The Effect of Sliding Calcaneal Osteotomy on Strain in the Medial Longitudinal Arch : An in Virto Study

Lee, Kyung Tai; Kim, Hyun Cheol

Abstract

One of the common cause of the acquired adult flat foot is posterior tibial tendon insufficiency whose etiology and development is different from that of congenital flat foot, and various methods, such as synovectomy, tendon transfer, calcaneal osteotomy and arthrodesis, can be used to treat the symptoms. The sliding calcaneal osteotomy has been recently introduced by Mark Myerson. The basic concept beneath this treatment is that by displacing distal part medially after a calcaneal osteotomy, the valgus strain in hindfoot can be relieved to place the joint back to the normal position. In order to find out the effect of the sliding calcaneal soteotomy on the flat foot, we measured the changes in the strain in the upper medial spring ligament complex underneath the talonavicular joint after the operation. Four right hand four left fresh frozen cadaver foot specimens, which included the distal half of the tibia were utilized. The spring ligament was isolated with its origin at the sustentaculum tali and insertion on the navicular. At the medial calcaneus the soft tissues were periostially dissected and a small incision was made over the lateral calcaneus for the purpose of visualization. For each specimen a calibrated open liquid metal strain gauge was secured at the origin and insertion of the ligament with superglue and the gauge was sutured along the length of the superomedial portion of the spring ligament complex allowing for the gauge to slide freely. A tibial rod was driven into the intramedullary canal and the foot was always placed in the neutral plantigrade position in the test fig such that the rod was vertical at all times. A initial strain measurement was obtained with only the weight of the platform (19.6N) on the tibia. Weights were added in 7 increments to a total 472 Newton and strains were recorded. Three trials were conducted. The specimens were then removed from the rig and an oblique osteotomy were conducted. A repeated measures analysis of variance showed a significant (p < 0.001) reduction in strain following the osteotomy. To conclude, the direct measurements support the concept that a calcaneal osteotomy provides an alteration which is favorable to unloading the medial arch.