Ankle injury: spiral fibula fracture
Finding ankle fractures on ultrasound.
A 60-year-old man presented for an online physiotherapy consultation during Covid Level 4 with left ankle pain, after waking up in the middle of the night with cramp, whereupon he got up and rolled his left ankle. His ankle was extensively bruised and swollen (figure 1, A&B), but he reported he was able to weight bear. Due to the extensive bruising and swelling he was referred for an urgent ultrasound examination query AITFL and peroneal injury.
He presented with a marked limp for the ultrasound examination (Philips iU22, L12-5 MHz and 15-7 MHz Hockey Stick transducers) of all compartments of his left ankle. The examination demonstrated a fibula distal spiral fracture and associated haemorrhage as well as a deltoid ligament sprain and capsulitis. Key findings (Figure 1, C&D): “The distal fibula has an oblique gap in the bone with mild malalignment consistent with a fracture. The fracture’s superior extent is 43mm above the fibula tip and goes inferiorly to the level of the anterior inferior tibiofibular (syndesmosis) ligament. A region of haemorrhage extends from the break over the anterior lateral ankle. No tear. The AITFL, PITFL, PTFL, ATFL, CFL, DTNL, bifurcate and posterior and middle deltoid ligaments, and the peroneus longus and brevis, the tibialis posterior and anterior, EHL, EDL, FDL and FHL tendons are normal. No joint effusion is seen.”
If you have followed previous posts regarding injuries in the ankle, you will perhaps be familiar with the idea that injuries presenting as lateral ankle injuries are likely to include findings elsewhere, such in the medial ankle or foot. Other previous posts have also primed you regarding the fact that we commonly find fractures which have been missed on x-ray, or fractures in cases who have not yet had x-ray.
While a case of this nature is not something we would consider to be a normal daily occurrence, neither is it something that is entirely uncommon, and serves as a good example of someone who presents in a way that no amount of experience or nuanced pattern recognition is sufficient.
This patient was weight-bearing, albeit with a notable antalgic gait, and had been since the injury suggesting clinical evaluation, such as with the Ottawa ankle rules, will still let some slip through the diagnostic cracks. Further, the nature and extent of the fracture was such that the ‘fix’ required surgical intervention over and above immobilisation in a moonboot or similar. Looking back at Scott Allen’s discussion on the importance of timing, here is a clear example of an instance where an early referral for imaging did change outcomes for the patient. For this individual, the ultrasound findings led to immediate x-ray, which showed the extent of the fracture in the fibula (Figure 1), requiring immediate surgery to stabilise.
Figure A: a comparison of the left and right ankle prior to imaging.
Figure B: the left ankle medial aspect prior to imaging.
Figure C: the displaced segment of the fibula, indicated by hashmarks.
Figure D: the fractured fibula with associated haemorrhage.
Figure E: the X-ray of the left ankle, displaced spiral fracture of the fibula clearly seen.
Figure F: the surgical repair of the left fibula spiral fracture.