Assessment of lateral hindfoot impingement with weightbearing multiplanar imaging in a flatfoot

Background Estimation of the lateral hindfoot impingement in the standing position in conventional radiography can be difficult due to superimposition of different bones. Patients with flat feet frequently suffer from pain around the lateral malleolus and sinus tarsi caused by osseous impingement in the lateral hindfoot. Weightbearing multiplanar images (tomosynthesis) yield tomographic images and can be taken while full weightbearing. Purpose To assess the availability of tomosynthesis to determine hindfoot lateral impingement. Material and Methods A total of 14 feet (in 13 patients) with acquired flatfoot deformity and lateral hindfoot pain were included (mean age 64 years; age range 55–80 years). All patients underwent tomosynthesis, radiography, and computed tomography (CT) (non-weightbearing). Talofibular, calcaneofibular, and talocalcaneal impingement were determined. To compare the number of impingements or to determine the area between each image, statistical evaluations were analyzed using the Mann–Whitney U-test (P < 0.05). Results On tomosynthesis, we clearly found talofibular impingement in three feet, calcaneofibular impingement in seven feet, and talocalcaneal impingement in 11 feet. Therefore, we could identify most impingements as “positive” compared to those on normal radiographs and CT images. The number of impingements in the calcaneofibular and talocalcaneal regions was significantly higher using tomosynthesis than when using CT (P < 0.05). Conclusion Tomosynthesis imaging makes it easier to obtain CT-like images in a short period of time, in a free position, including while standing, and provides useful information to assess lateral pain in patients with flatfoot deformity.