Journal of Radiation Medicine in the Tropics

CASE REPORT
Year
: 2022  |  Volume : 3  |  Issue : 1  |  Page : 32--34

Ultrasonography and magnetic resonance imaging findings of an occult tibial plateau fracture


Adeniyi Sunday Aderibigbe1, Oluwagbemiga Oluyoola Ayoola1, Oludare Uriel Ashaolu2, Olurotimi Olufunto Komolafe3,  
1 Department of Radiology, Obafemi Awolowo University; Department of Radiology, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria
2 Department of Orthopaedic Surgery and Traumatology, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria
3 Department of Radiology, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria

Correspondence Address:
Adeniyi Sunday Aderibigbe
Department of Radiology, Obafemi Awolowo University/Obafemi Awolowo University Teaching Hospitals Complex, P.M.B. 13, Ile-Ife
Nigeria

Abstract

We describe a case of posttraumatic lateral tibial plateau fracture that was not demonstrated by conventional radiography. Knee joint ultrasound showed mild lateral meniscal protrusion suggestive of an intra-articular injury, which was confirmed at magnetic resonance imaging to represent an occult lateral tibial plateau fracture. A high index of suspicion for occult fractures should be maintained in posttraumatic patients with ultrasound findings of meniscal protrusion, in spite of apparently normal X-ray findings.



How to cite this article:
Aderibigbe AS, Ayoola OO, Ashaolu OU, Komolafe OO. Ultrasonography and magnetic resonance imaging findings of an occult tibial plateau fracture.J Radiat Med Trop 2022;3:32-34


How to cite this URL:
Aderibigbe AS, Ayoola OO, Ashaolu OU, Komolafe OO. Ultrasonography and magnetic resonance imaging findings of an occult tibial plateau fracture. J Radiat Med Trop [serial online] 2022 [cited 2022 Dec 5 ];3:32-34
Available from: http://www.jrmt.org/text.asp?2022/3/1/32/350083


Full Text



 Introduction



Radiographically, occult and subtle fractures constitute a common diagnostic challenge in daily practice, accounting for up to 80% of the missed diagnoses in the emergency department.[1] These fractures are often classified as high-energy trauma fractures in the young, “fatigue fracture” from cyclical and sustained mechanical stress, and “insufficiency fracture” occurring in weakened bone.[2] Occult tibial plateau fracture (oTPF) has been previously reported in diverse populations and age groups.[3],[4],[5],[6] It is usually detected on advanced imaging modalities such as computed tomography (CT), magnetic resonance imaging (MRI), and nuclear medicine.[7] However, the utility of ultrasound (US) in suggesting the diagnosis is scarcely found in published literature, which may lead to a higher incidence of missed diagnosis in resource-limited settings. We report a missed case of tibial plateau fracture by conventional radiography, with a diagnosis reached following suspicious knee joint US findings and confirmatory knee MRI.

 Case Report



A 24-year-old male presented to the emergency department with diffuse right knee pain following a fall on a slippery surface. Anteroposterior and lateral radiographs of the right knee obtained 1 hour after injury revealed a moderate suprapatellar effusion, with no evidence of a fracture [Figure 1]. He was managed on an outpatient basis with a knee brace and oral analgesics. Knee US done about 72 h after the injury showed mild hypoechoic effusion and mild lateral meniscal protrusion [Figure 2]. Based on the US findings, an intra-articular injury was suspected, and a knee MRI was requested. The MRI was done 12 days after injury, and it showed an elongated wedge-shaped marrow hyperintensity with subtle central depression in the lateral tibial condyle [Figure 3]. No suggestion of meniscal tear or degeneration was noted, while the ultrasound finding of the lateral meniscal protrusion was not replicated convincingly on the MRI. Based on the imaging findings, the patient was given weight-bearing restrictions for 6 weeks. He achieved good functional outcomes at a 6-month follow-up, and a knee X-ray done 27 months later showed no evidence of knee arthrosis [Figure 4].{Figure 1}{Figure 2}{Figure 3}{Figure 4}

 Discussion



Most cases of high-energy trauma fractures presenting as oTPF were reported in individuals below the age of 40 years with a preponderance of the male gender,[3] similar to this case report. Injury is often preceded by a fall from height or a fall on a slippery surface as noted in the index patient.[2],[3]

In occult knee fractures, plain radiography rarely demonstrates alterations suggestive of a fracture, especially when the tibial plateau is involved.[3],[4] Berger et al.[3] identified other possible radiographic findings in occult fractures including effusion (similar to the index case) and focal area of increased marrow attenuation. However, radiographic suprapatellar effusion is nonspecific for diagnosing oTPF since it is also present in patients with overuse syndrome as well as posttraumatic ligamentous and meniscal injuries.[8]

In many low-resource settings, this radiograph “normality” usually results in a discontinuation of any further radiological evaluation, despite ultrasonography being a cheap and widely available modality for further assessment. Ultrasonography may readily suggest intra-articular injury, with Bonnefoy et al.[9] reporting that sonographic lipohemarthrosis is the most sensitive sign of intra-articular knee fracture when scanning the joint within 48 h of injury. Mild sonographic suprapatellar effusion (in keeping with posttraumatic hemarthrosis) was equally demonstrated in the index patient. While specific ultrasound findings have been described in femoral condylar and patellar fractures,[7],[9] the role of knee ultrasound (US) in suggesting or diagnosing occult tibial fractures was not found in our literature search, and to the best of our knowledge, this case report is the first to report ultrasonographic meniscal anomaly in occult tibial intercondylar fracture. We hypothesize that the mildly protruded lateral meniscus may be due to the mechanical effect of the subtle bony defect on the adjacent lateral meniscus.

Knee MRI done in the index case revealed findings similar to the related published case reports including cortical disruption of the tibial plateau, the reduced signal intensity of subcortical medullary bone, extensive marrow edema, and suprapatellar effusion.[3],[4],[5],[6],[7],[9],[10] The 9-day time gap between knee US and MRI in the index patient may explain absent meniscal protrusion on the MRI study. While Jarraya et al.[2] also observed increased T2 signal intensity in the adjacent collateral ligament (associated with sprain), none of the reviewed cases reported tear, abnormal signal intensity, or protrusion in the menisci. Furthermore, CT and bone scintigrams have shown a significant sensitivity in demonstrating osseous abnormality in oTPFs with scintigraphy being expectedly unspecific.[4],[11]

Non-operative conservative therapy is the preferred first-line treatment for nondisplaced or minimally displaced oTPF,[6] as illustrated in the index case. However, surgery may be required to align the joint surface when there is a significant displacement. Complications of tibial plateau fractures may include vascular injury in high-energy cases, while articular surface involvement may result in gonarthrosis.[4],[6],[7]

In conclusion, while CT and MRI are the preferred modalities for diagnosing occult tibial intra-articular fractures, US can be a useful adjunct in the radiological evaluation of knee trauma, especially in resource-limited settings.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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