A fractured fifth metatarsal is not a rare ultrasound imaging finding.
In the last post we presented you with a case of a patient who had rolled her right ankle, leading to a fracture of her fifth metatarsal bone, among several other injuries. Finding a fracture would almost certainly change the way her case was managed, and discussion of the implications for this patient would likely not be an interesting read. Instead, this post will focus on the ability of ultrasound to detect fractures.
As much as we prefer to preface discussions of this nature with a Socratic question, this time a statement of fact is a better fit; ultrasound can detect fractures. More than that, ultrasound is very good at doing so in locations where there is no acoustic shadow allowing direct access to the bone cortex involved,1 and especially when there is a focal area of tenderness.
Without doing the complete count, the current estimate for detection of fractures on cases referred to Sound Experience is around 3-4 per week, with most of these being found in the foot and ankle. Other locations fracture is detected include ribs, the fibula, shoulder greater tuberosity, wrist, fingers, and clavicle.
Anecdotally, many clinicians in the field of manual therapy display some surprise when discovering that ultrasound is a useful tool for the detection of bone fractures, despite its utility being recognised for some time. As long ago as 1988,2 ultrasound has been proposed as a possible addition or even alternative to standard plain film x-ray for the detection of fractures. In fact, this early work in paediatric clavicle fracture went as far as suggesting that ultrasound should be the preferred diagnostic procedure for clavicle fracture in neonates.2 In 1999, Wang and colleagues3 suggested that ultrasound was useful in the detection of cortical bone discontinuities and can identify fractures that are radiographically occult, a perspective echoed by Cho et al.,4 when they published their pictorial essay five years later.
More recent studies continue to demonstrate such benefit. For example, ultrasound has been demonstrated as being both sensitive and specific for the detection of extremity fractures,5 a finding supported by the results of a recent meta-analysis which suggested the pooled results of 48 studies offered sensitivity and specificity of 91% and 94% respectively.6 The authors of this review state that their findings clearly show ultrasound of bone surfaces can be used for the detection of injury.6
This whistle-stop tour of the literature making a convincing start on establishing the diagnostic utility of ultrasound in detecting fractures, it is worth briefly talking about how it might be used in clinical practice by primary healthcare providers. Firstly, it may well have caught your eye that ultrasound was helpful in detecting fractures that were not readily visible on x-ray.cf3 The point of including such research is to highlight the possibility of using ultrasound alongside conventional x-ray, as ultrasound has the resolution to resolve much smaller fractures; consider x-ray to be the ‘zoomed-out’ view, while ultrasound is the ‘zoomed-in’ view. In addition, where x-ray reports often identify bony fragments, ultrasound may identify the mechanism of injury producing such fragments, such as may be seen in a ligament avulsion, for example. Lastly, it appears there may be a role for ultrasound in monitoring the healing of fractures,1 meaning that fractures identified by any means could be monitored with ultrasound follow-up.
How could a diagnosis of fracture, such as is demonstrated in this case, change your management? Please feel free to tell us in the comments. In the meantime, don’t be shy to “query fracture?” in your referrals.
Coming in the next post:
The eagle-eyed among you will have detected an important point about where ultrasound can detect fractures: “… in locations where there is no acoustic shadow, allowing direct access to the bone cortex involved…”.
This means that ultrasound unequivocally cannot detect a fracture where such an acoustic shadow occurs, such as within a joint.
The next instalment in this short series of fracture discussions will be a case in which the findings suggested a fracture within a joint.
- Nicholson JA, Tsang STJ, MacGillivray TJ, Perks F, Simpson AHRW. What is the role of ultrasound in fracture management? Bone Jt Res [Internet]. 2019 [cited 2020 Sep 28];8(7):304–12. Available from: https://pubmed.ncbi.nlm.nih.gov/31463038/
- Katz R, Landman J, Dulitzky F, Bar-Ziv J. Fracture of the clavicle in the newborn. An ultrasound diagnosis. J Ultrasound Med [Internet]. 1988 [cited 2020 Sep 28];7(1):21–3. Available from: https://pubmed.ncbi.nlm.nih.gov/3276915/
- 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, Lee YH, Lee SM, Shahid MU, Suh KJ, Choi JH. Sonography of bone and bone-related diseases of the extremities. In: Journal of Clinical Ultrasound [Internet]. J Clin Ultrasound; 2004 [cited 2020 Sep 28]. p. 511–21. Available from: https://pubmed.ncbi.nlm.nih.gov/15558611/
- Døssing K, Mechlenburg I, Hansen LB, Søballe K, Østergaard H. The Use of Ultrasound to Exclude Extremity Fractures in Adults. JBJS Open Access [Internet]. 2017 Sep [cited 2020 Sep 28];2(3):e0007. Available from: https://pubmed.ncbi.nlm.nih.gov/30229220/
- Schmid GL, Lippmann S, Unverzagt S, Hofmann C, Deutsch T, Frese T. The investigation of suspected fracture-a comparison of ultrasound with conventional imaging: systematic review and meta-analysis [Internet]. Vol. 114, Deutsches Arzteblatt International. Deutscher Arzte-Verlag GmbH; 2017 [cited 2020 Sep 28]. p. 757–64. Available from: https://pubmed.ncbi.nlm.nih.gov/29202925/