Introduction: In many reports describing flatfoot deformities, the abnormality is described using observations from physical examination, radiographs, or foot imprints. Correlation of these measurements is often lacking, making determination of the magnitude of the deformity or its surgical correction difficult to quantify.
Material and methods: Weightbearing AP and lateral radiographs were obtained on 25 patients (39 feet) with a clinically apparent flatfoot deformity and an asymptomatic control group of 28 subjects (56 feet). Radiographs were examined for the lateral talometatarsal angle, the lateral talocalcaneal angle, calcaneal pitch, first metatarsocuneiform height, medial cuneiform -fifth metatarsal height, metatarsus primus elevatus, plantar gapping at the first metatarsocuneiform joint, the AP talonavicular coverage angle, and the metatarsus adductus angle. Harris mat imprints were obtained on each foot and measured for the magnitude of the flatfoot deformity. Physical examination included the subjective appearance to the examiner of the degree of pes planus (none, mild, moderate, severe), hindfoot valgus, and ankle range of motion. Photographs of the hindfoot were obtained in a standardized manner, and hindfoot valgus was measured from these photos and compared to the measured hindfoot valgus on the physical exam.
Results: Statistically significant differences between the two groups were found in the lateral talometatarsal angle, lateral talocalcaneal angle, calcaneal pitch, first metatarsocuneiform height, the AP talonavicular coverage angle, Harris mat imprint score, subjective pes planus score, hindfoot valgus measurement from both photographs and physical examination, ankle range of motion (all with a p value less than 0.01), and the metatarsus adductus angle (p = 0.019). No patient in the control group and 14 (36%) in the flatfoot group had evidence of plantar gapping at the first metatarsocuneiform joint. In the flatfoot group, statistically significant correlations were demonstrated between the Harris mat score and heel valgus as measured by photographic and physical examination, subjective pes planus grading by physical exam, the lateral talometatarsal angle, and the first metatarsocuneiform height.
Conclusion: This study validates the use of the Harris mat imprint as an effective method of quantifying the magnitude of a flatfoot deformity. We also found a statistically significant decrease in ankle range of motion in the flatfoot group, indicating that tightness of the gastrocsoleus complex is part of the pathophysiology of flatfoot deformity.