CT density analysis of the medial cuneiform.

BACKGROUND

A cannulated lag screw inserted through the medial cuneiform into the base of the second metatarsal is often utilized to reduce the diastasis and aid healing of Lisfranc injuries. Also procedures such as a midfoot or a Lapidus arthrodesis require adequate implant-bone purchase in the medial cuneiform. The medial cuneiform contains cancellous bone of varying density. Knowledge of density variation may be helpful for implant usage and manufacturing of area specific implants.

METHODS

In 60 randomly selected patients, mean computed tomography (CT) intensity in Hounsfield units was measured at 12 sampled locations within the medial cuneiform and served as a proxy for bone density. The patients' age, gender, and race were recorded. An analysis of variance (ANOVA) assessed the effect of age, gender, race, and sample site on bone density. Statistical testing assumed 95% level of confidence.

RESULTS

ANOVA showed age, gender, and sample site had significant effects (P < .001) on bone density, though race had no significant effect (P = .28). The distal-dorsal-lateral (DDL) site was significantly denser than all other sites (P < .001) except the middle-dorsal-lateral (MDL) (P = .53). The proximal-plantar-lateral (PPL) site was significantly less dense than all other sites (P < .001) except the middle-plantar-lateral/medial and the proximal-plantar-medial sites (P < .14). A general trend of density increasing in the distal and dorsal directions was evident, and within the dorsal sites there was a trend of increasing density in the lateral direction.

CONCLUSION

This is the first study to date to measure density of the medial cuneiform using living subjects. The sample size of 60 patients was also the largest of any study measuring density of this bone. We conclude that the densest area of the medial cuneiform is the most anterior, dorsal, and lateral portion.

CLINICAL RELEVANCE

The findings of this study may indicate the most optimal area for implant purchase in the medial cuneiform when reducing the diastasis between the base of the second metatarsal and medial cuneiform and for stabilization of the medial column.