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Reliability of clinically relevant 3D foot bone angles from quantitative computed tomography.

Gutekunst DJ, Liu L, Ju T, Prior FW, Sinacore DR - J Foot Ankle Res (2013)

Bottom Line: Two raters completed two repetitions each for twenty feet (10 right, 10 left), placing anatomic landmarks on the surfaces of calcaneus, talus, cuboid, and navicular.RMS-SD intra-rater precision ranged from 1.4 to 3.6° and 2.4 to 6.1°, respectively, for the two raters, which compares favorably to uni-planar radiographic precision.Greatest variability was in Navicular: Talus sagittal plane angle and Cuboid: Calcaneus frontal plane angle.

View Article: PubMed Central - HTML - PubMed

Affiliation: Applied Kinesiology Laboratory, Program in Physical Therapy, Washington University School of Medicine, St, Louis, MO 63108, USA. gutekunst.david@mayo.edu.

ABSTRACT

Background: Surgical treatment and clinical management of foot pathology requires accurate, reliable assessment of foot deformities. Foot and ankle deformities are multi-planar and therefore difficult to quantify by standard radiographs. Three-dimensional (3D) imaging modalities have been used to define bone orientations using inertial axes based on bone shape, but these inertial axes can fail to mimic established bone angles used in orthopaedics and clinical biomechanics. To provide improved clinical relevance of 3D bone angles, we developed techniques to define bone axes using landmarks on quantitative computed tomography (QCT) bone surface meshes. We aimed to assess measurement precision of landmark-based, 3D bone-to-bone orientations of hind foot and lesser tarsal bones for expert raters and a template-based automated method.

Methods: Two raters completed two repetitions each for twenty feet (10 right, 10 left), placing anatomic landmarks on the surfaces of calcaneus, talus, cuboid, and navicular. Landmarks were also recorded using the automated, template-based method. For each method, 3D bone axes were computed from landmark positions, and Cardan sequences produced sagittal, frontal, and transverse plane angles of bone-to-bone orientations. Angular reliability was assessed using intraclass correlation coefficients (ICCs) and the root mean square standard deviation (RMS-SD) for intra-rater and inter-rater precision, and rater versus automated agreement.

Results: Intra- and inter-rater ICCs were generally high (≥ 0.80), and the ICCs for each rater compared to the automated method were similarly high. RMS-SD intra-rater precision ranged from 1.4 to 3.6° and 2.4 to 6.1°, respectively, for the two raters, which compares favorably to uni-planar radiographic precision. Greatest variability was in Navicular: Talus sagittal plane angle and Cuboid: Calcaneus frontal plane angle. Precision of the automated, atlas-based template method versus the raters was comparable to each rater's internal precision.

Conclusions: Intra- and inter-rater precision suggest that the landmark-based methods have adequate test-retest reliability for 3D assessment of foot deformities. Agreement of the automated, atlas-based method with the expert raters suggests that the automated method is a valid, time-saving technique for foot deformity assessment. These methods have the potential to improve diagnosis of foot and ankle pathologies by allowing multi-planar quantification of deformities.

No MeSH data available.


Related in: MedlinePlus

Inertial axes reflecting bone shape. Surface maps of the 7 tarsal and 5 metatarsal bones, with a minimum bounding volume surrounding calcaneus representing the direction vectors for the principal inertial axis (red), second inertial axis (green), and third inertial axis (blue). (A) Lateral view of an exemplar foot, showing that the principal inertial axis reasonably approximates calcaneal pitch; (B) Posterior view of the foot, showing that the second and third inertial axes fail to align with clinically-relevant axes representing the local medial-lateral and inferior-superior axes of calcaneus.
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Figure 1: Inertial axes reflecting bone shape. Surface maps of the 7 tarsal and 5 metatarsal bones, with a minimum bounding volume surrounding calcaneus representing the direction vectors for the principal inertial axis (red), second inertial axis (green), and third inertial axis (blue). (A) Lateral view of an exemplar foot, showing that the principal inertial axis reasonably approximates calcaneal pitch; (B) Posterior view of the foot, showing that the second and third inertial axes fail to align with clinically-relevant axes representing the local medial-lateral and inferior-superior axes of calcaneus.

Mentions: These 3D imaging studies use the principal components method to define bone coordinate axes, meaning that the bone orientation axes reflect solely the bones’ shapes. While these inertial axes mimic clinical definitions of bone axes for long bones such as the metatarsals and phalanges, inertial axes may fail to align with clinical bone axes for the tarsals, particularly the lesser tarsals (cuboid and navicular) and the hind foot bones (calcaneus and talus). For example, while the primary inertial axis for calcaneus (red direction vectors in Figure 1A) approximates the measured angle of calcaneal pitch on a lateral X-ray, the second and third inertial axes (green and blue direction vectors in Figure 1B) provide inaccurate representations of the desired medial-lateral (green) and superior-inferior (blue) axes that are used to characterise frontal plane and transverse plane deformities.


