We think of the foot as a simple thing but it actually comprises one fourth of all the bones of the body, with 26 overall. Although some stability comes from the arch structure (the Roman arches did not require mortar) most of the stability of the foot is ligamentous.
It therefore should not be surprising that diagnosing foot injury and predicting complications is difficult. Ligaments are essentially invisible on xray. Weight-bearing radiographs, recommended by the American College of Radiology, are difficult to order on emergency department patients in acute pain and MRI is usually not available. Thus, some of these patients will not be diagnosable by us but we can protect these patients through clinical suspicion and follow-up.
After negative xrays. acute traumatic midfoot pain is usually a ligament injury of one sort or another. If stable, it will likely heal. If it is a third degree injury and unstable, it may require surgery.
The Lisfranc joint is eponymous for Jacques Lisfranc who treated a Napoleonic soldier who had fallen off his horse with his foot caught in the stirrup. Ultimately the patient developed gangrene and required amputation at what became known as the Lisfranc joint complex (tarsometatarsal joints).
Today we hear about injuries in the news if you watch football, especially in defensive linemen who pivot on the toes, stressing the tarsometatarsal joints. As they twist in this equinus position to get around the offensive tackle, the Lisfranc joint can rupture.
There are not sufficient studies on physical diagnosis of the Lisfranc joint but the review articles tend to recommend stressing the midfoot with lateral and medial stress, abduction and pronation, etc. If you have trouble remembering all the Latin words, just do what you do with stress testing of any orthopedic limb – check it in the x, y, and z axes.
Take Home Points:
Recognize midfoot pain as a potentially ligamentous injury
Palpate the tarsometarsal joints
Stress the tarsoemetarsal joints in the X, Y, and Z planes, if the patient allows