Objective: To assess the frequency of malalignment in the 1st, 2nd and 3rd tarso-metatarsal joints (Lisfranc joint) in cadaveric specimen and asymptomatic individuals utilizing oblique axial MR images.
Design and patients: Four fresh frozen cadaveric feet were dissected in the oblique axial plane at 5 mm slice thickness. Thirty MR studies in 29 patients who had no history of pain, trauma or surgery at the tarso-metatarsal area were included in our study. The 1st to 3rd tarso-metatarsal joints were evaluated on the MR studies and cadaveric slices by two musculoskeletal radiologists for (1) the presence of a medial and/or lateral step-off and (2) articular surface divergence.
Results: In the cadaveric dissections there were lateral step-offs in the 1st (n=3) and in the 2nd ray (n=3) respectively. No joint incongruity was evidenced. The MR studies in the patients population depicted 28 step-offs (9 medial, 19 lateral) in the 1st ray, 16 (2 medial, 14 lateral) in the 2nd ray and two in the 3rd ray. Joint incongruity was present in the 2nd ray (n=6) and in the 3rd ray (n=12). All the above findings were limited to a few images.
Conclusions: Isolated joint malalignment with otherwise normal findings (no ligamentous injury, no fracture and no bone marrow edema) might reflect normal anatomic features at the tarso-metatarsal joints and must be interpreted carefully.