Effect of calcaneal osteotomy and plantar fasciotomy on arch configuration in a flatfoot model

Seven fresh-frozen cadaver specimens had a calcaneal osteotomy performed obliquely through the posterior portion of the calcaneus. Angular relationships between the first metatarsal and talus were recorded with the use of a motion-analysis system in the transverse, sagittal, and coronal planes. The specimen was mounted in a testing machine and loaded via an intramedullary rod to 150, 350, and 550 N. A flatfoot model was created, and repeat measurements were obtained. The calcaneal osteotomy was then displaced 1 cm medially, and repeat measurements were made at each of the three load levels. The calcaneal osteotomy was then returned to its original position, the plantar fascia was divided, and the new angular measurements were obtained. The calcaneal osteotomy was again displaced 1 cm, and repeat angular measurements were obtained. A mild consistent flatfoot deformity was created in all three axes before the plantar fascia was cut. A statistically significant increase in deformity was noted after cutting the plantar fascia. A correction of the flatfoot deformity in all three planes occurred with the medial displacement of the calcaneal osteotomy, which was greater at the lower load levels. We noted that a medial displacement calcaneal osteotomy partially corrected a flatfoot deformity in all three planes. The correction occurred with or without an intact plantar fascia and, therefore, is independent of the structure. We also noted an increased deformity after dividing the plantar fascia. This study provides some biomechanical insight as to the corrective effect of a medial displacement calcaneal osteotomy in correcting a flatfoot deformity.