EFFECT OF CALCANEAL OSTEOTOMY AND PLANTAR FASCIOTOMY ON ARCH CONFIGURATION IN A FLATFOOT MODEL

Seven fresh-frozen cadaver specimens had a calcaneal osteotomy perform ed obliquely through the posterior portion of the calcaneus. Angular r elationships 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 load ed via an intramedullary rod to 150, 350, and 550 N. A flatfoot model was created, and repeat measurements were obtained. The calcaneal oste otomy was then displaced 1 cm medially, and repeat measurements were m ade at each of the three load levels. The calcaneal osteotomy was then returned to its original position, the plantar fascia was divided, an d the new angular measurements were obtained. The calcaneal osteotomy was again displaced 1 cm, and repeat angular measurements were obtaine d. A mild consistent flatfoot deformity was created in all three axes before the plantar fascia was cut. A statistically significant increas e in deformity was noted after cutting the plantar fascia. A correctio n of the flatfoot deformity in all three planes occurred with the medi al displacement of the calcaneal osteotomy, which was greater at the l ower load levels. We noted that a medial displacement calcaneal osteot omy partially corrected a flatfoot deformity in all three planes. The correction occurred with or without an intact plantar fascia and, ther efore, is independent of the structure. We also noted an increased def ormity after dividing the plantar fascia. This study provides some bio mechanical insight as to the corrective effect of a medial displacemen t calcaneal osteotomy in correcting a flatfoot deformity.