Radiographic and Pedobarographic Comparison of Femoral Head Allograft versus Block Plate with Dorsal Opening Wedge Medial Cuneiform Osteotomy: A Biomechanical Study

Abstract

The effect of the Cotton osteotomy has not been studied in isolation, and no alternative to bone graft has been investigated for this osteotomy. We hypothesized that there would be no difference in radiographic and pressure findings using the Cotton osteotomy with bone graft or an opening wedge block plate. Each specimen of eight matched pairs of lower extremities was loaded in simulated double-leg stance via pneumatic cylinders as described previously. Weightbearing lateral and anteroposterior radiographs and medial and lateral pressure measurements were obtained for all intact specimens. Specimens were randomly assigned to receive a Cotton osteotomy with a dorsal opening wedge allograft or an opening wedge plate. Each specimen was cycled at 3 Hz to 720 N for 5000 cycles and measurements were repeated. Calcaneal pitch was lower after the block plate procedure (mean +/- standard error of the mean) (intact, 23.4 +/- 1.2 degrees versus post-procedure, 21.8 +/- 1.1 degrees; p = 0.05). There was a significant difference (p < 0.05) in percentage of total plantar pressure medially and laterally between the intact specimen and the specimen after osteotomy with both methods. Pressure increased medially and decreased laterally. With the numbers available, these methods for performing a Cotton osteotomy did not differ in addressing lateral column overload. Dorsal opening wedge medial cuneiform osteotomy performed with femoral head allograft or a block plate may be effective both in reducing lateral column pressures and increasing medial column pressures when they are deficient preoperatively.