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(GOLDEN OLDIE) - Special tests for assessing meniscal tears within the knee: a systematic review and meta-analysis.
- This study agrees with previous systematic reviews that “special tests” for assessing meniscal tears are inaccurate.
- 20% of the time, these tests will incorrectly diagnose someone with a tear when they don’t have one.
- Joint line tenderness has been shown to be the most sensitive, followed by Thessaly’s at 20 degrees knee flexion. McMurrays test was the least sensitive test.
BACKGROUND & OBJECTIVE
Around 25,000 people in the UK are admitted to hospital annually to investigate or manage a meniscal tear. Diagnostically, beyond gold standard MRI or arthroscopy, clinicians rely on background information and previous medical history, clinical presentation and the use of “special tests” that are designed to “diagnose” meniscal tears of the knee. The accuracy of these special tests, including McMurrays, Appleys, Joint Line Tenderness (JLT) and the newer, more dynamic Thessaly’s test, remain unclear. Additionally, previous systematic reviews have included wide ranging populations with unclear definitions of testing procedures. Advances in methodological scrutiny and meta-analysis warrant a refined systematic review into special tests for the meniscus.
Building up a clinical picture of injury mechanism and pain presentation is likely to be supplemented with the use of these tests, rather than the tests primarily informing decision making.
Using PRISMA guidelines, a database search was undertaken to include studies that looked at diagnosing meniscus tears in adults (classed as 16 and above) using least one special test from the list above. This excluded tests under anaesthesia or on cadavers. Comparison to MRI or arthroscopy was considered gold standard for diagnosis. The quality of the papers was determined by methodologically reviewing risk of bias and level of heterogeneity (i.e. if studies use similar methods or if they vary a lot). This left 9 papers suitable for review.
A moderate to fair risk of bias. It was unclear whether gold standard reference testing was blinded. There was a variety of descriptions and techniques for the tests.
There was insufficient data to analyse Appley’s or Thessaly’s test at 5 degrees knee flexion.
McMurrays, JLT and Thessaly’s at 20 degrees flexion, did not demonstrate any accuracy in diagnosing a meniscal tear.
Sensitivity (if you have a tear, how likely is it that the test will correctly tell you) was poor - McMurrays 61%, Thessaly’s 75% and JLT, the most accurate, 83%.
All tests demonstrated specificity (If you don’t have tear, how likely is the test to correctly tell you that you do NOT have one) of around 80% - so 20% of the time, it’s a false positive.
This review took a wide variety of test procedures and applied them to a wide variety of patients, even when it set out to narrow the field to “adults only”.
Be aware of “verification bias” as this will increase the prevalence of a pathology and over estimate sensitivity and specificity. What does this mean? All but one study used arthroscopy as the gold standard, so participants were going to have surgery anyway, which suggests a high level of suspicion of a tear. Including non-symptomatic knees would decrease the bias.
Systematic reviews and meta-analysis’ pool data from varied methodological backgrounds, so sensitivity and specificity are not always accurate.
Despite updates in the literature, this systematic review agrees with its predecessors that special tests for the meniscus are inaccurate, and the authors go as far to say that their use is not recommended.
Consideration should be given to the risk of a false positive and the impact that may have on individuals regarding exercising and fear avoidance. The purpose of these tests is to determine if surgery is indicated or whether conservative treatment may be suitable. This does not mean identifying the specific tissues that are contributing to pain or dysfunction and this study does not support their use for this clinical reasoning. Mechanical instability or locking are signs that MRI and possible surgery is warranted, but more so in traumatic lesions as opposed to degenerative. This conclusion can be made without the need for special tests, which raises the question of their value for the primary clinician.
Additionally, these tests are rarely used in isolation and building up a clinical picture of injury mechanism and pain presentation is likely to be supplemented with the use of these tests, rather than the tests primarily informing decision making. However, much like positive MRI’s can be found in asymptomatic lumbar spines (1), MRI may confirm a tear in a pain-free knee, or a painful knee may be clear on imaging. Even surgery has been shown to be as effective as sham surgery in degenerative tears (2).
So with special tests being inaccurate, MRI prone to false-positives and surgery no better than placebo, are we in the dark on meniscal management? Evidence suggests that traumatic (sporting) meniscal tears may benefit from surgery, especially in the presence of locking. But for degenerative meniscal lesions, exercise therapy is recommended as the primary treatment choice (3). Future research is recommended to focus more on clinical presentations, signs and symptoms to investigate their prognostic value and informing a surgical vs conservative management route.
[Smith B, Thacker D, Crewesmith A and Hall M (2015) Special tests for assessing meniscal tears within the knee: a systematic review and meta-analysis. BMJ Evidence-Based Medicine, 20(3), pp.88-97.]()
- Baker, A.D., 2014. Abnormal magnetic-resonance scans of the lumbar spine in asymptomatic subjects. A prospective investigation. In Classic papers in orthopaedics (pp. 245-247). Springer, London.
- Moseley, J.B., O'Malley, K., Petersen, N.J., Menke, T.J., Brody, B.A., Kuykendall, D.H., Hollingsworth, J.C., Ashton, C.M. and Wray, N.P., 2002. A controlled trial of arthroscopic surgery for osteoarthritis of the knee. New England Journal of Medicine, 347(2), pp.81-88.
- Thorlund, J.B., Juhl, C.B., Ingelsrud, L.H. and Skou, S.T., 2018. Risk factors, diagnosis and non-surgical treatment for meniscal tears: evidence and recommendations: a statement paper commissioned by the Danish Society of Sports Physical Therapy (DSSF). Br J Sports Med, 52(9), pp.557-565.