LAUSR

BACKGROUND Although lengthening of the lateral column through an osteotomy of the anterior calcaneus is an integral component of flatfoot reconstruction in younger patients with flexible planovalgus deformities, the procedure has been implicated in iatrogenic calcaneocuboid (CC) subluxation and subsequent degenerative changes at the CC articulation. The purpose of this study is to characterize alterations at the CC joint after lateral column lengthening (LCL) and determine if Steinmann pin stabilization of the CC joint before distraction maintains a normal relationship. METHODS Seven matched pairs of fresh-frozen cadaveric feet underwent preprocedure plain radiography and cross-sectional computed tomography (CT) imaging. LCL by osteotomy through the anterior calcaneus was then performed. One foot of each matched pair had a single smooth Steinmann pin placed centrally across the CC joint before osteotomy distraction. Distraction across each osteotomy was then performed and maintained with a 12-mm porous titanium wedge. Repeat imaging was obtained and compared with preprocedure studies to quantify sagittal and rotational differences at the CC articulation. RESULTS Following LCL, plain radiography demonstrated statistically significant increases in the percentage of the calcaneal articular surface dorsal to the superior aspect of the cuboid in both the pinned (8.2% vs. 17.6%, P=0.02) and unpinned (12.5% vs. 16.3%, P=0.04) specimens. No difference in the percentage of subluxation was found between the 2 groups after LCL. CT imaging demonstrated statistically significant increases in rotation between the calcaneus and cuboid after LCL in both the pinned (7.6±5.6 degrees, P=0.01) and unpinned (17±12.3 degrees, P=0.01) specimens. The degree of rotation was greater in unpinned specimens after LCL (P=0.043). CONCLUSIONS Both sagittal and rotatory subluxation seem to occur at the CC joint after LCL regardless of pin stabilization. As a single pin would be expected to limit pure translation while having little effect on rotation, it is possible that the rotational changes identified on 3-dimensional imaging are interpreted as dorsal translation when viewed 2 dimensionally using plain radiography. Consideration should therefore be given to CC stabilization with 2 pins during LCL to prevent this rotatory subluxation. LEVEL OF EVIDENCE Level V-cadaver study.