Subtle injuries to the Lisfranc joint complex are difficult to diagnose clinically and radiographically and can ultimately result in obvious disability if misdiagnosed. However, no previous study has shown the true mean average distance between the base of the first and second metatarsals (the Lisfranc distance). Therefore, in the present study, the anatomic and radiographic parameters of the Lisfranc joint were studied in detail to assist in the evaluation of Lisfranc injuries. The parameters of the Lisfranc joint complex in 100 normal volunteers and 10 cadavers were measured, including the medial, lateral depth of the mortise joint, width and height of the second metatarsal base, and distance between the base of the first and second metatarsals. The mean average Lisfranc distance was 0.24 ± 0.06 mm in the left foot and 0.25 ± 0.06 mm in the right foot for the radiographic group (p = .089) and 0.39 ± 0.04 mm in the left foot and 0.37 ± 0.04 mm in the right foot for the cadaver group (p = .129). The medial depth and Lisfranc distance in the radiographic group were smaller than the same measurements in the cadaver group, and these differences were statistically significant (medial depth, p < .001;​ Lisfranc distance, p < .001). The lateral depth and second metatarsal height in the radiographic group were larger than the same measurements in the cadaver group, and these differences were statistically significant (lateral depth, p < .001;​ second metatarsal height, p < .001). The second metatarsal width was the same in the 2 groups (p = .651). In conclusion, if the Lisfranc distance is >3.0 mm radiographically, a subtle injury to the Lisfranc joint should be highly suspected. No test of stability was performed between shallow and narrow versus deeper and broader Lisfranc mortise configurations. We merely speculated that a deeper and wider mortise is likely to be more stable than one that is shallow and narrow, probably owing to the presence of broader ligaments.

Level of Clinical Evidence:​ 4