Reliability of clinically relevant 3D foot bone angles from quantitative computed tomography.

Gutekunst DJ, Liu L, Ju T, Prior FW, Sinacore DR - J Foot Ankle Res (2013)

Inertial axes reflecting bone shape. Surface maps of the 7 tarsal and 5 metatarsal bones, with a minimum bounding volume surrounding calcaneus representing the direction vectors for the principal inertial axis (red), second inertial axis (green), and third inertial axis (blue). (A) Lateral view of an exemplar foot, showing that the principal inertial axis reasonably approximates calcaneal pitch; (B) Posterior view of the foot, showing that the second and third inertial axes fail to align with clinically-relevant axes representing the local medial-lateral and inferior-superior axes of calcaneus.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3852332&req=5

Figure 1: Inertial axes reflecting bone shape. Surface maps of the 7 tarsal and 5 metatarsal bones, with a minimum bounding volume surrounding calcaneus representing the direction vectors for the principal inertial axis (red), second inertial axis (green), and third inertial axis (blue). (A) Lateral view of an exemplar foot, showing that the principal inertial axis reasonably approximates calcaneal pitch; (B) Posterior view of the foot, showing that the second and third inertial axes fail to align with clinically-relevant axes representing the local medial-lateral and inferior-superior axes of calcaneus.
Mentions: These 3D imaging studies use the principal components method to define bone coordinate axes, meaning that the bone orientation axes reflect solely the bones’ shapes. While these inertial axes mimic clinical definitions of bone axes for long bones such as the metatarsals and phalanges, inertial axes may fail to align with clinical bone axes for the tarsals, particularly the lesser tarsals (cuboid and navicular) and the hind foot bones (calcaneus and talus). For example, while the primary inertial axis for calcaneus (red direction vectors in Figure 1A) approximates the measured angle of calcaneal pitch on a lateral X-ray, the second and third inertial axes (green and blue direction vectors in Figure 1B) provide inaccurate representations of the desired medial-lateral (green) and superior-inferior (blue) axes that are used to characterise frontal plane and transverse plane deformities.

Bottom Line: Two raters completed two repetitions each for twenty feet (10 right, 10 left), placing anatomic landmarks on the surfaces of calcaneus, talus, cuboid, and navicular.RMS-SD intra-rater precision ranged from 1.4 to 3.6° and 2.4 to 6.1°, respectively, for the two raters, which compares favorably to uni-planar radiographic precision.Greatest variability was in Navicular: Talus sagittal plane angle and Cuboid: Calcaneus frontal plane angle.

View Article: PubMed Central - HTML - PubMed

Affiliation: Applied Kinesiology Laboratory, Program in Physical Therapy, Washington University School of Medicine, St, Louis, MO 63108, USA. gutekunst.david@mayo.edu.

ABSTRACT

Background: Surgical treatment and clinical management of foot pathology requires accurate, reliable assessment of foot deformities. Foot and ankle deformities are multi-planar and therefore difficult to quantify by standard radiographs. Three-dimensional (3D) imaging modalities have been used to define bone orientations using inertial axes based on bone shape, but these inertial axes can fail to mimic established bone angles used in orthopaedics and clinical biomechanics. To provide improved clinical relevance of 3D bone angles, we developed techniques to define bone axes using landmarks on quantitative computed tomography (QCT) bone surface meshes. We aimed to assess measurement precision of landmark-based, 3D bone-to-bone orientations of hind foot and lesser tarsal bones for expert raters and a template-based automated method.

Methods: Two raters completed two repetitions each for twenty feet (10 right, 10 left), placing anatomic landmarks on the surfaces of calcaneus, talus, cuboid, and navicular. Landmarks were also recorded using the automated, template-based method. For each method, 3D bone axes were computed from landmark positions, and Cardan sequences produced sagittal, frontal, and transverse plane angles of bone-to-bone orientations. Angular reliability was assessed using intraclass correlation coefficients (ICCs) and the root mean square standard deviation (RMS-SD) for intra-rater and inter-rater precision, and rater versus automated agreement.

Results: Intra- and inter-rater ICCs were generally high (≥ 0.80), and the ICCs for each rater compared to the automated method were similarly high. RMS-SD intra-rater precision ranged from 1.4 to 3.6° and 2.4 to 6.1°, respectively, for the two raters, which compares favorably to uni-planar radiographic precision. Greatest variability was in Navicular: Talus sagittal plane angle and Cuboid: Calcaneus frontal plane angle. Precision of the automated, atlas-based template method versus the raters was comparable to each rater's internal precision.

Conclusions: Intra- and inter-rater precision suggest that the landmark-based methods have adequate test-retest reliability for 3D assessment of foot deformities. Agreement of the automated, atlas-based method with the expert raters suggests that the automated method is a valid, time-saving technique for foot deformity assessment. These methods have the potential to improve diagnosis of foot and ankle pathologies by allowing multi-planar quantification of deformities.

No MeSH data available.


Related in: MedlinePlus