular (TN) joint. These findings support performing soft tissue release at the TN joint to abduct and derotate the midfoot as a first step for targeted deformity correction. Level of Evidence: Level III, retrospective case-control study.

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“…We analysed two sets of feet: the first dataset consists of three fresh-frozen full lower limbs (male; age: 77.7 ± 7.8 years; height: 175.3 ± 5.8 cm; weight: 87.0 ± 15.7 Kg) from cadaver dissection with no history of previous pathologies and was meant to overcome limits due to ionizing radiation during CT scans (normal feet dataset). The second dataset includes three patients (female/male: 1/2; age: 47.3 ± 20.1 years; height: 175.7 ± 9.0 cm; weight: 74.7 ± 7.0 Kg) affected by flat feet taken from a previous study [ 29 ], to provide an initial exploitation on pathological feet of the presently proposed ARS (flat feet dataset).…”

Section: Methodsmentioning

confidence: 99%

New anatomical reference systems for the bones of the foot and ankle complex: definitions and exploitation on clinical conditions

Conconi

Pompili

Sancisi

et al. 2021

Journal of Foot and Ankle Research

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Background A complete definition of anatomical reference systems (ARS) for all bones of the foot and ankle complex is lacking. Using a morphological approach, we propose new ARS for these bones with the aim of being highly repeatable, consistent among individuals, clinically interpretable, and also suited for a sound kinematic description. Methods Three specimens from healthy donors and three patients with flat feet were scanned in weight-bearing CT. The foot bones were segmented and ARS defined according to the proposed approach. To assess repeatability, intra class coefficients (ICC) were computed both intra- and inter-operator. Consistency was evaluated as the mean of the standard deviations of the ARS position and orientation, both within normal and flat feet. Clinical interpretability was evaluated by providing a quantification of the curvature variation in the medial-longitudinal and transverse arches and computing the Djiann-Annonier angle for normal and flat feet from these new ARS axes. To test the capability to also provide a sound description of the foot kinematics, the alignment between mean helical axes (MHA) and ARS axes was quantified. Results ICC was 0.99 both inter- and intra-operator. Rotational consistency was 4.7 ± 3.5 ° and 6.2 ± 4.4° for the normal and flat feet, respectively; translational consistency was 4.4 ± 4.0 mm and 5.4 ± 2.9 mm for the normal and flat feet, respectively. In both these cases, the consistency was better than what was achieved by using principal axes of inertia. Curvature variation in the arches were well described and the measurements of the Djiann-Annoier angles from both normal and flat feet matched corresponding clinical observations. The angle between tibio-talar MHA and ARS mediolateral axis in the talus was 12.3 ± 6.0, while the angle between talo-calcaneal MHA and ARS anteroposterior axis in the calcaneus was 17.2 ± 5.6, suggesting good capability to represent joint kinematics. Conclusions The proposed ARS definitions are robust and provide a solid base for the 3-dimensional description of posture and motion of the foot and ankle complex from medical imaging.

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Angular and linear measurements of adult flexible flatfoot via weight-bearing CT scans and 3D bone reconstruction tools

Cited by 39 publications

References 65 publications

2D Manual vs 3D Automated Assessment of Alignment in Normal and Charcot-Marie-Tooth Cavovarus Feet Using Weightbearing CT

2D Manual vs 3D Automated Assessment of Alignment in Normal and Charcot-Marie-Tooth Cavovarus Feet Using Weightbearing CT

Cavovarus With a Twist: Midfoot Coronal and Axial Plane Rotational Deformity in Charcot-Marie-Tooth Disease

New anatomical reference systems for the bones of the foot and ankle complex: definitions and exploitation on clinical conditions

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