Plantar pressures in the forefoot after lateral column lengthening: a cadaver study comparing the Evans osteotomy and calcaneocuboid fusion.

BACKGROUND

Excessive varus alignment of the forefoot after lateral column lengthening has been reported to lead to overloading of the lateral foot. The purpose of this study was to investigate whether there is a difference between the Evans opening wedge calcaneal osteotomy (Evans) and the calcaneocuboid distraction arthrodesis (CCDA) with respect to lateral forefoot loading.

METHODS

In each of 12 matched pairs of cadaver feet, plantar pressure measurements of the intact specimens were obtained during simulated foot-flat and early heel-rise phases of gait and again after randomly performing the Evans procedure on one foot and the CCDA on the other foot. Cervical plate fixation was used for immediate stability.

RESULTS

Both procedures resulted in statistically significant increased loading of the lateral forefoot and decreased loading of the medial forefoot compared with the preoperative status. The relative increase in lateral pressures was statistically greater with the CCDA than with the Evans. The average increase in pressure under the fifth metatarsal head in the foot-flat phase was 46% +/- 42% (range-4% to 141%) with the Evans and 104% +/- 58% (range 9% to 216%) with the CCDA (p = 0.003). In the early heel-rise phase, the increase in pressure was 50% +/- 43% (range 2% to 108%) and 96% +/- 65% (range 12% to 263%), respectively (p = 0.02).

CONCLUSION

The experimental data suggest that lateral column overload may be more likely with the CCDA than with the Evans. Physicians should be aware of the likelihood of increasing lateral column loads with both the CCDA and the Evans procedure. It may be possible to avoid this problem by using less lateral column lengthening than the 1 cm used in this study or by considering a medial column arthrodesis or plantarflexion osteotomy to balance forefoot loading.