We conducted an investigation into the relative associations of magnetic resonance imaging (MRI)-defined pathologic features of the spring ligament and/or tibialis posterior tendon with radiographic evidence of a planovalgus foot position. A total of 161 patient images (MRI and plain radiographs) obtained from the foot and ankle clinic (2008 to 2011) were retrospectively reviewed. All 161 patients (64 male and 97 female; mean age 45.9years, range 18 to 86) were included in the analysis. Lateral weightbearing radiographs were analyzed for the talo-first metatarsal angle ≥ 5°, calcaneal pitch ≤ 20°, and talocalcaneal angle ≥ 45°. A positive finding for ≥ 1 measurements identified a radiographic planovalgus position of the foot. The radiographic deformity was analyzed against the MRI evidence of either spring ligament or tibialis posterior tendon pathologic features for significance (p<.05). Evidence of a spring ligament abnormality was strongly associated with a planovalgus foot position, reaching high levels of statistical significance in all 3 categories of radiographic deformity (odds ratio 9.2, p<.0001). Abnormalities of the tibialis posterior tendon failed to demonstrate significance, unless grade I changes were excluded, and grade II and III appearances were analyzed in isolation (odds ratio 2.9, p=.04). Although absolute causal relationships were not tested, this investigation has clearly demonstrated that MRI-defined abnormalities of the spring ligament complex are possibly of at least equal importance to tibialis posterior dysfunction for the presence of a moderate to severe radiographic planovalgus foot position. © 2014 American College of Foot and Ankle Surgeons.