Weight-Bearing Computed Tomography of the Foot and Ankle: An Update and Future Directions

Abstract

Spatial understanding of osteoarticular deformities of the foot and ankle is vital to correct diagnosis and therapeutic decision making. Poor reproducibility in conventional standing radiography in three orthogonal views has driven the development of weight-bearing computed tomography (WBCT) technology over the last decade. We analyzed the available literature on WBCT imaging in patients with foot and ankle disorders by performing a literature review of relevant clinical studies in multiple databases including PubMed, MedLine, and Scopus from January 1999 to October 2017. WBCT imaging allows correct evaluation of foot and ankle anatomy with the patient in a standing position, providing images with high spatial resolution, short image acquisition time, low dose of radiation, and costs which are similar to other available imaging technologies. This diagnostic tool can be used for decision making in the treatment of deformities of the ankle, hindfoot, midfoot, and forefoot. Level of Evidence III; Systematic review of level III studies.

Weight-bearing MR Imaging of Knee, Ankle and Foot

“…During interpretation, the radiologist must pay attention above all to changes in the bone alignment/ angulation and the width of the articular spaces. 4,[30][31][32][33] Flatfoot (pes planus) is a congenital or acquired deformity of the foot characterized by the collapse of the medial longitudinal arch; in adults, it is most frequently caused by the presence of a posterior tibial tendon dysfunction resulting in planovalgus deformity of the hindfoot. Flatfoot is assessed radiographically as a concave dorsal deviation of the midfoot evaluated on the weight-bearing lateral film, whereas the opposite condition, with dorsal convexity, is termed a cavus foot.…”

“…If the medial longitudinal arch is restored to its normal alignment on non-weightbearing radiographs, the flat foot is said to be flexible. 29,[34][35][36] Several lines and angle measurements have been described for the assessment of the foot alignment, and all of them are evaluated on standing radiographs: 4,[35][36][37] • The calcaneal inclination angle is the angle formed by a line tangent to the inferior cortex of the calcaneus and the horizontal plantar plane; it reflects the height of the plantar The orthostatic MRI examination is also useful in the evaluation of the biomechanical changes of the ankle and foot in patients with mid-talar and subtalar joint pathologies. In our experience in the evaluation of patients with traumatic and overload pathologies of the coxa pedis, we found an increase of the alterations of the spring ligament and the sinus tarsi in weight-bearing scans.…”

“…For pes planus, information obtained under physiologic weight-bearing conditions probably better represents changes relevant to surgical planning. 4,29,[35][36][37] The following quantitative parameters are evaluated on this view:…”

“…In addition to weight-bearing MRI, recent advances in sectional imaging have led to the development of cone-beam computed tomography (CBCT) and weight-bearing computed tomography (WBCT) scanners designed for the imaging of the lower extremities with the patient in an upright standing position. 4,34,36 These scanners are equipped with a small gantry oriented horizontally close to floor level that allows a wide range of movements. The increased distance of the gantry from the trunk region also decreases the scattered radiation from the scan area, with measured radiation doses ranging from 0.01 to 0.03 mSv per joint scan.…”

“…2,3 Recent developments in computed tomography (CT) and magnetic resonance imaging (MRI) scanner design also allow sectional imaging of the lower extremities with patients in an upright standing position. 4,5 This review offers an overview of the different techniques used in the imaging of the lower limbs under load, with particular focus on the results and the advantages over conventional imaging.…”