This is Barry Bellosis, one of the musculoskeletal radiology fellows at Stanford University. 14 year old female with worsening chronic recurrent left midfoot pain after an acute injury during a high school volleyball concern for left shank injury. When examining the tarsal metatarsal joint, we want to look at the alignment of the metatarsal in relation to the tarsal bone such as the first metatarsal to the medial cuneiform on the AP view and on the oblique view we can best assess the alignment of the third metatarsal and the lateral cuneiform. About 20 to 40% are missed on x-rays because some can be subtle. Weight-bearing views can be helpful if tolerated. Stress views for exam under anesthesia could be useful. There are signs that could suggest the presence of this frank injury including tarsal metatarsal joint subluxation, flex sign, metatarsal neck fracture, compression fracture of cuboid and diastasis of the medial and middle cuneiforms. Flex sign is an oscious fragment at the first intermetatarsal space representing an avulsion fracture of the Lisfranc ligament. This should not be confused with a normal variant os intermetatarsum which is an accessory obstacle projecting at the first intermetatarsal space which could be seen in the dorsal aspect of the TMT joint on lateral view. On a different patient, 28 year old athlete with midfoot pain, on this non weight-bearing radiograph we can see a subtle widening of the first intermetatarsal space not so much on the oblique view, but on the lateral view we could see some soft tissue swelling at the dorsum of the foot. Comparing this to a weight-bearing radiograph, we can see that there is increased widening on the weight-bearing radiograph and incongruency of the second metatarsal and middle cuneiform which is more obvious than the non weight-bearing radiograph. On our oblique view we can see that the third metatarsal space and the lateral cuneiform is malaligned which is very difficult to appreciate in the non weight-bearing view. CT can be used to detect for fractures, assess for alignment and diastasis and can be used for pre-op planning. We can see this 3D imaging showing dorsal subluxation of the metatarsals in relation to the cuneiforms also seen here in our sagittal imaging. The coronal shows malalignment of the first and second TMT joint and also the third TMT joint. When there is persistent concern for lisfranc injury in the presence of normal radiograph, MRI without contrast can be performed to assess for lisfranc ligament complex injury. We look at the dorsal ligament, the interosseous ligament which is the lisfranc ligament proper and the plantar ligament. We use all sequences and planes to assess for these ligaments. The dorsal band however could be best assessed on your axial imaging such as in this axial T2 fat set showing this hypointense band from the medial cuneiform to the base of the second metatarsal. The interosseous ligament can also be seen in the axial imaging or coronal imaging. The plantar ligament could be seen in axial and the coronal and it's sent from the medial cuneiform to the base of the second metatarsal and additional band to the third metatarsal base. Here in our coronal T1 imaging we can see the two bands arising from the medial cuneiform. This is in a different patient showing a high grade tear of the dorsal band as demonstrated by this defect at the proximal attachment of the dorsal band. We do not see the continuity of this band to the medial cuneiform compared to the normal band that we saw. The same patient also have a low grade sprain of the interosseous ligament showing increased signal here of the interosseous ligament in our axial T2 fat set. In our coronal T2 fat set imaging we can see the band from the medial cuneiform to the base of the second metatarsal and our coronal T1 imaging also demonstrates this increased signal of the interosseous ligament.

2nd Edition, CASE 13

2nd Edition

Foot and Ankle

Lisfranc injuries

radiographic imaging

MRI techniques

ligament integrity

diagnostic challenges