Inspiration:
Jacobi/Montefiore Follow-Up Rounds
Andrew Barbera, PGY-3
The Case
32M no PMH p/w left foot pain
Triage vitals: 98 117/80 RR: 97 RR: 17 T: 98 O2: 100%
HPI
32M p/w left foot pain x 3 days after dropping AC unit onto foot
- Patient had to twist foot in order to remove it from underneath AC unit
- Went to hospital immediately afterwards, X-rays at the time were negative
- Discharged with ACE bandage and crutches
- Patient’s foot continued to swell, extremely painful, unable to bear weight on left
Physical Exam
Gen: No apparent distress, using crutches to ambulate
HEENT: NCAT, MMM, EOMI, no facial asymmetry. Neck supple
Extremity: left food edematous, tender over 3rd, 4th, and 5th metatarsal. Able to range toes. 2+ DP bilaterally. Sensation intact to fine touch bilaterally. No point tenderness noted over the ankle. No lower leg swelling or tenderness
Neuro: no gross neurological deficit
X-ray: XR of left foot notes no visible fracture
CT foot: fracture at base of left 2nd metatarsal
Weight bearing XR of left foot: widening between base of 1st and 2nd metatarsal consistent with Lisfranc injury
Disposition: OR for ORIF on day 3 of admission
Lisfranc Injuries
Definition: a lis franc fracture is an injury of the tarsometatarsal joint (TMT) complex. It is a very easily missed/misdiagnosed fracture.
Normal anatomy: the lisfranc joint complex includes the bones (see below) and ligaments that connect the midfoot to the forefoot and includes the 5 tarsometatarsal joints. The lisfranc ligament connects the lateral aspect of the medial cuneiform to the medial aspect of the 2nd metatarsal. A lisfranc injury is anything from a sprain to a complete disruption of the midfoot.
Mechanism of Lisfranc injuries:
Lisfranc injuries are common in direct trauma resulting in crush injuries. In patients who have injuries suggesting a crush mechanism (compartment syndrome, vascular injuries, etc.) keep lisfranc injuries in mind. Of note, the dorsalis pedis artery passes between the 1st and 2nd metatarsals.
They are also common in indirect trauma causing twisting of a pronated food (forced external rotation) or axial loading of the foot in a fixed equinus position. These injuries can also be associated with cuboid bone fractures caused by compression of the bases of the 4th and 5th metatarsal heads
Presentation
Common symptoms of indirect lisfranc injuries include swelling and pain in the midfoot, bruising of the bottom of the foot (plantar echymoses is pathognomonic), swelling out of proportion with a normal X-ray, midfoot instability, tenderness over dorsal TMT joints. Any patient with a twisting or crush injury can have a lisfranc injury. This specific injury is especially common in athletes.
What to look for in plain films?
In the AP film, the medial border of the 2nd metatarsal should be collinear with the medial border of the 2nd (intermediate) cuneiform.
This AP film shows normal alignment. The 2nd metatarsal forms a straight line with the 2nd cuneiform bone.
AP radiograph of a Lisfranc injury. Notice the disallignment between the 2nd metatarsal (the yellow line) and the 2nd (intermediate) cuneiform bone (the red line). This is diagnostic of a Lisfranc injury.
This diagnosis can be missed on regular X-ray, so if suspicion is high, a weight-bearing AP radiograph is necessary to evaluate the space between the 1st and 2nd metatarsals
In an oblique plain film, evaluation of the lateral midfoot becomes possible. A normal oblique X-ray shows alligment of the 2nd through 4th TMT joints:
An abnormal oblique film notes disallignment of the TMT joints (circle below)
If, as in the above case presentation, a patient’s complaint is suspicious for a fracture and plain films are negative, CT is recommended. A 2012 study notes that X-rays correctly identified Lisfranc injuries in only 68.9% of cases with a sensitivity of 84.4% and a specificity of 53.3%.
Treatment
Stable injuries with minimal displacement/fractures can be managed nonoperatively. These patients should wear a short leg cast or walking boot for 6-10w and should be non-weightbearing initially. These patients need close followup and a repeat X-ray 2 weeks after the initial injury.
Unstable injuries with significant fractures or displacement require operative management (ORIF with screw fixation).
Sources:
Gotha, Heather E., MD, Craig R. Lareau, MD, and Todd A. Fellars, MD. “Diagnosis and Management of Lisfranc Injuries and Metatarsal Fractures.”Rhode Island Medical Journal (2013). Rhode Island Medical Journal. Web.
Trevino, Saul G., MD, John S. Early, MD, Allison M. Wade, MD, Santaram Vallurupalli, MD, David Flood, MD, Francisco Talavera, PharmD, PhD, Thomas M. DeBerardino, MD, and James K. Deorio, MD. “Lisfranc Fracture Dislocation.”Lisfranc Fracture Dislocation. Medscape, 4 Jan. 2016. Web. 05 Feb. 2016.
As is the case with missing hip fractures on xrays, it is not uncommon to miss significant mid-foot fractures on foot xrays. We have had pts with normal foot xrays with multiple metacarpal fractures and with a Lisfranc fracture requiring surgery. The latter pt initially had normal foot xrays at a prestigious Manhattan hospital before presenting to us. The big question is which pts with foot injuries and normal xrays require a CT (or MRI) of their foot? Although there is no literature regarding this question, it would be prudent to consider CT in the pt with significant mid-foot swelling, tenderness or ecchymosis or inability to ambulate. Another question is whether to repeat xrays in a pt presenting from another hospital with normal xrays. It may be worthwhile to repeat the xrays as the slightly different angle of the xray beam may reveal a fracture not seen on the previous xrays. Another subtle sign of a Lisfranc fracture is the fleck sign which is a tiny piece of bone between the base of the 4th and 5th metatarsals