It is 2am and there is a trauma patient in the resus area. Primary survey does not reveal any injuries. On secondary survey, you note that the patient has a swollen left foot and your next step is obviously to x-ray the area of interest to look for any fractures. In the meantime patient wants to know if he can be discharged as he has to fly out to a remote area for work soon. The x-rays are here. Would you let him go? What do the x-rays show?
The x-ray shows Lisfranc’s fracture dislocation. There is lateral subluxation of 2nd to 5th metatarsal bases. There is an avulsion fracture of base of 2nd metatarsal. The cuboid is also fractured. The lateral view shows a small step deformity at the base of metatarsals.
Normally, in the AP view of the foot, medial margin of the 2nd metatarsal should align with the medial margin of the intermediate cuneifom bone as shown below (red line).
Normally in the oblique view, medial margin of the 3rd metatarsal should align with the medial margin of the lateral cuneiform as shown below (blue line).
Compare the lines in Lisfranc’s fracture dislocation below. The AP view shows significant displacement of the 2nd metatarsal base and the oblique view shows some displacement of the 3rd metatarsal base.
Do you need to ring ortho at 3 am? Not unless there is associated neurovascular injury (dorsalis pedis) or evidence of compartment syndrome. But definitely at 7am.
An interesting clinical sign that may be seen in a Lisfranc’s injury is plantar ecchymosis sign as shown below.
(Plantar ecchymosis sign, image courtesy www.orthopaedia.com)[/peekaboo_content]