Biomechanical Comparison of Hintermann and Evans Osteotomy for Lateral Column Lengthening

CATEGORY: Hindfoot, Midfoot/Forefoot INTRODUCTION/PURPOSE: Both Evans and Hintermann procedures are opening wedge calcaneal osteotomies used for lateral column lengthening in flatfoot reconstruction. Risks of lateral column lengthening include lateral forefoot overload and increased calcaneocuboid (CC) joint pressure. The Evans osteotomy is preformed closer to the CC joint increasing the theoretical risk of higher CC pressures. The Hintermann technique is a more posteriorly located osteotomy developed to avoid destabilization of the anterior calcaneal fragment and subsequent CC joint incongruency. The purpose of this study is to biomechanically compare the Evans and Hintermann osteotomies through analysis of CC joint pressures and forefoot plantar pressures after sequential lengthening of the lateral column. METHODS: A flatfoot model with radiographic confirmation was created in 10 matched cadaveric specimens which were then randomly selected to undergo either the Evans or Hintermann osteotomy. Specimens were physiologically loaded and the peak pressure of the CC joint and forefoot plantar pressures were measured under the following conditions: (1) intact foot, (2) flatfoot, and (3) sequential lengthening of the lateral column from 6 mm to 14 mm, in 2 mm increments. RESULTS: Lateral column lengthening lead to significantly increased pressure across the CC joint in both the Evans and Hintermann specimens. With increasing lateral column length, mean peak CC pressures ranged from 2.9–4.0 and 1.2–2.2 times intact CC pressure for the Evans and Hintermann group, respectively. Normalized mean and normalized peak CC pressures were significantly higher in the Evans osteotomy group compared to the Hintermann group at every level of distraction (see figure). The CC pressures under each testing condition were normalized with respect to the intact foot. Forefoot lateral plantar pressures were significantly increased in specimens corrected with Evans osteotomy at 10 mm and 12 mm of distraction compared to the intact foot. CONCLUSION: The Evans osteotomy lead to significantly higher CC pressures than the Hintermann osteotomy. This data suggests the Hintermann osteotomy for flatfoot reconstruction minimizes increase in CC joint pressures and could reduce the risk of subsequent CC osteoarthritis.