Comparison of deformity with respect to the talus in patients with posterior tibial tendon dysfunction and controls using multiplanar weight-bearing imaging or conventional radiography.

BACKGROUND

Posterior tibial tendon dysfunction varies in location and severity. Weight-bearing radiographs have been validated to assess posterior tibial tendon dysfunction, yet their two-dimensional nature and the inability of the patients to achieve full weight-bearing during acquisition are limitations. Multiplanar modified sectional weight-bearing imaging is a novel modality, yielding computed tomography-like images compared with radiographs, yet with true weight-bearing, shorter acquisition time, and lower radiation. The aim of this study was to test two hypotheses: first, multiplanar weight-bearing imaging would localize deformity with respect to the talus in patients with posterior tibial dysfunction compared with controls, and second, multiplanar weight-bearing imaging would correlate with specific radiographic parameters of posterior tibial tendon dysfunction on weight-bearing radiographs.

METHODS

Weight-bearing radiographs and multiplanar modified sectional weight-bearing images of the foot and ankle were made for twenty-three patients with flexible posterior tibial tendon dysfunction. Ten patients with imaging for unrelated pathological conditions served as controls. Thirteen radiographic parameters on the transverse, sagittal, and coronal views of multiplanar weight-bearing imaging in the study group were evaluated and compared with those in the control group. The same parameters on standing weight-bearing radiographs of patients in the study group were compared with those in the control group.

RESULTS

Significant differences between study and control groups were found on multiplanar weight-bearing imaging for six of thirteen radiographic parameters (p < 0.05), notably the sagittal talonavicular angle as well as sagittal and transverse talar-first metatarsal angles (p = 0.027, p = 0.003, and p = 0.004, respectively). However, only one parameter on weight-bearing radiographs (lateral talar-first metatarsal angle) reached significance (p < 0.05). Correlation showed excellent, very good, and good agreement between both imaging modalities for three, two, and five parameters, respectively.

CONCLUSIONS

Deformity with respect to the talus in posterior tibial tendon dysfunction is multifactorial, but was notably seen at the talonavicular joint in the sagittal plane with both modalities. Good to excellent agreement was found between weight-bearing radiographs and multiplanar weight-bearing images for many parameters; however, a greater number of significant differences was found between the flatfoot and control groups for multiplanar weight-bearing images. This implies a potential role for multiplanar modified sectional weight-bearing imaging as a more informative tool to assess posterior tibial tendon dysfunction in the physiological, full weight-bearing position.