Magnetic resonance imaging of internal derangements of the knee.

BackgroundPreoperative magnetic resonance imaging (MRI) has internationally been proven to reduce unnecessary knee arthroscopies and assist with surgical planning. This has the advantage of avoiding unnecessary surgery and the associated anaesthetic risk, as well as reducing costs. No data were found in the recently published literature assessing the accuracy of MRI interpretation of knee ligament injury in the public sector locally.ObjectivesThis pilot study aimed to determine the accuracy of MRI in detecting non-osseous knee injury in a resource-limited tertiary-level academic hospital in Pretoria, South Africa, compared to the gold standard arthroscopy findings.MethodThis was an exploratory retrospective analysis of 39 patients who had MRI and arthroscopy at Steve Biko Academic Hospital (SBAH). True positive, true negative, false positive and false negative results were extrapolated from findings in both modalities and translated into sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) for each structure.ResultsNegative predictive values were recorded as 97%, 81%, 90% and 100% (anterior cruciate ligament [ACL], medial meniscus [MM], lateral meniscus [LM] and posterior cruciate ligament [PCL], respectively), which were comparative to recently published international literature. The PPV results were lower than those previously evaluated at 55%, 58%, 55% and not applicable. The sensitivities and specificities of the ligaments were 83%, 58%, 83% and not applicable; and 87%, 81%, 70% and not applicable, respectively.ConclusionMagnetic resonance imaging was found to be sensitive and specific, with a high NPV noted in all structures evaluated. Negative results can therefore be used to avoid unnecessary surgery to the benefit of the patient and state. The study reiterates that high accuracy can be obtained from MRI on a 1.5-tesla non-dedicated scanner, with interpretation by generalist radiologists.

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“…4 Arthroscopy is also user dependant and subject to its unique set of errors, limiting its accuracy. 14…”

Section: Introductionmentioning

confidence: 99%

The accuracy of magnetic resonance imaging diagnosis of non-osseous knee injury at Steve Biko Academic Hospital

2019

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“…The reliability of magnetic resonance (MR) imaging in detecting meniscal tears is well recognized [2,4,12,17]. Bucket-handle tears of the menisci usually involve the medial meniscus and begin with a vertical or oblique orientation that starts in the posterior horn and propagates longitudinally and anteriorly.…”

Section: Introductionmentioning

confidence: 99%

The flipped meniscus sign

et al. 1993

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Meniscal fragments may be difficult to detect on magnetic resonance (MR) imaging and yet are clinically significant. This paper describes and illustrates the MR appearance of an easily overlooked meniscal fragment. Ten knees, each appearing to show an abnormally large anterior meniscal horn (8 mm or more in height) were prospectively identified on MR images. In each case demonstrable large tears of the ipsilateral posterior horns were present (same meniscus as had large anterior horns). The lateral meniscus was involved in nine cases and the medial in one. Two of the ten patients imaged had surgically proven bucket-handle meniscal tears as well as meniscal fragments overlying the ipsilateral anterior horn. In one case previous MR imaging at our institution had demonstrated the affected anterior horn to be of normal caliber. The striking MR appearance of an abnormally enlarged anterior meniscal horn in association with a tear of the ipsilateral posterior horn suggests the presence of a meniscal fragment or of a posteriorly detached bucket-handle tear of the posterior horn of the meniscus.

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“…2 8 , 29, 30, 31, 32, 33). Typically, the medial meniscus, in its posterior portions, will demonstrate tight adherence to the medial collateral ligaments while more anteriorly, a small amount of fat is commonly present between the collateral ligaments and the meniscus, (Figures 2 and 3) (16).…”

Section: Mri Of the Normal Meniscusmentioning

confidence: 99%

“…The lateral meniscus and its posterior horn will normally demonstrate an area of slightly increased signal intensity obliquely oriented. This represents the popliteus tendon tunnel track and is a normal finding (5,4,16).…”

Section: Mri Of the Normal Meniscusmentioning

confidence: 99%