Radiologic morphology of the calcaneus: a study of radiologic angles in a pediatric population

Radiographic measurements of the talus and calcaneus in the adult pes planus foot type

OBJECTIVE

A distinctive feature of the modern human foot is the presence of a medial longitudinal arch when weight-bearing. Although the talus and calcaneus play a major role in the structure and function of the human foot, the association between the morphology of these bones and longitudinal arch height has not been fully investigated. A better understanding of this relationship may assist in the interpretation of pedal remains of fossil hominins, where features of the foot and ankle morphology have been described as providing evidence for the presence of a longitudinal arch.

METHODS

For this study, weight-bearing radiographs of 103 patients from an urban US Level 1 trauma center, taken as part of a clinical examination for medical evaluation, were selected. These radiographs were classified as to foot type by arch height as defined using the calcaneal inclination angle. From this group, 68 radiographs were suitable for linear and angular measurements of the talus and 74 of the calcaneus. The relationships between these measurements and arch height were explored using least squared linear regression analysis.

RESULTS

The results demonstrate that angular measurements of the calcaneus (particularly those that reflect the relationship of the talar articular facets to each other and the tilt of the calcaneocuboid joint to the longitudinal axis of the calcaneus) are predictive of arch height (r² = .29-.44 p ≤ .001). All angular measurements of the talus and all examined linear measurements of both the talus and calcaneus were not predictive of arch height.

DISCUSSION

These results suggest that certain angular measurements of the calcaneus are associated with arch height in the modern human foot. While this information is useful in the interpretation of hominin pedal remains, the relationship of the morphology of these bones, as well as other bones of the foot, to arch height is complex, requiring further investigation.

The Relationship Between Angular Osteologic and Radiographic Measurements of the Human Talus and Calcaneus

BACKGROUND

Radiographic imaging of the foot is commonly performed when medical evaluation is indicated. Angular measurements between bones may be assessed as part of the examination for trauma and foot biomechanics. However, angular relationships between surfaces of the physical bone as they compare with the bone's radiographic image has had limited investigation.

METHODS

For this study, 54 human feet from amputated limbs were imaged in standard radiographic views and skeletonized. Selected angular measurements were taken on each skeletonized talus and calcaneus and were compared with those taken from radiographic images using paired Student t tests and linear regression analysis.

RESULTS

Transverse plane measurements of the talus were not significantly different (P ≥ .05), associating strongly (r² = 0.67-0.75; all P < .001). Most transverse and sagittal plane measurements of the calcaneus were not significantly different (P ≥ .05), with transverse plane measurements more strongly associated (r² = 0.70-0.77; all P < .001) than sagittal plane measurements (r² = 0.35-0.78; all P < .001).

CONCLUSIONS

Selected angular measurements of the talus and calcaneus taken from radiographic images can be compared quantitatively with the physical bone, demonstrating that angular measurements from radiographic images provide useful information concerning both of these bones. This knowledge can be applied to the understanding of the morphology of the calcaneus and talus as it relates to human foot biomechanics and should also be of use in the interpretation of the human fossil pedal record.

Lateral Tibiocalcaneal Angle As a Determinant for Percutaneous Achilles Tenotomy for Idiopathic Clubfeet

BACKGROUND

The aim of the present study was to evaluate the clinical value of using the lateral tibiocalcaneal (LTiC) angle, measured on a lateral radiograph made with the foot and ankle in maximal dorsiflexion, instead of the ankle dorsiflexion (ADF) angle, measured on physical examination, as a determining indicator of the need for percutaneous Achilles tenotomy after Ponseti serial cast treatment of idiopathic clubfoot.

METHODS

We identified patients with idiopathic clubfoot who had been treated at our institution between March 2006 and June 2012. After exclusion of patients with Diméglio grade-I clubfoot and those followed for less than two years, 125 idiopathic clubfeet were evaluated. The clubfeet were grouped according to their LTiC and ADF angles, after which we evaluated the clinical outcomes of each group and investigated the prognostic effects of each angle-based decision regarding whether to perform percutaneous Achilles tenotomy.

RESULTS

Patients with a favorable LTiC angle (≤80°) showed no sagittal relapse even though none underwent percutaneous Achilles tenotomy. In contrast, patients with an unfavorable LTiC angle (>80°) had a high chance of sagittal relapse if percutaneous Achilles tenotomy had not been performed, even when they had a favorable ADF angle (≥15°). The LTiC-angle-based decision showed the most significant prognostic value in multivariate analyses of relapse-free and surgery-free survival rates.

CONCLUSIONS

The LTiC angle measured on simple radiographs is a more objective and prognostic indicator of the need for percutaneous Achilles tenotomy, as compared with the ADF angle measured on physical examination, in patients with idiopathic clubfoot.

LEVEL OF EVIDENCE

Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.