Foot injury: medial cuneiform fracture.
An 18-year-old woman presented suffering from left foot pain. Three weeks prior she had had her foot stood on while playing rugby at a high school tournament out of town, causing ongoing pain over the forefoot, particularly with loaded plantarflexion. Her pain was isolated to the base of the medial-to-mid tarso-metatarsal regions. An x-ray two days after the injury while still out of town showed no fracture, but reported a lucency at the base of the 5th metatarsal which may require further investigation.
Ultrasound examination (Philips iU22, L12-5 MHz and 15-7 MHz Hockey Stick transducers) of the her left foot was performed. The examination demonstrated a medial cuneiform bone fracture and dorsal 1-2 TMT joint region ligament injury. Repeat x-ray is to follow.” Key findings (Figure 1) included “The cuneiform dorsal aspect has a slightly displaced fracture of the mid part tracking obliquely through to the anterior fibular corner. The 1-2 TMT joints region dorsal Lisfranc ligament is thick and reduced echogenic. Standing views do not show significant widening at the 1/2 TMT joints. The TMT joints and remaining midfoot, the tibialis anterior and posterior, EHL and EDL tendons are normal.”
Fractures in feet that are occult to x-ray1,2 may be seen on ultrasound, and in fact we regularly find them even in instances when we scan patients who have already had x-ray with nothing seen. Finding this fracture triggered a referral for repeat x-ray (a review of the previous x-ray is a possible alternative) to examine the extent of the fracture. The x-ray was followed by a CT scan due to concern about i) the fracture ii) the Lisfranc ligament injury, & iii) extent of fracture widening from weight bearing for 3 weeks. Following the CT scan she was booked for surgery.
While the ultrasound-visualised weightbearing tests suggested that the damaged tarso-metatarsal (Lisfranc) ligaments maintained enough integrity to limit joint gapping, either the ligament injury or the fracture considered alone may direct management toward immobilisation, and the two together and such protection is very likely prudent.
If we were to imagine that the fracture was uncomplicated and relatively benign, the most charitable conclusion possible would appear to be that while the injury may not have progressed, stressing the bone in the early stages of healing by weightbearing in walking, let alone running or training, likely caused a degree of discomfort which wasn’t easy to justify. Add to this that common treatment of Lisfranc injuries of this type typically involves a period of boot immobilisation, and given delayed management of Lisfranc injuries may have deleterious sequelae, including limitations in activity, persistent pain, and potentially progressive post-traumatic arthritis3 and the decision to immobilise seems a simple one.
Toward the other extreme of the spectrum, and remembering that ultrasound isn’t able to ascertain the extent of the fracture, while waiting for the remaining diagnostic information from the second x-ray weight-bearing may have worsened the injury, which is likely what happened in this case. Thinking she did not have a fracture she returned to netball training and attempted to play a game in the following 3 weeks. Anecdotally, athletes often play when injured, and are used to playing with discomfort. It is worth returning to the fact that while the tarso-metatarsal ligaments were able to stabilise the joint at the time of imaging, they were not intact. With this fact in mind, a return to weigh-bearing prematurely was unlikely to have been prudent, and a decision to do so would require some very careful and considered justification that is difficult to envisage.
Figure A: shows fractured left medial cuneiform, long view.
Figure B: shows shows the fractured left medial cuneiform, axial view.
Figure C: shows the 1st/2nd tarso-metatarsal joint showing thick Lisfranc ligament, axial view.
Figure D: shows comparison of fracture left cuneiform with normal right cuneiform.
References:
Wang CL, Shieh JY, Wang TG, Hsieh FJ. Sonographic detection of occult fractures in the foot and ankle. J Clin Ultrasound [Internet]. 1999 Oct [cited 2020 Sep 28];27(8):421–5. Available from: https://pubmed.ncbi.nlm.nih.gov/10477883/
Cho KH, Wansaicheong GKL. Ultrasound of the foot and ankle. Ultrasound Clin [Internet]. 2012;7(4):487–503. Available from: http://dx.doi.org/10.1016/j.cult.2012.08.004
Clare MP. Lisfranc injuries. Curr Rev Musculoskelet Med [Internet]. 2017 Mar 1 [cited 2021 Aug 23];10(1):81. Available from: /pmc/articles/PMC5344858/