Arthrodiastasis of the Lateral Column With Medial Fusion: A Retrospective Examination of Medial Double and Lapidus Arthrodeses

Arthrodiastasis of the calcaneocuboid joint after medial double arthrodesis has been described, but the extent remains unreported. We present our comparative findings after medial double and Lapidus fusion on the effects of the calcaneocuboid joint. Adults undergoing medial column fusion with internal fixation and a minimal clinical and radiographic follow-up period of 3 months were included. Subjects were excluded for Charcot deformity, previous arthrodesis surgery, and history of calcaneocuboid joint trauma or surgery. Although 52 patients were identified, 32 (mean age 56.69 ± 12.56 years; 11 males) met the study criteria (15 medial double and 17 Lapidus procedures). The height of the calcaneocuboid joint on the lateral radiograph and width of the calcaneocuboid joint on the anteroposterior radiograph were measured postoperatively and fixed, given the overlap often noted preoperatively in flatfoot deformities. The joint depth was measured at 3 points and averaged both preoperatively and postoperatively on lateral and anteroposterior radiographs. The volume of the calcaneocuboid joint (mm3) was the primary endpoint. Medial column fusion elicited a statistically significant mean increase of 32% in calcaneocuboid joint diastasis (p < .001). The percent change in diastasis volume was statistically different between the medial double (61.90% ± 40.59%) and the Lapidus (5.71% ± 14.84%, p < .001) fusion procedures. These results confirmed our hypothesis that arthrodesis of the more proximal medial column joints would produce greater lateral column arthrodiastasis. Adding to the published data, medial double arthrodesis increased the volume of the calcaneocuboid joint by 62%.