Ortho Hors D'oeuvres (Answer):
To review, this is a 22 year-old female presenting with left midfoot pain after lateral compression forces.
Questions and Answers:
1) What are the findings on radiograph?
In this patient's radiograph, there is a cortical irregularity at the dorsum of the medial cuneiform, most impressive on the oblique and lateral views. She has no other apparent fractures or dislocations on this static series. To review the basic bony anatomy of the midfoot, see below:
The midfoot is comprised of the navicular bone, the cuneiforms, and the cuboid. The cuneiforms and the navicular bone combine to make the medial and intermediate columns. The cuboid, on the lateral aspect of the foot, is the sole midfoot contributor to the lateral column of the foot. There are two significant joints associated with the midfoot--the Lisfranc joint, which encompasses the articulation between midfoot and forefoot (ie the cuboid and cuneiforms and the metatarsals) and the Chopart joint, which encompasses the articulation between hindfoot and midfoot (ie the talus and calcaneus and the navicular and cuboid).
The midfoot complex is highly articulated and has significant ligamentous connections, therefore isolated fractures of the midfoot are very rare, accounting for only 3.6 out of every 10,000 fractures. Cuneiform fractures account for approximately 1.7% of all midfoot fractures, while cuboid fractures are more common, accounting for 50% of midfoot fractures.
2) What are the next steps in evaluation?
Interestingly, approximately 0.1-2.4% of the population have a bipartite medial cuneiform, so radiographic findings concerning for cuneiform fracture should be verified by tenderness to palpation on physical examination. This patient, with her tenderness to palpation on physical examination, likely has a true cuneiform fracture and may need further imaging depending on physical exam findings.
Cuneiform fractures are easily overlooked on radiograph and commonly associated with a Lisfranc injury, which is also difficult to diagnose by static radiograph alone (approximately 33% of static radiographs miss a Lisfranc or Chopart joint injury). Joint space widening over 2mm between the metatarsals or from cuneiform to metatarsal is indicative of possible associated joint injury. If no joint space widening is visualized on static radiographs, weight-bearing films should be obtained to appropriately rule out Lisfranc injury. If a patient is unable to tolerate weight-bearing films, they will need definitive MRI or dynamic films for further evaluation, although this can occur on an outpatient basis.
If a patient has significant tenderness over the cuneiform with associated plantar ecchymosis, but no visualized injuries on radiograph, it is not unreasonable to obtain a CT to identify fractures and appropriately guide follow-up.
3) What is the appropriate definitive management?
This patient was able to bear weight with pain and had no signficant joint displacement on weight-bearing films. In patients with nondisplaced avulsion fractures without associated joint space laxity or pain, it is appropriate to place them in a posterior short-leg splint with non-weight-bearing instructions and recommend follow-up with orthopedics within 5 days for further dynamic imaging or MRI as needed.
If patients have any sign of fracture comminution, articular instability, or significant associated fractures or column shortening, they should also be placed in a posterior short-leg splint with non-weight-bearing instructions. These patients will require operative fixation so it is prudent to assure orthopedic follow-up prior to discharge.
Benirschke SK, Meinberg E, Anderson SA, Jones CB, Cole PA. Fractures and dislocations of the midfoot: Lisfranc and Chopart injuries. J Bone Joint Surg Am. 2012 Jul 18;94(14):1325-37.
Chang GH, Chang EY, Chung CB, Resnick DL. Bipartite Medial Cuneiform: Case Report and Retrospective Review of 1000 Magnetic Resonance Imaging Studies. Case Report Med. 2014:130979.
Eraslan A, Ozyurek S, Erol B, Ercan E. Isolated medial cuneiform fracture: a commonly missed fracture. BMJ Case Rep.2013 May 22;2013.
Melhorn AT, Schmal H, Legrand MA, Sudkamp NP, Strohm PC. Classification and Outcome of Fracture-Dislocation of the Cuneiform Bones. J Foot Ankle Surg. 2016 Nov-Dec;55(6):1249-1255.