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Three Part Question

IN [Adults presenting with a history of traumatic soft tissue injury] IS [Ultrasound as good as Computerised Tomography] AT [diagnosing Myositis Ossificans Circumscripta].

Clinical Scenario

A 28-year-old male football player has a blunt trauma to his quadriceps sustained 5 days previously. He now has painful, localised focal swelling over the lateral aspect of the mid-thigh and limited painful knee flexion. You suspect he may be developing Myositis Ossificans Circumscripta (MOC) within the Vastus Lateralis muscle. You decide that he would benefit from further investigation in the form of imaging. You have access to immediate point-of-care access to diagnostic ultrasound (US), but you wish to know if US will give you an accurate diagnosis comparable to that of the gold standard, computerised tomography (CT).

Search Strategy

The MEDLINE (1946-05/2020), CINAHL (1982-05/2020), AMED (1985 – 05/2020), EMBASE (1996 – 05/2020) and PubMed (1996-05/2020) databases were searched using the OVID interface. The Cochrane Library was also searched using the same strategy. The Cochrane Library was also searched using the strategy:

(Myositis Ossificans OR Myositis Ossificans Circumscripta OR Myositis Ossificans OR Heterotopic Ossification) AND (Ultrasonography OR Sonography OR Ultrasonics OR Ultrasound) AND (Computed Tomography Scan OR Computerised Tomography).

All searches strategies were limited to Human AND English language.

1. Myositis Ossificans Circumscripta.mp.
2. Myositis Ossificans Traumatica.mp.
3. Myositis Ossificans.mp.
4. Heterotopic Ossification.mp.
5. Ultrasonography.mp.
6. Sonography.mp.
7. Ultrasonics.mp.
8. Ultrasound.mp.
9. Computed Tomography.mp.
10. Computerised Tomography.mp.
11. 1 or 2 or 3 or 4
12. 5 or 6 or 7 or 8
13. 9 or 10
14. 11 and 12 and 13

Search Outcome

The search originally yielded forty-three papers. However, only 3 papers answered the three-part question.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Ergun, T, et al. 2008 Turkey	A 49-year-old Turkish women who presented with a 4-week history of gradually worsening, tenderness over the right thoracic, upper abdominal region. No history of trauma or any significant medical history (including hereditary musculoskeletal disorders).	Level 4; A single patient case report with CT as reference standard.	Accuracy of X-ray, US and CT in the diagnosis of suspected MO.	US demonstrated the characteristic appearance of early/intermediate MO with evidence of a 1cm mass and dense acoustic shadowing, that are not typically visible with plain radiographs.	The case report is descriptive and retrospective and therefore subject to recall bias. No information regarding the expertise of the clinician who carried out the ultrasound. Uncertain if the same clinician reported on the X-ray, CT and carried out the ultrasound (i.e. if the clinician or radiologist was blinded from the ultrasound or working diagnosis).
Landolsi, M, et al. 2017 Tunisia	A 29-year-old man presented with an isolated painful right thigh mass located ventrally in the distal one-third of the thigh, 4 weeks following an RTA.	Level 4; A single patient case report with CT as reference standard.	Accuracy of X-ray, US and CT in the diagnosis of suspected MO.	Ultrasound of the right thigh demonstrated diffuse calcifications of soft tissues. The main difficulty is in a malignant mimicking lesion therefore CT is considered the gold standard for MO diagnosis.	The case report is descriptive and retrospective and therefore subject to recall bias. No information regarding the expertise of the clinician who carried out the ultrasound. It is unclear whether the results of the reference standard were interpreted without knowledge of the results of the index test – therefore difficult to rule out ‘information bias’ and overestimation of diagnostic accuracy. No clarity on the accuracy of reporting or whether the images were double read/reported.
O’Brien S. 2017 Australia	A 16-year-old female patient who presented in August 2016, reporting a painful lump in her mid-posterior left thigh which had been present for several days after returning from a ski trip.	Level 4; A single patient case report with CT as reference standard.	Accuracy of X-ray, MRI, US and CT in the diagnosis of suspected MO.	US appearance demonstrated an ovoid, hypoechoic mass without infiltrative borders. Appearance was typically non-specific with differentials including osteosarcoma. US may demonstrate peripheral calcification & acoustic shadowing which can differentiate MOC from malignant ossifying tumours, which typically demonstrate centrally located osseous deposits. Plain radiography generally fails to reveal any abnormality in the early stages of MO. CT is the gold standard for evaluating the muscle and identifying perilesional oedema typical of MOC while excluding bone marrow and cortical abnormalities.	No information regarding the clinician or clinicians who carried out the ultrasound, their relative level of experience/expertise in utilising US for diagnostic purposes. No information regarding who reported on the X-ray, CT and who carried out the ultrasound. No information to indicate who reported on the X-ray, CT and who carried out the US or if they were blinded to US or the working diagnosis therefore unable to rule out ‘information bias’ and overestimation of diagnostic accuracy.

Comment(s)

Three papers identified were all level 4 case reports. Each study utilised diagnostic US in the early stages of clinical presentation, when the differential diagnosis included MOC. US demonstrated the characteristic MOC changes in the soft tissue prior to that of X-ray, which may be useful and promote the adoption of early treatment to prevent bone formation. However, US is limited and cannot conclusively differentiate MOC from more sinister pathologies (i.e. osteosarcoma) that may mimic the clinical and diagnostic presentation of MOC. Therefore, CT must always be considered the imaging modality of choice and gold standard when MOC is suspected. Early, accurate diagnosis is paramount to ensure patient safety, therefore the combination of CT for initial diagnosis coupled with US as an early alert and monitoring tool may be considered as a reasonable strategy.

Clinical Bottom Line

Further research of more substantial rigor is necessary before we can safely conclude that diagnostic ultrasound is as good as CT at diagnosing early soft tissue changes consistent with MO. US may be used in the acute setting as an early alert intervention and quantitative monitoring adjunct for MOC, but this should be coupled with CT to ensure a safe and definitive diagnosis is achieved.

References

1. Ergun T, Lakadamyali, H, Lakadamyali, H, et al. Myositis Ossificans in the right inferior thoracic wall as an unusual cause of lower thoracic-upper abdominal pain: Report of a case Surgery Today 2008; 38: 962-964.
2. Landolsi M, Mrad T. Case Report: Traumatic myositis ossificans circumscripta (MOC) BMJ 2017; 2017:bcr-2017-219422.
3. O’Brien S. Non-traumatic myositis ossificans circumscripta Sonography 2017; 4: 88-92.