A New Technique to Increase Reliability in Measuring the Axis of Bone

A New Paradigm in Foot and Ankle Outcomes?: Away From Radiographs and Toward Patient-Centered Outcomes

Having reasonable outcome measures is essential to unbiased research. For years, provider-measured outcomes have been valued as they are more objective and convenient for investigators. However, with the popularity of patient-centered medical care delivery, patient-reported outcome measures are appropriately becoming more popular in foot and ankle research.

Techniques for 3D foot bone orientation angles in weight-bearing from cone-beam computed tomography

BACKGROUND

For the diagnosis and treatment of foot and ankle disorders, objective quantification of the absolute and relative orientation angles is necessary. The present work aims at assessing novel techniques for 3D measures of foot bone angles from current Cone-Beam technology.

METHODS

A normal foot was scanned via weight-bearing CT and 3D-model of each bone was obtained. Principal Component Analysis, landmark-based and mid-diaphyseal axes were exploited to obtain bone anatomical references. Absolute and relative angles between calcaneus and first metatarsal bone were calculated both in 3D and in a simulated sagittal projections. The effects of malpositioning were also investigated via rotations of the entire foot model.

RESULTS

Large angle variations were found between the different definitions. For the 3D relative orientation, variations larger than 10 degrees were found. Foot malposition in axial rotation or in varus/valgus can result in errors larger than 5 and 3 degrees, respectively.

CONCLUSIONS

New measures of foot bone orientation are possible in 3D and in weight-bearing, removing operator variability and the effects of foot positioning.