3D CT to Diagnose Lisfranc Injury
These immediately practical and helpful discoveries are especially useful if the patient can't stand for weightbearing plain films
What’s the Claim?
A neat study evaluated three proposed radiographic signs (outlined below) of Lisfranc joint injury on 3D CT scans:
- All three signs had very high sensitivity and specificity: 92% to 97% sensitivity and 92% to 93% specificity (with broadly overlapping 95% CIs suggesting they did not differ from one another).
- The presence of any of the three signs was associated with markedly increased odds of Lisfranc joint injury being present (Mercedes sign: OR 6 [95% CI 4 to 8], peeking metatarsal sign: OR 8 [95% CI 5 to 10], and peeking cuneiform sign: OR 6 [95% CI 4 to 9]).
The gold standard for the presence of Lisfranc injury in this study was surgical examination. Intra- and interobserver reliability were extraordinarily high for a study of a new diagnostic test — kappa values in the 0.8 to > 0.9 range, both among orthopaedic residents and subspecialist foot and ankle surgeons — perhaps suggesting that 3D CT is easier to interpret than some other modalities.
